Merge remote-tracking branch 'origin/main' into r7551

.github/workflows/release-desktop.yml

@@ -766,6 +766,7 @@ jobs:
     env:
       GH_REPO: ${{ github.repository }}
       APP_VERSION: ${{ needs.prepare-version.outputs.app_version }}
+      PYPI_VERSION: ${{ needs.prepare-version.outputs.pypi_version }}
       STUDIO_VERSION: ${{ needs.prepare-version.outputs.studio_version }}
       DESKTOP_RELEASE_TAG: ${{ needs.prepare-version.outputs.desktop_release_tag }}
       DESKTOP_PRERELEASE: ${{ needs.prepare-version.outputs.prerelease }}
@@ -911,6 +912,8 @@ jobs:
           notes = pathlib.Path(os.environ['RUNNER_TEMP'], 'desktop-release-notes.md').read_text()
           metadata = {
               'version': os.environ['APP_VERSION'],
+              # App version is SemVer; CHANGELOG.md is keyed by the backend release.
+              'pypi_version': os.environ['PYPI_VERSION'],
               'notes': notes,
               'pub_date': datetime.datetime.now(datetime.timezone.utc).isoformat(timespec='milliseconds').replace('+00:00', 'Z'),
               'platforms': {

.github/workflows/startup-profile-ci.yml

@@ -0,0 +1,156 @@
+# SPDX-License-Identifier: AGPL-3.0-only
+# Copyright 2026-present the Unsloth AI Inc. team. All rights reserved.
+
+# Measures where Studio's startup time goes, on each platform.
+#
+# Nothing recorded a number before: main.py logs "lifespan startup completed in X ms"
+# and studio_test_kit polls /healthz, but both throw the elapsed time away. A first
+# local run (Linux, warm cache, 18-core server) put `import main` at 5.7-6.6s BEFORE
+# the server can bind, dominated by eager module-level imports pulled in by routes:
+# torch ~1.9s self, unsloth_zoo ~0.8s, routes ~0.6s, transformers ~0.5s.
+#
+# Not a gate yet: --max-healthz-seconds exists, but a budget should come from
+# observed numbers rather than a guess.
+
+name: Startup profile
+
+on:
+  pull_request:
+    paths:
+      # The measured import graph is the whole backend tree: main.py imports auth,
+      # core, hub, loggers, models, picker, routes and utils at module scope.
+      - 'studio/backend/**'
+      - '!studio/backend/tests/**'
+      # The launch phase spawns `unsloth studio --api-only`, so the CLI counts too.
+      - 'unsloth_cli/**'
+      - 'studio/src-tauri/src/preflight**'
+      # The profiler hardcodes the desktop argv that process.rs::backend_args builds,
+      # so a change there must schedule a run or the two silently diverge.
+      - 'studio/src-tauri/src/process.rs'
+      - 'scripts/profile_startup.py'
+      - '.github/workflows/startup-profile-ci.yml'
+      # The job profiles whatever `install.sh --local` built: the installers pick the
+      # venv's Python and the dependency specs, and pyproject's include list is what
+      # makes --local overlay studio.backend*.
+      - 'install.sh'
+      - 'install.ps1'
+      - 'pyproject.toml'
+      # --local also runs the checkout's setup scripts (install.sh picks
+      # $_REPO_ROOT/studio/setup.sh, the editable install resolves setup.ps1 to the
+      # repo), and both call install_python_stack.py, which picks the dependencies.
+      - 'studio/setup.sh'
+      - 'studio/setup.ps1'
+      - 'studio/install_python_stack.py'
+  workflow_dispatch:
+    inputs:
+      repeats:
+        description: 'launch repeats per OS (median reported)'
+        type: string
+        default: '3'
+
+concurrency:
+  group: ${{ github.workflow }}-${{ github.ref }}
+  cancel-in-progress: true
+
+permissions:
+  contents: read
+
+jobs:
+  profile:
+    name: startup ${{ matrix.os }}
+    runs-on: ${{ matrix.os }}
+    timeout-minutes: 60
+    continue-on-error: true
+    strategy:
+      fail-fast: false
+      matrix:
+        os: [ubuntu-latest, macos-14, windows-latest]
+
+    env:
+      UNSLOTH_STUDIO_HOME: ${{ github.workspace }}/.studio-home
+      # A wildcard bind calls ifconfig.me on the startup path; loopback times our code.
+      UNSLOTH_STUDIO_DISABLE_PUBLIC_CHECK: '1'
+
+    steps:
+      - uses: actions/checkout@de0fac2e4500dabe0009e67214ff5f5447ce83dd  # v6.0.2
+        with:
+          persist-credentials: false
+
+      - name: Install Studio
+        shell: bash
+        env:
+          GH_TOKEN: ${{ secrets.GITHUB_TOKEN }}
+        run: |
+          set -o pipefail
+          mkdir -p logs
+          # --local is load-bearing: it overlays the checkout, so the profiled server
+          # is this diff. Without it install.sh resolves unsloth from PyPI.
+          if [ "${{ runner.os }}" = "Windows" ]; then
+            pwsh -NoProfile -File ./install.ps1 --local 2>&1 | tee logs/install.log
+          else
+            bash install.sh --local 2>&1 | tee logs/install.log
+          fi
+
+      - name: Profile startup
+        shell: bash
+        run: |
+          BIN="$UNSLOTH_STUDIO_HOME/unsloth_studio/bin/unsloth"
+          [ -x "$BIN" ] || BIN="$UNSLOTH_STUDIO_HOME/unsloth_studio/Scripts/unsloth.exe"
+          [ -x "$BIN" ] || BIN=""
+          # Profile imports with the INSTALLED interpreter: that venv is what launches.
+          PY="$UNSLOTH_STUDIO_HOME/unsloth_studio/bin/python"
+          [ -x "$PY" ] || PY="$UNSLOTH_STUDIO_HOME/unsloth_studio/Scripts/python.exe"
+          [ -x "$PY" ] || PY="$(command -v python3 || command -v python)"
+          python3 scripts/profile_startup.py \
+            --python "$PY" \
+            ${BIN:+--bin "$BIN"} \
+            --repeats "${{ inputs.repeats || '3' }}" \
+            --json "startup-${{ matrix.os }}.json" 2>&1 | tee logs/profile.log
+
+      - name: Summary
+        if: always()
+        shell: bash
+        run: |
+          f="startup-${{ matrix.os }}.json"
+          [ -f "$f" ] || { echo "no profile produced"; exit 0; }
+          python3 - "$f" >> "$GITHUB_STEP_SUMMARY" <<'PY'
+          import json, sys
+          d = json.load(open(sys.argv[1]))
+          print(f"### {d['platform']} / {d['machine']} (py {d['python']}, {d['cpu_count']} cpu)\n")
+          imp = d.get("imports", {})
+          # Gate on ok: a failed `import main` still leaves rows, so a total can lie.
+          if imp.get("ok"):
+              print(f"**`import main`: {imp['total_seconds']}s**\n")
+              print("| package | self ms |")
+              print("|---|---:|")
+              for k, v in list(imp.get("self_by_package_ms", {}).items())[:8]:
+                  print(f"| {k} | {v} |")
+              print()
+          else:
+              print("**`import main` failed - no valid import profile**\n")
+              print("```\n" + (imp.get("error") or "")[-1500:] + "\n```\n")
+          lau = d.get("launch") or {}
+          runs = len(lau.get("runs") or [])
+          failed = lau.get("failed_runs") or 0
+          if lau.get("healthz_median_seconds") is not None:
+              # The aggregates cover only the runs that reached healthz, so flag the
+              # failures: bare numbers would read as a normal fast startup.
+              note = f" _({runs - failed} of {runs} launches; {failed} never became healthy)_" if failed else ""
+              print(f"**time to a healthy port: {lau['healthz_median_seconds']}s median, "
+                    f"{lau['healthz_max_seconds']}s max**{note}\n")
+          elif lau.get("skipped"):
+              print(f"_launch phase skipped: {lau['skipped']}_\n")
+          elif runs:
+              print(f"**no launch measurement: all {runs} launches failed to become healthy**\n")
+          PY
+
+      - name: Upload profile
+        if: always()
+        uses: actions/upload-artifact@043fb46d1a93c77aae656e7c1c64a875d1fc6a0a  # v7.0.1
+        with:
+          name: startup-profile-${{ matrix.os }}
+          path: |
+            startup-*.json
+            logs/
+          retention-days: 14
+          if-no-files-found: warn

.gitignore

@@ -208,6 +208,9 @@ tmp/
 **/node_modules/
 auth.db
 
+# Packaging snapshot of the root CHANGELOG.md (written by build.sh)
+studio/CHANGELOG.md
+
 # Tauri local build/generated output
 studio/src-tauri/target/
 studio/src-tauri/gen/

CHANGELOG.md

@@ -0,0 +1,88 @@
+# Changelog
+
+Release notes for Unsloth and Unsloth Studio.
+
+Unsloth Studio reads this file to show release notes inside the "New Unsloth
+version" update popup. Edit it here and the popup picks the change up on the
+next update check, with no release or rebuild required.
+
+## Format
+
+Every release is a level-2 heading whose first token is the version, optionally
+followed by a date:
+
+```md
+## 2026.7.6 - 2026-07-22
+```
+
+`## [2026.7.6] - 2026-07-22` and `## v2026.7.6` also work. Everything under a
+heading, up to the next level-2 heading, is that release's notes and renders as
+Markdown in the popup.
+
+Notes are matched to one exact version. When Studio offers an update to
+`2026.7.6` it renders the `2026.7.6` section and nothing else. If that section
+is missing, the popup links out to the online changelog rather than showing
+notes from an unrelated release, so a new version needs its own section here
+before its notes can appear.
+
+Keep the newest release at the top. Lead each bullet with the change itself:
+the collapsed popup highlights the first sentence and dims the rest.
+`## Unreleased` is ignored by the popup, so it is safe to stage notes there and
+rename the heading at release time.
+
+<!-- Add new releases directly below this line. -->
+
+## Unreleased
+
+## 2026.7.5
+
+### What's Changed
+
+- AMD support is here. Train, run RL, chat with and deploy 500+ models on
+  Radeon, Instinct, Ryzen and data center GPUs across Windows, WSL and Linux,
+  up to 2x faster with 70% less VRAM and no accuracy loss.
+- Intel XPU support lands in Studio, so Arc and Data Center GPUs run chat and
+  training alongside the NVIDIA, AMD and Apple paths.
+- Local speech to text dictation runs fully offline, with slim Whisper bundles
+  and a picker for custom models.
+- DoRA training is available in Studio, selectable next to LoRA and full
+  fine-tuning in the training tab.
+- The update popup previews release notes inline, pulled from this file and
+  matched to the exact version being offered.
+
+### AMD, 23 July update
+
+Our AMD collaboration, custom Triton kernels and math algorithms bring local
+training and inference to AMD hardware. The 23 July update builds on the
+[AMD release](https://github.com/unslothai/unsloth/releases/tag/v0.1.501-beta):
+
+- RDNA2 and Gorgon Halo are supported, and the installer no longer fails to
+  detect GPUs on Strix Halo and other AMD cards.
+- RDNA4 handling is better, and HIP and ROCm failures are caught and fixed
+  automatically instead of stopping the install.
+- Unified memory safetensors loading is 2x faster, with much faster gradient
+  checkpointing on unified memory devices.
+- Voice dictation through whisper.cpp has preliminary support.
+- Rollback environments left by installs no longer eat 5GB of disk. They are
+  cleaned up automatically.
+
+Optimized ROCm builds cover GGUF and safetensors inference, and ROCm
+compatibility is improved for MI300X and MI325X. Full guide:
+[unsloth.ai/docs/basics/amd](https://unsloth.ai/docs/basics/amd).
+
+### Running larger models
+
+- Automatic GPU placement, or pick exactly which GPUs and layers to use.
+- Move MoE expert layers into system memory so larger models fit.
+- Split a model across several GPUs, or use tensor parallelism.
+- Hardware settings are saved per model and quant.
+
+### Also in this release
+
+- Remote access with `unsloth studio --secure` over free HTTPS via Cloudflare.
+- Web search reads PDF papers and manuals, and parallel tool calls, reasoning
+  output and tool retries are more reliable.
+- The model download location is configurable, so weights can live on a second
+  drive instead of the default cache.
+- Stalled Hugging Face XET downloads retry over standard HTTP, and existing
+  GGUF files are reused instead of downloaded again.

MANIFEST.in

@@ -0,0 +1,2 @@
+include _changelog_build.py
+include CHANGELOG.md

_changelog_build.py

@@ -0,0 +1,36 @@
+# SPDX-License-Identifier: AGPL-3.0-only
+# Copyright 2026-present the Unsloth AI Inc. team. All rights reserved.
+
+"""Snapshot CHANGELOG.md into the studio package at build time.
+
+CHANGELOG.md at the repo root stays the one file to edit. Copying it here,
+rather than in build.sh, means every packaging path ships it, so release notes
+still render when the popup cannot reach GitHub."""
+
+from __future__ import annotations
+
+import shutil
+from pathlib import Path
+
+from setuptools.command.build_py import build_py as _build_py
+
+ROOT = Path(__file__).resolve().parent
+SOURCE = ROOT / "CHANGELOG.md"
+SNAPSHOT = ROOT / "studio" / "CHANGELOG.md"
+
+
+class build_py(_build_py):
+    def run(self) -> None:
+        # Beside the sources only if writable (PEP 517 may build an immutable
+        # checkout); into the staging directory always.
+        if SOURCE.is_file():
+            try:
+                shutil.copyfile(SOURCE, SNAPSHOT)
+            except OSError:
+                pass
+        super().run()
+        if not SOURCE.is_file():
+            return
+        staged = Path(self.build_lib) / "studio" / "CHANGELOG.md"
+        staged.parent.mkdir(parents = True, exist_ok = True)
+        shutil.copyfile(SOURCE, staged)

build.sh

@@ -103,9 +103,13 @@ else
     STUDIO_STAMPED_VERSION="$(python scripts/stamp_studio_release.py)"
 fi
 
-# 4. Build wheel/sdist
+# 4. Build wheel/sdist. _changelog_build.py snapshots CHANGELOG.md into the studio
+# package so release notes render offline.
 python -m build
 
+# Drop the snapshot so a source checkout never serves a stale copy.
+rm -f studio/CHANGELOG.md
+
 if [ "${1:-}" = "publish" ]; then
     python scripts/stamp_studio_release.py --verify-dist dist --expected "$STUDIO_STAMPED_VERSION"
 fi

install.ps1

@@ -57,6 +57,26 @@ function Install-UnslothStudio {
         }
     }
 
+    # Machine arch; Get-TauriDiagArch above reports the process. An emulated x64 shell on
+    # ARM64 reports AMD64, but PROCESSOR_ARCHITEW6432 is ARM64 in exactly that case.
+    function Get-HostMachineArch {
+        $osArch = ""
+        try { $osArch = [System.Runtime.InteropServices.RuntimeInformation]::OSArchitecture.ToString() } catch { $osArch = "" }
+        $signals = @([string]$env:PROCESSOR_ARCHITEW6432, [string]$env:PROCESSOR_ARCHITECTURE, $osArch)
+        foreach ($s in $signals) {
+            if ($s.ToLowerInvariant() -eq "arm64") { return "arm64" }
+        }
+        foreach ($s in $signals) {
+            if ([string]::IsNullOrWhiteSpace($s)) { continue }
+            switch ($s.ToLowerInvariant()) {
+                "amd64" { return "x86_64" }
+                "x64" { return "x86_64" }
+                "x86" { return "x86" }
+            }
+        }
+        return "unknown"
+    }
+
     function Get-TauriTorchIndexFamily {
         param([string]$TorchIndexUrl)
         if ($SkipTorch) { return "none" }
@@ -1124,10 +1144,27 @@ exit 0
         return $false
     }
 
+    # The interpreter's own arch, asked of it: win-amd64|win-arm64|win32|"".
+    function Get-PythonPlatformTag {
+        param([string]$Exe)
+        try {
+            return (& $Exe -c "import sysconfig; print(sysconfig.get_platform())" 2>$null | Out-String).Trim().ToLowerInvariant()
+        } catch { return "" }
+    }
+
     # Returns @{ Version = "3.13"; Path = "C:\...\python.exe" } or $null.
     # The resolved Path is passed to `uv venv --python` to prevent uv from
     # re-resolving the version string back to a conda interpreter.
     function Find-CompatiblePython {
+        # -X64Only: best installed x64 interpreter or $null, never ARM64. Last resort for
+        # Install-X64Python, where x64 of a lower-priority minor beats ARM64.
+        param([switch]$X64Only)
+        # Windows on ARM: prefer x64. pyarrow (via datasets) and hf-transfer ship no
+        # win_arm64 wheel, so a native ARM64 Python source-builds both and dies on CMake /
+        # Rust minutes in; x64 runs fine emulated. ARM64 is still returned when it is all
+        # there is, and the caller then bootstraps x64 or warns.
+        $preferX64 = $X64Only -or ((Get-HostMachineArch) -eq "arm64")
+        $candidates = @()
         # Try the Python Launcher first (most reliable on Windows)
         # py.exe resolves to the standard CPython install, not conda.
         # Prefer the requested $PythonVersion, then newest-first fallback.
@@ -1145,7 +1182,8 @@ exit 0
                         # Resolve the actual executable path and verify it is not conda-based
                         $resolvedExe = (& $pyLauncher.Source "-$minor" -c "import sys; print(sys.executable)" 2>$null | Out-String).Trim()
                         if ($resolvedExe -and (Test-Path $resolvedExe) -and -not (Test-IsCondaPython $resolvedExe)) {
-                            return @{ Version = $ver; Path = $resolvedExe }
+                            if (-not $preferX64) { return @{ Version = $ver; Path = $resolvedExe; Arch = "" } }
+                            $candidates += @{ Version = $ver; Path = $resolvedExe }
                         }
                     }
                 } catch {}
@@ -1166,11 +1204,53 @@ exit 0
                 try {
                     $out = & $cmd.Source --version 2>&1 | Out-String
                     if ($out -match "Python (3\.1[1-3])\.\d+") {
-                        return @{ Version = $Matches[1]; Path = $cmd.Source }
+                        if (-not $preferX64) { return @{ Version = $Matches[1]; Path = $cmd.Source; Arch = "" } }
+                        $candidates += @{ Version = $Matches[1]; Path = $cmd.Source }
                     }
                 } catch {}
             }
         }
+        # `py -3.12` runs the launcher's preferred build, normally the native ARM64 one, so
+        # a same-minor x64 install that is neither preferred nor on PATH never becomes a
+        # candidate. `-3.12-64` cannot disambiguate (deprecated, it only means "not
+        # 32-bit"), so enumerate every registration with -0p and probe each path.
+        if ($preferX64) {
+            foreach ($pyLauncher in @(Get-Command py -All -CommandType Application -ErrorAction SilentlyContinue)) {
+                if ($pyLauncher.Source -match $script:CondaSkipPattern) { continue }
+                $listed = @()
+                try { $listed = @(& $pyLauncher.Source "-0p" 2>$null) } catch {}
+                foreach ($line in $listed) {
+                    # " -V:3.12 *   C:\...\python.exe": tag, optional default marker, path.
+                    $m = [regex]::Match([string]$line, '(?i)^\s*-\S+\s+\*?\s*"?(?<p>\S.*?\.exe)"?\s*$')
+                    if (-not $m.Success) { continue }
+                    $exe = $m.Groups['p'].Value.Trim()
+                    if ($candidates | Where-Object { $_.Path -eq $exe }) { continue }
+                    if (-not (Test-Path -LiteralPath $exe)) { continue }
+                    if (Test-IsCondaPython $exe) { continue }
+                    try {
+                        $out = & $exe --version 2>&1 | Out-String
+                        if ($out -match "Python (3\.1[1-3])\.\d+") {
+                            $candidates += @{ Version = $Matches[1]; Path = $exe }
+                        }
+                    } catch {}
+                }
+            }
+        }
+        # Prefer x64, but only within one minor: $minors is the caller's version preference,
+        # so ranking on arch alone would answer UNSLOTH_PYTHON=3.12 with an x64 3.13 and
+        # never bootstrap x64 3.12. Probing costs a subprocess, so non-ARM returned above.
+        foreach ($c in $candidates) {
+            $tag = Get-PythonPlatformTag $c.Path
+            $c.Arch = if ($tag -eq "win-amd64") { "x86_64" } elseif ($tag -eq "win-arm64") { "arm64" } else { "unknown" }
+        }
+        foreach ($minor in $minors) {
+            $sameMinor = @($candidates | Where-Object { $_.Version -eq $minor })
+            if ($sameMinor.Count -eq 0) { continue }
+            $x64 = $sameMinor | Where-Object { $_.Arch -eq "x86_64" } | Select-Object -First 1
+            if ($x64) { return $x64 }
+            if (-not $X64Only) { return $sameMinor[0] }
+        }
+        if (-not $X64Only -and $candidates.Count -gt 0) { return $candidates[0] }
         return $null
     }
 
@@ -1181,8 +1261,11 @@ exit 0
     # (no UAC), putting python.exe + the py launcher on PATH. Mirrors the uv ->
     # astral.sh fallback below. Returns @{ Version; Path } or $null.
     function Install-PythonFromPythonOrg {
+        # $Arch overrides the host arch, to pull x64 onto an ARM64 box.
+        param([string]$Arch = "")
         # python.org ships one installer per architecture.
-        $archSuffix = switch (Get-TauriDiagArch) {
+        $targetArch = if ($Arch) { $Arch } else { Get-TauriDiagArch }
+        $archSuffix = switch ($targetArch) {
             "x86_64" { "-amd64" }
             "arm64"  { "-arm64" }
             "x86"    { "" }
@@ -1247,6 +1330,28 @@ exit 0
         return (Find-CompatiblePython)
     }
 
+    # ── Windows on ARM: get an x64 CPython ──
+    # --architecture x64 forces winget off the ARM64 build; python.org takes the same override.
+    function Install-X64Python {
+        if ($script:WingetAvailable) {
+            $prevEAP = $ErrorActionPreference
+            $ErrorActionPreference = "Continue"
+            try {
+                winget install -e --id "Python.Python.$PythonVersion" --source winget --architecture x64 --accept-package-agreements --accept-source-agreements
+            } catch { }
+            $ErrorActionPreference = $prevEAP
+            Refresh-SessionPath
+            $found = Find-CompatiblePython
+            if ($found -and $found.Arch -eq "x86_64") { return $found }
+            substep "winget could not provide an x64 Python -- trying python.org..." "Yellow"
+        }
+        $found = Install-PythonFromPythonOrg -Arch "x86_64"
+        if ($found -and $found.Arch -eq "x86_64") { return $found }
+        # Nothing installable (offline / no winget): an x64 build of another supported minor
+        # still runs the wheels ARM64 cannot, so take it over the native interpreter.
+        return (Find-CompatiblePython -X64Only)
+    }
+
     # ── Install Python if no compatible version (3.11-3.13) found ──
     # Find-CompatiblePython returns @{ Version = "3.13"; Path = "C:\...\python.exe" } or $null.
     Write-TauriLog "STEP" "Installing Python"
@@ -1318,6 +1423,26 @@ exit 0
             return (Exit-InstallFailure "Python installation failed")
         }
     }
+    # ── Windows on ARM: swap a native ARM64 interpreter for x64 ──
+    # pyarrow and hf-transfer publish no win_arm64 wheel, so an ARM64 Python source-builds
+    # both and fails deep into the run. Warn up front if x64 is unobtainable.
+    if ($DetectedPython -and (Get-HostMachineArch) -eq "arm64" -and $DetectedPython.Arch -ne "x86_64") {
+        substep "windows on arm: only a native ARM64 Python $($DetectedPython.Version) was found." "Yellow"
+        substep "pyarrow and hf-transfer publish no win_arm64 wheels, so installing x64 Python..." "Yellow"
+        $X64Python = Install-X64Python
+        if ($X64Python) {
+            $DetectedPython = $X64Python
+            step "python" "using x64 Python $($DetectedPython.Version) under emulation"
+        } else {
+            Write-Host "[WARN] Could not install an x64 Python on this ARM64 machine." -ForegroundColor Yellow
+            Write-Host "       Continuing with ARM64 Python $($DetectedPython.Version), but the install is likely to fail:" -ForegroundColor Yellow
+            Write-Host "       pyarrow (via datasets) and hf-transfer ship no win_arm64 wheels and will be" -ForegroundColor Yellow
+            Write-Host "       built from source, which needs CMake plus the MSVC and Rust toolchains." -ForegroundColor Yellow
+            Write-Host "       Fix: install x64 Python from https://www.python.org/downloads/windows/" -ForegroundColor Yellow
+            Write-Host "       (choose 'Windows installer (64-bit)', not ARM64), then re-run this installer." -ForegroundColor Yellow
+        }
+    }
+
     $DiagPythonVersion = $PythonVersion
     if ($DetectedPython) { $DiagPythonVersion = $DetectedPython.Version }
     $InitialGpuBranch = "unknown"
@@ -2438,6 +2563,13 @@ exit 0
             }
         } else {
             Write-TauriLog "STEP" "Installing PyTorch"
+            # Windows on ARM lacks only torchaudio (whl/cpu win_arm64: torch 42,
+            # torchvision 60, torchaudio 0), so drop that pin instead of aborting. Ask the
+            # interpreter, not PROCESSOR_ARCHITECTURE; reached when no x64 Python exists.
+            $VenvPlatform = ""
+            try {
+                $VenvPlatform = (& $VenvPython -c "import sysconfig; print(sysconfig.get_platform())" 2>$null | Out-String).Trim().ToLowerInvariant()
+            } catch { $VenvPlatform = "" }
             substep "installing PyTorch ($(Remove-IndexUrlCredentials $TorchIndexUrl))..."
             # Bound the companions to the capped torch on EVERY index, cu<digits>
             # families included: torchaudio 2.11 dropped its exact torch pin from
@@ -2445,7 +2577,13 @@ exit 0
             # resolve a mismatched 2.11.0 build. Mirrors install.sh.
             $_pinVisionSpec = "torchvision>=0.19,<0.26.0"
             $_pinAudioSpec = "torchaudio>=2.4,<2.11.0"
-            $torchInstallExit = Invoke-InstallCommandRetry -Label "install PyTorch" { uv pip install --python $VenvPython "torch>=2.4,<2.11.0" $_pinVisionSpec $_pinAudioSpec --default-index $TorchIndexUrl }
+            $_torchSpecs = @("torch>=2.4,<2.11.0", $_pinVisionSpec, $_pinAudioSpec)
+            if ($VenvPlatform -eq "win-arm64") {
+                substep "windows on arm: skipping torchaudio (upstream publishes no"
+                substep "win_arm64 wheel); torch and torchvision install normally."
+                $_torchSpecs = @("torch>=2.4,<2.11.0", $_pinVisionSpec)
+            }
+            $torchInstallExit = Invoke-InstallCommandRetry -Label "install PyTorch" { uv pip install --python $VenvPython @_torchSpecs --default-index $TorchIndexUrl }
             if ($torchInstallExit -ne 0) {
                 Write-Host "[ERROR] Failed to install PyTorch (exit code $torchInstallExit)" -ForegroundColor Red
                 return (Exit-InstallFailure "Failed to install PyTorch (exit code $torchInstallExit)" $torchInstallExit)

pyproject.toml

@@ -47,9 +47,14 @@ version = {attr = "unsloth.models._utils.__version__"}
 [tool.setuptools]
 include-package-data = true
 
+[tool.setuptools.cmdclass]
+# Snapshots CHANGELOG.md into studio/ so every build path ships it.
+build_py = "_changelog_build.build_py"
+
 [tool.setuptools.package-data]
 unsloth_cli = ["codex_fallback_prompt.md", "pi_subagent.ts"]
 studio = [
+    "CHANGELOG.md",
     "*.sh",
     "*.ps1",
     "*.bat",

scripts/profile_startup.py

@@ -0,0 +1,377 @@
+#!/usr/bin/env python3
+# SPDX-License-Identifier: AGPL-3.0-only
+# Copyright 2026-present the Unsloth AI Inc. team. All rights reserved. See /studio/LICENSE.AGPL-3.0
+
+"""Measure where Unsloth Studio's startup time goes, per platform.
+
+Nothing measured this before: the backend logs "lifespan startup completed in X ms"
+but no test or CI job asserted a budget, and studio_test_kit discards the elapsed
+time of its /healthz poll. A first local run (Linux, warm cache, fast server CPU)
+found `import main` alone costs 6.6s before the server can bind, dominated by eager
+module-level imports pulled in by the `routes` package:
+
+    torch          1930 ms self
+    unsloth_zoo     914 ms self
+    routes          779 ms self
+    transformers    524 ms self
+
+Phases measured:
+  import   `python -X importtime -c "import main"`, top cumulative + per-package self
+  spawn    process start -> first byte on stdout
+  healthz  process start -> /api/health (or /healthz) answers 200
+  lifespan the backend's own "lifespan startup completed in X ms" log line
+
+Usage:
+    python scripts/profile_startup.py --repeats 3 --json out.json
+    python scripts/profile_startup.py --import-only     # no server, no port needed
+
+Exit code is 0 unless --max-healthz-seconds is given and exceeded.
+"""
+
+from __future__ import annotations
+
+import argparse
+import json
+import math
+import os
+import platform
+import re
+import shutil
+import socket
+import statistics
+import subprocess
+import sys
+import threading
+import time
+import urllib.error
+import urllib.request
+from pathlib import Path
+
+REPO_ROOT = Path(__file__).resolve().parents[1]
+BACKEND = REPO_ROOT / "studio" / "backend"
+
+_IMPORTTIME_RE = re.compile(r"import time:\s+(\d+)\s+\|\s+(\d+)\s+\|(\s*)(\S.*)")
+
+
+def _free_port() -> int:
+    with socket.socket() as s:
+        s.bind(("127.0.0.1", 0))
+        return int(s.getsockname()[1])
+
+
+def profile_imports(python: str, top: int = 15) -> dict:
+    """Cumulative and self import cost for the backend's module graph.
+
+    Run in a subprocess with -X importtime: the numbers are only meaningful for a
+    cold interpreter, and importing in-process would measure a warm sys.modules.
+    """
+    proc = subprocess.run(
+        [python, "-X", "importtime", "-c", "import sys; sys.path.insert(0, '.'); import main"],
+        cwd = BACKEND,
+        capture_output = True,
+        text = True,
+        timeout = 900,
+    )
+    rows = []
+    for line in proc.stderr.splitlines():
+        m = _IMPORTTIME_RE.match(line)
+        if m:
+            rows.append((int(m.group(1)), int(m.group(2)), m.group(4).strip()))
+    if not rows:
+        return {"ok": False, "error": (proc.stderr or proc.stdout)[-2000:]}
+    if proc.returncode != 0:
+        # Rows survive up to the failure, so any total from a partial graph is wrong.
+        return {
+            "ok": False,
+            "error": (proc.stderr or proc.stdout)[-2000:],
+            "partial_rows": len(rows),
+        }
+
+    by_cum = sorted(rows, key = lambda r: -r[1])
+    # Total comes from the `main` row, not by_cum[0]: -X importtime also prints the
+    # interpreter's own startup graph (`site`), which can outrank a trivial main.
+    main_row = next((r for r in reversed(rows) if r[2] == "main"), None)
+    if main_row is None:
+        return {
+            "ok": False,
+            "error": "no `import main` row in -X importtime output\n"
+            + (proc.stderr or proc.stdout)[-2000:],
+        }
+    self_by_pkg: dict[str, int] = {}
+    for self_us, _cum, name in rows:
+        pkg = name.split(".")[0]
+        self_by_pkg[pkg] = self_by_pkg.get(pkg, 0) + self_us
+
+    return {
+        "ok": True,
+        "total_seconds": round(main_row[1] / 1e6, 3),
+        "top_cumulative": [
+            {"module": n, "seconds": round(c / 1e6, 3)} for _s, c, n in by_cum[:top]
+        ],
+        "self_by_package_ms": {
+            k: round(v / 1000) for k, v in sorted(self_by_pkg.items(), key = lambda x: -x[1])[:top]
+        },
+    }
+
+
+def _terminate_tree(proc: subprocess.Popen) -> None:
+    """Stop the server AND its children, which on Windows are a separate process.
+
+    CI profiles `Scripts/unsloth.exe`, a distlib launcher stub that CreateProcess's
+    the venv python and waits, so terminate() reaps the stub only: the real backend
+    keeps the inherited stdout handle, the reader thread never sees EOF, and
+    --repeats strands one server per iteration on the shared UNSLOTH_STUDIO_HOME.
+    taskkill /T walks the tree, as unsloth_cli/commands/start.py already does.
+    """
+    if proc.poll() is not None:
+        return
+    if os.name == "nt":
+        try:
+            killed = subprocess.run(
+                ["taskkill", "/PID", str(proc.pid), "/T", "/F"],
+                capture_output = True,
+                timeout = 30,
+                check = False,
+            )
+            if killed.returncode == 0:
+                return
+        except Exception:
+            # taskkill missing or timed out; fall through so the stub still dies.
+            pass
+        # check=False: a nonzero taskkill does not raise, so fall through as well.
+    proc.terminate()
+
+
+def profile_launch(
+    bin_path: str,
+    port: int,
+    timeout_s: int = 300,
+) -> dict:
+    """Spawn the backend the way the desktop app does and time it to first 200."""
+    log_lines: list[str] = []
+    first_byte: list[float] = []
+    t0 = time.perf_counter()
+    proc = subprocess.Popen(
+        [bin_path, "studio", "--api-only", "-H", "127.0.0.1", "-p", str(port)],
+        cwd = REPO_ROOT,
+        stdout = subprocess.PIPE,
+        stderr = subprocess.STDOUT,
+        text = True,
+        bufsize = 1,
+    )
+
+    def _drain() -> None:
+        # Runs alongside the health polling: the first read timestamps the spawn
+        # phase, and an undrained pipe blocks the backend before it binds.
+        for line in proc.stdout:
+            if not first_byte:
+                first_byte.append(time.perf_counter() - t0)
+            log_lines.append(line.rstrip("\n"))
+
+    reader = threading.Thread(target = _drain, daemon = True)
+    reader.start()
+
+    t_healthz = None
+    deadline = t0 + timeout_s
+    try:
+        while time.perf_counter() < deadline:
+            if proc.poll() is not None:
+                break
+            if t_healthz is None:
+                for url in (
+                    f"http://127.0.0.1:{port}/api/health",
+                    f"http://127.0.0.1:{port}/healthz",
+                ):
+                    try:
+                        with urllib.request.urlopen(url, timeout = 2) as r:
+                            if r.status == 200:
+                                t_healthz = time.perf_counter() - t0
+                                break
+                    except (urllib.error.URLError, OSError, TimeoutError):
+                        pass
+            if t_healthz is not None:
+                break
+            time.sleep(0.25)
+    finally:
+        _terminate_tree(proc)
+        try:
+            # Safe: the reader drains the pipe, so the child cannot block on write().
+            proc.wait(timeout = 30)
+        except subprocess.TimeoutExpired:
+            proc.kill()
+            proc.wait()
+        reader.join(timeout = 10)
+
+    t_first_byte = first_byte[0] if first_byte else None
+    lifespan_ms = None
+    for line in log_lines:
+        m = re.search(r"lifespan startup completed in ([\d.]+)ms", line)
+        if m:
+            lifespan_ms = float(m.group(1))
+    return {
+        "spawn_seconds": round(t_first_byte, 3) if t_first_byte is not None else None,
+        "healthz_seconds": round(t_healthz, 3) if t_healthz is not None else None,
+        "lifespan_ms": lifespan_ms,
+        "reached_healthz": t_healthz is not None,
+        "log_tail": log_lines[-25:],
+    }
+
+
+def python_version_of(python: str) -> str:
+    """Version of the interpreter that runs the imports, not the one running us.
+
+    --python points at the installed Studio venv while this script runs under the
+    runner's system python, so platform.python_version() would label it wrong.
+    """
+    if python == sys.executable:
+        return platform.python_version()
+    try:
+        proc = subprocess.run(
+            [python, "-c", "import platform; print(platform.python_version())"],
+            capture_output = True,
+            text = True,
+            timeout = 60,
+        )
+        if proc.returncode == 0 and proc.stdout.strip():
+            return proc.stdout.strip()
+    except (OSError, subprocess.SubprocessError):
+        pass
+    return "unknown"
+
+
+def find_bin() -> str | None:
+    home = os.environ.get("UNSLOTH_STUDIO_HOME") or str(Path.home() / ".unsloth" / "studio")
+    names = ["unsloth.exe", "unsloth"] if platform.system() == "Windows" else ["unsloth"]
+    subdirs = ["unsloth_studio/Scripts", "unsloth_studio/bin", "bin", "Scripts"]
+    for sd in subdirs:
+        for n in names:
+            p = Path(home) / sd / n
+            if p.exists():
+                return str(p)
+    return shutil.which("unsloth")
+
+
+def main(argv: list[str]) -> int:
+    ap = argparse.ArgumentParser(
+        description = __doc__, formatter_class = argparse.RawDescriptionHelpFormatter
+    )
+    ap.add_argument(
+        "--repeats",
+        type = int,
+        default = 1,
+        help = "launch repeats; the median is reported (imports are measured once)",
+    )
+    ap.add_argument(
+        "--python",
+        default = sys.executable,
+        help = "interpreter used for the import profile (default: this one)",
+    )
+    ap.add_argument("--bin", help = "path to the unsloth CLI (default: autodetect)")
+    ap.add_argument(
+        "--import-only",
+        action = "store_true",
+        help = "skip the server phases (no install needed beyond the deps)",
+    )
+    ap.add_argument(
+        "--max-healthz-seconds",
+        type = float,
+        help = "fail if the median time to a healthy port exceeds this",
+    )
+    ap.add_argument("--json", help = "write the full report here")
+    a = ap.parse_args(argv)
+    # range(0) launches nothing, leaving the budget check with nothing to fail on.
+    if a.repeats < 1:
+        ap.error("--repeats must be at least 1")
+    # Same reason: --import-only never launches anything.
+    if a.import_only and a.max_healthz_seconds is not None:
+        ap.error("--max-healthz-seconds cannot be combined with --import-only")
+    # nan and inf parse fine as floats but `med > budget` is then always False,
+    # so the gate would report success without ever bounding anything.
+    if a.max_healthz_seconds is not None and not math.isfinite(a.max_healthz_seconds):
+        ap.error("--max-healthz-seconds must be a finite number")
+
+    report: dict = {
+        "platform": platform.system().lower(),
+        "machine": platform.machine(),
+        "python": python_version_of(a.python),
+        "cpu_count": os.cpu_count(),
+    }
+
+    print("== import graph ==")
+    report["imports"] = profile_imports(a.python)
+    imp = report["imports"]
+    if imp.get("ok"):
+        print(f"  import main: {imp['total_seconds']}s")
+        for row in imp["top_cumulative"][:8]:
+            print(f"    {row['seconds']:7.3f}s  {row['module']}")
+        print("  self time by package (ms):")
+        for k, v in list(imp["self_by_package_ms"].items())[:8]:
+            print(f"    {v:8} ms  {k}")
+    else:
+        print(f"  FAILED: {imp.get('error', '')[:400]}")
+
+    if not a.import_only:
+        bin_path = a.bin or find_bin()
+        if not bin_path:
+            print(
+                "== launch == skipped: no unsloth CLI found "
+                "(set UNSLOTH_STUDIO_HOME or pass --bin)"
+            )
+            report["launch"] = {"skipped": "no unsloth CLI found"}
+        else:
+            print(f"== launch == {bin_path}")
+            runs = []
+            for i in range(a.repeats):
+                r = profile_launch(bin_path, _free_port())
+                runs.append(r)
+                print(
+                    f"  run {i + 1}: healthz={r['healthz_seconds']}s "
+                    f"lifespan={r['lifespan_ms']}ms reached={r['reached_healthz']}"
+                )
+            got = [r["healthz_seconds"] for r in runs if r["healthz_seconds"] is not None]
+            report["launch"] = {
+                "runs": runs,
+                "failed_runs": sum(1 for r in runs if not r["reached_healthz"]),
+                "healthz_median_seconds": round(statistics.median(got), 3) if got else None,
+                "healthz_max_seconds": round(max(got), 3) if got else None,
+            }
+            if got:
+                print(
+                    f"  median time to healthy port: {report['launch']['healthz_median_seconds']}s"
+                )
+
+    if a.json:
+        Path(a.json).write_text(json.dumps(report, indent = 2), encoding = "utf-8")
+        print(f"\nwrote {a.json}")
+
+    if a.max_healthz_seconds is not None:
+        launch = report.get("launch") or {}
+        med = launch.get("healthz_median_seconds")
+        failed = launch.get("failed_runs") or 0
+        if failed:
+            # Failed launches fail the budget; dropping them would keep only the fast ones.
+            print(
+                f"::error::startup regression: {failed} of {len(launch.get('runs') or [])} "
+                f"launches never became healthy within the timeout"
+            )
+            return 1
+        if med is None:
+            # Nothing measured: exiting 0 would pass a requested budget without a
+            # single health request, so fail closed.
+            print(
+                "::error::startup regression: no healthz measurement, so the "
+                f"{a.max_healthz_seconds}s budget was never checked "
+                f"({launch.get('skipped') or 'launch phase produced no runs'})"
+            )
+            return 1
+        elif med > a.max_healthz_seconds:
+            print(
+                f"::error::startup regression: {med}s median to a healthy port "
+                f"exceeds the {a.max_healthz_seconds}s budget"
+            )
+            return 1
+    return 0
+
+
+if __name__ == "__main__":
+    raise SystemExit(main(sys.argv[1:]))

studio/backend/auth/storage.py

@@ -76,7 +76,13 @@ def _load_bootstrap_password() -> Optional[str]:
     global _bootstrap_password
     _bootstrap_password = None
     if _BOOTSTRAP_PW_PATH.is_file():
-        bootstrap_password = _BOOTSTRAP_PW_PATH.read_text(encoding = "utf-8").strip()
+        # No caller handles a raise, so an unreadable file has to mean "no bootstrap
+        # password", not a dead backend. We write UTF-8, so bytes that will not
+        # decode are damage whose plaintext is worthless anyway.
+        try:
+            bootstrap_password = _BOOTSTRAP_PW_PATH.read_text(encoding = "utf-8").strip()
+        except (OSError, UnicodeDecodeError):
+            return _bootstrap_password
         if bootstrap_password:
             _bootstrap_password = bootstrap_password
     return _bootstrap_password

studio/backend/cloudflare_tunnel.py

@@ -310,6 +310,7 @@ class CloudflareTunnel:
                 stderr = subprocess.STDOUT,
                 stdin = subprocess.DEVNULL,
                 text = True,
+                encoding = "utf-8",
                 errors = "replace",
                 bufsize = 1,
                 **_windows_hidden_kwargs(),

studio/backend/core/data_recipe/local_callable_validators.py

@@ -257,6 +257,8 @@ def _run_oxc_batch(
             cwd = str(_OXC_TOOL_DIR),
             input = json.dumps(payload),
             text = True,
+            encoding = "utf-8",
+            errors = "replace",
             capture_output = True,
             check = False,
             env = env,

studio/backend/core/inference/inference.py

@@ -567,7 +567,7 @@ class InferenceBackend:
                         _meta_path = Path(config.path) / "export_metadata.json"
                         try:
                             if _meta_path.exists():
-                                _meta = json.loads(_meta_path.read_text(encoding = "utf-8"))
+                                _meta = json.loads(_meta_path.read_text(encoding = "utf-8-sig"))
                                 if _meta.get("base_model"):
                                     processor_source = _meta["base_model"]
                         except Exception:

studio/backend/core/inference/llama_cpp.py

@@ -85,6 +85,7 @@ from core.tool_healing import (
     strip_outside_think,
 )
 from utils.native_path_leases import child_env_without_native_path_secret
+from utils.child_stdio import utf8_child_env
 from utils.hf_xet_fallback import hf_hub_download_with_xet_fallback
 from utils.subprocess_compat import (
     windows_hidden_subprocess_kwargs as _windows_hidden_subprocess_kwargs,
@@ -581,7 +582,7 @@ def _load_swa_cache() -> dict:
         if _SWA_CACHE is not None:
             return _SWA_CACHE
         try:
-            with open(_swa_cache_path(), encoding = "utf-8") as f:
+            with open(_swa_cache_path(), encoding = "utf-8-sig") as f:
                 _SWA_CACHE = json.load(f)
                 if not isinstance(_SWA_CACHE, dict):
                     _SWA_CACHE = {}
@@ -632,7 +633,7 @@ def _fetch_swa_entry_from_hf(repo_id: str) -> Optional[object]:
             repo_type = "model",
             cache_dir = active_hf_hub_cache(),
         )
-        with open(cfg_path, encoding = "utf-8") as f:
+        with open(cfg_path, encoding = "utf-8-sig") as f:
             cfg = json.load(f)
     except Exception:
         return None
@@ -3046,6 +3047,7 @@ class LlamaCppBackend:
                 [bin_path, "--help"],
                 capture_output = True,
                 text = True,
+                encoding = "utf-8",
                 errors = "replace",
                 timeout = 10,
                 check = False,
@@ -3618,6 +3620,8 @@ class LlamaCppBackend:
                 ],
                 capture_output = True,
                 text = True,
+                encoding = "utf-8",
+                errors = "replace",
                 timeout = 10,
                 env = child_env_without_native_path_secret(),
                 **_windows_hidden_subprocess_kwargs(),
@@ -3732,7 +3736,7 @@ class LlamaCppBackend:
                 encoding = "utf-8",
                 errors = "replace",
                 timeout = 15,
-                env = env,
+                env = utf8_child_env(env),
                 **_windows_hidden_subprocess_kwargs(),
             )
             if result.returncode != 0:
@@ -5482,7 +5486,9 @@ class LlamaCppBackend:
             stdout = subprocess.PIPE,
             stderr = subprocess.STDOUT,
             text = True,
-            env = env,
+            encoding = "utf-8",
+            errors = "replace",
+            env = utf8_child_env(env),
             **_windows_hidden_subprocess_kwargs(),
             **_child_popen_kwargs(),
         )
@@ -6696,6 +6702,8 @@ class LlamaCppBackend:
             stdout = subprocess.PIPE,
             stderr = subprocess.STDOUT,
             text = True,
+            encoding = "utf-8",
+            errors = "replace",
             env = env,
             **_windows_hidden_subprocess_kwargs(),
             **_child_popen_kwargs(),
@@ -8712,6 +8720,8 @@ class LlamaCppBackend:
                             stdout = subprocess.PIPE,
                             stderr = subprocess.STDOUT,
                             text = True,
+                            encoding = "utf-8",
+                            errors = "replace",
                             env = env,
                             **_windows_hidden_subprocess_kwargs(),
                             **_child_popen_kwargs(),
@@ -10214,6 +10224,8 @@ class LlamaCppBackend:
                     ["pgrep", "-a", "-f", "llama-server"],
                     capture_output = True,
                     text = True,
+                    encoding = "utf-8",
+                    errors = "replace",
                     timeout = 5,
                     env = child_env_without_native_path_secret(),
                 )

studio/backend/core/inference/worker.py

@@ -151,7 +151,7 @@ def _resolve_lora_4bit(mc, load_in_4bit: bool) -> bool:
     import json
 
     try:
-        with open(adapter_cfg_path, encoding = "utf-8") as f:
+        with open(adapter_cfg_path, encoding = "utf-8-sig") as f:
             adapter_cfg = json.load(f)
         training_method = adapter_cfg.get("unsloth_training_method")
         if training_method == "lora" and load_in_4bit:
@@ -963,7 +963,7 @@ def run_inference_process(
     if _local_adapter_cfg.is_file():
         try:
             _lora_base = (
-                _json.loads(_local_adapter_cfg.read_text(encoding = "utf-8")).get(
+                _json.loads(_local_adapter_cfg.read_text(encoding = "utf-8-sig")).get(
                     "base_model_name_or_path"
                 )
                 or None

studio/backend/core/rag/embed_llama_server.py

@@ -103,6 +103,8 @@ class LlamaServerBackend:
                 [binary, "--help"],
                 capture_output = True,
                 text = True,
+                encoding = "utf-8",
+                errors = "replace",
                 timeout = 30,
                 **windows_hidden_subprocess_kwargs(),
             )
@@ -331,6 +333,8 @@ class LlamaServerBackend:
             stdout = subprocess.PIPE,
             stderr = subprocess.STDOUT,
             text = True,
+            encoding = "utf-8",
+            errors = "replace",
             env = env,
             **windows_hidden_subprocess_kwargs(),
             **child_popen_kwargs(),

studio/backend/core/rag/embeddings.py

@@ -100,7 +100,7 @@ def _st_module_subdirs(name: str, token: str | None) -> tuple[str, ...]:
             path = Path(normalize_path(name)).expanduser() / "modules.json"
             if not path.is_file():
                 return ()
-            data = json.loads(path.read_text(encoding = "utf-8"))
+            data = json.loads(path.read_text(encoding = "utf-8-sig"))
         else:
             from huggingface_hub import hf_hub_download
             from huggingface_hub.utils import EntryNotFoundError
@@ -115,7 +115,7 @@ def _st_module_subdirs(name: str, token: str | None) -> tuple[str, ...]:
                 )
             except EntryNotFoundError:
                 return ()
-            data = json.loads(open(local, encoding = "utf-8").read())
+            data = json.loads(open(local, encoding = "utf-8-sig").read())
         subdirs = []
         for module in data or ():
             sub = str((module or {}).get("path", "")).strip().strip("/")

studio/backend/core/training/worker.py

@@ -43,6 +43,7 @@ if sys.platform.startswith("linux") and "HSA_ENABLE_DXG_DETECTION" not in os.env
         pass
 
 logger = get_logger(__name__)
+from utils.child_stdio import utf8_child_env
 from utils.hardware import apply_gpu_ids
 from utils.training_runs import build_default_output_dir_name
 from utils.wheel_utils import (
@@ -385,6 +386,10 @@ def _install_package_wheel_first(
         "stdout": _sp.PIPE,
         "stderr": _sp.STDOUT,
         "text": True,
+        "encoding": "utf-8",
+        "errors": "replace",
+        # Make the Python child emit the UTF-8 we decode above.
+        "env": utf8_child_env(),
     }
     if is_hip:
         _run_kwargs["timeout"] = 1800
@@ -606,6 +611,9 @@ def _ensure_flash_linear_attention_unconditional(event_queue: Any) -> bool:
             stdout = _sp.PIPE,
             stderr = _sp.STDOUT,
             text = True,
+            encoding = "utf-8",
+            errors = "replace",
+            env = utf8_child_env(),
             timeout = _TILELANG_INSTALL_TIMEOUT_S,
         )
     except _sp.TimeoutExpired:
@@ -849,6 +857,9 @@ def _run_pip(cmd: list[str], event_queue: Any, label: str) -> bool:
             stdout = _sp.PIPE,
             stderr = _sp.STDOUT,
             text = True,
+            encoding = "utf-8",
+            errors = "replace",
+            env = utf8_child_env(),
             timeout = _TILELANG_INSTALL_TIMEOUT_S,
         )
     except _sp.TimeoutExpired:

studio/backend/hub/services/models/ollama.py

@@ -215,7 +215,7 @@ def _ollama_model_info_from_manifest(
         return None
 
     try:
-        manifest = json.loads(tag_file.read_text(encoding = "utf-8"))
+        manifest = json.loads(tag_file.read_text(encoding = "utf-8-sig"))
     except (json.JSONDecodeError, OSError, UnicodeDecodeError) as e:
         logger.debug("Skipping unreadable/invalid Ollama manifest %s: %s", tag_file, e)
         return None
@@ -228,7 +228,7 @@ def _ollama_model_info_from_manifest(
         config_blob = _ollama_blob_path(blobs_dir, config_digest)
         if config_blob is not None and _safe_is_file(config_blob):
             try:
-                cfg = json.loads(config_blob.read_text(encoding = "utf-8"))
+                cfg = json.loads(config_blob.read_text(encoding = "utf-8-sig"))
                 model_type = cfg.get("model_type", "")
                 file_type = cfg.get("file_type", "")
             except (json.JSONDecodeError, OSError, UnicodeDecodeError) as e:

studio/backend/hub/utils/download_registry.py

@@ -464,6 +464,8 @@ def _read_marker_value(marker: Path) -> Optional[str]:
             return None
         value = marker.read_text(encoding = "utf-8").strip()
     except (OSError, UnicodeDecodeError):
+        # UnicodeDecodeError is a ValueError, so it would escape and abort
+        # prepare_cache_for_transport. An unknown value just purges and restarts.
         return None
     return value if value in VALID_TRANSPORTS else None
 

studio/backend/loggers/config.py

@@ -42,8 +42,12 @@ class LogConfig:
         log_level_name = os.getenv("LOG_LEVEL", "INFO").upper()
         log_level = getattr(logging, log_level_name, logging.INFO)
 
-        if sys.platform == "win32":
-            for stream in (sys.stdout, sys.stderr):
+        # Non-ASCII on a non-UTF-8 stream raises UnicodeEncodeError (Windows,
+        # LANG=C), so key off the stream, not the platform.
+        for stream in (sys.stdout, sys.stderr):
+            if getattr(stream, "encoding", "") and not str(stream.encoding).lower().replace(
+                "-", ""
+            ).startswith("utf8"):
                 if hasattr(stream, "reconfigure"):
                     try:
                         stream.reconfigure(encoding = "utf-8", errors = "replace")

studio/backend/main.py

@@ -347,6 +347,7 @@ from utils.update_status import (
     get_studio_install_source_status,
     get_studio_update_status,
 )
+from utils.changelog import get_release_notes, is_supported_version_query
 from utils.studio_version import get_studio_version
 from utils.api_errors import install_api_error_handlers
 
@@ -1154,6 +1155,18 @@ def studio_update_status(_current_subject: str = Depends(get_current_subject)):
     return get_studio_update_status(UNSLOTH_VERSION)
 
 
+@app.get("/api/studio/release-notes")
+def studio_release_notes(
+    version: str = Query(..., max_length = 64),
+    refresh: bool = Query(False),
+    _current_subject: str = Depends(get_current_subject),
+):
+    """Return CHANGELOG.md notes for exactly `version` (never a nearby one)."""
+    if not is_supported_version_query(version):
+        raise HTTPException(status_code = 422, detail = "Invalid version.")
+    return get_release_notes(version, refresh = refresh)
+
+
 @app.get(
     "/api/studio/download-transport-capabilities",
     response_model = TransportCapabilities,

studio/backend/plugins/data-designer-github-repo-seed/src/data_designer_github_repo_seed/scraper_impl/state_store.py

@@ -6,10 +6,93 @@
 from __future__ import annotations
 
 import json
+import locale
 import os
 import threading
 from pathlib import Path
-from typing import Any, Dict
+from typing import Any, Dict, NamedTuple
+
+
+def _locale_encoding() -> str:
+    """The codepage a pre-UTF-8 release here would have written, or "".
+
+    Empty on a UTF-8 host, where there is no codepage to attribute the file to.
+    """
+    try:
+        preferred = locale.getencoding()
+    except AttributeError:  # Python < 3.11
+        preferred = locale.getpreferredencoding(False)
+    if preferred.lower().replace("-", "").replace("_", "") == "utf8":
+        return ""
+    return preferred
+
+
+# Trail bytes can land on JSON punctuation, so a single-byte fallback misreads these.
+_DOUBLE_BYTE_ENCODINGS = ("cp932", "cp936", "cp949", "cp950")
+
+
+def _parse(raw: bytes, encoding: str) -> Any:
+    """Parse one JSON document under *encoding*, or None if it does not.
+
+    RecursionError is a RuntimeError, so nesting json.loads will not descend is
+    the one parse failure the other three miss. Both callers run this outside
+    any further handler, so it has to answer None here or a single damaged
+    record aborts the scraper at startup instead of being skipped.
+    """
+    try:
+        return json.loads(raw.decode(encoding))
+    except (UnicodeDecodeError, LookupError, ValueError, RecursionError):
+        return None
+
+
+class _Reading(NamedTuple):
+    as_utf8: Any
+    as_legacy: Any
+
+
+def _read_line(raw: bytes, codepage: str) -> _Reading:
+    """Read one line as UTF-8 and as a codepage, for dedup keys only.
+
+    Requiring valid JSON, not merely a successful decode, is what separates a
+    genuine legacy record from a half-written UTF-8 one: a torn multibyte
+    character decodes under cp1252 but leaves the JSON unterminated. Some byte
+    strings parse both ways, e.g. cp1251 ``Р°`` is ``D0 B0``, which is also
+    UTF-8 ``а``.
+
+    The codepage reading is never authoritative, because the file's own encoding
+    cannot be recovered from its bytes. Reading a cp1251 shard on a cp1252
+    machine turns ``Привет`` into ``Ïðèâåò`` and every byte of it decodes
+    cleanly, so a successful decode proves nothing about who wrote it. It is
+    used only to recover the dedup keys, which are ASCII ids and come back the
+    same under any of these, so the first reading that parses will do.
+
+    That is also why several are tried. latin-1 alone mangles the double-byte
+    codepages: cp932 ``表`` is ``95 5C``, and latin-1 turns the trail byte into
+    a JSON backslash, so the record fails to parse and its id is forgotten.
+    """
+    as_utf8 = _parse(raw, "utf-8")
+    # A record that reads as UTF-8 needs no second reading: re-parsing cost 2.8x on a
+    # 76 MB shard, and these reach gigabytes. Only a dict, since key lookup falls
+    # through to the codepage when UTF-8 yields none.
+    if isinstance(as_utf8, dict):
+        return _Reading(as_utf8, None)
+    for encoding in (codepage, "latin-1", *_DOUBLE_BYTE_ENCODINGS):
+        if not encoding:
+            continue
+        as_legacy = _parse(raw, encoding)
+        if as_legacy is not None:
+            return _Reading(as_utf8, as_legacy)
+    return _Reading(as_utf8, None)
+
+
+class _Scan(NamedTuple):
+    """What a pass over an existing shard established about it."""
+
+    legacy: bool  # enough evidence to trust the codepage reading's keys
+    readable: bool
+    saw_non_ascii: bool  # some line's meaning depends on the encoding
+    utf8_keys: set  # keys from lines UTF-8 could read
+    legacy_keys: set  # keys only the codepage reading yields
 
 
 class StateStore:
@@ -18,12 +101,19 @@ class StateStore:
         self.path.parent.mkdir(parents = True, exist_ok = True)
         self._lock = threading.Lock()
         self._data: Dict[str, Any] = {}
+        # Read whole, and UTF-8 only unlike the shards below: a checkpoint holds
+        # nothing but base64 cursors and booleans, so a codepage retry could only ever
+        # add non-ASCII. That would resume on a mojibaked cursor, which GitHub rejects
+        # with INVALID_CURSOR_ARGUMENTS, and the empty page it returns marks the stream
+        # done and skips the rest for good. Dropping a damaged checkpoint re-scrapes
+        # from the first page, which the writers dedup.
         if self.path.exists():
             try:
-                with self.path.open(encoding = "utf-8") as f:
-                    self._data = json.load(f)
-            except Exception:
-                self._data = {}
+                raw = self.path.read_bytes()
+            except OSError:
+                raw = b""
+            data = _parse(raw, "utf-8")
+            self._data = data if isinstance(data, dict) else {}
 
     def get(
         self,
@@ -63,24 +153,83 @@ class JsonlWriter:
         self.path = Path(path)
         self.path.parent.mkdir(parents = True, exist_ok = True)
         self._lock = threading.Lock()
-        self._fh = self.path.open("a", buffering = 1, encoding = "utf-8")
         self._count_seen_keys: set[str] = set()
-        # Preload seen keys for dedup across resumes
+        self._codepage = _locale_encoding()
+        self._ensure_ascii = False
+        encoding = "utf-8"
         if self.path.exists() and self.path.stat().st_size > 0:
-            try:
-                # No guess is safe for a file an older build wrote in the
-                # operator's locale, so read past whatever will not decode.
-                with self.path.open(encoding = "utf-8", errors = "replace") as f:
-                    for line in f:
-                        try:
-                            obj = json.loads(line)
-                            k = self._key(obj)
-                            if k is not None:
-                                self._count_seen_keys.add(k)
-                        except Exception:
-                            pass
-            except Exception:
-                pass
+            scan = self._scan_existing()
+            self._count_seen_keys = scan.utf8_keys
+            if scan.legacy:
+                self._count_seen_keys |= scan.legacy_keys
+            if scan.saw_non_ascii or not scan.readable:
+                # Never convert: the writing encoding is unrecoverable and guessing
+                # mojibakes the records. Pure ASCII appends store identically under
+                # every codepage, and json.loads turns the \uXXXX escapes back.
+                encoding = "ascii"
+                self._ensure_ascii = True
+        self._fh = self.path.open("a", buffering = 1, encoding = encoding, errors = "strict")
+
+    def _scan_existing(self) -> _Scan:
+        """Read the shard once to recover dedup keys and judge its encoding.
+
+        Line by line: these shards reach gigabytes on a large scrape, so neither
+        the bytes nor the decoded text are held whole.
+
+        The verdict weighs the whole file. Each line with non-ASCII bytes votes:
+        one that parses only under the codepage is evidence of a legacy shard,
+        one that parses as UTF-8 is evidence against, since arbitrary codepage
+        text almost never forms valid multibyte UTF-8. A single corrupt byte in
+        a healthy shard therefore cannot outvote the records around it, and a
+        genuinely legacy shard has a legacy vote on every line that carries an
+        umlaut.
+
+        More than one such line is required, because a single one is genuinely
+        undecidable: a legacy record holding one accented character and an ASCII
+        record holding one stray byte are the same shape. Reading it as damage
+        risks a duplicate; reading it as legacy marks an unreadable record seen
+        and blocks the retry that would replace it, losing it for good. Only one
+        of those is recoverable.
+
+        The verdict only picks which reading supplies the dedup keys. The file
+        itself is never rewritten either way, so a wrong answer costs at most a
+        duplicate, never a corrupted record.
+        """
+        legacy_votes = 0
+        utf8_votes = 0
+        saw_non_ascii = False
+        utf8_keys: set[str] = set()
+        legacy_keys: set[str] = set()
+        try:
+            with self.path.open("rb") as handle:
+                for raw in handle:
+                    line = raw.strip()
+                    reading = _read_line(line, self._codepage)
+                    # ASCII reads the same everywhere: no vote, no constraint.
+                    if not line.isascii():
+                        saw_non_ascii = True
+                        if reading.as_utf8 is None and reading.as_legacy is not None:
+                            legacy_votes += 1
+                        elif reading.as_utf8 is not None:
+                            utf8_votes += 1
+                    # Kept apart so a damaged line does not block its own retry.
+                    if isinstance(reading.as_utf8, dict):
+                        key = self._key(reading.as_utf8)
+                        if key is not None:
+                            utf8_keys.add(key)
+                    elif isinstance(reading.as_legacy, dict):
+                        key = self._key(reading.as_legacy)
+                        if key is not None:
+                            legacy_keys.add(key)
+        except OSError:
+            return _Scan(False, False, False, utf8_keys, legacy_keys)
+        return _Scan(
+            legacy_votes > 1 and legacy_votes > utf8_votes,
+            True,
+            saw_non_ascii,
+            utf8_keys,
+            legacy_keys,
+        )
 
     def _key(self, obj: dict) -> str | None:
         for k in ("id", "node_id", "number", "sha", "url"):
@@ -99,7 +248,7 @@ class JsonlWriter:
                 return False
             if k is not None:
                 self._count_seen_keys.add(k)
-            self._fh.write(json.dumps(obj, default = str, ensure_ascii = False))
+            self._fh.write(json.dumps(obj, default = str, ensure_ascii = self._ensure_ascii))
             self._fh.write("\n")
             self._fh.flush()
         return True

studio/backend/plugins/data-designer-unstructured-seed/src/data_designer_unstructured_seed/impl.py

@@ -30,6 +30,8 @@ class UnstructuredSeedReader(SeedReader[UnstructuredSeedSource]):
                     meta = json_mod.loads(meta_path.read_text(encoding = "utf-8"))
                     orig_name = meta.get("original_filename", path_obj.name)
                 except (json_mod.JSONDecodeError, OSError, UnicodeDecodeError):
+                    # Undecodable metadata is as malformed as invalid JSON, so
+                    # fall back to the file's own name rather than abort the seed.
                     pass
             file_entries.append((path_obj, orig_name))
 

studio/backend/routes/inference.py

@@ -4434,7 +4434,7 @@ def _effective_load_in_4bit(config: ModelConfig, requested: bool) -> bool:
     if not adapter_cfg_path.exists():
         return load_in_4bit
     try:
-        with open(adapter_cfg_path, encoding = "utf-8") as f:
+        with open(adapter_cfg_path, encoding = "utf-8-sig") as f:
             adapter_cfg = json.load(f)
         if not isinstance(adapter_cfg, dict):  # malformed -> keep requested
             return load_in_4bit

studio/backend/routes/models.py

@@ -722,7 +722,7 @@ def _scan_ollama_dir(ollama_dir: Path, limit: Optional[int] = None) -> List[Loca
             stem_hash = hashlib.sha256(manifest_key.encode()).hexdigest()[:10]
 
             try:
-                manifest = json.loads(tag_file.read_text(encoding = "utf-8"))
+                manifest = json.loads(tag_file.read_text(encoding = "utf-8-sig"))
             except (json.JSONDecodeError, OSError, UnicodeDecodeError) as e:
                 logger.debug(
                     "Skipping unreadable/invalid Ollama manifest %s: %s",
@@ -738,7 +738,7 @@ def _scan_ollama_dir(ollama_dir: Path, limit: Optional[int] = None) -> List[Loca
                 config_blob = blobs_dir / config_digest.replace(":", "-")
                 if config_blob.is_file():
                     try:
-                        cfg = json.loads(config_blob.read_text(encoding = "utf-8"))
+                        cfg = json.loads(config_blob.read_text(encoding = "utf-8-sig"))
                         model_type = cfg.get("model_type", "")
                         file_type = cfg.get("file_type", "")
                     except (json.JSONDecodeError, OSError, UnicodeDecodeError) as e:
@@ -1042,7 +1042,7 @@ def _dir_has_downloaded_model(directory: Path, max_entries: int = 4000) -> bool:
                 if not m.is_file():
                     continue
                 try:
-                    manifest = json.loads(m.read_text(encoding = "utf-8"))
+                    manifest = json.loads(m.read_text(encoding = "utf-8-sig"))
                 except (json.JSONDecodeError, OSError, ValueError):
                     continue
                 for layer in manifest.get("layers") or []:
@@ -3360,6 +3360,8 @@ def _wsl_reveal_in_explorer(path: Path) -> bool:
             ["wslpath", "-w", str(path)],
             capture_output = True,
             text = True,
+            encoding = "utf-8",
+            errors = "replace",
             check = True,
             timeout = 10,
         ).stdout.strip()

studio/backend/run.py

@@ -786,6 +786,8 @@ def _remove_pid_file():
             stored = _PID_FILE.read_text(encoding = "utf-8").strip()
             if stored == str(os.getpid()):
                 _PID_FILE.unlink(missing_ok = True)
+    # Runs first in _graceful_shutdown: a corrupt PID file raising here would
+    # abandon the children the rest of that function exists to kill.
     except (OSError, UnicodeDecodeError):
         pass
 

studio/backend/tests/test_chat_text_encoding.py

@@ -0,0 +1,195 @@
+# SPDX-License-Identifier: AGPL-3.0-only
+# Copyright 2026-present the Unsloth AI Inc. team. All rights reserved. See /studio/LICENSE.AGPL-3.0
+
+"""Model text stays intact when it carries non-ASCII.
+
+``open()`` and ``Path.read_text()`` fall back to ``locale.getencoding()`` when
+no ``encoding`` is passed. On Windows that is the ANSI codepage, not UTF-8, so
+a chat template or model config holding ``ä ö ü → 世`` mojibakes or raises
+``UnicodeDecodeError``. These files are UTF-8, so the reads must say so.
+
+Each fixture writes raw UTF-8 (``ensure_ascii = False``), matching what
+Hugging Face actually ships, rather than ASCII ``\\uXXXX`` escapes.
+"""
+
+from __future__ import annotations
+
+import json
+import subprocess
+import sys
+import textwrap
+from pathlib import Path
+
+
+BACKEND_ROOT = Path(__file__).resolve().parent.parent
+
+
+def test_config_json_round_trips_non_ascii(tmp_path: Path) -> None:
+    from utils import transformers_version
+
+    name = "Modell für Grüße 世界"
+    (tmp_path / "config.json").write_text(
+        json.dumps({"model_type": "llama", "_name_or_path": name}, ensure_ascii = False),
+        encoding = "utf-8",
+    )
+    transformers_version._config_json_cache.clear()
+
+    cfg = transformers_version._load_config_json(str(tmp_path))
+
+    assert cfg is not None
+    assert cfg["_name_or_path"] == name
+
+
+def test_tokenizer_config_round_trips_non_ascii_chat_template(tmp_path: Path) -> None:
+    """Chat templates commonly hold ``→`` and smart quotes, which cp1252 mangles."""
+    from utils import transformers_version
+
+    template = "{{ '→ Grüße 世界' }}"
+    (tmp_path / "tokenizer_config.json").write_text(
+        json.dumps(
+            {"tokenizer_class": "TokenizersBackend", "chat_template": template},
+            ensure_ascii = False,
+        ),
+        encoding = "utf-8",
+    )
+    transformers_version._tokenizer_class_cache.clear()
+
+    assert transformers_version._check_tokenizer_config_needs_v5(str(tmp_path)) is True
+
+
+def test_config_json_survives_a_utf8_bom(tmp_path: Path) -> None:
+    """Notepad wrote "UTF-8 with BOM" by default for years, so hand-edited
+    configs on Windows carry one. Plain utf-8 keeps the BOM and json.load then
+    fails on it; utf-8-sig strips it and is identical otherwise."""
+    from utils import transformers_version
+
+    name = "Grüße 世界"
+    (tmp_path / "config.json").write_text(
+        json.dumps({"model_type": "llama", "_name_or_path": name}, ensure_ascii = False),
+        encoding = "utf-8-sig",
+    )
+    transformers_version._config_json_cache.clear()
+
+    cfg = transformers_version._load_config_json(str(tmp_path))
+
+    assert cfg is not None
+    assert cfg["_name_or_path"] == name
+
+
+def test_remote_code_scan_reads_non_ascii_sources(tmp_path: Path) -> None:
+    """A German Windows profile also puts umlauts in the model sources scanned."""
+    from utils.security import remote_code_scan
+
+    source = "# Grüße über Öl\nVALUE = '世界'\n"
+    # newline = "" pins the bytes on disk, so Windows line end translation cannot make the
+    # read back differ by \r. open() because Path.write_text() only grew newline in 3.10.
+    with open(
+        tmp_path / "modeling_custom.py",
+        "w",
+        encoding = "utf-8",
+        newline = "",
+    ) as handle:
+        handle.write(source)
+
+    files = remote_code_scan.repo_remote_code_files(str(tmp_path))
+
+    assert files["modeling_custom.py"] == source
+
+
+def test_model_config_reads_do_not_rely_on_the_locale_encoding(tmp_path: Path) -> None:
+    """The reads above pass anywhere the locale is already UTF-8, which hides
+    the Windows bug on Linux and macOS. ``-X warn_default_encoding`` makes
+    CPython flag any text I/O that falls back to the locale, so this fails on
+    every platform if an ``encoding`` argument goes missing again."""
+    # The readers swallow exceptions, so record the warnings instead of raising.
+    script = textwrap.dedent(
+        f"""
+        import sys, warnings
+        sys.path.insert(0, {str(BACKEND_ROOT)!r})
+        from utils import transformers_version
+
+        target = {str(tmp_path)!r}
+        with warnings.catch_warnings(record = True) as caught:
+            warnings.simplefilter("always")
+            transformers_version._config_json_cache.clear()
+            transformers_version._tokenizer_class_cache.clear()
+            assert transformers_version._load_config_json(target) is not None
+            assert transformers_version._check_tokenizer_config_needs_v5(target) is True
+
+        missing = [str(w.message) for w in caught if w.category is EncodingWarning]
+        if missing:
+            sys.exit("text I/O fell back to the locale encoding: " + "; ".join(missing))
+        """
+    )
+    for name, payload in (
+        ("config.json", {"model_type": "llama", "_name_or_path": "Grüße"}),
+        ("tokenizer_config.json", {"tokenizer_class": "TokenizersBackend"}),
+    ):
+        (tmp_path / name).write_text(json.dumps(payload, ensure_ascii = False), encoding = "utf-8")
+
+    result = subprocess.run(
+        [sys.executable, "-X", "warn_default_encoding", "-c", script],
+        capture_output = True,
+        text = True,
+        encoding = "utf-8",
+        errors = "replace",
+        timeout = 120,
+    )
+
+    assert result.returncode == 0, result.stderr
+
+
+def test_utf8_child_env_round_trips_non_ascii(tmp_path: Path) -> None:
+    """A Python child encodes stdout with its locale unless told otherwise, so
+    reading its pipe as utf-8 needs the child told to emit utf-8."""
+    from utils.child_stdio import utf8_child_env
+
+    payload = "Grüße über Öl → 世界"
+    child = tmp_path / "child.py"
+    child.write_text("import sys\nsys.stdout.write(" + repr(payload) + ")\n", encoding = "utf-8")
+
+    env = utf8_child_env()
+    assert env["PYTHONIOENCODING"] == "utf-8"
+
+    proc = subprocess.run(
+        [sys.executable, str(child)],
+        capture_output = True,
+        text = True,
+        encoding = "utf-8",
+        errors = "replace",
+        env = env,
+        timeout = 120,
+    )
+
+    assert proc.returncode == 0, proc.stderr
+    assert proc.stdout == payload
+
+
+def test_python_children_are_told_to_emit_utf8() -> None:
+    """Any child we decode as utf-8 must also be told to write utf-8, or a
+    cp1252 console silently mangles what it prints."""
+    import ast
+
+    offenders: list[str] = []
+    for path in sorted(BACKEND_ROOT.rglob("*.py")):
+        parts = path.relative_to(BACKEND_ROOT).parts
+        if any(p in ("tests", "node_modules", "plugins", "__pycache__") for p in parts):
+            continue
+        source = path.read_text(encoding = "utf-8")
+        for node in ast.walk(ast.parse(source, filename = str(path))):
+            if not isinstance(node, ast.Call):
+                continue
+            func = node.func
+            if not (isinstance(func, ast.Attribute) and func.attr in ("run", "Popen")):
+                continue
+            segment = ast.get_source_segment(source, node) or ""
+            if "sys.executable" not in segment or 'encoding = "utf-8"' not in segment:
+                continue
+            if "utf8_child_env" in segment or "PYTHONIOENCODING" in segment:
+                continue
+            offenders.append(f"{path.name}:{node.lineno}")
+
+    assert not offenders, (
+        "these spawn a Python child and decode it as utf-8 without setting the "
+        "child's own stdio encoding; wrap env in utf8_child_env():\n  " + "\n  ".join(offenders)
+    )

studio/backend/tests/test_rocm_multi_gpu_vram_system_wide.py

@@ -45,8 +45,20 @@ def _build_structlog_stub():
 _maybe_stub("loggers", _build_loggers_stub)
 _maybe_stub("structlog", _build_structlog_stub)
 
+import pytest
+
 import utils.hardware.hardware as hw  # noqa: E402
 
+# The DRM/KFD readers below are Linux-only in production: _rocm_linux_amdgpu_cards and
+# _rocm_linux_sysfs_vram_by_pci_gb return early unless platform.system() is "Linux", and
+# _rocm_kfd_gpu_pci_ids only ever globs /sys/class/kfd. Their fake sysfs tree needs PCI
+# addresses like "0000:00:02.0" as directory names and POSIX separators in the paths the
+# readers match; Windows permits neither, so the tree cannot be represented there.
+linux_only = pytest.mark.skipif(
+    not sys.platform.startswith("linux"),
+    reason = "covers Linux-only DRM/KFD sysfs parsing driven by a fake /sys tree",
+)
+
 
 def _device(
     index,
@@ -99,6 +111,7 @@ def _fake_drm(tmp_path, monkeypatch, cards):
     return card_paths
 
 
+@linux_only
 def test_linux_vram_keyed_by_pci_excludes_foreign_adapters(monkeypatch, tmp_path):
     # Foreign (non-amdgpu) adapters contribute no entry, so they cannot shift ordinals.
     monkeypatch.setattr(hw.platform, "system", lambda: "Linux")
@@ -117,6 +130,7 @@ def test_linux_vram_keyed_by_pci_excludes_foreign_adapters(monkeypatch, tmp_path
     }
 
 
+@linux_only
 def test_linux_vram_omits_bad_cards_without_shifting(monkeypatch, tmp_path):
     # A zero-total card has no entry; identity keying means its absence renumbers nothing.
     monkeypatch.setattr(hw.platform, "system", lambda: "Linux")
@@ -131,6 +145,7 @@ def test_linux_vram_omits_bad_cards_without_shifting(monkeypatch, tmp_path):
     assert hw._rocm_linux_sysfs_vram_by_pci_gb() == {"0000:41:00.0": (2.0, 16.0)}
 
 
+@linux_only
 def test_linux_vram_omits_amd_card_without_vram_files(monkeypatch, tmp_path):
     # An APU with no mem_info_vram_* files has no entry; the discrete card keeps its address.
     monkeypatch.setattr(hw.platform, "system", lambda: "Linux")
@@ -174,6 +189,7 @@ def _fake_kfd(tmp_path, monkeypatch, nodes):
     return node_paths
 
 
+@linux_only
 def test_kfd_lists_gpu_nodes_in_device_order(monkeypatch, tmp_path):
     # The CPU node (simd_count 0) takes no ordinal; GPU nodes in node-id order are HIP's order.
     monkeypatch.setattr(hw.platform, "system", lambda: "Linux")
@@ -189,12 +205,14 @@ def test_kfd_lists_gpu_nodes_in_device_order(monkeypatch, tmp_path):
     assert hw._rocm_kfd_gpu_pci_ids() == ["0000:03:00.0", "0000:41:00.0"]
 
 
+@linux_only
 def test_kfd_decodes_domain_device_and_function(monkeypatch, tmp_path):
     monkeypatch.setattr(hw.platform, "system", lambda: "Linux")
     _fake_kfd(tmp_path, monkeypatch, [(1, 64, (0xC1 << 8) | (0x1F << 3) | 5, 0x1234, _AMD)])
     assert hw._rocm_kfd_gpu_pci_ids() == ["1234:c1:1f.5"]
 
 
+@linux_only
 def test_kfd_skips_non_amd_gpu_nodes(monkeypatch, tmp_path):
     # An NVIDIA KFD node is not a HIP device: it must take no ordinal, else it
     # shifts every AMD GPU and ROCm device 1 resolves to AMD GPU 0.
@@ -212,6 +230,7 @@ def test_kfd_skips_non_amd_gpu_nodes(monkeypatch, tmp_path):
     assert hw._rocm_kfd_gpu_pci_ids() == ["0000:03:00.0", "0000:41:00.0"]
 
 
+@linux_only
 def test_kfd_fails_closed_when_a_gpu_has_no_location(monkeypatch, tmp_path):
     # Dropping an unplaceable AMD GPU shifts later ordinals; fail closed for the whole map.
     monkeypatch.setattr(hw.platform, "system", lambda: "Linux")
@@ -226,6 +245,7 @@ def test_kfd_fails_closed_when_a_gpu_has_no_location(monkeypatch, tmp_path):
     assert hw._rocm_kfd_gpu_pci_ids() == []
 
 
+@linux_only
 def test_kfd_fails_closed_when_a_node_is_unreadable(monkeypatch, tmp_path):
     # An unreadable node could be a GPU; assuming otherwise would shift ordinals.
     monkeypatch.setattr(hw.platform, "system", lambda: "Linux")
@@ -241,6 +261,23 @@ def test_kfd_fails_closed_when_a_node_is_unreadable(monkeypatch, tmp_path):
     assert hw._rocm_kfd_gpu_pci_ids() == []
 
 
+@linux_only
+def test_kfd_fails_closed_when_a_node_does_not_decode(monkeypatch, tmp_path):
+    # UnicodeDecodeError is a ValueError, so it slips past `except OSError` and
+    # would shift every later HIP ordinal.
+    monkeypatch.setattr(hw.platform, "system", lambda: "Linux")
+    paths = _fake_kfd(
+        tmp_path,
+        monkeypatch,
+        [
+            (1, 304, (0x03 << 8) | 0, 0, _AMD),
+            (2, 304, (0x41 << 8) | 0, 0, _AMD),
+        ],
+    )
+    (Path(paths[0]) / "properties").write_bytes(b"simd_count 304\nvendor_id \x80\xff\n")
+    assert hw._rocm_kfd_gpu_pci_ids() == []
+
+
 def test_kfd_absent_yields_no_device_order(monkeypatch):
     monkeypatch.setattr(hw.glob, "glob", lambda pattern: [])
     assert hw._rocm_kfd_gpu_pci_ids() == []
@@ -422,6 +459,10 @@ def test_visible_utilization_rocm_fallback_overlays(monkeypatch):
     ):
         monkeypatch.delenv(_var, raising = False)
     monkeypatch.setattr(hw, "IS_ROCM", True)
+    # No AMD adapter data on this host. On Windows this branch runs ahead of the torch
+    # fallback under test, and probing it imports torch, which the CI runner does not
+    # install. Off Windows the real function is never reached, so this changes nothing.
+    monkeypatch.setattr(hw, "_rocm_windows_per_device_vram", lambda ids: [])
     monkeypatch.setattr(hw, "get_device", lambda: hw.DeviceType.CUDA)
     monkeypatch.setattr(hw, "_smi_query", lambda *a, **k: None)  # amd-smi unavailable
     monkeypatch.setattr(
@@ -450,6 +491,10 @@ def test_visible_utilization_rocm_fallback_overlays(monkeypatch):
 def test_visible_utilization_relative_index_skips_overlay(monkeypatch):
     # UUID/MIG mask gives relative indices; the overlay matches physical index, so it must not run.
     monkeypatch.setattr(hw, "IS_ROCM", True)
+    # No AMD adapter data on this host. On Windows this branch runs ahead of the torch
+    # fallback under test, and probing it imports torch, which the CI runner does not
+    # install. Off Windows the real function is never reached, so this changes nothing.
+    monkeypatch.setattr(hw, "_rocm_windows_per_device_vram", lambda ids: [])
     monkeypatch.setattr(hw, "get_device", lambda: hw.DeviceType.CUDA)
     monkeypatch.setattr(hw, "_smi_query", lambda *a, **k: None)
     monkeypatch.setattr(

studio/backend/tests/test_text_io_encoding.py

@@ -0,0 +1,809 @@
+# SPDX-License-Identifier: AGPL-3.0-only
+# Copyright 2026-present the Unsloth AI Inc. team. All rights reserved. See /studio/LICENSE.AGPL-3.0
+
+"""Text I/O must name its encoding, or Windows silently uses the ANSI codepage.
+
+``open()``, ``Path.read_text()`` and ``subprocess(text = True)`` fall back to
+``locale.getencoding()`` when no ``encoding`` is passed. On Windows that is
+cp1252 (or cp932, cp1251, ... by system locale), not UTF-8, so a chat template,
+model config or path containing ``ä ö ü → 世`` mojibakes or raises
+``UnicodeDecodeError`` mid-load. Studio's files are UTF-8, so say so.
+"""
+
+from __future__ import annotations
+
+import ast
+import importlib.util
+import json
+import os
+from pathlib import Path
+from types import SimpleNamespace
+
+import pytest
+
+
+BACKEND_ROOT = Path(__file__).resolve().parent.parent
+
+# Not runtime source. Shipped plugins under plugins/*/src are, so only builds are skipped.
+_SKIPPED_DIRS = ("node_modules", "build", "tests", "__pycache__")
+
+# Path.open()'s signature is what tells it apart from other libraries' open(),
+# e.g. fitz.open(stream=...) and av.open(..., metadata_errors=...).
+_FILE_MODE_CHARS = set("rwxabt+")
+_PATH_OPEN_ARGS = ("mode", "buffering", "encoding", "errors", "newline")
+_PATH_OPEN_KWARGS = set(_PATH_OPEN_ARGS)
+_PATH_OPEN_ENCODING_ARG = _PATH_OPEN_ARGS.index("encoding")
+
+_SUBPROCESS_CALLS = {"run", "Popen", "check_output", "check_call", "call"}
+
+# open(file, mode, buffering, encoding, ...), and os.fdopen forwards the same
+# signature with a descriptor in place of the path.
+_OPEN_ENCODING_ARG = 3
+
+
+def _studio_sources() -> list[Path]:
+    return [
+        path
+        for path in sorted(BACKEND_ROOT.rglob("*.py"))
+        if not any(part in _SKIPPED_DIRS for part in path.relative_to(BACKEND_ROOT).parts)
+    ]
+
+
+def _has_keyword(node: ast.Call, name: str) -> bool:
+    return any(keyword.arg == name for keyword in node.keywords)
+
+
+def _mode_is_binary(node: ast.Call) -> bool:
+    mode: str | None = None
+    if len(node.args) >= 2 and isinstance(node.args[1], ast.Constant):
+        value = node.args[1].value
+        mode = value if isinstance(value, str) else None
+    for keyword in node.keywords:
+        if keyword.arg == "mode" and isinstance(keyword.value, ast.Constant):
+            value = keyword.value.value
+            if isinstance(value, str):
+                mode = value
+    return bool(mode and "b" in mode)
+
+
+def _open_has_encoding(node: ast.Call) -> bool:
+    """open()/os.fdopen() also take encoding positionally: open(p, "w", 1, "utf-8")."""
+    return _has_keyword(node, "encoding") or len(node.args) > _OPEN_ENCODING_ARG
+
+
+def _path_open_mode(node: ast.Call) -> str | None:
+    if node.args and isinstance(node.args[0], ast.Constant):
+        value = node.args[0].value
+        if isinstance(value, str):
+            return value
+    for keyword in node.keywords:
+        if keyword.arg == "mode" and isinstance(keyword.value, ast.Constant):
+            value = keyword.value.value
+            if isinstance(value, str):
+                return value
+    return None
+
+
+def _is_path_open(node: ast.Call) -> bool:
+    """True only for calls matching ``Path.open``'s signature."""
+    if len(node.args) > len(_PATH_OPEN_ARGS):
+        return False
+    if any(k.arg not in _PATH_OPEN_KWARGS for k in node.keywords):
+        return False
+    mode = _path_open_mode(node)
+    if mode is not None:
+        return bool(mode) and set(mode) <= _FILE_MODE_CHARS
+    return not node.args
+
+
+def _path_open_has_encoding(node: ast.Call) -> bool:
+    """Path.open() also takes encoding positionally: open("w", 1, "utf-8")."""
+    return _has_keyword(node, "encoding") or len(node.args) > _PATH_OPEN_ENCODING_ARG
+
+
+def _call_name(node: ast.Call) -> str | None:
+    func = node.func
+    if isinstance(func, ast.Name):
+        return func.id
+    if isinstance(func, ast.Attribute):
+        return func.attr
+    return None
+
+
+def _subprocess_names(tree: ast.AST) -> set[str]:
+    """Names subprocess is reachable under here, e.g. `import subprocess as _sp`."""
+    names = set()
+    for node in ast.walk(tree):
+        if isinstance(node, ast.Import):
+            for alias in node.names:
+                if alias.name == "subprocess":
+                    names.add(alias.asname or alias.name)
+    return names
+
+
+def _subprocess_aliases(tree: ast.AST, names: set[str]) -> set[str]:
+    """Plain names bound to a subprocess callable, called without the module.
+
+    ``install_wheel(run = subprocess.run)`` calls its injected ``run`` as a bare
+    name, so matching only the attribute form leaves those installer calls
+    unguarded. Imports, assignments and parameter defaults all bind one.
+    """
+
+    def _is_bound(value: ast.expr | None) -> bool:
+        return (
+            isinstance(value, ast.Attribute)
+            and value.attr in _SUBPROCESS_CALLS
+            and isinstance(value.value, ast.Name)
+            and value.value.id in names
+        )
+
+    aliases: set[str] = set()
+    for node in ast.walk(tree):
+        if isinstance(node, ast.ImportFrom) and node.module == "subprocess":
+            aliases.update(a.asname or a.name for a in node.names if a.name in _SUBPROCESS_CALLS)
+        elif isinstance(node, ast.Assign) and _is_bound(node.value):
+            aliases.update(t.id for t in node.targets if isinstance(t, ast.Name))
+        elif isinstance(node, ast.AnnAssign) and _is_bound(node.value):
+            if isinstance(node.target, ast.Name):
+                aliases.add(node.target.id)
+        elif isinstance(node, (ast.FunctionDef, ast.AsyncFunctionDef)):
+            args = node.args
+            positional = args.posonlyargs + args.args
+            # Defaults cover the tail of the positional parameters; kw_defaults
+            # is aligned with kwonlyargs already, holding None where absent.
+            padded = [None] * (len(positional) - len(args.defaults)) + list(args.defaults)
+            pairs = list(zip(positional, padded)) + list(zip(args.kwonlyargs, args.kw_defaults))
+            aliases.update(arg.arg for arg, default in pairs if _is_bound(default))
+    return aliases
+
+
+def _is_subprocess_call(node: ast.Call, names: set[str], aliases: set[str]) -> bool:
+    func = node.func
+    if isinstance(func, ast.Name):
+        return func.id in aliases
+    if not isinstance(func, ast.Attribute) or func.attr not in _SUBPROCESS_CALLS:
+        return False
+    value = func.value
+    return isinstance(value, ast.Name) and value.id in names
+
+
+def _text_mode_subprocess(node: ast.Call) -> bool:
+    for keyword in node.keywords:
+        if keyword.arg not in ("text", "universal_newlines"):
+            continue
+        if isinstance(keyword.value, ast.Constant) and keyword.value.value is True:
+            return True
+    return False
+
+
+def _text_mode_dict(node: ast.Dict) -> bool:
+    """A ``{"text": True, ...}`` literal with no "encoding" key."""
+    keys = [k.value for k in node.keys if isinstance(k, ast.Constant)]
+    if "encoding" in keys:
+        return False
+    for key, value in zip(node.keys, node.values):
+        if not isinstance(key, ast.Constant) or key.value not in (
+            "text",
+            "universal_newlines",
+        ):
+            continue
+        if isinstance(value, ast.Constant) and value.value is True:
+            return True
+    return False
+
+
+def _splatted_names(tree: ast.AST) -> set[str]:
+    """Names handed to a call as ``**name``."""
+    names = set()
+    for node in ast.walk(tree):
+        if isinstance(node, ast.Call):
+            for keyword in node.keywords:
+                if keyword.arg is None and isinstance(keyword.value, ast.Name):
+                    names.add(keyword.value.id)
+    return names
+
+
+def _encoding_assigned_later(tree: ast.AST, name: str) -> bool:
+    """``name["encoding"] = ...`` somewhere, so the literal need not carry it."""
+    for node in ast.walk(tree):
+        if not isinstance(node, ast.Subscript) or not isinstance(node.ctx, ast.Store):
+            continue
+        target, key = node.value, node.slice
+        if isinstance(target, ast.Name) and target.id == name:
+            if isinstance(key, ast.Constant) and key.value == "encoding":
+                return True
+    return False
+
+
+def _splatted_kwargs_offenders(tree: ast.AST) -> list[ast.Dict]:
+    """Text-mode kwargs built in a dict and splatted into a call.
+
+    Kwargs are collected in a dict and splatted (``run(cmd, **run_kwargs)``)
+    where a branch has to add a timeout or an env, and the call is often through
+    a helper, so neither the callee nor the keywords are visible at the call
+    site. Only dicts that reach a call this way are judged: an unrelated payload
+    that happens to carry ``"text": True`` is not subprocess configuration.
+    """
+    found = []
+    # ``run(cmd, **{...})``: the literal is at the call already.
+    for node in ast.walk(tree):
+        if not isinstance(node, ast.Call):
+            continue
+        for keyword in node.keywords:
+            if keyword.arg is None and isinstance(keyword.value, ast.Dict):
+                if _text_mode_dict(keyword.value):
+                    found.append(keyword.value)
+    splatted = _splatted_names(tree)
+    if not splatted:
+        return found
+    for node in ast.walk(tree):
+        targets = []
+        if isinstance(node, ast.Assign):
+            targets = [t for t in node.targets if isinstance(t, ast.Name)]
+        elif isinstance(node, ast.AnnAssign) and isinstance(node.target, ast.Name):
+            targets = [node.target]
+        if not targets or not isinstance(node.value, ast.Dict):
+            continue
+        if not _text_mode_dict(node.value):
+            continue
+        for target in targets:
+            if target.id in splatted and not _encoding_assigned_later(tree, target.id):
+                found.append(node.value)
+                break
+    return found
+
+
+def _offenders(path: Path) -> list[str]:
+    source = path.read_text(encoding = "utf-8")
+    tree = ast.parse(source, filename = str(path))
+    subprocess_names = _subprocess_names(tree)
+    subprocess_aliases = _subprocess_aliases(tree, subprocess_names)
+    found: list[str] = []
+    for node in _splatted_kwargs_offenders(tree):
+        found.append(
+            f"{path.name}:{node.lineno}: subprocess kwargs with text = True and no encoding"
+        )
+    for node in ast.walk(tree):
+        if not isinstance(node, ast.Call):
+            continue
+        name = _call_name(node)
+
+        if _is_subprocess_call(node, subprocess_names, subprocess_aliases):
+            if _text_mode_subprocess(node) and not _has_keyword(node, "encoding"):
+                found.append(f"{path.name}:{node.lineno}: subprocess(text = True) without encoding")
+            continue
+
+        if name == "open" and isinstance(node.func, ast.Name):
+            if _mode_is_binary(node) or _open_has_encoding(node):
+                continue
+            found.append(f"{path.name}:{node.lineno}: open() without encoding")
+            continue
+
+        # os.fdopen(fd, "w") is open() on a descriptor, so text mode takes the
+        # same locale default. Its mode defaults to "r", i.e. text, like open's.
+        if name == "fdopen":
+            if _mode_is_binary(node) or _open_has_encoding(node):
+                continue
+            found.append(f"{path.name}:{node.lineno}: os.fdopen() without encoding")
+            continue
+
+        if name == "open" and isinstance(node.func, ast.Attribute):
+            if not _is_path_open(node) or _path_open_has_encoding(node):
+                continue
+            if _path_open_mode(node) and "b" in _path_open_mode(node):
+                continue
+            found.append(f"{path.name}:{node.lineno}: Path.open() without encoding")
+            continue
+
+        if name in ("read_text", "write_text") and isinstance(node.func, ast.Attribute):
+            if _has_keyword(node, "encoding"):
+                continue
+            # importlib.metadata Distribution.read_text() takes no encoding kwarg.
+            if isinstance(node.func.value, ast.Name) and node.func.value.id == "dist":
+                continue
+            found.append(f"{path.name}:{node.lineno}: {name}() without encoding")
+    return found
+
+
+@pytest.mark.parametrize("path", _studio_sources(), ids = lambda p: str(p.name))
+def test_text_io_names_its_encoding(path: Path) -> None:
+    offenders = _offenders(path)
+    assert not offenders, (
+        "Text I/O without an explicit encoding falls back to the Windows ANSI "
+        'codepage and corrupts non-ASCII (ä ö ü → 世). Pass encoding = "utf-8":\n  '
+        + "\n  ".join(offenders)
+    )
+
+
+_STATE_STORE = (
+    BACKEND_ROOT
+    / "plugins/data-designer-github-repo-seed/src"
+    / "data_designer_github_repo_seed/scraper_impl/state_store.py"
+)
+
+
+def _load_state_store(codepage: str):
+    """Load state_store with the writing machine's codepage pinned."""
+    spec = importlib.util.spec_from_file_location(f"state_store_{codepage}", _STATE_STORE)
+    module = importlib.util.module_from_spec(spec)
+    spec.loader.exec_module(module)
+    module.locale = SimpleNamespace(
+        getencoding = lambda: codepage,
+        getpreferredencoding = lambda _ = True: codepage,
+    )
+    return module
+
+
+@pytest.mark.parametrize(
+    ("codepage", "name"), [("cp1252", "Jürgen"), ("cp1251", "Юрий"), ("cp932", "田中")]
+)
+def test_resuming_a_legacy_jsonl_keeps_one_encoding(
+    tmp_path: Path, codepage: str, name: str
+) -> None:
+    """A scrape written before UTF-8 was explicit must resume, not duplicate."""
+    path = tmp_path / "out.jsonl"
+    records = [{"id": 1, "author": name}, {"id": 2, "author": name}]
+    body = "".join(json.dumps(r, ensure_ascii = False) + "\n" for r in records)
+    path.write_bytes(body.encode(codepage))
+    before = path.read_bytes()
+
+    writer = _load_state_store(codepage).JsonlWriter(path)
+    try:
+        # Seen keys survive the resume, so a repeat is refused, not appended.
+        assert writer.has("id:1") and writer.has("id:2")
+        assert writer.write(records[0]) is False
+        assert writer.write({"id": 3, "author": name}) is True
+    finally:
+        writer.close()
+
+    # Never converted, so it still reads in its own codepage; the append is ASCII.
+    blob = path.read_bytes()
+    assert blob.startswith(before)
+    assert blob[len(before) :].isascii()
+    lines = [json.loads(x) for x in blob.decode(codepage).splitlines() if x.strip()]
+    assert len(lines) == 3
+    assert [line["author"] for line in lines] == [name] * 3
+
+
+def test_a_coincidentally_utf8_legacy_line_is_left_alone(tmp_path: Path) -> None:
+    """cp1251 `Р°` is D0 B0, which is also UTF-8 `а`, and nothing can tell them apart."""
+    path = tmp_path / "out.jsonl"
+    ambiguous = "Р°"
+    assert ambiguous.encode("cp1251").decode("utf-8") == "а"  # the trap
+    authors = ["Привет", "Здравствуйте", "Москва", ambiguous]
+    path.write_bytes(
+        b"".join(
+            json.dumps({"id": i, "author": a}, ensure_ascii = False).encode("cp1251") + b"\n"
+            for i, a in enumerate(authors)
+        )
+    )
+    before = path.read_bytes()
+
+    _load_state_store("cp1251").JsonlWriter(path).close()
+
+    # Untouched, so the ambiguity never had to be resolved.
+    assert path.read_bytes() == before
+    rows = [json.loads(x) for x in path.read_text(encoding = "cp1251").splitlines() if x.strip()]
+    assert [row["author"] for row in rows] == authors
+
+
+@pytest.mark.parametrize(
+    ("codepage", "word"), [("cp1251", "Привет"), ("cp932", "こんにちは"), ("cp1252", "Jürgen")]
+)
+def test_a_moved_shard_is_not_rewritten_by_guesswork(
+    tmp_path: Path, codepage: str, word: str
+) -> None:
+    """Off the writing machine there is no codepage to attribute the file to."""
+    path = tmp_path / "out.jsonl"
+    # Two records: a lone non-UTF-8 line would count as damage, not legacy.
+    path.write_bytes(
+        b"".join(
+            json.dumps({"id": i, "author": word}, ensure_ascii = False).encode(codepage) + b"\n"
+            for i in (1, 4)
+        )
+    )
+    before = path.read_bytes()
+
+    # A UTF-8 host: latin-1 would read cp1251 `Привет` back as `Ïðèâåò`.
+    writer = _load_state_store("utf-8").JsonlWriter(path)
+    try:
+        assert writer.has("id:1")  # ASCII keys still recover
+        assert writer.write({"id": 2, "author": "Grüße"}) is True
+    finally:
+        writer.close()
+
+    blob = path.read_bytes()
+    assert blob.startswith(before)  # never rewritten
+    assert blob[len(before) :].isascii()  # appended as \uXXXX, so no second encoding
+    rows = [json.loads(x) for x in blob.decode(codepage).splitlines() if x.strip()]
+    assert [row["author"] for row in rows] == [word, word, "Grüße"]
+
+
+def test_an_all_ambiguous_shard_still_gets_ascii_appends(tmp_path: Path) -> None:
+    """Every line valid under both readings still means the append must not pick one."""
+    path = tmp_path / "out.jsonl"
+    ambiguous = "Р°"  # cp1251 D0 B0, also valid UTF-8 for "а"
+    path.write_bytes(
+        b"".join(
+            json.dumps({"id": i, "a": ambiguous}, ensure_ascii = False).encode("cp1251") + b"\n"
+            for i in range(3)
+        )
+    )
+    before = path.read_bytes()
+
+    writer = _load_state_store("cp1251").JsonlWriter(path)
+    try:
+        assert writer.write({"id": 9, "a": "世界"}) is True
+    finally:
+        writer.close()
+
+    blob = path.read_bytes()
+    assert blob.startswith(before)
+    # ASCII, so the appended record survives whichever reading is chosen.
+    assert blob[len(before) :].isascii()
+    for codec in ("cp1251", "utf-8"):
+        rows = [json.loads(x) for x in blob.decode(codec).splitlines() if x.strip()]
+        assert rows[-1]["a"] == "世界"
+
+
+def test_a_damaged_line_in_an_ascii_shard_does_not_block_its_retry(tmp_path: Path) -> None:
+    """With no non-ASCII records to outvote it, one damaged line is still damage."""
+    path = tmp_path / "out.jsonl"
+    path.write_bytes(
+        b'{"id": 1, "author": "alice"}\n'
+        + b'{"id": 99, "author": "bad \x96 byte"}\n'
+        + b'{"id": 2, "author": "bob"}\n'
+    )
+
+    writer = _load_state_store("cp1252").JsonlWriter(path)
+    try:
+        assert writer.has("id:1") and writer.has("id:2")
+        assert not writer.has("id:99")
+        assert writer.write({"id": 99, "author": "good byte"}) is True
+    finally:
+        writer.close()
+
+
+def test_a_damaged_line_does_not_block_its_own_retry(tmp_path: Path) -> None:
+    """Its key comes from the codepage reading, which a UTF-8 shard did not pick."""
+    path = tmp_path / "out.jsonl"
+    path.write_bytes(
+        json.dumps({"id": 1, "author": "Jürgen"}, ensure_ascii = False).encode()
+        + b"\n"
+        + b'{"id": 99, "author": "bad \x96 byte"}\n'
+    )
+
+    writer = _load_state_store("cp1252").JsonlWriter(path)
+    try:
+        assert writer.has("id:1")
+        assert not writer.has("id:99")
+        assert writer.write({"id": 99, "author": "good byte"}) is True
+    finally:
+        writer.close()
+
+
+def test_one_damaged_byte_does_not_relabel_a_utf8_shard(tmp_path: Path) -> None:
+    """A complete JSON line with a stray 0x96 parses as cp1252, but is only one vote."""
+    path = tmp_path / "out.jsonl"
+    healthy = ["Jürgen", "Grüße", "Björn"]
+    path.write_bytes(
+        json.dumps({"id": 0, "author": healthy[0]}, ensure_ascii = False).encode()
+        + b"\n"
+        + b'{"id": 99, "author": "bad \x96 byte"}\n'
+        + b"".join(
+            json.dumps({"id": i, "author": a}, ensure_ascii = False).encode() + b"\n"
+            for i, a in enumerate(healthy[1:], start = 1)
+        )
+    )
+    before = path.read_bytes()
+
+    _load_state_store("cp1252").JsonlWriter(path).close()
+
+    # Untouched, so the healthy records were never re-read as cp1252.
+    assert path.read_bytes() == before
+    rows = []
+    for line in path.read_bytes().splitlines():
+        try:
+            rows.append(json.loads(line.decode()))
+        except (UnicodeDecodeError, ValueError):
+            continue
+    assert [row["author"] for row in rows] == healthy
+
+
+def test_a_torn_line_does_not_relabel_a_utf8_shard(tmp_path: Path) -> None:
+    """One interrupted append must not get the whole shard read as cp1252."""
+    path = tmp_path / "out.jsonl"
+    good = [{"id": 1, "author": "Jürgen"}, {"id": 3, "author": "Grüße"}]
+    torn = '{"id": 2, "author": "Jürgen"}'.encode()[:-6]  # cut mid-character
+    path.write_bytes(
+        json.dumps(good[0], ensure_ascii = False).encode()
+        + b"\n"
+        + torn
+        + b"\n"
+        + json.dumps(good[1], ensure_ascii = False).encode()
+        + b"\n"
+    )
+    before = path.read_bytes()
+
+    writer = _load_state_store("cp1252").JsonlWriter(path)
+    try:
+        assert writer.has("id:1") and writer.has("id:3")
+        assert not writer.has("id:2")  # torn line yields no key
+    finally:
+        writer.close()
+
+    # Untouched: no rewrite, so no record was re-encoded into mojibake.
+    after = path.read_bytes()
+    assert after.startswith(before)
+    assert "Jürgen".encode() in after
+    assert "Jürgen".encode("utf-8").decode("cp1252").encode() not in after
+
+
+def test_an_undecodable_transport_marker_reads_as_unknown(tmp_path: Path) -> None:
+    """Pinning the decode turns an undecodable marker into UnicodeDecodeError,
+    which is a ValueError and so is not an OSError. Before the pin those bytes
+    simply read as an unknown value and the caller safely purged and restarted
+    the partial download; letting the error escape aborts the transfer instead.
+    """
+    import sys
+
+    backend = str(Path(__file__).resolve().parent.parent)
+    if backend not in sys.path:
+        sys.path.insert(0, backend)
+    from hub.utils import download_registry as registry
+
+    marker = tmp_path / ".transport"
+    marker.write_bytes(b"\x80\xffnative\n")
+    assert registry._read_marker_value(marker) is None
+    # A readable but unknown value takes the same path (the behaviour restored).
+    marker.write_text("something-else\n", encoding = "utf-8")
+    assert registry._read_marker_value(marker) is None
+
+
+def test_a_torn_cache_ref_reads_as_not_cached(tmp_path: Path, monkeypatch) -> None:
+    """hf_cache_snapshot_dir answers "is this model already on disk", and the
+    offline embedding checks turn a raise into a 500. A refs/main holding a byte
+    the codepage used to decode into a nonsense commit simply missed the snapshot
+    dir before the pin; it has to keep missing it."""
+    import sys
+
+    backend = str(Path(__file__).resolve().parent.parent)
+    if backend not in sys.path:
+        sys.path.insert(0, backend)
+    from utils import utils as backend_utils
+
+    good_root = tmp_path / "good"
+    torn_root = tmp_path / "torn"
+    for root, ref_bytes in ((torn_root, b"\x80\xff\n"), (good_root, b"abc123\n")):
+        repo = root / "models--Org--Model"
+        (repo / "refs").mkdir(parents = True)
+        (repo / "refs" / "main").write_bytes(ref_bytes)
+    (good_root / "models--Org--Model" / "snapshots" / "abc123").mkdir(parents = True)
+
+    monkeypatch.setattr(backend_utils, "_hf_cache_roots", lambda: [torn_root])
+    assert backend_utils.hf_cache_snapshot_dir("Org/Model") is None
+    # The torn root is skipped, not fatal: a healthy second root still answers.
+    monkeypatch.setattr(backend_utils, "_hf_cache_roots", lambda: [torn_root, good_root])
+    found = backend_utils.hf_cache_snapshot_dir("Org/Model")
+    assert found is not None and found.name == "abc123"
+
+
+def test_a_corrupt_pid_file_does_not_abort_shutdown(tmp_path: Path, monkeypatch) -> None:
+    """_remove_pid_file runs first in _graceful_shutdown, so a raise there leaves
+    the inference, export, training and tunnel children alive."""
+    import sys
+
+    backend = str(Path(__file__).resolve().parent.parent)
+    if backend not in sys.path:
+        sys.path.insert(0, backend)
+    import run as studio_run
+
+    pid_file = tmp_path / "studio.pid"
+    pid_file.write_bytes(b"\x80\xff")
+    monkeypatch.setattr(studio_run, "_PID_FILE", pid_file)
+    studio_run._remove_pid_file()
+    # Not this process's PID, so the file stays; the point is that it returned.
+    assert pid_file.exists()
+
+    pid_file.write_text(str(os.getpid()), encoding = "utf-8")
+    studio_run._remove_pid_file()
+    assert not pid_file.exists()
+
+
+def test_the_kwargs_guard_only_judges_dicts_that_reach_a_call(tmp_path: Path) -> None:
+    """Only a dict splatted into a call is subprocess configuration. An unrelated
+    payload that happens to carry "text": True is not, and neither is one whose
+    encoding is filled in on a later line."""
+    cases = {
+        "offender.py": 'kw = {"text": True}\nrun(cmd, **kw)\n',
+        "annotated.py": 'kw: dict = {"universal_newlines": True}\nrun(cmd, **kw)\n',
+        "payload.py": 'payload = {"text": True}\nrequests.post(url, json = payload)\n',
+        "inline.py": 'run(cmd, **{"text": True})\n',
+        "later.py": 'kw = {"text": True}\nkw["encoding"] = "utf-8"\nrun(cmd, **kw)\n',
+        "carried.py": 'kw = {"text": True, "encoding": "utf-8"}\nrun(cmd, **kw)\n',
+    }
+    flagged = set()
+    for name, source in cases.items():
+        path = tmp_path / name
+        path.write_text(source, encoding = "utf-8")
+        if any("subprocess kwargs" in line for line in _offenders(path)):
+            flagged.add(name)
+    assert flagged == {"offender.py", "annotated.py", "inline.py"}, flagged
+
+
+def test_the_guard_follows_subprocess_through_an_alias(tmp_path: Path) -> None:
+    """install_wheel() takes ``run = subprocess.run`` and calls it as a bare
+    name, so an attribute-only match let both of its installer calls drop their
+    encoding unnoticed. A name bound to something else is still not subprocess."""
+    cases = {
+        "param_default.py": (
+            "import subprocess\n"
+            "def install(*, run = subprocess.run):\n"
+            "    run(cmd, text = True)\n"
+        ),
+        "assigned.py": "import subprocess\n_run = subprocess.run\n_run(cmd, text = True)\n",
+        "imported.py": "from subprocess import check_output\ncheck_output(cmd, text = True)\n",
+        "renamed.py": "from subprocess import run as _r\n_r(cmd, universal_newlines = True)\n",
+        "encoded.py": (
+            "import subprocess\n"
+            "def install(*, run = subprocess.run):\n"
+            '    run(cmd, text = True, encoding = "utf-8")\n'
+        ),
+        "unrelated.py": "def run(cmd, text = False):\n    pass\nrun(cmd, text = True)\n",
+    }
+    flagged = set()
+    for name, source in cases.items():
+        path = tmp_path / name
+        path.write_text(source, encoding = "utf-8")
+        if any("subprocess(text = True)" in line for line in _offenders(path)):
+            flagged.add(name)
+    assert flagged == {"param_default.py", "assigned.py", "imported.py", "renamed.py"}, flagged
+
+
+def test_the_guard_sees_os_fdopen(tmp_path: Path) -> None:
+    """os.fdopen(fd, mode) is open() on a descriptor and takes the same locale
+    default in text mode, so leaving it out let the swap lock file keep the
+    codepage on the write side while its reader was pinned to UTF-8."""
+    cases = {
+        "text.py": 'import os\nos.fdopen(fd, "w")\n',
+        "default_mode.py": "import os\nos.fdopen(fd)\n",  # defaults to "r", still text
+        "binary.py": 'import os\nos.fdopen(fd, "wb")\n',
+        "keyword.py": 'import os\nos.fdopen(fd, "w", encoding = "utf-8")\n',
+        "positional.py": 'import os\nos.fdopen(fd, "w", 1, "utf-8")\n',
+    }
+    flagged = set()
+    for name, source in cases.items():
+        path = tmp_path / name
+        path.write_text(source, encoding = "utf-8")
+        if any("fdopen" in line for line in _offenders(path)):
+            flagged.add(name)
+    assert flagged == {"text.py", "default_mode.py"}, flagged
+
+
+def test_an_undecodable_bootstrap_password_does_not_stop_startup(
+    tmp_path: Path, monkeypatch
+) -> None:
+    """ensure_default_admin calls _load_bootstrap_password for every existing
+    admin and the lifespan calls that with no handler, so a raise here takes the
+    whole backend down instead of ignoring an unusable file."""
+    import sys
+
+    backend = str(Path(__file__).resolve().parent.parent)
+    if backend not in sys.path:
+        sys.path.insert(0, backend)
+    from auth import storage
+
+    pw_file = tmp_path / ".bootstrap_password"
+    pw_file.write_bytes(b"\x80\xffnot-utf8\n")
+    monkeypatch.setattr(storage, "_BOOTSTRAP_PW_PATH", pw_file)
+    assert storage._load_bootstrap_password() is None
+
+    # A readable one still loads, so this is a narrowing of failure, not of function.
+    pw_file.write_text("correct horse battery staple\n", encoding = "utf-8")
+    assert storage._load_bootstrap_password() == "correct horse battery staple"
+
+
+def test_a_damaged_checkpoint_resets_instead_of_resuming_on_a_broken_cursor(tmp_path: Path) -> None:
+    """A checkpoint holds only base64 cursors and booleans, so a codepage reading
+    can only ever add non-ASCII, never recover any. Resuming on a mojibaked cursor
+    sends GitHub one it answers with INVALID_CURSOR_ARGUMENTS, and the empty page
+    that comes back marks the stream done and skips the rest of it for good.
+    Dropping the checkpoint only replays pages the writers already dedup."""
+    module = _load_state_store("cp1252")
+    cursor = "Y3Vyc29yOnYyOpK0MjAxMi0wMi0xNlQwNjo1Mzo0MVrOADGL_A=="
+    healthy = json.dumps({"issues_cursor": cursor, "issues_done": False}, indent = 2)
+    path = tmp_path / "octocat__Hello-World.json"
+
+    path.write_text(healthy, encoding = "utf-8")
+    assert module.StateStore(path).get("issues_cursor") == cursor
+
+    # Written by a pre-UTF-8 release in the operator's codepage. Nothing is lost
+    # by reading UTF-8 only, because an all-ASCII document is the same bytes.
+    path.write_bytes(healthy.encode("cp1252"))
+    assert module.StateStore(path).get("issues_cursor") == cursor
+
+    # One damaged byte inside the cursor: still a whole JSON document under a
+    # single-byte codepage, so only refusing that reading resets the checkpoint.
+    raw = healthy.encode()
+    at = raw.index(b"MjAxMi0wMi0xNlQ") + 3
+    path.write_bytes(raw[:at] + b"\x96" + raw[at + 1 :])
+    assert json.loads(path.read_bytes().decode("latin-1"))["issues_cursor"] != cursor
+    store = module.StateStore(path)
+    assert store.all() == {}
+    assert store.get("issues_cursor") is None
+
+
+def test_a_utf8_record_is_not_parsed_a_second_time(tmp_path: Path) -> None:
+    """These shards reach gigabytes and every resume reads all of one, so a
+    record that already read as UTF-8 must not be decoded and parsed again under
+    the codepage. The legacy reading exists only to recover keys UTF-8 could not."""
+    module = _load_state_store("cp1252")
+    calls: list[str] = []
+    real_parse = module._parse
+
+    def counting_parse(raw, encoding):
+        calls.append(encoding)
+        return real_parse(raw, encoding)
+
+    module._parse = counting_parse
+    try:
+        healthy = json.dumps({"id": 1, "author": "Jürgen"}).encode("utf-8")
+        reading = module._read_line(healthy, "cp1252")
+        assert reading.as_utf8 == {"id": 1, "author": "Jürgen"}
+        assert calls == ["utf-8"], calls
+
+        # A line UTF-8 cannot read still falls through to the codepage, the whole point.
+        calls.clear()
+        legacy = json.dumps({"id": 2, "author": "Jürgen"}, ensure_ascii = False).encode("cp1252")
+        reading = module._read_line(legacy, "cp1252")
+        assert reading.as_utf8 is None
+        assert reading.as_legacy == {"id": 2, "author": "Jürgen"}
+        assert calls == ["utf-8", "cp1252"], calls
+    finally:
+        module._parse = real_parse
+
+
+def _too_deeply_nested_json() -> str:
+    """A JSON document nested past what this interpreter will descend into.
+
+    Probed rather than hardcoded: the depth json.loads gives up at is bounded by
+    sys.getrecursionlimit() up to 3.11 and by the C recursion limit from 3.12,
+    which sys.setrecursionlimit no longer moves and which varies by micro
+    version. That is ~995 on 3.9 and ~9999 on 3.13.
+    """
+    depth = 1
+    while depth <= 1 << 17:
+        document = "[" * depth + "]" * depth
+        try:
+            json.loads(document)
+        except RecursionError:
+            return document
+        depth *= 2
+    pytest.skip("this interpreter parses arbitrarily nested JSON")
+
+
+def test_an_unparseably_nested_document_is_discarded_not_raised(tmp_path: Path) -> None:
+    """json.loads answers nesting it cannot descend with RecursionError, which is
+    a RuntimeError and so is neither a ValueError nor a UnicodeDecodeError.
+    _parse is called outside any other handler in both StateStore.__init__ and
+    JsonlWriter._scan_existing, so letting it escape aborts the scraper at
+    startup on a file the catch-all it replaced simply discarded."""
+    module = _load_state_store("cp1252")
+    nested = _too_deeply_nested_json()
+
+    checkpoint = tmp_path / "octocat__Hello-World.json"
+    checkpoint.write_text(nested, encoding = "utf-8")
+    assert module.StateStore(checkpoint).all() == {}  # reset, not raised
+
+    shard = tmp_path / "out.jsonl"
+    shard.write_text(
+        nested + "\n" + json.dumps({"id": 1}) + "\n" + json.dumps({"id": 2}) + "\n",
+        encoding = "utf-8",
+    )
+    writer = module.JsonlWriter(shard)
+    try:
+        # Skipped like any other unreadable line, so its neighbours still yield the dedup
+        # keys that keep the resume from re-fetching them.
+        assert writer.has("id:1") and writer.has("id:2")
+    finally:
+        writer.close()

studio/backend/tests/test_training_worker_flash_attn.py

@@ -9,8 +9,28 @@ import sys
 from typing import Any
 from unittest import mock
 
+import pytest
+
 from core.training import worker
 
+# The runtime install is Linux-only, so elsewhere these return before any status.
+linux_only = pytest.mark.skipif(
+    not sys.platform.startswith("linux"),
+    reason = "the runtime flash-attn install is gated to Linux",
+)
+
+# causal-conv1d and flash-linear-attention are NOT Linux-gated: both installers bail out
+# on `sys.platform == "win32"` alone (no prebuilt wheel for Windows) and run everywhere
+# else, macOS included. linux_only here would skip cases that legitimately pass off Linux.
+not_on_windows = pytest.mark.skipif(
+    sys.platform == "win32",
+    reason = (
+        "mirrors the sys.platform == 'win32' bail-out in "
+        "_ensure_flash_linear_attention_unconditional and "
+        "_ensure_causal_conv1d_fast_path"
+    ),
+)
+
 
 def _missing_flash_attn_import():
     real_import = builtins.__import__
@@ -55,6 +75,7 @@ def test_should_try_runtime_flash_attn_install_threshold_and_skip(monkeypatch):
     assert worker._should_try_runtime_flash_attn_install(32768) is False
 
 
+@linux_only
 def test_runtime_flash_attn_prefers_prebuilt_wheel(monkeypatch):
     statuses: list[str] = []
 
@@ -82,6 +103,7 @@ def test_runtime_flash_attn_prefers_prebuilt_wheel(monkeypatch):
     assert statuses == ["Installing flash-attn for faster training..."]
 
 
+@linux_only
 def test_runtime_flash_attn_falls_back_to_pypi(monkeypatch):
     calls: list[list[str]] = []
     statuses: list[str] = []
@@ -113,12 +135,7 @@ def test_runtime_flash_attn_falls_back_to_pypi(monkeypatch):
     )
     monkeypatch.setattr(worker, "install_wheel", mock.Mock())
 
-    def fake_run(
-        cmd,
-        stdout = None,
-        stderr = None,
-        text = None,
-    ):
+    def fake_run(cmd, **kwargs):
         calls.append(list(cmd))
         return subprocess.CompletedProcess(cmd, 0, "")
 
@@ -139,6 +156,7 @@ def test_runtime_flash_attn_skip_env_avoids_all_install_work(monkeypatch):
     worker._sp.run.assert_not_called()
 
 
+@not_on_windows
 def test_causal_conv1d_fast_path_preserves_wheel_first_install_args(monkeypatch):
     install_mock = mock.Mock(return_value = True)
     monkeypatch.setattr(worker, "_install_package_wheel_first", install_mock)
@@ -160,6 +178,7 @@ def test_causal_conv1d_fast_path_preserves_wheel_first_install_args(monkeypatch)
     )
 
 
+@not_on_windows
 def test_causal_conv1d_fast_path_includes_qwen3_6_variants(monkeypatch):
     install_mock = mock.Mock(return_value = True)
     monkeypatch.setattr(worker, "_install_package_wheel_first", install_mock)
@@ -225,6 +244,7 @@ def _pin_fla_model_types(monkeypatch):
     )
 
 
+@not_on_windows
 def test_flash_linear_attention_installs_pinned_pair_for_qwen3_5(monkeypatch):
     _pin_fla_model_types(monkeypatch)
     monkeypatch.setattr(worker.shutil, "which", lambda name: "/usr/bin/uv")
@@ -277,6 +297,7 @@ def test_flash_linear_attention_skips_for_ssm_only_models(monkeypatch):
     run_mock.assert_not_called()
 
 
+@not_on_windows
 def test_flash_linear_attention_matches_full_qwen3_family(monkeypatch):
     monkeypatch.setattr(worker.shutil, "which", lambda name: "/usr/bin/uv")
     run_mock = mock.Mock(return_value = mock.Mock(returncode = 0, stdout = ""))
@@ -331,6 +352,7 @@ def test_flash_linear_attention_skipped_via_env(monkeypatch):
     run_mock.assert_not_called()
 
 
+@not_on_windows
 def test_flash_linear_attention_skipped_below_torch_2_7(monkeypatch):
     _pin_fla_model_types(monkeypatch)
     monkeypatch.delenv(worker._FLA_SKIP_ENV, raising = False)
@@ -349,6 +371,7 @@ def test_flash_linear_attention_skipped_below_torch_2_7(monkeypatch):
     assert any("torch>=" in s for s in statuses)
 
 
+@not_on_windows
 def test_flash_linear_attention_install_includes_einops(monkeypatch):
     _pin_fla_model_types(monkeypatch)
     monkeypatch.delenv(worker._FLA_SKIP_ENV, raising = False)
@@ -375,6 +398,7 @@ def test_flash_linear_attention_install_includes_einops(monkeypatch):
     assert f"fla-core=={worker._FLA_CORE_PACKAGE_VERSION}" in args
 
 
+@not_on_windows
 def test_flash_linear_attention_logs_post_install_import_failure(monkeypatch):
     """pip exits 0 but `import fla.modules` still fails (missing transitive)."""
     _pin_fla_model_types(monkeypatch)
@@ -421,6 +445,7 @@ def test_tilelang_backend_skipped_on_unsupported_linux_arch(monkeypatch):
     run_mock.assert_not_called()
 
 
+@linux_only
 def test_tilelang_backend_pins_only_binary(monkeypatch):
     _pin_fla_model_types(monkeypatch)
     monkeypatch.delenv(worker._TILELANG_SKIP_ENV, raising = False)
@@ -462,6 +487,7 @@ def _force_missing_tilelang_imports(monkeypatch):
     monkeypatch.setattr(builtins, "__import__", fake_import)
 
 
+@linux_only
 def test_tilelang_backend_installs_pinned_pair_for_qwen3_5(monkeypatch):
     _pin_fla_model_types(monkeypatch)
     monkeypatch.delenv(worker._TILELANG_SKIP_ENV, raising = False)
@@ -486,6 +512,7 @@ def test_tilelang_backend_installs_pinned_pair_for_qwen3_5(monkeypatch):
     assert any("Installing TileLang" in s for s in statuses)
 
 
+@linux_only
 def test_tilelang_backend_reinstalls_when_tvm_ffi_is_broken(monkeypatch):
     """Repair path issues TWO pip calls:
 
@@ -555,6 +582,7 @@ def test_tilelang_backend_skipped_on_windows(monkeypatch):
     run_mock.assert_not_called()
 
 
+@linux_only
 def test_tilelang_backend_swallows_install_timeout(monkeypatch):
     _pin_fla_model_types(monkeypatch)
     monkeypatch.delenv(worker._TILELANG_SKIP_ENV, raising = False)
@@ -609,6 +637,7 @@ def test_tilelang_backend_skipped_via_env(monkeypatch):
     run_mock.assert_not_called()
 
 
+@linux_only
 def test_tilelang_backend_swallows_install_failure(monkeypatch):
     _pin_fla_model_types(monkeypatch)
     monkeypatch.delenv(worker._TILELANG_SKIP_ENV, raising = False)
@@ -673,6 +702,7 @@ def _patch_iu_gates(monkeypatch, fla_gate, conv_gate):
     monkeypatch.setattr(_iu, "is_causal_conv1d_available", conv_gate)
 
 
+@not_on_windows
 def test_hook_installs_when_gate_returns_false(monkeypatch):
     _pin_fla_model_types(monkeypatch)
     fla_gate = _make_fake_gate(initial_return = False)
@@ -976,6 +1006,7 @@ def test_hook_does_install_tilelang_for_qwen35(monkeypatch):
     tile_install.assert_called_once()
 
 
+@linux_only
 def test_tilelang_repair_does_not_touch_torch_cuda_stack(monkeypatch):
     """Finding #2: the broken-tvm-ffi repair must use --no-deps on the
     forced step so --force-reinstall doesn't cascade through
@@ -1119,6 +1150,7 @@ def test_hook_runs_tilelang_repair_when_fla_already_true(monkeypatch):
     tile_install.assert_called_once()
 
 
+@not_on_windows
 def test_fla_installer_force_reinstalls_when_older_version_present(monkeypatch):
     """Finding #8: an older `flash-linear-attention` that is importable
     but below the pin must force a reinstall (not no-op).
@@ -1583,15 +1615,10 @@ def test_install_respects_user_gcc_install_dir(monkeypatch):
     )
     _make_hip_install_env(monkeypatch, gcc_dir = "/usr/lib/gcc/x86_64-linux-gnu/13")
 
-    captured: dict[str, str] | None = {"_called": "no"}
+    captured: dict[str, str] = {}
 
     def fake_run(cmd, **kwargs):
-        env = kwargs.get("env")
-        if env is not None:
-            captured.clear()
-            captured.update(env)
-        else:
-            captured["_called"] = "yes_no_env"
+        captured.update(kwargs.get("env") or {})
         return subprocess.CompletedProcess(cmd, 0, "")
 
     monkeypatch.setattr(worker._sp, "run", fake_run)
@@ -1607,14 +1634,11 @@ def test_install_respects_user_gcc_install_dir(monkeypatch):
         release_base_url = "https://example.com",
     )
 
-    # subprocess.run invoked without env override (user already set
-    # HIPCC_COMPILE_FLAGS_APPEND with --gcc-install-dir, so we left the
-    # env alone — the existing value is inherited).
-    assert captured == {"_called": "yes_no_env"}
+    assert captured["HIPCC_COMPILE_FLAGS_APPEND"] == "--gcc-install-dir=/opt/custom/gcc-13"
 
 
 def test_install_does_not_inject_env_on_cuda(monkeypatch):
-    """CUDA path (no hip_version in env) → no env override at all."""
+    """CUDA path (no hip_version in env) → no HIP flag injected."""
     monkeypatch.delenv("HIPCC_COMPILE_FLAGS_APPEND", raising = False)
     monkeypatch.setattr(builtins, "__import__", _missing_module_import("causal_conv1d"))
     monkeypatch.setattr(
@@ -1641,7 +1665,7 @@ def test_install_does_not_inject_env_on_cuda(monkeypatch):
     captured: dict[str, Any] = {}
 
     def fake_run(cmd, **kwargs):
-        captured["env_in_kwargs"] = "env" in kwargs
+        captured.update(kwargs.get("env") or {})
         return subprocess.CompletedProcess(cmd, 0, "")
 
     monkeypatch.setattr(worker._sp, "run", fake_run)
@@ -1657,5 +1681,5 @@ def test_install_does_not_inject_env_on_cuda(monkeypatch):
         release_base_url = "https://example.com",
     )
 
-    # CUDA branch never sets the env, never invokes the gcc helper.
-    assert captured.get("env_in_kwargs") is False
+    # env is always passed (to force UTF-8), but never the HIP flag.
+    assert "HIPCC_COMPILE_FLAGS_APPEND" not in captured

studio/backend/utils/child_stdio.py

@@ -0,0 +1,22 @@
+# SPDX-License-Identifier: AGPL-3.0-only
+# Copyright 2026-present the Unsloth AI Inc. team. All rights reserved. See /studio/LICENSE.AGPL-3.0
+
+"""Make a Python child agree with the parent that its pipes are UTF-8.
+
+A child's ``sys.stdout`` uses ``locale.getpreferredencoding()``, which on
+Windows is the ANSI code page. Reading that pipe as UTF-8 would then mangle any
+non-ASCII the child prints, so the child has to be told which encoding to emit.
+Only needed for Python children; llama.cpp and node already emit UTF-8.
+"""
+
+from __future__ import annotations
+
+import os
+from typing import Mapping, Optional
+
+
+def utf8_child_env(env: Optional[Mapping[str, str]] = None) -> dict[str, str]:
+    """Copy *env* (or the current environment) with UTF-8 stdio forced."""
+    child = dict(os.environ if env is None else env)
+    child["PYTHONIOENCODING"] = "utf-8"
+    return child

studio/backend/utils/hardware/amd.py

@@ -144,6 +144,8 @@ def _run_amd_smi(*args: str, timeout: int = _AMD_SMI_DEFAULT_TIMEOUT) -> Optiona
             ["amd-smi", *args, "--json"],
             capture_output = True,
             text = True,
+            encoding = "utf-8",
+            errors = "replace",
             timeout = timeout,
             env = _amd_env,
             **windows_hidden_subprocess_kwargs(),

studio/backend/utils/hardware/hardware.py

@@ -830,6 +830,8 @@ def _rocm_windows_perf_counter_gpu_util_pct() -> Optional[float]:
             ["powershell", "-NoProfile", "-NonInteractive", "-Command", ps],
             capture_output = True,
             text = True,
+            encoding = "utf-8",
+            errors = "replace",
             timeout = 5,
         )
         if r.returncode != 0 or not r.stdout.strip():
@@ -1027,6 +1029,8 @@ def _rocm_windows_perf_counter_vram_by_adapter() -> Optional[list[tuple[str, flo
             ["powershell", "-NoProfile", "-NonInteractive", "-Command", ps],
             capture_output = True,
             text = True,
+            encoding = "utf-8",
+            errors = "replace",
             timeout = 5,
         )
         if r.returncode != 0 or not r.stdout.strip():

studio/backend/utils/hardware/nvidia.py

@@ -55,6 +55,8 @@ def get_physical_gpu_count() -> Optional[int]:
             ["nvidia-smi", "-L"],
             capture_output = True,
             text = True,
+            encoding = "utf-8",
+            errors = "replace",
             timeout = 5,
             env = child_env_without_native_path_secret(),
             **_windows_hidden_subprocess_kwargs(),
@@ -81,6 +83,8 @@ def get_primary_gpu_utilization() -> dict[str, Any]:
             ],
             capture_output = True,
             text = True,
+            encoding = "utf-8",
+            errors = "replace",
             timeout = 5,
             env = child_env_without_native_path_secret(),
             **_windows_hidden_subprocess_kwargs(),
@@ -131,6 +135,8 @@ def get_visible_gpu_utilization(
             ],
             capture_output = True,
             text = True,
+            encoding = "utf-8",
+            errors = "replace",
             timeout = 5,
             env = child_env_without_native_path_secret(),
             **_windows_hidden_subprocess_kwargs(),
@@ -215,6 +221,8 @@ def get_backend_visible_gpu_info(
             ],
             capture_output = True,
             text = True,
+            encoding = "utf-8",
+            errors = "replace",
             timeout = 10,
             env = child_env_without_native_path_secret(),
             **_windows_hidden_subprocess_kwargs(),

studio/backend/utils/llama_cpp_update.py

@@ -121,7 +121,14 @@ def _installed_build_number(binary: Optional[str]) -> Optional[int]:
     if not binary:
         return None
     try:
-        proc = subprocess.run([binary, "--version"], capture_output = True, text = True, timeout = 20)
+        proc = subprocess.run(
+            [binary, "--version"],
+            capture_output = True,
+            text = True,
+            encoding = "utf-8",
+            errors = "replace",
+            timeout = 20,
+        )
     except Exception:  # pragma: no cover - defensive
         return None
     m = re.search(r"version:\s*(\d+)", (proc.stderr or "") + (proc.stdout or ""))

studio/backend/utils/mlx_repair.py

@@ -254,7 +254,7 @@ def _transformers_constraint_args() -> tuple[list[str], str | None]:
     except Exception:
         return [], None
     fd, path = tempfile.mkstemp(prefix = "mlx_repair_", suffix = ".txt")
-    with os.fdopen(fd, "w") as fh:
+    with os.fdopen(fd, "w", encoding = "utf-8") as fh:
         fh.write(f"transformers=={transformers_version}\n")
     return ["--constraint", path], path
 
@@ -290,6 +290,8 @@ def attempt_mlx_repair(*, timeout: int = _REPAIR_TIMEOUT_S) -> bool:
             stdout = subprocess.PIPE,
             stderr = subprocess.STDOUT,
             text = True,
+            encoding = "utf-8",
+            errors = "replace",
             timeout = timeout,
         )
     except subprocess.TimeoutExpired:

studio/backend/utils/models/checkpoints.py

@@ -129,7 +129,7 @@ def _read_checkpoint_loss(checkpoint_path: Path) -> Optional[float]:
     if not trainer_state.exists():
         return None
     try:
-        with open(trainer_state, encoding = "utf-8") as f:
+        with open(trainer_state, encoding = "utf-8-sig") as f:
             state = json.load(f)
         log_history = state.get("log_history", [])
         if log_history:
@@ -174,18 +174,18 @@ def scan_checkpoints(
             metadata: dict = {}
             try:
                 if adapter_config.exists():
-                    cfg = json.loads(adapter_config.read_text(encoding = "utf-8"))
+                    cfg = json.loads(adapter_config.read_text(encoding = "utf-8-sig"))
                     metadata["base_model"] = cfg.get("base_model_name_or_path")
                     metadata["peft_type"] = cfg.get("peft_type")
                     metadata["lora_rank"] = cfg.get("r")
                 elif config_file.exists():
-                    cfg = json.loads(config_file.read_text(encoding = "utf-8"))
+                    cfg = json.loads(config_file.read_text(encoding = "utf-8-sig"))
                     metadata["base_model"] = cfg.get("_name_or_path")
 
                 # Detect BNB quantization from config.json
                 if config_file.exists():
                     if "cfg" not in dir():
-                        cfg = json.loads(config_file.read_text(encoding = "utf-8"))
+                        cfg = json.loads(config_file.read_text(encoding = "utf-8-sig"))
                     quant_cfg = cfg.get("quantization_config")
                     if (
                         isinstance(quant_cfg, dict)

studio/backend/utils/models/model_config.py

@@ -37,6 +37,7 @@ import yaml
 
 
 from utils.native_path_leases import child_env_without_native_path_secret
+from utils.child_stdio import utf8_child_env
 from utils.hf_cache_settings import active_hf_hub_cache, get_hf_cache_paths
 from utils.subprocess_compat import (
     windows_hidden_subprocess_kwargs as _windows_hidden_subprocess_kwargs,
@@ -631,7 +632,7 @@ def _raw_config_has_vision_config(
                     cache_dir = active_hf_hub_cache(),
                 )
             )
-        config = json.loads(config_path.read_text(encoding = "utf-8"))
+        config = json.loads(config_path.read_text(encoding = "utf-8-sig"))
         architectures = config.get("architectures") or []
         model_type = config.get("model_type")
         explicit_vision = (
@@ -774,8 +775,12 @@ def _is_vision_model_subprocess(model_name: str, hf_token: Optional[str] = None)
             ],
             capture_output = True,
             text = True,
+            encoding = "utf-8",
+            errors = "replace",
             timeout = 60,
-            env = get_hf_cache_paths().child_env(child_env_without_native_path_secret()),
+            env = utf8_child_env(
+                get_hf_cache_paths().child_env(child_env_without_native_path_secret())
+            ),
             **_windows_hidden_subprocess_kwargs(),
         )
 
@@ -1083,7 +1088,7 @@ def _detect_audio_from_tokenizer(
                     ]:
                         tok_file = snapshot / tok_path
                         if tok_file.exists():
-                            tok_config = json.loads(tok_file.read_text(encoding = "utf-8"))
+                            tok_config = json.loads(tok_file.read_text(encoding = "utf-8-sig"))
                             read_any = True
                             result = _check_token_patterns(tok_config)
                             if result:
@@ -2283,7 +2288,7 @@ def scan_exported_models(
                 export_meta = run_dir / "export_metadata.json"
                 try:
                     if export_meta.exists():
-                        meta = json.loads(export_meta.read_text(encoding = "utf-8"))
+                        meta = json.loads(export_meta.read_text(encoding = "utf-8-sig"))
                         base_model = meta.get("base_model")
                 except Exception:
                     pass
@@ -2312,7 +2317,7 @@ def scan_exported_models(
                 if adapter_config.exists():
                     export_type = "lora"
                     try:
-                        cfg = json.loads(adapter_config.read_text(encoding = "utf-8"))
+                        cfg = json.loads(adapter_config.read_text(encoding = "utf-8-sig"))
                         base_model = cfg.get("base_model_name_or_path")
                     except Exception:
                         pass
@@ -2321,7 +2326,7 @@ def scan_exported_models(
                     export_meta = checkpoint_dir / "export_metadata.json"
                     try:
                         if export_meta.exists():
-                            meta = json.loads(export_meta.read_text(encoding = "utf-8"))
+                            meta = json.loads(export_meta.read_text(encoding = "utf-8-sig"))
                             base_model = meta.get("base_model")
                     except Exception:
                         pass
@@ -2334,7 +2339,7 @@ def scan_exported_models(
                         export_meta = meta_dir / "export_metadata.json"
                         try:
                             if export_meta.exists():
-                                meta = json.loads(export_meta.read_text(encoding = "utf-8"))
+                                meta = json.loads(export_meta.read_text(encoding = "utf-8-sig"))
                                 base_model = meta.get("base_model")
                                 if base_model:
                                     break
@@ -2354,7 +2359,7 @@ def scan_exported_models(
                     outputs_adapter_cfg = resolve_output_dir(run_dir.name) / "adapter_config.json"
                     try:
                         if outputs_adapter_cfg.exists():
-                            cfg = json.loads(outputs_adapter_cfg.read_text(encoding = "utf-8"))
+                            cfg = json.loads(outputs_adapter_cfg.read_text(encoding = "utf-8-sig"))
                             base_model = cfg.get("base_model_name_or_path")
                     except Exception:
                         pass
@@ -2380,7 +2385,7 @@ def get_base_model_from_checkpoint(checkpoint_path: str) -> Optional[str]:
 
         adapter_config_path = checkpoint_path_obj / "adapter_config.json"
         if adapter_config_path.exists():
-            with open(adapter_config_path, "r", encoding = "utf-8") as f:
+            with open(adapter_config_path, "r", encoding = "utf-8-sig") as f:
                 config = json.load(f)
                 base_model = config.get("base_model_name_or_path")
                 if base_model:
@@ -2389,7 +2394,7 @@ def get_base_model_from_checkpoint(checkpoint_path: str) -> Optional[str]:
 
         config_path = checkpoint_path_obj / "config.json"
         if config_path.exists():
-            with open(config_path, "r", encoding = "utf-8") as f:
+            with open(config_path, "r", encoding = "utf-8-sig") as f:
                 config = json.load(f)
                 for key in ("model_name", "_name_or_path"):
                     base_model = config.get(key)
@@ -2445,7 +2450,7 @@ def get_base_model_from_lora(lora_path: str) -> Optional[str]:
         # adapter_config.json first
         adapter_config_path = lora_path_obj / "adapter_config.json"
         if adapter_config_path.exists():
-            with open(adapter_config_path, "r", encoding = "utf-8") as f:
+            with open(adapter_config_path, "r", encoding = "utf-8-sig") as f:
                 config = json.load(f)
                 base_model = config.get("base_model_name_or_path")
                 if base_model:
@@ -2535,7 +2540,7 @@ def get_base_model_from_lora_identifier(
             last_exc = exc
             continue
         try:
-            with open(cfg_path, "r", encoding = "utf-8") as f:
+            with open(cfg_path, "r", encoding = "utf-8-sig") as f:
                 base_model = json.load(f).get("base_model_name_or_path")
         except Exception as exc:
             logger.warning("Could not parse adapter_config.json for '%s': %s", identifier, exc)
@@ -2781,7 +2786,7 @@ class ModelConfig:
                 meta_path = gguf_dir / "export_metadata.json"
                 if meta_path.exists():
                     try:
-                        meta = json.loads(meta_path.read_text(encoding = "utf-8"))
+                        meta = json.loads(meta_path.read_text(encoding = "utf-8-sig"))
                         base = meta.get("base_model")
                         if base and is_vision_model(base, hf_token = hf_token):
                             base_is_vision = True
@@ -2912,7 +2917,7 @@ class ModelConfig:
                         token = hf_token,
                         cache_dir = active_hf_hub_cache(),
                     )
-                    with open(config_path, "r", encoding = "utf-8") as f:
+                    with open(config_path, "r", encoding = "utf-8-sig") as f:
                         adapter_config = json.load(f)
                     base_model = adapter_config.get("base_model_name_or_path")
                     if base_model:

studio/backend/utils/node_runtime.py

@@ -79,6 +79,8 @@ def _node_version_ok(executable: str) -> bool:
             [executable, "-v"],
             capture_output = True,
             text = True,
+            encoding = "utf-8",
+            errors = "replace",
             timeout = _NODE_VERSION_PROBE_TIMEOUT_SECONDS,
             **windows_hidden_subprocess_kwargs(),
         )

studio/backend/utils/paths/storage_roots.py

@@ -212,7 +212,7 @@ def lmstudio_model_dirs() -> list[Path]:
     settings_path = Path.home() / ".lmstudio" / "settings.json"
     if settings_path.is_file():
         try:
-            with open(settings_path, encoding = "utf-8") as f:
+            with open(settings_path, encoding = "utf-8-sig") as f:
                 settings = json.load(f)
             downloads = settings.get("downloadsFolder", "")
             if downloads:

studio/backend/utils/prebuilt/update_flow.py

@@ -24,6 +24,7 @@ from typing import Callable, Optional
 
 import structlog
 
+from utils.child_stdio import utf8_child_env
 from utils.process_lifetime import child_popen_kwargs
 
 logger = structlog.get_logger(__name__)
@@ -159,6 +160,8 @@ def resolve_prebuilt_for_host(
             cmd,
             capture_output = True,
             text = True,
+            encoding = "utf-8",
+            errors = "replace",
             timeout = 60,
         )
         out = (proc.stdout or "").strip()
@@ -303,7 +306,10 @@ def stream_installer(
         stdout = subprocess.PIPE,
         stderr = subprocess.STDOUT,
         text = True,
-        env = env,
+        encoding = "utf-8",
+        errors = "replace",
+        # Make the Python child emit the UTF-8 we decode above.
+        env = utf8_child_env(env),
         **child_popen_kwargs(),
     )
     timed_out = threading.Event()

studio/backend/utils/security/consent.py

@@ -142,7 +142,7 @@ def _load_remote_code_configs(model_name: str, hf_token: Optional[str] = None) -
             for name in _REMOTE_CODE_CONFIG_FILES:
                 p = root / name
                 if p.is_file():
-                    configs.append(json.loads(p.read_text(encoding = "utf-8")))
+                    configs.append(json.loads(p.read_text(encoding = "utf-8-sig")))
             return configs
 
         from huggingface_hub import hf_hub_download
@@ -164,7 +164,7 @@ def _load_remote_code_configs(model_name: str, hf_token: Optional[str] = None) -
                 # Transient/auth failure is not "absent" -> fail closed to "unknown" so
                 # the caller scans (a tokenizer/processor-only auto_map must not slip by).
                 return None
-            configs.append(json.loads(Path(p).read_text(encoding = "utf-8")))
+            configs.append(json.loads(Path(p).read_text(encoding = "utf-8-sig")))
         # Every config was read or a genuine 404 -> an empty list is a definitive
         # "no auto_map", not "unknown".
         return configs

studio/backend/utils/security/file_security.py

@@ -199,7 +199,7 @@ def _indexed_shard_paths(
                 inconclusive = True  # transient: an index that might exist could not be read
                 continue
             try:
-                weight_map = (json.loads(open(index_path, encoding = "utf-8").read()) or {}).get(
+                weight_map = (json.loads(open(index_path, encoding = "utf-8-sig").read()) or {}).get(
                     "weight_map"
                 ) or {}
                 for shard in weight_map.values():
@@ -328,7 +328,7 @@ def _st_load_roots(snapshot: Path) -> list:
     roots = [snapshot]
     try:
         import json
-        modules = json.loads((snapshot / "modules.json").read_text(encoding = "utf-8"))
+        modules = json.loads((snapshot / "modules.json").read_text(encoding = "utf-8-sig"))
     except (OSError, ValueError):
         return roots  # no / invalid modules.json -> snapshot root is the only load root
     for module in modules or ():
@@ -355,7 +355,7 @@ def _indexed_pickle_shards(index_path: Path, root: Path, snapshot: Path) -> list
     try:
         # JSON is UTF-8 by spec; pin it so a non-ASCII index is not misdecoded (and needlessly
         # blocked) under Windows' cp1252 default.
-        parsed = json.loads(index_path.read_text(encoding = "utf-8"))
+        parsed = json.loads(index_path.read_text(encoding = "utf-8-sig"))
     except (OSError, ValueError) as exc:
         raise OSError(f"unreadable weight index: {index_path}") from exc
     weight_map = parsed.get("weight_map") if isinstance(parsed, dict) else None

studio/backend/utils/security/remote_code_approvals.py

@@ -69,7 +69,7 @@ def approval_target_key(targets) -> str:
 def _load() -> dict:
     """Parsed store, or an empty skeleton on any error (fail-safe = re-prompt)."""
     try:
-        with open(_store_path(), encoding = "utf-8") as f:
+        with open(_store_path(), encoding = "utf-8-sig") as f:
             data = json.load(f)
         # Validate the shape, not just the version: a hand-edited ``subjects`` that is not a
         # dict (e.g. ``[]``) would otherwise crash lookup/record instead of failing safe.

studio/backend/utils/security/remote_code_scan.py

@@ -454,7 +454,7 @@ def repo_remote_code_files(model_name: str, hf_token: Optional[str] = None) -> d
                 p = root / name
                 if p.is_file():
                     try:
-                        ext_refs |= _auto_map_refs(json.loads(p.read_text(encoding = "utf-8")))
+                        ext_refs |= _auto_map_refs(json.loads(p.read_text(encoding = "utf-8-sig")))
                     except Exception:
                         pass
             if not _add_external_refs(files, ext_refs, hf_token, model_name):
@@ -483,7 +483,7 @@ def repo_remote_code_files(model_name: str, hf_token: Optional[str] = None) -> d
                     f"{model_name}: config {cfg_name} could not be fetched ({exc})"
                 ) from exc
             try:
-                refs |= _auto_map_refs(json.loads(Path(cfg_path).read_text(encoding = "utf-8")))
+                refs |= _auto_map_refs(json.loads(Path(cfg_path).read_text(encoding = "utf-8-sig")))
             except Exception:
                 pass
         own_refs = {fn for repo, fn in refs if repo is None}
@@ -616,7 +616,7 @@ def external_auto_map_repos(model_name: str, hf_token: Optional[str] = None) ->
                 if not p.is_file():
                     continue
                 try:
-                    refs = _auto_map_refs(json.loads(p.read_text(encoding = "utf-8")))
+                    refs = _auto_map_refs(json.loads(p.read_text(encoding = "utf-8-sig")))
                 except Exception:
                     continue
                 repos.update(repo for repo, _fn in refs if repo)
@@ -638,7 +638,7 @@ def external_auto_map_repos(model_name: str, hf_token: Optional[str] = None) ->
             except Exception:
                 continue
             try:
-                refs = _auto_map_refs(json.loads(Path(cfg_path).read_text(encoding = "utf-8")))
+                refs = _auto_map_refs(json.loads(Path(cfg_path).read_text(encoding = "utf-8-sig")))
             except Exception:
                 continue
             repos.update(repo for repo, _fn in refs if repo)

studio/backend/utils/ssm_runtime.py

@@ -23,6 +23,7 @@ import threading
 from typing import Any, Callable, Optional
 
 from loggers import get_logger
+from utils.child_stdio import utf8_child_env
 from utils.wheel_utils import (
     direct_wheel_url,
     install_wheel,
@@ -254,6 +255,12 @@ def _install_kernel(
         "stdout": subprocess.PIPE,
         "stderr": subprocess.STDOUT,
         "text": True,
+        # pip and the compilers it drives write UTF-8 down this pipe; the Windows
+        # ANSI codepage would mojibake or raise over a fine install.
+        "encoding": "utf-8",
+        "errors": "replace",
+        # Make the Python child emit the UTF-8 we decode above.
+        "env": utf8_child_env(),
     }
     if is_hip:
         run_kwargs["timeout"] = 1800  # ROCm builds can take 10-30 min
@@ -261,7 +268,8 @@ def _install_kernel(
         if "--gcc-install-dir" not in existing:
             gcc_dir = _hipcc_gcc_install_dir()
             if gcc_dir:
-                _env = os.environ.copy()
+                # Extends the UTF-8 env above rather than replacing it.
+                _env = dict(run_kwargs["env"])
                 _env["HIPCC_COMPILE_FLAGS_APPEND"] = (
                     f"{existing} --gcc-install-dir={gcc_dir}".strip()
                 )

studio/backend/utils/studio_version.py

@@ -60,6 +60,8 @@ def _exact_git_studio_tag(repo_root: Path) -> str | None:
             stdout = subprocess.PIPE,
             stderr = subprocess.DEVNULL,
             text = True,
+            encoding = "utf-8",
+            errors = "replace",
             timeout = _GIT_TIMEOUT_SECONDS,
         )
     except (OSError, subprocess.TimeoutExpired):
@@ -81,6 +83,8 @@ def _git_branch(repo_root: Path) -> str | None:
             stdout = subprocess.PIPE,
             stderr = subprocess.DEVNULL,
             text = True,
+            encoding = "utf-8",
+            errors = "replace",
             timeout = _GIT_TIMEOUT_SECONDS,
         )
     except (OSError, subprocess.TimeoutExpired):

studio/backend/utils/transformers_version.py

@@ -44,6 +44,7 @@ import time
 from pathlib import Path
 
 from utils.native_path_leases import child_env_without_native_path_secret
+from utils.child_stdio import utf8_child_env
 from utils.hf_cache_settings import get_hf_cache_paths
 from utils.subprocess_compat import (
     windows_hidden_subprocess_kwargs as _windows_hidden_subprocess_kwargs,
@@ -420,7 +421,7 @@ def _resolve_base_model(model_name: str) -> str:
     adapter_cfg_path = local_path / "adapter_config.json"
     if _safe_is_file(adapter_cfg_path):
         try:
-            with open(adapter_cfg_path, encoding = "utf-8") as f:
+            with open(adapter_cfg_path, encoding = "utf-8-sig") as f:
                 cfg = json.load(f)
             base = cfg.get("base_model_name_or_path")
             if base:
@@ -437,7 +438,7 @@ def _resolve_base_model(model_name: str) -> str:
     config_json_path = local_path / "config.json"
     if _safe_is_file(config_json_path):
         try:
-            with open(config_json_path, encoding = "utf-8") as f:
+            with open(config_json_path, encoding = "utf-8-sig") as f:
                 cfg = json.load(f)
             # Unsloth writes model_name, HF writes _name_or_path; skip a self-reference.
             for _key in ("model_name", "_name_or_path"):
@@ -544,7 +545,7 @@ def _adapter_base_from_hf_cache(model_name: str) -> str | None:
         )
         for cfg_path in candidates:
             if cfg_path.is_file():
-                base = json.loads(cfg_path.read_text(encoding = "utf-8")).get(
+                base = json.loads(cfg_path.read_text(encoding = "utf-8-sig")).get(
                     "base_model_name_or_path"
                 )
                 return base or None
@@ -616,7 +617,7 @@ def _check_tokenizer_config_needs_v5(model_name: str, hf_token: str | None = Non
     local_tc = local_path / "tokenizer_config.json"
     if _safe_is_file(local_tc):
         try:
-            with open(local_tc, encoding = "utf-8") as f:
+            with open(local_tc, encoding = "utf-8-sig") as f:
                 data = json.load(f)
             tokenizer_class = data.get("tokenizer_class", "")
             result = tokenizer_class in _TRANSFORMERS_5_TOKENIZER_CLASSES
@@ -706,7 +707,7 @@ def _config_json_from_hf_cache(model_name: str) -> dict | None:
         )
         for cfg_path in candidates:
             if cfg_path.is_file():
-                with open(cfg_path, encoding = "utf-8") as f:
+                with open(cfg_path, encoding = "utf-8-sig") as f:
                     return json.load(f)
     except Exception as exc:
         logger.debug("HF cache config.json lookup failed for '%s': %s", model_name, exc)
@@ -731,7 +732,7 @@ def _load_config_json(model_name: str, hf_token: str | None = None) -> dict | No
     local_cfg = Path(model_name) / "config.json"
     if _safe_is_file(local_cfg):
         try:
-            with open(local_cfg, encoding = "utf-8") as f:
+            with open(local_cfg, encoding = "utf-8-sig") as f:
                 cfg = json.load(f)
             _config_json_cache[cache_key] = cfg
             return cfg
@@ -1271,9 +1272,10 @@ def _probe_autoconfig(target_dir: str, model_name: str, hf_token: str | None) ->
             [sys.executable, "-c", _PROBE_CONFIG_SCRIPT, target_dir, model_name],
             capture_output = True,
             text = True,
+            encoding = "utf-8",
             errors = "replace",
             timeout = _PROBE_TIMEOUT_SECS,
-            env = env,
+            env = utf8_child_env(env),
             **_windows_hidden_subprocess_kwargs(),
         )
     except subprocess.TimeoutExpired:
@@ -1811,7 +1813,11 @@ def _install_to_dir(pkg: str, target_dir: str) -> bool:
             stdout = subprocess.PIPE,
             stderr = subprocess.STDOUT,
             text = True,
-            env = get_hf_cache_paths().child_env(child_env_without_native_path_secret()),
+            encoding = "utf-8",
+            errors = "replace",
+            env = utf8_child_env(
+                get_hf_cache_paths().child_env(child_env_without_native_path_secret())
+            ),
             **_windows_hidden_subprocess_kwargs(),
         )
         if result.returncode == 0:
@@ -1834,7 +1840,9 @@ def _install_to_dir(pkg: str, target_dir: str) -> bool:
         stdout = subprocess.PIPE,
         stderr = subprocess.STDOUT,
         text = True,
-        env = get_hf_cache_paths().child_env(child_env_without_native_path_secret()),
+        encoding = "utf-8",
+        errors = "replace",
+        env = utf8_child_env(get_hf_cache_paths().child_env(child_env_without_native_path_secret())),
         **_windows_hidden_subprocess_kwargs(),
     )
     if result.returncode != 0:
@@ -2079,7 +2087,7 @@ class SidecarSwapInProgress(RuntimeError):
 
 def _read_swap_lock(path: Path) -> dict | None:
     try:
-        data = json.loads(path.read_text(encoding = "utf-8"))
+        data = json.loads(path.read_text(encoding = "utf-8-sig"))
         return data if isinstance(data, dict) else {}
     except FileNotFoundError:
         return None
@@ -2120,7 +2128,7 @@ def try_begin_sidecar_swap(kind: str = "install") -> bool:
                 break
         if fd is not None:
             try:
-                with os.fdopen(fd, "w") as f:
+                with os.fdopen(fd, "w", encoding = "utf-8") as f:
                     f.write(
                         json.dumps(
                             {"pid": os.getpid(), "at": time.time(), "token": token, "kind": kind}
@@ -2466,7 +2474,11 @@ def _ensure_venv_llmcompressor_exists() -> bool:
             stdout = subprocess.PIPE,
             stderr = subprocess.STDOUT,
             text = True,
-            env = get_hf_cache_paths().child_env(child_env_without_native_path_secret()),
+            encoding = "utf-8",
+            errors = "replace",
+            env = utf8_child_env(
+                get_hf_cache_paths().child_env(child_env_without_native_path_secret())
+            ),
             **_windows_hidden_subprocess_kwargs(),
         )
         last_out = result.stdout or ""

studio/backend/utils/update_status.py

@@ -30,6 +30,7 @@ PYPI_SUCCESS_TTL_SECONDS = 12 * 60 * 60
 PYPI_FAILURE_TTL_SECONDS = 60 * 60
 RELEASE_NOTES_URL = "https://unsloth.ai/docs/new/changelog"
 DISABLE_ENV_VAR = "UNSLOTH_DISABLE_UPDATE_CHECK"
+FAKE_UPDATE_ENV_VAR = "UNSLOTH_STUDIO_FAKE_UPDATE"
 
 LOCAL_INSTALL_SOURCES = {"editable", "local_path", "vcs", "local_repo"}
 
@@ -107,11 +108,32 @@ def get_studio_install_source_status(current_version: str) -> dict[str, Any]:
     )
 
 
+def _is_version(value: str) -> bool:
+    try:
+        Version(value)
+    except InvalidVersion:
+        return False
+    return True
+
+
 def get_studio_update_status(current_version: str) -> dict[str, Any]:
     """Return public, read-only update status for the web UI."""
     install_source = detect_install_source()
+    disabled = os.environ.get(DISABLE_ENV_VAR) == "1"
 
-    if os.environ.get(DISABLE_ENV_VAR) == "1":
+    # Dev-only: the popup is PyPI-install-only, so fake a version to review it
+    # from a checkout. The documented opt-out still wins.
+    forced_version = os.environ.get(FAKE_UPDATE_ENV_VAR, "").strip()
+    if forced_version and not disabled and _is_version(forced_version):
+        return _status_response(
+            current_version = current_version,
+            latest_version = forced_version,
+            install_source = "pypi",
+            update_available = True,
+            can_show_web_notification = True,
+        )
+
+    if disabled:
         return _status_response(
             current_version = current_version,
             latest_version = None,

studio/backend/utils/utils.py

@@ -114,6 +114,8 @@ def hf_cache_snapshot_dir(model_name: str) -> Optional[Path]:
                 snapshot = repo_dir / "snapshots" / commit
                 if snapshot.is_dir():
                     return snapshot
+            # UnicodeDecodeError is a ValueError, not an OSError: a torn refs
+            # file must keep meaning "not cached here", not fail the offline check.
             except (OSError, UnicodeDecodeError):
                 continue
     return None

studio/backend/utils/wheel_utils.py

@@ -15,6 +15,7 @@ import urllib.request
 from typing import Callable
 
 from utils.native_path_leases import child_env_without_native_path_secret
+from utils.child_stdio import utf8_child_env
 from utils.subprocess_compat import windows_hidden_subprocess_kwargs
 
 _logger = logging.getLogger(__name__)
@@ -43,6 +44,8 @@ def has_blackwell_gpu() -> bool:
             stdout = subprocess.PIPE,
             stderr = subprocess.DEVNULL,
             text = True,
+            encoding = "utf-8",
+            errors = "replace",
             timeout = 10,
             env = child_env_without_native_path_secret(),
         )
@@ -102,8 +105,10 @@ def probe_torch_wheel_env(*, timeout: int | None = None) -> dict[str, str] | Non
             stdout = subprocess.PIPE,
             stderr = subprocess.PIPE,
             text = True,
+            encoding = "utf-8",
+            errors = "replace",
             timeout = timeout,
-            env = child_env_without_native_path_secret(),
+            env = utf8_child_env(child_env_without_native_path_secret()),
             **windows_hidden_subprocess_kwargs(),
         )
     except subprocess.TimeoutExpired:
@@ -201,6 +206,8 @@ def install_wheel(
             stdout = subprocess.PIPE,
             stderr = subprocess.STDOUT,
             text = True,
+            encoding = "utf-8",
+            errors = "replace",
             env = child_env_without_native_path_secret(),
         )
         attempts.append(("uv", result))
@@ -213,7 +220,10 @@ def install_wheel(
         stdout = subprocess.PIPE,
         stderr = subprocess.STDOUT,
         text = True,
-        env = child_env_without_native_path_secret(),
+        encoding = "utf-8",
+        errors = "replace",
+        # Make the Python child emit the UTF-8 we decode above.
+        env = utf8_child_env(child_env_without_native_path_secret()),
     )
     attempts.append(("pip", result))
     return attempts

studio/backend/utils/whisper_cpp_update.py

@@ -121,7 +121,14 @@ def _installed_whisper_version(binary: Optional[str]) -> Optional[str]:
     if not binary:
         return None
     try:
-        proc = subprocess.run([binary, "--version"], capture_output = True, text = True, timeout = 20)
+        proc = subprocess.run(
+            [binary, "--version"],
+            capture_output = True,
+            text = True,
+            encoding = "utf-8",
+            errors = "replace",
+            timeout = 20,
+        )
     except Exception:  # pragma: no cover - defensive
         return None
     m = re.search(r"v?(\d+\.\d+\.\d+)", (proc.stderr or "") + (proc.stdout or ""))

studio/frontend/src/app/provider.tsx

@@ -214,7 +214,8 @@ function TauriUpdateLayer({
   }
 
   return (
-    <div className="pointer-events-none fixed bottom-4 right-4 z-[9998] flex w-[calc(100vw-2rem)] max-w-[400px] flex-col items-stretch gap-2">
+    // Capped like the browser stack: the download panel shares it, so both must fit.
+    <div className="pointer-events-none fixed bottom-4 right-4 z-[9998] flex max-h-[calc(100dvh_-_2rem)] flex-col items-end gap-2">
       <UpdateBanner
         status={update.status}
         info={update.info}
@@ -223,6 +224,7 @@ function TauriUpdateLayer({
         isExternalServer={isExternalServer}
         updatePolicyMode={update.updatePolicyMode}
         manualReleaseUrl={update.manualReleaseUrl}
+        releasePageUrl={update.releasePageUrl}
         positioned={false}
         onInstall={update.installUpdate}
         onDismiss={update.dismiss}
@@ -379,9 +381,11 @@ function TauriWrapper({ children }: { children: ReactNode }) {
     return (
       <>
         {children}
-        {/* One bottom-right stack so overlays never overlap; they stack with a
-            gap, download panel anchored at the corner with banners above. */}
-        <div className="pointer-events-none fixed bottom-4 right-4 z-[9998] flex w-[calc(100vw-2rem)] max-w-[400px] flex-col items-stretch gap-2">
+        {/* One bottom-right stack so overlays never overlap: download panel at the
+            corner, banners above, each owning its width. */}
+        {/* Capped to the viewport, or a long download list plus expanded notes
+            pushes the top of the stack off screen. */}
+        <div className="pointer-events-none fixed bottom-4 right-4 z-[9998] flex max-h-[calc(100dvh_-_2rem)] flex-col items-end gap-2">
           <WebUpdateBanner
             positioned={false}
             enabled={!WEB_UPDATE_HIDDEN_ROUTES.has(pathname)}

studio/frontend/src/components/app-sidebar.tsx

@@ -1226,7 +1226,9 @@ export function AppSidebar() {
                     openNewChat(null);
                   }}
                   className={cn(
-                    "flex items-center gap-[6px] select-none transition-opacity",
+                    // min-w-0 so a narrow sidebar truncates the wordmark
+                    // instead of pushing the search icon over the logo.
+                    "flex min-w-0 items-center gap-[6px] select-none transition-opacity",
                     chatDisabled && "pointer-events-none opacity-50",
                   )}
                   aria-label={t("shell.aria.home")}
@@ -1238,17 +1240,17 @@ export function AppSidebar() {
                   <img
                     src="/circle-logo-small.png"
                     alt="Unsloth"
-                    className="h-[calc(26px+0.5rem*var(--ui-font-scale,1))] w-[calc(26px+0.5rem*var(--ui-font-scale,1))] rounded-full object-cover"
+                    className="h-[calc(26px+0.5rem*var(--ui-font-scale,1))] w-[calc(26px+0.5rem*var(--ui-font-scale,1))] shrink-0 rounded-full object-cover"
                   />
-                  <span className="font-heading text-[calc(13px+0.5rem*var(--ui-font-scale,1))] font-semibold tracking-[0em] leading-none text-black dark:text-white dark:tracking-[0.02em]">
+                  <span className="truncate font-heading text-[calc(13px+0.5rem*var(--ui-font-scale,1))] font-semibold tracking-[0em] leading-none text-black dark:text-white dark:tracking-[0.02em]">
                     unsloth
                   </span>
-                  <span className="nav-badge ml-0.5 inline-flex items-center justify-center rounded-full border border-nav-beta-border px-[5px] pt-[3px] pb-[2px] text-[calc(0.5rem*var(--ui-font-scale,1))] font-medium leading-none tracking-[0.04em] text-nav-fg-muted antialiased subpixel-antialiased shadow-[0_1px_2px_rgba(0,0,0,0.06)] dark:shadow-[0_1px_2px_rgba(0,0,0,0.35)]">
+                  <span className="nav-badge ml-0.5 inline-flex shrink-0 items-center justify-center rounded-full border border-nav-beta-border px-[5px] pt-[3px] pb-[2px] text-[calc(0.5rem*var(--ui-font-scale,1))] font-medium leading-none tracking-[0.04em] text-nav-fg-muted antialiased subpixel-antialiased shadow-[0_1px_2px_rgba(0,0,0,0.06)] dark:shadow-[0_1px_2px_rgba(0,0,0,0.35)]">
                     {t("shell.beta")}
                   </span>
                 </Link>
               )}
-              <div className="flex items-center gap-0.5">
+              <div className="flex shrink-0 items-center gap-0.25">
                 <Tooltip>
                   <TooltipPrimitive.Trigger asChild>
                     <button
@@ -1257,7 +1259,7 @@ export function AppSidebar() {
                         useChatSearchStore.getState().open();
                         closeMobileIfOpen();
                       }}
-                      className="inline-flex h-[33px] w-[32px] cursor-pointer items-center justify-center rounded-[10px] text-nav-icon-idle dark:text-nav-fg-muted transition-colors hover:bg-nav-surface-hover hover:text-black dark:hover:text-white focus-visible:outline-none focus-visible:ring-1 focus-visible:ring-ring"
+                      className="inline-flex h-[33px] w-[28px] cursor-pointer items-center justify-center rounded-[10px] text-nav-icon-idle dark:text-nav-fg-muted transition-colors hover:bg-nav-surface-hover hover:text-black dark:hover:text-white focus-visible:outline-none focus-visible:ring-1 focus-visible:ring-ring"
                       aria-label={t("shell.navigation.search")}
                     >
                       <HugeiconsIcon icon={Search01Icon} strokeWidth={1.75} className="size-icon" />
@@ -1281,7 +1283,7 @@ export function AppSidebar() {
                       <button
                         type="button"
                         onClick={togglePinned}
-                        className="inline-flex h-[33px] w-[32px] cursor-pointer items-center justify-center rounded-[10px] text-nav-icon-idle dark:text-nav-fg-muted transition-colors hover:bg-nav-surface-hover hover:text-black dark:hover:text-white focus-visible:outline-none focus-visible:ring-1 focus-visible:ring-ring"
+                        className="inline-flex h-[33px] w-[28px] cursor-pointer items-center justify-center rounded-[10px] text-nav-icon-idle dark:text-nav-fg-muted transition-colors hover:bg-nav-surface-hover hover:text-black dark:hover:text-white focus-visible:outline-none focus-visible:ring-1 focus-visible:ring-ring"
                         aria-label={t("shell.aria.closeSidebar")}
                       >
                         <HugeiconsIcon icon={LayoutAlignLeftIcon} strokeWidth={1.75} className="size-icon" />
@@ -1325,10 +1327,10 @@ export function AppSidebar() {
         )}
       </SidebarHeader>
 
-      {/* Uniform pl-1.5 pr-2 keeps every hover pill the same width, inset from the edge. */}
+      {/* Uniform pl-1.5 pr-1.75 keeps every hover pill the same width, inset from the edge. */}
       <SidebarGroup
         className={cn(
-          "group-data-[collapsible=icon]:px-0 pl-1.5 pr-2 shrink-0 transition-[padding]",
+          "group-data-[collapsible=icon]:px-0 pl-1.5 pr-1.75 shrink-0 transition-[padding]",
           showCompactMacBrand ? "pt-0" : "pt-[9px]",
           // Scrolled: New Chat is pinned, give a little gap below it.
           scrolled ? "pb-[5px]" : "pb-px",
@@ -1417,7 +1419,7 @@ export function AppSidebar() {
           scrolled && "is-scrolled",
         )}
       >
-        <SidebarGroup className="group-data-[collapsible=icon]:px-0 pl-1.5 pr-2 py-0 shrink-0">
+        <SidebarGroup className="group-data-[collapsible=icon]:px-0 pl-1.5 pr-1.75 py-0 shrink-0">
           <SidebarGroupContent>
             <SidebarMenu>
               <NavItem
@@ -1499,7 +1501,7 @@ export function AppSidebar() {
               </CollapsibleTrigger>
             </SidebarGroupLabel>
             <CollapsibleContent>
-              <SidebarGroupContent className="pl-1.5 pr-2">
+              <SidebarGroupContent className="pl-1.5 pr-1.75">
                 <SidebarMenu>
                   <NavItem
                     icon={TestTubeOutlineIcon}
@@ -1574,7 +1576,7 @@ export function AppSidebar() {
                   </CollapsibleTrigger>
                 </SidebarGroupLabel>
                 <CollapsibleContent>
-                  <SidebarGroupContent className="pl-1.5 pr-2">
+                  <SidebarGroupContent className="pl-1.5 pr-1.75">
                     <SidebarMenu>
                       {pinnedProjectRecords.map((project) => {
                         const projectChats =
@@ -1721,7 +1723,7 @@ export function AppSidebar() {
                 </CollapsibleTrigger>
               </SidebarGroupLabel>
               <CollapsibleContent>
-                <SidebarGroupContent className="pl-1.5 pr-2">
+                <SidebarGroupContent className="pl-1.5 pr-1.75">
                   <SidebarMenu>
                     {recentChatItems.map((item) =>
                       renderChatSidebarItem(item, "recent"),
@@ -1753,7 +1755,7 @@ export function AppSidebar() {
               </CollapsibleTrigger>
             </SidebarGroupLabel>
             <CollapsibleContent>
-              <SidebarGroupContent className="pl-1.5 pr-2">
+              <SidebarGroupContent className="pl-1.5 pr-1.75">
                 <SidebarMenu>
                   {runItems.map((run) => {
                     // Explicit selection wins. Otherwise highlight the active

studio/frontend/src/components/llama-update-banner.tsx

@@ -134,7 +134,7 @@ export function LlamaUpdateBanner({
       className={cn(
         positioned
           ? "fixed bottom-4 right-4 z-[9998] w-[calc(100vw-2rem)] max-w-[400px]"
-          : "pointer-events-auto w-full",
+          : "pointer-events-auto w-[calc(100vw-2rem)] max-w-[400px]",
       )}
       data-testid="llama-update-banner"
     >

studio/frontend/src/components/tauri/update-banner.tsx

@@ -2,6 +2,7 @@
 // Copyright 2026-present the Unsloth AI Inc. team. All rights reserved. See /studio/LICENSE.AGPL-3.0
 
 import { Button } from "@/components/ui/button";
+import { ReleaseNotesPanel } from "@/components/update/release-notes-panel";
 import type {
   DesktopUpdatePolicyMode,
   RetainedUpdateFailure,
@@ -22,6 +23,8 @@ interface UpdateBannerProps {
   isExternalServer?: boolean;
   updatePolicyMode: DesktopUpdatePolicyMode;
   manualReleaseUrl: string | null;
+  // Release page for this version, preferred over the generic changelog.
+  releasePageUrl?: string | null;
   // false fills a shared overlay stack; true self-anchors.
   positioned?: boolean;
   onInstall: () => void;
@@ -30,6 +33,7 @@ interface UpdateBannerProps {
 }
 
 const EASE_OUT_QUART: [number, number, number, number] = [0.165, 0.84, 0.44, 1];
+const LEADING_V = /^v/;
 
 function formatVersion(version: string | null | undefined): string {
   if (!version) return "";
@@ -44,6 +48,7 @@ export function UpdateBanner({
   isExternalServer = false,
   updatePolicyMode,
   manualReleaseUrl,
+  releasePageUrl = null,
   positioned = true,
   onInstall,
   onDismiss,
@@ -52,6 +57,8 @@ export function UpdateBanner({
   const [copying, setCopying] = useState(false);
   const [manualReport, setManualReport] = useState<string | null>(null);
   const [manualMessage, setManualMessage] = useState<string | null>(null);
+  // Version whose notes are expanded; a new offer collapses the panel.
+  const [notesVersion, setNotesVersion] = useState<string | null>(null);
   const showFailure = Boolean(lastFailure) && !dismissed;
   const showAvailable = status === "available" && !dismissed && !showFailure;
   const show = showFailure || (showAvailable && Boolean(info));
@@ -62,6 +69,11 @@ export function UpdateBanner({
   const currentVersion = formatVersion(info?.currentVersion);
   const latestVersion = formatVersion(info?.version);
   const Icon = showFailure ? CircleAlert : Download;
+  // Keyed by the backend release, not the app's SemVer; headings drop the v.
+  const notesTargetVersion =
+    (info?.pypiVersion ?? info?.version)?.replace(LEADING_V, "") ?? null;
+  const notesOpen =
+    notesTargetVersion !== null && notesVersion === notesTargetVersion;
 
   async function handleCopyDiagnostics() {
     setCopying(true);
@@ -94,13 +106,14 @@ export function UpdateBanner({
           exit={{ opacity: 0, y: 8, scale: 0.97 }}
           transition={{ duration: 0.35, ease: EASE_OUT_QUART }}
           className={cn(
+            // Wider than the other overlays: notes preview plus three buttons.
             positioned
-              ? "fixed bottom-4 right-4 z-[9999] w-[calc(100vw-2rem)] max-w-[400px]"
-              : "pointer-events-auto w-full",
+              ? "fixed bottom-4 right-4 z-[9999] w-[calc(100vw-2rem)] max-w-[448px]"
+              : "pointer-events-auto flex min-h-0 w-[calc(100vw-2rem)] max-w-[448px] flex-col",
           )}
           data-testid="tauri-update-banner"
         >
-          <div className="relative overflow-hidden rounded-[24px] bg-white px-5 pb-4 pt-5 shadow-[0_2px_8px_-2px_rgba(0,0,0,0.16)] dark:bg-card dark:shadow-[0_8px_28px_-6px_rgba(0,0,0,0.28)]">
+          <div className="relative flex max-h-[calc(100dvh_-_2rem)] flex-col overflow-hidden rounded-[24px] bg-white px-5 pb-4 pt-5 shadow-[0_2px_8px_-2px_rgba(0,0,0,0.16)] dark:bg-card dark:shadow-[0_8px_28px_-6px_rgba(0,0,0,0.28)]">
             <button
               type="button"
               onClick={onDismiss}
@@ -160,7 +173,40 @@ export function UpdateBanner({
               </p>
             )}
 
-            <div className="mt-4 flex flex-wrap items-center justify-end gap-x-1 gap-y-2">
+            {!showFailure && notesTargetVersion ? (
+              <ReleaseNotesPanel
+                version={notesTargetVersion}
+                open={notesOpen}
+                // Used only if CHANGELOG.md has no section for this version.
+                fallbackMarkdown={info?.body ?? null}
+                className="min-h-0 flex-1"
+                releaseNotesUrl={releasePageUrl ?? manualReleaseUrl}
+              />
+            ) : null}
+
+            <div
+              className={cn(
+                "mt-4 flex flex-wrap items-center gap-x-1 gap-y-2",
+                !showFailure && notesTargetVersion
+                  ? "justify-between"
+                  : "justify-end",
+              )}
+            >
+              {!showFailure && notesTargetVersion ? (
+                <Button
+                  size="sm"
+                  variant="ghost"
+                  // same type size as the action buttons
+                  className="-ml-2 h-auto whitespace-nowrap rounded-full px-2.5 py-2 text-ui-13 font-medium text-foreground"
+                  onClick={() =>
+                    setNotesVersion(notesOpen ? null : notesTargetVersion)
+                  }
+                  aria-expanded={notesOpen}
+                  data-testid="tauri-update-release-notes-toggle"
+                >
+                  {notesOpen ? "Hide release notes" : "Show release notes"}
+                </Button>
+              ) : null}
               {showFailure ? (
                 <>
                   <Button
@@ -187,28 +233,31 @@ export function UpdateBanner({
                     onClick={onInstall}
                     disabled={installDisabled}
                   >
-                    {isManualLinuxPackage ? "Open release page" : "Retry update"}
+                    {isManualLinuxPackage
+                      ? "Open release page"
+                      : "Retry update"}
                   </Button>
                 </>
               ) : (
-                <>
+                // wrap + right-align so the action pair stays together
+                <div className="flex flex-wrap items-center justify-end gap-x-1 gap-y-2">
                   <Button
                     size="sm"
                     variant="ghost"
-                    className="h-auto rounded-full px-3 py-2 text-ui-13 font-medium text-foreground"
+                    className="h-auto whitespace-nowrap rounded-full px-2.5 py-2 text-ui-13 font-medium text-foreground"
                     onClick={onDismiss}
                   >
                     Remind me later
                   </Button>
                   <Button
                     size="sm"
-                    className="-mr-1 h-auto rounded-full px-3.5 py-2 text-ui-13"
+                    className="-mr-1 h-auto whitespace-nowrap rounded-full px-3 py-2 text-ui-13"
                     onClick={onInstall}
                     disabled={installDisabled}
                   >
                     {isManualLinuxPackage ? "Open release page" : "Update"}
                   </Button>
-                </>
+                </div>
               )}
             </div>
             {manualMessage && (

studio/frontend/src/components/tauri/window-titlebar.tsx

@@ -2,6 +2,7 @@
 // Copyright 2026-present the Unsloth AI Inc. team. All rights reserved. See /studio/LICENSE.AGPL-3.0
 
 import { useSidebarPin } from "@/hooks/use-sidebar-pin";
+import { useSidebarWidth } from "@/hooks/use-sidebar-width";
 import { isTauri } from "@/lib/api-base";
 import { cn } from "@/lib/utils";
 import {
@@ -110,9 +111,13 @@ export function WindowTitlebar({
   const [enabled] = useState(shouldUseCustomWindowTitlebar);
   const [maximized, setMaximized] = useState(false);
   const { pinned, togglePinned } = useSidebarPin();
+  // The titlebar sits outside the sidebar wrapper, so it cannot inherit
+  // --sidebar-width. Read the resized width from the same store instead.
+  const { width } = useSidebarWidth();
   const sidebarWidth = showSidebarSurface
     ? pinned
-      ? "var(--studio-sidebar-expanded-width,17.5rem)"
+      ? // The live value only exists mid-drag; otherwise the committed width.
+        `var(--studio-sidebar-live-width, ${width}px)`
       : "var(--studio-sidebar-collapsed-width,3rem)"
     : "0px";
   const contentBorderLeft = pinned ? `calc(${sidebarWidth} + 12px)` : "0px";

studio/frontend/src/components/ui/panel-resize-handle.tsx

@@ -0,0 +1,317 @@
+// SPDX-License-Identifier: AGPL-3.0-only
+// Copyright 2026-present the Unsloth AI Inc. team. All rights reserved. See /studio/LICENSE.AGPL-3.0
+
+"use client"
+
+import * as React from "react"
+
+import { cn } from "@/lib/utils"
+import {
+  Tooltip,
+  TooltipContent,
+  TooltipTrigger,
+} from "@/components/ui/tooltip"
+import { getClientPlatform } from "@/components/tauri/window-titlebar"
+
+/** Pointer travel (px) below which a drag counts as a plain click. */
+const DRAG_SLOP = 4
+/** A compatibility click lands immediately after pointer-up. */
+const CLICK_COMPAT_WINDOW_MS = 300
+/** Arrow-key resize step for keyboard users. */
+const RESIZE_STEP = 16
+
+type DragState = {
+  startX: number
+  startWidth: number
+  moved: boolean
+}
+
+export type PanelResizeHandleProps = {
+  /** Which edge of the panel the handle sits on. */
+  edge: "left" | "right"
+  open: boolean
+  width: number
+  /** Uncapped stored preference, so a capped drag does not lower it. */
+  stored: number
+  min: number
+  max: number
+  clamp: (px: number) => number
+  setWidth: (px: number) => void
+  resetWidth: () => void
+  onToggle: () => void
+  /** Element to paint the live width onto, and the property to paint. */
+  target: () => HTMLElement | null
+  cssVar: string
+  /** Measured to start a drag from the rendered size when collapsed. */
+  measure: () => number
+  label: string
+  toggleLabel: string
+  /** Translated tooltip copy; the caller owns the translation layer. */
+  collapseHint: string
+  expandHint: string
+  dragHint: string
+  /** Shown in the tooltip when the panel has a toggle shortcut. */
+  shortcut?: string
+  dataSlot?: string
+  className?: string
+  /** Mirrors the live width onto :root for chrome outside the panel. */
+  rootVar?: string
+}
+
+/**
+ * A draggable panel edge: drag to resize, click to collapse or expand. Arrow
+ * keys resize, Home restores the default. The width is painted straight to the
+ * target while dragging and only persisted on release.
+ */
+export function PanelResizeHandle({
+  edge,
+  open,
+  width,
+  stored,
+  min,
+  max,
+  clamp,
+  setWidth,
+  resetWidth,
+  onToggle,
+  target,
+  cssVar,
+  measure,
+  label,
+  toggleLabel,
+  collapseHint,
+  expandHint,
+  dragHint,
+  shortcut,
+  dataSlot = "panel-resize-handle",
+  className,
+  rootVar,
+}: PanelResizeHandleProps) {
+  const ref = React.useRef<HTMLButtonElement>(null)
+  const dragRef = React.useRef<DragState | null>(null)
+  const [dragging, setDragging] = React.useState(false)
+  const [hovered, setHovered] = React.useState(false)
+  const [focused, setFocused] = React.useState(false)
+  const [isMacPlatform] = React.useState(() => getClientPlatform().includes("mac"))
+  const hint = shortcut ? shortcut.replace("Mod", isMacPlatform ? "⌘" : "Ctrl+") : null
+
+  // Cached on pointer down so no DOM walk per move.
+  const targetRef = React.useRef<HTMLElement | null>(null)
+  const frameRef = React.useRef(0)
+  const pendingRef = React.useRef(0)
+  // What the pointer asked for, before the viewport cap. Committing the capped
+  // value instead would quietly downgrade a stored preference on a narrow window.
+  const rawRef = React.useRef(0)
+  // When a pointer sequence last ended. The browser's compatibility click
+  // lands in the same tick, so only a click that close behind is a duplicate.
+  // A timestamp cannot go stale the way an armed flag does: a genuine cancel
+  // emits no click, and a later assistive-tech click still gets through.
+  const handledAtRef = React.useRef(0)
+  const committedRef = React.useRef(width)
+  React.useEffect(() => {
+    committedRef.current = width
+  }, [width])
+
+  const paint = React.useCallback(
+    (value: string) => {
+      targetRef.current?.style.setProperty(cssVar, value)
+      if (rootVar) {
+        document.documentElement.style.setProperty(rootVar, value)
+      }
+    },
+    [cssVar, rootVar],
+  )
+
+  // Resizing relayouts the whole shell, and pointermove fires faster than the
+  // display refreshes, so coalesce to one paint per frame.
+  const paintWidth = React.useCallback(
+    (px: number) => {
+      pendingRef.current = px
+      if (frameRef.current) return
+      frameRef.current = requestAnimationFrame(() => {
+        frameRef.current = 0
+        paint(`${pendingRef.current}px`)
+      })
+    },
+    [paint],
+  )
+
+  const endDrag = React.useCallback(() => {
+    // Only a sequence that actually started can produce a compatibility click.
+    // This also runs as the effect cleanup, where no drag happened.
+    if (dragRef.current) handledAtRef.current = Date.now()
+    dragRef.current = null
+    if (frameRef.current) {
+      cancelAnimationFrame(frameRef.current)
+      frameRef.current = 0
+    }
+    // Hand the property back to the committed value. A commit re-renders with
+    // the new width; a cancel or a no-commit drag keeps DOM and store in step.
+    paint(`${committedRef.current}px`)
+    if (rootVar) document.documentElement.style.removeProperty(rootVar)
+    targetRef.current?.removeAttribute("data-resizing")
+    document.documentElement.removeAttribute("data-panel-resizing")
+    targetRef.current = null
+    setDragging(false)
+    document.body.style.removeProperty("cursor")
+    document.body.style.removeProperty("user-select")
+  }, [paint, rootVar])
+
+  const handlePointerDown = (event: React.PointerEvent<HTMLButtonElement>) => {
+    if (event.button !== 0) return
+    event.preventDefault()
+    event.currentTarget.setPointerCapture(event.pointerId)
+    targetRef.current = target()
+    // Collapsed: grow from the rendered size so the edge tracks the pointer.
+    const start = open ? width : measure()
+    dragRef.current = { startX: event.clientX, startWidth: start, moved: false }
+    pendingRef.current = start
+    rawRef.current = start
+    targetRef.current?.setAttribute("data-resizing", "true")
+    document.documentElement.setAttribute("data-panel-resizing", "true")
+    setDragging(true)
+    document.body.style.setProperty("cursor", "col-resize")
+    document.body.style.setProperty("user-select", "none")
+  }
+
+  const handlePointerMove = (event: React.PointerEvent<HTMLButtonElement>) => {
+    const drag = dragRef.current
+    if (!drag) return
+    // A panel whose handle is on its left edge grows as the pointer moves left.
+    const delta = (edge === "left" ? -1 : 1) * (event.clientX - drag.startX)
+    if (!drag.moved && Math.abs(delta) < DRAG_SLOP) return
+    drag.moved = true
+
+    const next = drag.startWidth + delta
+    rawRef.current = next
+    if (!open) {
+      // Past the minimum, dragging the collapsed edge reopens it.
+      if (next >= min) {
+        paintWidth(clamp(next))
+        onToggle()
+      }
+      return
+    }
+    // Dragging inward stops at the minimum. Collapsing is click or the shortcut.
+    paintWidth(clamp(next))
+  }
+
+  const handlePointerUp = (event: React.PointerEvent<HTMLButtonElement>) => {
+    const drag = dragRef.current
+    if (!drag) return
+    if (event.currentTarget.hasPointerCapture(event.pointerId)) {
+      event.currentTarget.releasePointerCapture(event.pointerId)
+    }
+    endDrag()
+
+    if (!drag.moved) {
+      onToggle()
+      return
+    }
+    // A drag below the minimum leaves the stored width alone.
+    if (!open) return
+    // Capped: the visible edge is already at the cap, so an outward pull cannot
+    // express intent beyond it. Committing would silently lower the larger
+    // hidden preference. A deliberate inward drag still commits.
+    if (stored > max && rawRef.current >= max) return
+    // Commit what was asked for, not the capped paint, so a drag on a narrow
+    // window cannot shrink a larger stored preference. setWidth clamps.
+    setWidth(rawRef.current)
+  }
+
+  const handleKeyDown = (event: React.KeyboardEvent<HTMLButtonElement>) => {
+    // The collapse/expand the label advertises, for keyboard users. Pointer-up
+    // handles it for the mouse; a synthesized click never reaches it.
+    if (event.key === "Enter" || event.key === " ") {
+      // preventDefault cancels the native click, so nothing follows to guard
+      // against; arming here would swallow the next assistive-tech click.
+      event.preventDefault()
+      onToggle()
+      return
+    }
+    const outward = edge === "left" ? "ArrowLeft" : "ArrowRight"
+    const inward = edge === "left" ? "ArrowRight" : "ArrowLeft"
+    if (event.key === outward || event.key === inward) {
+      event.preventDefault()
+      if (!open) {
+        // Collapsed there is nothing to resize, so the outward arrow reopens.
+        if (event.key === outward) onToggle()
+        return
+      }
+      if (event.key === outward && stored > max && width >= max) return
+      setWidth(width + (event.key === outward ? RESIZE_STEP : -RESIZE_STEP))
+      return
+    }
+    if (event.key === "Home") {
+      event.preventDefault()
+      resetWidth()
+    }
+  }
+
+  // Clear a stuck cursor override if we unmount mid-drag.
+  React.useEffect(() => endDrag, [endDrag])
+
+  return (
+    <Tooltip open={(hovered || focused) && !dragging}>
+      <TooltipTrigger asChild>
+        <button
+          ref={ref}
+          type="button"
+          data-slot={dataSlot}
+          data-dragging={dragging || undefined}
+          aria-label={open ? label : toggleLabel}
+          {...(open ? { "aria-orientation": "vertical" as const } : {})}
+          {...(open
+            ? { "aria-valuenow": width, "aria-valuemin": min, "aria-valuemax": max }
+            : {})}
+          role={open ? "separator" : "button"}
+          onPointerDown={handlePointerDown}
+          onPointerMove={handlePointerMove}
+          onPointerUp={handlePointerUp}
+          onPointerCancel={endDrag}
+          onKeyDown={handleKeyDown}
+          onClick={() => {
+            // Switch and voice control activate by dispatching a bare click
+            // with no pointer or key events, which nothing else here catches.
+            if (Date.now() - handledAtRef.current < CLICK_COMPAT_WINDOW_MS) return
+            onToggle()
+          }}
+          onPointerEnter={() => setHovered(true)}
+          onPointerLeave={() => setHovered(false)}
+          onFocus={(event) => setFocused(event.target.matches(":focus-visible"))}
+          onBlur={() => setFocused(false)}
+          className={cn(
+            "absolute inset-y-0 z-30 hidden w-2 touch-none select-none sm:block",
+            edge === "left" ? "-left-1" : "-right-1",
+            // `!` overrides the app-wide hand cursor on buttons.
+            open
+              ? "cursor-col-resize!"
+              : edge === "left"
+                ? "cursor-w-resize!"
+                : "cursor-e-resize!",
+            // Sits exactly on the panel border so hover recolours one line.
+            "after:absolute after:inset-y-0 after:w-px after:bg-transparent after:transition-colors after:duration-150",
+            edge === "left" ? "after:left-1" : "after:right-1",
+            "hover:after:bg-sidebar-ring/25 data-dragging:after:bg-sidebar-ring/25",
+            // The app zeroes the native outline on buttons, so mark focus here.
+            "focus-visible:outline-none focus-visible:after:bg-sidebar-ring/60",
+            className,
+          )}
+        />
+      </TooltipTrigger>
+      <TooltipContent
+        side={edge === "left" ? "left" : "right"}
+        align="center"
+        className="tooltip-compact"
+      >
+        <span className="flex flex-col gap-px">
+          <span>
+            {open ? collapseHint : expandHint}
+            {hint ? ` ${hint}` : ""}
+          </span>
+          <span className="opacity-70">{dragHint}</span>
+        </span>
+      </TooltipContent>
+    </Tooltip>
+  )
+}

studio/frontend/src/components/ui/sidebar.tsx

@@ -24,13 +24,21 @@ import {
   TooltipContent,
   TooltipTrigger,
 } from "@/components/ui/tooltip"
+import { PanelResizeHandle } from "@/components/ui/panel-resize-handle"
+import { useT } from "@/i18n"
 import { useIsMobile } from "@/hooks/use-mobile"
+import {
+  SIDEBAR_WIDTH_DEFAULT,
+  SIDEBAR_WIDTH_MIN,
+  clampSidebarWidth,
+  useSidebarWidth,
+} from "@/hooks/use-sidebar-width"
 import { HugeiconsIcon } from "@hugeicons/react"
 import { LayoutAlignLeftIcon } from "@hugeicons/core-free-icons"
 
 const noop = () => {}
 
-const SIDEBAR_WIDTH = "17.5rem"
+const SIDEBAR_WIDTH = `${SIDEBAR_WIDTH_DEFAULT}px`
 const SIDEBAR_WIDTH_ICON = "3rem"
 const SIDEBAR_KEYBOARD_SHORTCUT = "b"
 
@@ -46,6 +54,11 @@ type SidebarContextProps = {
   pinned: boolean
   setPinned: (value: boolean) => void
   togglePinned: () => void
+  width: number
+  storedWidth: number
+  maxWidth: number
+  setWidth: (value: number) => void
+  resetWidth: () => void
 }
 
 const SidebarContext = React.createContext<SidebarContextProps | null>(null)
@@ -80,6 +93,13 @@ function SidebarProvider({
 }) {
   const isMobile = useIsMobile()
   const [openMobile, setOpenMobile] = React.useState(false)
+  const {
+    width,
+    max: maxWidth,
+    stored: storedWidth,
+    setWidth,
+    resetWidth,
+  } = useSidebarWidth()
 
   const prevIsMobileRef = React.useRef(isMobile)
   React.useEffect(() => {
@@ -163,8 +183,13 @@ function SidebarProvider({
       pinned,
       setPinned,
       togglePinned,
+      width,
+      storedWidth,
+      maxWidth,
+      setWidth,
+      resetWidth,
     }),
-    [state, open, setOpen, isMobile, openMobile, setOpenMobile, toggleSidebar, hasPinMode, pinned, setPinned, togglePinned]
+    [state, open, setOpen, isMobile, openMobile, setOpenMobile, toggleSidebar, hasPinMode, pinned, setPinned, togglePinned, width, storedWidth, maxWidth, setWidth, resetWidth]
   )
 
   return (
@@ -173,7 +198,8 @@ function SidebarProvider({
         data-slot="sidebar-wrapper"
         style={
           {
-            "--sidebar-width": SIDEBAR_WIDTH,
+            // The drag handle writes this same property live while resizing.
+            "--sidebar-width": `${width}px`,
             "--sidebar-width-icon": SIDEBAR_WIDTH_ICON,
             ...style,
           } as React.CSSProperties
@@ -311,11 +337,64 @@ function Sidebar({
         >
           {children}
         </div>
+        <SidebarResizeHandle side={side} />
       </div>
     </div>
   )
 }
 
+/**
+ * The sidebar's draggable edge, over the shared panel handle.
+ */
+function SidebarResizeHandle({
+  className,
+  side = "left",
+}: {
+  className?: string
+  side?: "left" | "right"
+}) {
+  const { open, toggleSidebar, width, storedWidth, maxWidth, setWidth, resetWidth } =
+    useSidebar()
+  const ref = React.useRef<HTMLDivElement>(null)
+  const t = useT()
+
+  return (
+    <div ref={ref} className="contents">
+      <PanelResizeHandle
+        edge={side === "right" ? "left" : "right"}
+        open={open}
+        width={width}
+        stored={storedWidth}
+        min={SIDEBAR_WIDTH_MIN}
+        max={maxWidth}
+        clamp={clampSidebarWidth}
+        setWidth={setWidth}
+        resetWidth={resetWidth}
+        onToggle={toggleSidebar}
+        target={() =>
+          ref.current?.closest<HTMLElement>('[data-slot="sidebar-wrapper"]') ?? null
+        }
+        cssVar="--sidebar-width"
+        // The custom titlebar renders outside the wrapper and cannot inherit it.
+        rootVar="--studio-sidebar-live-width"
+        measure={() =>
+          ref.current
+            ?.closest<HTMLElement>('[data-slot="sidebar-container"]')
+            ?.getBoundingClientRect().width ?? SIDEBAR_WIDTH_MIN
+        }
+        label={t("shell.aria.resizeSidebar")}
+        toggleLabel={t("shell.aria.openSidebar")}
+        collapseHint={t("shell.resize.collapse")}
+        expandHint={t("shell.resize.expand")}
+        dragHint={t("shell.resize.drag")}
+        shortcut="ModB"
+        dataSlot="sidebar-resize-handle"
+        className={className}
+      />
+    </div>
+  )
+}
+
 function SidebarTrigger({
   className,
   onClick,
@@ -777,6 +856,7 @@ export {
   SidebarMenuSubItem,
   SidebarProvider,
   SidebarRail,
+  SidebarResizeHandle,
   SidebarSeparator,
   SidebarTrigger,
   useSidebar,

studio/frontend/src/components/update/release-notes-panel.tsx

@@ -0,0 +1,251 @@
+// SPDX-License-Identifier: AGPL-3.0-only
+// Copyright 2026-present the Unsloth AI Inc. team. All rights reserved. See /studio/LICENSE.AGPL-3.0
+
+import { MarkdownPreview } from "@/components/markdown/markdown-preview";
+import { useReleaseNotes } from "@/hooks/use-release-notes";
+import { resolveChangelogLinks } from "@/lib/changelog-links";
+import { releaseNotesPreview } from "@/lib/release-notes-preview";
+import { cn } from "@/lib/utils";
+import {
+  type ReactElement,
+  type ReactNode,
+  useEffect,
+  useMemo,
+  useRef,
+} from "react";
+
+interface ReleaseNotesPanelProps {
+  // Notes are looked up for this exact version only.
+  version: string;
+  // Collapsed previews the top bullets; expanded scrolls the full notes.
+  open: boolean;
+  // Desktop updater's body, used only if CHANGELOG.md has no section here.
+  fallbackMarkdown?: string | null;
+  releaseNotesUrl?: string | null;
+  className?: string;
+}
+
+const NOTES_LINK_CLASS =
+  "shrink-0 whitespace-nowrap text-ui-11 font-medium text-foreground underline underline-offset-2";
+
+function NotesMessage({
+  children,
+  action,
+}: {
+  children: ReactNode;
+  action?: ReactNode;
+}): ReactElement {
+  return (
+    <div className="flex items-center justify-between gap-2 px-1 py-2">
+      <p className="text-ui-11 text-muted-foreground">{children}</p>
+      {action}
+    </div>
+  );
+}
+
+function ChangelogLink({ href }: { href: string }): ReactElement {
+  return (
+    <a
+      href={href}
+      target="_blank"
+      rel="noopener noreferrer"
+      className={NOTES_LINK_CLASS}
+      data-testid="update-release-notes-link"
+    >
+      Open changelog
+    </a>
+  );
+}
+
+export function ReleaseNotesPanel({
+  version,
+  open,
+  fallbackMarkdown = null,
+  releaseNotesUrl = null,
+  className,
+}: ReleaseNotesPanelProps): ReactElement | null {
+  // Fetched with the popup: the collapsed preview needs the notes too.
+  const { state, notes, retry } = useReleaseNotes({ version, enabled: true });
+  const scrollRef = useRef<HTMLElement | null>(null);
+
+  // The fallback stands in for "no section in the changelog", which the hook
+  // reports as ready. An error is retryable, and the desktop fallback is the
+  // updater's static blurb, so taking it there would hide Retry until cache expiry.
+  const source = notes?.matched
+    ? notes.markdown
+    : state === "error"
+      ? null
+      : (fallbackMarkdown ?? null);
+  // Notes target the repository, so relative links must point back at it.
+  const markdown = useMemo(
+    () => (source === null ? null : resolveChangelogLinks(source)),
+    [source],
+  );
+
+  // Notes that are only a code block or a table preview as nothing.
+  const preview = useMemo(
+    () => (markdown === null ? null : releaseNotesPreview(markdown)),
+    [markdown],
+  );
+
+  // Start at the top on expand, and again once async notes land.
+  useEffect(() => {
+    if (open && markdown && scrollRef.current) {
+      scrollRef.current.scrollTop = 0;
+    }
+  }, [open, markdown]);
+
+  // Caller's URL wins: the API returns only the generic changelog, while the
+  // desktop banner passes this version's release page.
+  const notesUrl = releaseNotesUrl ?? notes?.releaseNotesUrl;
+  const link = notesUrl ? <ChangelogLink href={notesUrl} /> : null;
+
+  // Nothing previewable yet or ever: keep the collapsed popup compact.
+  if (
+    !open &&
+    (!markdown ||
+      state === "loading" ||
+      state === "idle" ||
+      preview?.items.length === 0)
+  ) {
+    return null;
+  }
+
+  return (
+    <div
+      className={cn("mt-3 flex min-h-0 flex-col", className)}
+      data-testid="update-release-notes-panel"
+      data-notes-state={state}
+      data-notes-version={version}
+      data-notes-open={open}
+    >
+      {/* borderless fill, lighter than the card in dark mode */}
+      <div className="flex min-h-0 flex-col rounded-[14px] bg-muted/40 px-3 py-1 dark:bg-white/[0.06]">
+        {markdown ? (
+          open ? (
+            <section
+              ref={scrollRef}
+              // biome-ignore lint/a11y/noNoninteractiveTabindex: keyboard-scrollable region
+              tabIndex={0}
+              aria-label={`Release notes for version ${version}`}
+              // Long notes scroll here instead of pushing the buttons off screen.
+              className="hover-scrollbar max-h-64 min-h-0 flex-1 overflow-y-auto overscroll-contain py-3 pr-1"
+              data-testid="update-release-notes-scroll"
+            >
+              <MarkdownPreview
+                markdown={markdown}
+                // Streamdown ships headings at mt-6 and code at text-sm, and
+                // clears max-width on descendants, so rescale and re-cap both.
+                className="max-h-none overflow-visible border-0 bg-transparent p-0 text-ui-11 [&_[data-streamdown=link-safety-modal]>*]:max-w-md [&_img]:h-auto [&_img]:max-w-full [&>*:first-child]:mt-0 [&>*>*:first-child]:mt-0 [&_code]:text-[0.92em] [&_h1]:mt-4 [&_h1]:font-heading [&_h1]:text-ui-13 [&_h2]:mt-4 [&_h2]:font-heading [&_h2]:text-ui-13 [&_h3]:mt-4 [&_h3]:font-heading [&_h3]:text-ui-11 [&_pre]:text-[0.92em]"
+              />
+              {notes?.truncated ? (
+                <p className="mt-2 text-ui-10 text-muted-foreground/80">
+                  Notes truncated. See the full changelog.
+                </p>
+              ) : null}
+            </section>
+          ) : (
+            <ReleaseNotesSummary preview={preview} />
+          )
+        ) : (
+          <NotesStatus
+            state={state}
+            version={version}
+            link={link}
+            retry={retry}
+          />
+        )}
+      </div>
+      {open && markdown && link ? (
+        <div className="mt-2 flex justify-end px-1">{link}</div>
+      ) : null}
+    </div>
+  );
+}
+
+/** Collapsed view: the first few bullets, one line each where possible. */
+function ReleaseNotesSummary({
+  preview,
+}: {
+  preview: ReturnType<typeof releaseNotesPreview> | null;
+}): ReactElement | null {
+  if (preview === null || preview.items.length === 0) {
+    return null;
+  }
+  const { items, remaining } = preview;
+
+  return (
+    <ul
+      className="space-y-1 py-2 pr-1"
+      data-testid="update-release-notes-summary"
+    >
+      {items.map((item, index) => (
+        <li
+          // Two releases can carry the same bullet text, so index is the key.
+          key={`${index}-${item.lead}`}
+          className="flex gap-1.5 text-ui-11 leading-snug text-muted-foreground"
+        >
+          <span aria-hidden="true" className="text-muted-foreground/60">
+            &bull;
+          </span>
+          <span className="line-clamp-2 min-w-0">
+            {/* lead sentence carries the change */}
+            <span className="font-medium text-foreground">{item.lead}</span>
+            {item.rest ? <span> {item.rest}</span> : null}
+          </span>
+        </li>
+      ))}
+      {remaining > 0 ? (
+        <li className="pl-3 text-ui-10 text-muted-foreground/70">
+          +{remaining} more
+        </li>
+      ) : null}
+    </ul>
+  );
+}
+
+function NotesStatus({
+  state,
+  version,
+  link,
+  retry,
+}: {
+  state: ReturnType<typeof useReleaseNotes>["state"];
+  version: string;
+  link: ReactNode;
+  retry: () => void;
+}): ReactElement {
+  if (state === "loading" || state === "idle") {
+    return <NotesMessage>Loading release notes...</NotesMessage>;
+  }
+
+  if (state === "error") {
+    return (
+      <NotesMessage
+        action={
+          // The changelog page may be reachable when the lookup is not.
+          <span className="flex shrink-0 items-center gap-3">
+            <button
+              type="button"
+              onClick={retry}
+              className={NOTES_LINK_CLASS}
+              data-testid="update-release-notes-retry"
+            >
+              Retry
+            </button>
+            {link}
+          </span>
+        }
+      >
+        Could not load release notes.
+      </NotesMessage>
+    );
+  }
+
+  // Matched nothing: link out rather than show another release's notes.
+  return (
+    <NotesMessage action={link}>
+      No release notes published for {version} yet.
+    </NotesMessage>
+  );
+}

studio/frontend/src/components/web/update-banner.tsx

@@ -2,6 +2,7 @@
 // Copyright 2026-present the Unsloth AI Inc. team. All rights reserved. See /studio/LICENSE.AGPL-3.0
 
 import { Button } from "@/components/ui/button";
+import { ReleaseNotesPanel } from "@/components/update/release-notes-panel";
 import { type DeviceType, usePlatformStore } from "@/config/env";
 import { useWebUpdateCheck } from "@/hooks/use-web-update-check";
 import { isTauri } from "@/lib/api-base";
@@ -40,6 +41,7 @@ export function WebUpdateBanner({
   const deviceType = usePlatformStore((s) => s.deviceType);
   const installCmd = installCommandForDevice(deviceType);
   const [copiedVersion, setCopiedVersion] = useState<string | null>(null);
+  const [notesVersion, setNotesVersion] = useState<string | null>(null);
   const dismissTimerRef = useRef<ReturnType<typeof setTimeout> | null>(null);
 
   useEffect(() => {
@@ -68,6 +70,8 @@ export function WebUpdateBanner({
   }
 
   const copied = status != null && copiedVersion === status.latestVersion;
+  // Keyed by version so a new offer collapses the panel.
+  const notesOpen = status != null && notesVersion === status.latestVersion;
 
   return (
     <AnimatePresence>
@@ -78,13 +82,14 @@ export function WebUpdateBanner({
           exit={{ opacity: 0, y: 8, scale: 0.97 }}
           transition={{ duration: 0.35, ease: EASE_OUT_QUART }}
           className={cn(
+            // Wider than the other overlays: notes preview plus three buttons.
             positioned
-              ? "fixed bottom-4 right-4 z-[9999] w-[calc(100vw-2rem)] max-w-[400px]"
-              : "pointer-events-auto w-full",
+              ? "fixed bottom-4 right-4 z-[9999] w-[calc(100vw-2rem)] max-w-[448px]"
+              : "pointer-events-auto flex min-h-0 w-[calc(100vw-2rem)] max-w-[448px] flex-col",
           )}
           data-testid="web-update-banner"
         >
-          <div className="relative overflow-hidden rounded-[24px] bg-white px-5 pb-4 pt-5 shadow-[0_2px_8px_-2px_rgba(0,0,0,0.16)] dark:bg-card dark:shadow-[0_8px_28px_-6px_rgba(0,0,0,0.28)]">
+          <div className="relative flex max-h-[calc(100dvh_-_2rem)] flex-col overflow-hidden rounded-[24px] bg-white px-5 pb-4 pt-5 shadow-[0_2px_8px_-2px_rgba(0,0,0,0.16)] dark:bg-card dark:shadow-[0_8px_28px_-6px_rgba(0,0,0,0.28)]">
             <button
               type="button"
               onClick={dismiss}
@@ -127,22 +132,33 @@ export function WebUpdateBanner({
               </div>
             </div>
 
+            <ReleaseNotesPanel
+              version={status.latestVersion}
+              open={notesOpen}
+              releaseNotesUrl={RELEASE_NOTES_URL}
+              className="min-h-0 flex-1"
+            />
+
+            {/* one row at one type size; wraps only on narrow viewports */}
             <div className="mt-4 flex flex-wrap items-center justify-between gap-y-2">
-              <a
-                href={RELEASE_NOTES_URL}
-                target="_blank"
-                rel="noopener noreferrer"
-                className="-ml-2 whitespace-nowrap rounded-full px-2.5 py-2 text-ui-13 font-medium text-foreground transition-colors hover:bg-muted"
-                data-testid="web-update-release-notes-link"
+              <Button
+                size="sm"
+                variant="ghost"
+                className="-ml-2 h-auto whitespace-nowrap rounded-full px-2.5 py-2 text-ui-13 font-medium text-foreground"
+                onClick={() =>
+                  setNotesVersion(notesOpen ? null : status.latestVersion)
+                }
+                aria-expanded={notesOpen}
+                data-testid="web-update-release-notes-toggle"
               >
-                Release notes
-              </a>
+                {notesOpen ? "Hide release notes" : "Show release notes"}
+              </Button>
               {/* wrap + right-align so buttons stack instead of clipping on very narrow banners */}
               <div className="flex flex-wrap items-center justify-end gap-x-1 gap-y-2">
                 <Button
                   size="sm"
                   variant="ghost"
-                  className="h-auto rounded-full px-3 py-2 text-ui-13 font-medium text-foreground"
+                  className="h-auto whitespace-nowrap rounded-full px-2.5 py-2 text-ui-13 font-medium text-foreground"
                   onClick={snooze}
                   data-testid="web-update-snooze-button"
                 >
@@ -151,7 +167,7 @@ export function WebUpdateBanner({
                 <Button
                   size="sm"
                   // -mr optically aligns the filled pill's edge with the card padding
-                  className="-mr-1 h-auto rounded-full px-3.5 py-2 text-ui-13"
+                  className="-mr-1 h-auto whitespace-nowrap rounded-full px-3 py-2 text-ui-13"
                   onClick={handleCopyCommand}
                   data-testid="web-update-copy-button"
                 >

studio/frontend/src/features/chat/chat-settings-sheet.tsx

@@ -18,6 +18,7 @@ import {
   DropdownMenuTrigger,
 } from "@/components/ui/dropdown-menu";
 import { InfoHint } from "@/components/ui/info-hint";
+import { PanelResizeHandle } from "@/components/ui/panel-resize-handle";
 import {
   InputGroup,
   InputGroupAddon,
@@ -44,7 +45,13 @@ import { Tooltip, TooltipContent } from "@/components/ui/tooltip";
 import { NumericValueInput, snapToStep } from "@/features/model-picker";
 import { RetrievalSettingsSection } from "@/features/rag";
 import { useLlamaUpdateCheck } from "@/hooks/use-llama-update-check";
+import {
+  CHAT_SETTINGS_WIDTH_MIN,
+  clampChatSettingsWidth,
+  useChatSettingsWidth,
+} from "@/hooks/use-chat-settings-width";
 import { useIsMobile } from "@/hooks/use-mobile";
+import { useT } from "@/i18n";
 import { ChevronDownStandardIcon } from "@/lib/chevron-icons";
 import { toast } from "@/lib/toast";
 import { cn } from "@/lib/utils";
@@ -52,7 +59,7 @@ import { Edit03Icon, LayoutAlignRightIcon } from "@hugeicons/core-free-icons";
 import { HugeiconsIcon } from "@hugeicons/react";
 import { Braces, ChevronDown, ExternalLink } from "lucide-react";
 import { Tooltip as TooltipPrimitive } from "radix-ui";
-import { Fragment, type ReactNode } from "react";
+import { type CSSProperties, Fragment, type ReactNode } from "react";
 import { useCallback, useEffect, useMemo, useRef, useState } from "react";
 import { OpenAICodeExecSection } from "./components/openai-code-exec-section";
 import { PermissionModeDropdown } from "./permission-mode-select";
@@ -363,6 +370,15 @@ export function ChatSettingsPanel({
   onExternalProviderChange,
   externalProviderType = null,
 }: ChatSettingsPanelProps) {
+  const asideRef = useRef<HTMLElement>(null);
+  const t = useT();
+  const {
+    width: settingsWidth,
+    max: settingsMax,
+    stored: settingsStored,
+    setWidth: setSettingsWidth,
+    resetWidth: resetSettingsWidth,
+  } = useChatSettingsWidth();
   // Local models show every knob; providerCapabilities is only consulted when
   // isExternalModel. Unknown providers fall back to the OpenAI-compat shape via
   // getProviderCapabilities, so these flags never undercount support.
@@ -461,6 +477,23 @@ export function ChatSettingsPanel({
   // When the prompt overflows the inline box, clicking opens the popup editor.
   const systemPromptBoxRef = useRef<HTMLTextAreaElement>(null);
   const [systemPromptOverflows, setSystemPromptOverflows] = useState(false);
+  const promptObserverRef = useRef<ResizeObserver | null>(null);
+  const measurePromptRef = useRef<() => void>(() => {});
+  // The section unmounts its textarea when collapsed, so observe through a
+  // callback ref: a stored observer would cling to the detached node and the
+  // remounted one would never be measured.
+  const attachPromptBox = useCallback((node: HTMLTextAreaElement | null) => {
+    systemPromptBoxRef.current = node;
+    promptObserverRef.current?.disconnect();
+    promptObserverRef.current = null;
+    if (!node || typeof ResizeObserver === "undefined") return;
+    // Resizing rewraps the prompt, and a drag changes the width through a
+    // custom property without re-rendering, so watch the box itself.
+    const observer = new ResizeObserver(() => measurePromptRef.current());
+    observer.observe(node);
+    promptObserverRef.current = observer;
+    measurePromptRef.current();
+  }, []);
   const [activePresetBaseline, setActivePresetBaseline] = useState(params);
   const presets = useMemo(() => {
     return getOrderedPresets(customPresets);
@@ -746,15 +779,20 @@ export function ChatSettingsPanel({
   }, [open]);
 
   useEffect(() => {
-    const el = systemPromptBoxRef.current;
-    setSystemPromptOverflows(
-      currentSystemPrompt.length > 0 &&
-        el != null &&
-        el.clientHeight > 0 &&
-        el.scrollHeight > el.clientHeight + 1,
-    );
+    measurePromptRef.current = () => {
+      const el = systemPromptBoxRef.current;
+      setSystemPromptOverflows(
+        currentSystemPrompt.length > 0 &&
+          el != null &&
+          el.clientHeight > 0 &&
+          el.scrollHeight > el.clientHeight + 1,
+      );
+    };
+    measurePromptRef.current();
   }, [currentSystemPrompt, open]);
 
+  useEffect(() => () => promptObserverRef.current?.disconnect(), []);
+
   const settingsScrollRef = useRef<HTMLDivElement>(null);
 
   const settingsContent = (
@@ -1124,7 +1162,7 @@ export function ChatSettingsPanel({
             )}
           >
             <textarea
-              ref={systemPromptBoxRef}
+              ref={attachPromptBox}
               value={currentSystemPrompt}
               onChange={(e) => set("systemPrompt")(e.target.value)}
               onMouseDown={(e) => {
@@ -1433,17 +1471,47 @@ export function ChatSettingsPanel({
 
   return (
     <aside
+      ref={asideRef}
       data-tour="chat-settings"
+      data-slot="chat-settings-panel"
       className={cn(
-        "relative z-50 shrink-0 overflow-hidden bg-panel-surface text-panel-surface-fg font-heading",
-        open ? "w-[17rem] border-l border-sidebar-border" : "w-0",
+        "relative z-50 shrink-0 bg-panel-surface text-panel-surface-fg font-heading",
+        open
+          ? "w-(--chat-settings-width) border-l border-sidebar-border"
+          : "w-0 overflow-hidden",
       )}
-      style={{
-        height: "calc(100% - var(--studio-custom-titlebar-height, 0px))",
-        marginTop: "var(--studio-custom-titlebar-height, 0px)",
-      }}
+      style={
+        {
+          "--chat-settings-width": `${settingsWidth}px`,
+          height: "calc(100% - var(--studio-custom-titlebar-height, 0px))",
+          marginTop: "var(--studio-custom-titlebar-height, 0px)",
+        } as CSSProperties
+      }
     >
-      <div className="h-full w-full">{settingsContent}</div>
+      {open ? (
+      <PanelResizeHandle
+        edge="left"
+        open={open}
+        width={settingsWidth}
+        stored={settingsStored}
+        min={CHAT_SETTINGS_WIDTH_MIN}
+        max={settingsMax}
+        clamp={clampChatSettingsWidth}
+        setWidth={setSettingsWidth}
+        resetWidth={resetSettingsWidth}
+        onToggle={() => onOpenChange?.(!open)}
+        target={() => asideRef.current}
+        cssVar="--chat-settings-width"
+        measure={() => asideRef.current?.getBoundingClientRect().width ?? 0}
+        label={t("shell.aria.resizeRunSettings")}
+        toggleLabel={t("shell.aria.openRunSettings")}
+        collapseHint={t("shell.resize.collapse")}
+        expandHint={t("shell.resize.expand")}
+        dragHint={t("shell.resize.drag")}
+        dataSlot="chat-settings-resize-handle"
+      />
+      ) : null}
+      <div className="h-full w-full overflow-hidden">{settingsContent}</div>
     </aside>
   );
 }

studio/frontend/src/features/hub/catalog/on-device-folders-dialog.tsx

@@ -23,12 +23,21 @@ import {
   removeScanFolder,
 } from "@/features/hub";
 import { FolderBrowser } from "@/features/model-picker";
-import { openModelsDir } from "@/features/native-intents";
+import {
+  openModelsDir,
+  pickHuggingFaceCacheDir,
+} from "@/features/native-intents";
+import {
+  type HuggingFaceCacheSettings,
+  loadHuggingFaceCacheSettings,
+  updateHuggingFaceCacheSettings,
+} from "@/features/settings";
 import { isTauri } from "@/lib/api-base";
 import { toast } from "@/lib/toast";
 import { cn } from "@/lib/utils";
 import {
   Delete02Icon,
+  DownloadCircle01Icon,
   FileSearchIcon,
   FolderAddIcon,
   FolderExportIcon,
@@ -49,6 +58,12 @@ function formatError(error: unknown): string {
   return error instanceof Error ? error.message : String(error);
 }
 
+function formatFreeSpace(bytes: number | null): string | null {
+  if (bytes === null || !Number.isFinite(bytes)) return null;
+  const gb = bytes / 1024 ** 3;
+  return gb >= 10 ? `${Math.round(gb)} GB free` : `${gb.toFixed(1)} GB free`;
+}
+
 export function OnDeviceFoldersDialog({
   open,
   onOpenChange,
@@ -68,6 +83,11 @@ export function OnDeviceFoldersDialog({
   );
   const refreshIdRef = useRef(0);
   const mutationVersionRef = useRef(0);
+  const [downloadCache, setDownloadCache] =
+    useState<HuggingFaceCacheSettings | null>(null);
+  const [downloadCacheLoaded, setDownloadCacheLoaded] = useState(false);
+  const [downloadBrowserOpen, setDownloadBrowserOpen] = useState(false);
+  const [downloadSaving, setDownloadSaving] = useState(false);
 
   const sortedFolders = useMemo(
     () => [...folders].sort((a, b) => a.path.localeCompare(b.path)),
@@ -108,10 +128,66 @@ export function OnDeviceFoldersDialog({
     return () => window.clearTimeout(timer);
   }, [open, refreshFolders]);
 
+  useEffect(() => {
+    if (!open) return;
+    let cancelled = false;
+    // The dialog stays mounted between opens, so re-arm the flag or a reopen
+    // shows the previous answer as if it were fresh.
+    setDownloadCacheLoaded(false);
+    loadHuggingFaceCacheSettings()
+      // Indexed locations do not depend on this. Null drops the stale path
+      // rather than offer Change against a location we could not confirm.
+      .catch(() => null)
+      .then((settings) => {
+        if (cancelled) return;
+        setDownloadCache(settings);
+        setDownloadCacheLoaded(true);
+      });
+    return () => {
+      cancelled = true;
+    };
+  }, [open]);
+
   const handleInventoryChanged = useCallback(() => {
     onInventoryChange?.();
   }, [onInventoryChange]);
 
+  // Relocating the cache changes which repos are on disk, but
+  // updateHuggingFaceCacheSettings already bumps the inventory version, which
+  // re-fetches every source. Refreshing here too would scan twice, since the
+  // two rounds carry different version keys and cannot be deduplicated.
+  const saveDownloadLocation = useCallback(async (nextPath: string | null) => {
+    setDownloadSaving(true);
+    try {
+      const settings = await updateHuggingFaceCacheSettings(nextPath);
+      setDownloadCache(settings);
+      toast.success("Download location updated", {
+        description: settings.cacheHome,
+      });
+    } catch (err) {
+      toast.error("Couldn't update the download location", {
+        description: formatError(err),
+      });
+    } finally {
+      setDownloadSaving(false);
+    }
+  }, []);
+
+  const changeDownloadLocation = useCallback(async () => {
+    if (!isTauri) {
+      setDownloadBrowserOpen(true);
+      return;
+    }
+    try {
+      const picked = await pickHuggingFaceCacheDir();
+      if (picked) await saveDownloadLocation(picked);
+    } catch (err) {
+      toast.error("Couldn't open the folder picker", {
+        description: formatError(err),
+      });
+    }
+  }, [saveDownloadLocation]);
+
   const handleAdd = useCallback(
     async (rawPath: string) => {
       const nextPath = rawPath.trim();
@@ -182,10 +258,10 @@ export function OnDeviceFoldersDialog({
     <>
       <Dialog open={open} onOpenChange={onOpenChange}>
         <DialogContent
-          className="gap-0 overflow-hidden p-0 sm:max-w-[620px] lg:max-w-[660px] xl:max-w-[680px] [&_[data-slot=dialog-close]]:right-3 [&_[data-slot=dialog-close]]:top-3"
+          className="flex max-h-[90dvh] flex-col gap-0 overflow-hidden p-0 sm:max-w-[620px] lg:max-w-[660px] xl:max-w-[680px] [&_[data-slot=dialog-close]]:right-3 [&_[data-slot=dialog-close]]:top-3"
           overlayClassName="bg-black/20 backdrop-blur-none"
         >
-          <DialogHeader className="border-b border-border/60 px-5 py-4">
+          <DialogHeader className="shrink-0 border-b border-border/60 px-5 py-4">
             <DialogTitle className="text-ui-15">
               On-device locations
             </DialogTitle>
@@ -195,7 +271,78 @@ export function OnDeviceFoldersDialog({
             </DialogDescription>
           </DialogHeader>
 
-          <div className="space-y-4 px-5 py-4">
+          <div className="min-h-0 flex-1 space-y-4 overflow-y-auto px-5 py-4">
+            <div className="rounded-[14px] border border-border/70 bg-muted/20 p-3">
+              <div className="mb-2 flex items-center gap-2 text-ui-12 font-medium text-foreground">
+                <HugeiconsIcon
+                  icon={DownloadCircle01Icon}
+                  strokeWidth={1.75}
+                  className="size-3.5 text-muted-foreground"
+                />
+                Download location
+              </div>
+
+              <div className="flex flex-col gap-2 sm:flex-row sm:items-center">
+                <Input
+                  readOnly={true}
+                  aria-label="Model download location"
+                  value={
+                    downloadCache?.cacheHome ??
+                    (downloadCacheLoaded ? "Unknown" : "Loading...")
+                  }
+                  title={downloadCache?.cacheHome}
+                  className="field-soft h-9 min-w-0 flex-1 rounded-full px-3 font-mono text-ui-12"
+                />
+                <div className="flex shrink-0 items-center gap-2">
+                  <Button
+                    type="button"
+                    variant="outline"
+                    size="sm"
+                    onClick={() => void changeDownloadLocation()}
+                    disabled={!downloadCache?.editable || downloadSaving}
+                    className="h-9 rounded-full px-3 text-ui-12p5"
+                  >
+                    {downloadSaving ? (
+                      <Spinner className="size-3.5" />
+                    ) : (
+                      <HugeiconsIcon
+                        icon={FolderSearchIcon}
+                        strokeWidth={1.75}
+                        data-icon="inline-start"
+                        className="size-3.5"
+                      />
+                    )}
+                    Change
+                  </Button>
+                  {downloadCache?.isCustom ? (
+                    <Button
+                      type="button"
+                      variant="ghost"
+                      size="sm"
+                      onClick={() => void saveDownloadLocation(null)}
+                      disabled={downloadSaving}
+                      className="h-9 rounded-full px-3 text-ui-12p5 text-muted-foreground"
+                    >
+                      Use default
+                    </Button>
+                  ) : null}
+                </div>
+              </div>
+
+              <p className="mt-2 text-ui-10p5 text-muted-foreground">
+                {downloadCache?.source === "environment"
+                  ? `Managed by the ${
+                      downloadCache.environmentVariable ?? "HF_HOME"
+                    } environment variable.`
+                  : [
+                      "New downloads only. Models already on disk stay where they are.",
+                      formatFreeSpace(downloadCache?.freeBytes ?? null),
+                    ]
+                      .filter(Boolean)
+                      .join(" · ")}
+              </p>
+            </div>
+
             <div className="rounded-[14px] border border-border/70 bg-muted/20 p-3">
               <div className="mb-2 flex items-center gap-2 text-ui-12 font-medium text-foreground">
                 <HugeiconsIcon
@@ -425,6 +572,16 @@ export function OnDeviceFoldersDialog({
         onOpenChange={setBrowserOpen}
         onSelect={(selectedPath) => void handleAdd(selectedPath)}
       />
+
+      <FolderBrowser
+        open={!isTauri && downloadBrowserOpen}
+        onOpenChange={setDownloadBrowserOpen}
+        onSelect={(selectedPath) => void saveDownloadLocation(selectedPath)}
+        initialPath={downloadCache?.cacheHome}
+        title="Choose model download location"
+        confirmLabel="Use for future downloads"
+        showModelHints={false}
+      />
     </>
   );
 }

studio/frontend/src/features/hub/download-manager/download-manager-panel.tsx

@@ -201,8 +201,10 @@ export function DownloadManagerPanel({
       className={cn(
         // Standalone: anchor bottom-right. In a shared stack (positioned=false)
         // flow as a right-aligned row so overlays stack instead of overlapping.
+        // min-h-0 there: a flex item's min-height defaults to auto, so the capped
+        // stack would squeeze the update card instead of this list.
         "pointer-events-none",
-        positioned ? "fixed bottom-4 right-4 z-50" : "flex justify-end",
+        positioned ? "fixed bottom-4 right-4 z-50" : "flex min-h-0 justify-end",
       )}
     >
       {collapsed ? (
@@ -229,7 +231,7 @@ export function DownloadManagerPanel({
           </TooltipContent>
         </Tooltip>
       ) : (
-        <div className="hub-download-panel pointer-events-auto w-[min(400px,calc(100vw-2rem))] overflow-hidden">
+        <div className="hub-download-panel pointer-events-auto flex min-h-0 w-[min(400px,calc(100vw-2rem))] flex-col overflow-hidden">
           <div className="flex items-center gap-2 border-b border-foreground/[0.07] py-2 pl-4 pr-3">
             <span className="min-w-0 flex-1 truncate text-ui-12p5 font-semibold text-foreground">
               {headerLabel}

studio/frontend/src/features/settings/index.ts

@@ -3,6 +3,11 @@
 
 export { SettingsDialog } from "./settings-dialog";
 export { loadEmbeddingModelSettings } from "./api/embedding-model";
+export {
+  loadHuggingFaceCacheSettings,
+  updateHuggingFaceCacheSettings,
+} from "./api/hugging-face-cache";
+export type { HuggingFaceCacheSettings } from "./api/hugging-face-cache";
 export {
   loadPersonalization,
   savePersonalization,

studio/frontend/src/features/settings/settings-dialog.tsx

@@ -35,7 +35,10 @@ import {
   useRef,
   useState,
 } from "react";
-import { SETTINGS_SEARCH_INDEX } from "./settings-search";
+import {
+  SETTINGS_SEARCH_INDEX,
+  SETTINGS_SEARCH_KEYWORDS,
+} from "./settings-search";
 import {
   type SettingsTab,
   useSettingsDialogStore,
@@ -157,8 +160,12 @@ export function SettingsDialog() {
     return TABS.map((tab) => {
       const tabLabel = t(tab.labelKey);
       const entries = SETTINGS_SEARCH_INDEX[tab.id]
-        .map((key) => t(key))
-        .filter((label) => label.toLowerCase().includes(q));
+        .filter((key) => {
+          if (t(key).toLowerCase().includes(q)) return true;
+          const keywordsKey = SETTINGS_SEARCH_KEYWORDS[key];
+          return keywordsKey ? t(keywordsKey).toLowerCase().includes(q) : false;
+        })
+        .map((key) => t(key));
       const deduped = [...new Set(entries)];
       return {
         tab,

studio/frontend/src/features/settings/settings-search.ts

@@ -146,3 +146,15 @@ export const SETTINGS_SEARCH_INDEX: Record<SettingsTab, TranslationKey[]> = {
     "settings.about.shutDownStudio",
   ],
 };
+
+/**
+ * Extra terms a row matches on, beyond its own label. The value is a
+ * translation key holding space-separated synonyms; it is never rendered.
+ * Search matched labels only, so "models folder" or "directory" found nothing.
+ */
+export const SETTINGS_SEARCH_KEYWORDS: Partial<
+  Record<TranslationKey, TranslationKey>
+> = {
+  "settings.resources.storage.modelsFolder":
+    "settings.resources.storage.modelsFolderKeywords",
+};

studio/frontend/src/features/settings/tabs/general-tab.tsx

@@ -74,6 +74,8 @@ const PREFS_KEYS: string[] = [
   LOCALE_STORAGE_KEY,
   // UI state
   "sidebar_pinned",
+  "sidebar_width",
+  "chat_settings_width",
   "unsloth_sidebar_navigate_open",
   "unsloth_settings_active_tab",
   // Chat runtime prefs

studio/frontend/src/hooks/use-chat-settings-width.ts

@@ -0,0 +1,20 @@
+// SPDX-License-Identifier: AGPL-3.0-only
+// Copyright 2026-present the Unsloth AI Inc. team. All rights reserved. See /studio/LICENSE.AGPL-3.0
+
+import { createPanelWidthStore } from "./use-panel-width.ts";
+
+/** The previous fixed 17rem, at a 16px root font size. */
+export const CHAT_SETTINGS_WIDTH_DEFAULT = 272;
+/** Below this the sliders and their value pills start colliding. */
+export const CHAT_SETTINGS_WIDTH_MIN = 248;
+export const CHAT_SETTINGS_WIDTH_MAX = 560;
+
+const store = createPanelWidthStore({
+  key: "chat_settings_width",
+  min: CHAT_SETTINGS_WIDTH_MIN,
+  max: CHAT_SETTINGS_WIDTH_MAX,
+  fallback: CHAT_SETTINGS_WIDTH_DEFAULT,
+});
+
+export const clampChatSettingsWidth = store.clamp;
+export const useChatSettingsWidth = store.useWidth;

studio/frontend/src/hooks/use-panel-width.ts

@@ -0,0 +1,138 @@
+// SPDX-License-Identifier: AGPL-3.0-only
+// Copyright 2026-present the Unsloth AI Inc. team. All rights reserved. See /studio/LICENSE.AGPL-3.0
+
+import { useCallback, useSyncExternalStore } from "react";
+
+/** Never let one panel eat more than this share of a narrow window. */
+const MAX_VIEWPORT_FRACTION = 0.4;
+
+export type PanelWidthStore = {
+  /** Clamps to what the current viewport allows. */
+  clamp: (px: number) => number;
+  useWidth: () => {
+    width: number;
+    max: number;
+    /** The uncapped stored preference. */
+    stored: number;
+    setWidth: (value: number) => void;
+    resetWidth: () => void;
+  };
+};
+
+/**
+ * A persisted, viewport-aware width for a draggable panel. The preference is
+ * stored whole and an effective width is derived from it, so narrowing the
+ * window shrinks the panel without losing what the user picked.
+ */
+export function createPanelWidthStore({
+  key,
+  min,
+  max,
+  fallback,
+}: {
+  key: string;
+  min: number;
+  max: number;
+  fallback: number;
+}): PanelWidthStore {
+  function maxWidth(): number {
+    if (typeof window === "undefined") return max;
+    // The floor wins on a narrow window; collapsing is the escape.
+    return Math.max(min, Math.min(max, window.innerWidth * MAX_VIEWPORT_FRACTION));
+  }
+
+  /** Clamps to the absolute range, ignoring the viewport. */
+  function clampStored(px: number): number {
+    if (!Number.isFinite(px)) return fallback;
+    return Math.min(max, Math.max(min, Math.round(px)));
+  }
+
+  function clamp(px: number): number {
+    return Math.min(maxWidth(), clampStored(px));
+  }
+
+  function load(): number {
+    if (typeof window === "undefined") return fallback;
+    try {
+      const raw = window.localStorage.getItem(key);
+      if (raw === null) return fallback;
+      return clampStored(Number.parseFloat(raw));
+    } catch {
+      return fallback;
+    }
+  }
+
+  let storedWidth = load();
+  let effectiveWidth = clamp(storedWidth);
+  let effectiveMax = maxWidth();
+  const listeners = new Set<() => void>();
+
+  let lastStored = storedWidth;
+
+  function recompute() {
+    const nextWidth = clamp(storedWidth);
+    const nextMax = maxWidth();
+    if (
+      nextWidth === effectiveWidth &&
+      nextMax === effectiveMax &&
+      storedWidth === lastStored
+    ) {
+      return;
+    }
+    effectiveWidth = nextWidth;
+    effectiveMax = nextMax;
+    lastStored = storedWidth;
+    listeners.forEach((cb) => cb());
+  }
+
+  function subscribe(cb: () => void) {
+    // With no subscribers there is no resize listener, so the cache can be
+    // stale after a resize on a route that hides every panel. Refresh first;
+    // useSyncExternalStore re-reads the snapshot right after subscribing.
+    recompute();
+    listeners.add(cb);
+    if (typeof window === "undefined") {
+      return () => listeners.delete(cb);
+    }
+    // Keep tabs in sync, same as the pin flag.
+    const onStorage = (e: StorageEvent) => {
+      if (e.key === key || e.key === null) {
+        storedWidth = load();
+        effectiveWidth = clamp(storedWidth);
+        effectiveMax = maxWidth();
+        cb();
+      }
+    };
+    window.addEventListener("storage", onStorage);
+    window.addEventListener("resize", recompute);
+    return () => {
+      listeners.delete(cb);
+      window.removeEventListener("storage", onStorage);
+      window.removeEventListener("resize", recompute);
+    };
+  }
+
+  function setWidthGlobal(next: number) {
+    const stored = clampStored(next);
+    if (stored !== storedWidth) {
+      storedWidth = stored;
+      try {
+        window.localStorage.setItem(key, String(stored));
+      } catch {}
+    }
+    recompute();
+  }
+
+  function useWidth() {
+    const width = useSyncExternalStore(subscribe, () => effectiveWidth, () => fallback);
+    // What the viewport actually allows right now, for aria-valuemax.
+    const panelMax = useSyncExternalStore(subscribe, () => effectiveMax, () => max);
+    // The uncapped preference, so a capped drag can avoid lowering it.
+    const preference = useSyncExternalStore(subscribe, () => storedWidth, () => fallback);
+    const setWidth = useCallback((value: number) => setWidthGlobal(value), []);
+    const resetWidth = useCallback(() => setWidthGlobal(fallback), []);
+    return { width, max: panelMax, stored: preference, setWidth, resetWidth };
+  }
+
+  return { clamp, useWidth };
+}

studio/frontend/src/hooks/use-release-notes.ts

@@ -0,0 +1,146 @@
+// SPDX-License-Identifier: AGPL-3.0-only
+// Copyright 2026-present the Unsloth AI Inc. team. All rights reserved. See /studio/LICENSE.AGPL-3.0
+
+import { authFetch, hasAuthToken } from "@/features/auth";
+import { apiUrl } from "@/lib/api-base";
+import { useCallback, useEffect, useRef, useState } from "react";
+
+// Keyed to one exact version, so a new update never pairs with older notes.
+export interface ReleaseNotes {
+  version: string;
+  markdown: string | null;
+  matched: boolean;
+  truncated: boolean;
+  source: string | null;
+  releaseNotesUrl: string | null;
+  // Set when the lookup itself failed, as opposed to a version with no notes.
+  error: string | null;
+}
+
+export type ReleaseNotesState = "idle" | "loading" | "ready" | "error";
+
+// Desktop auto-auth installs its token after first paint, so a startup popup can
+// ask before one exists. Wait briefly rather than fail.
+const AUTH_POLL_MS = 250;
+const AUTH_POLL_LIMIT = 40;
+
+interface UseReleaseNotesOptions {
+  version: string | null | undefined;
+  enabled?: boolean;
+}
+
+type ApiObject = Record<string, unknown>;
+
+function stringOrNull(value: ApiObject, key: string): string | null {
+  const field = value[key];
+  return typeof field === "string" && field.length > 0 ? field : null;
+}
+
+function toReleaseNotes(value: unknown, version: string): ReleaseNotes | null {
+  if (!value || typeof value !== "object") {
+    return null;
+  }
+  const payload = value as ApiObject;
+  const notesVersion = stringOrNull(payload, "version");
+  // A response for another version is not usable here.
+  if (notesVersion !== version) {
+    return null;
+  }
+  const markdown = stringOrNull(payload, "markdown");
+  return {
+    version,
+    markdown,
+    matched: payload.matched === true && markdown !== null,
+    truncated: payload.truncated === true,
+    source: stringOrNull(payload, "source"),
+    releaseNotesUrl: stringOrNull(payload, "release_notes_url"),
+    error: stringOrNull(payload, "error"),
+  };
+}
+
+async function fetchReleaseNotes(
+  version: string,
+  refresh = false,
+): Promise<ReleaseNotes | null> {
+  const query = `version=${encodeURIComponent(version)}${refresh ? "&refresh=true" : ""}`;
+  // authFetch, not fetch: an expired token is refreshed and retried.
+  const res = await authFetch(apiUrl(`/api/studio/release-notes?${query}`));
+  if (!res.ok) {
+    throw new Error(`Release notes request failed: ${res.status}`);
+  }
+
+  return toReleaseNotes(await res.json(), version);
+}
+
+export function useReleaseNotes({
+  version,
+  enabled = true,
+}: UseReleaseNotesOptions) {
+  const [state, setState] = useState<ReleaseNotesState>("idle");
+  const [notes, setNotes] = useState<ReleaseNotes | null>(null);
+  // Version the current state belongs to; a change invalidates it.
+  const requestedVersionRef = useRef<string | null>(null);
+  // Identifies one request, so an earlier response cannot overwrite a later one.
+  const requestIdRef = useRef(0);
+
+  const load = useCallback((target: string, refresh = false) => {
+    requestedVersionRef.current = target;
+    requestIdRef.current += 1;
+    const requestId = requestIdRef.current;
+    setState("loading");
+    setNotes(null);
+    fetchReleaseNotes(target, refresh)
+      .then((next) => {
+        // A newer request owns the state now.
+        if (requestIdRef.current !== requestId) {
+          return;
+        }
+        setNotes(next);
+        // A reported failure is retryable; "no notes for this version" is not.
+        const failed = !next || (!next.matched && next.error !== null);
+        setState(failed ? "error" : "ready");
+      })
+      .catch(() => {
+        if (requestIdRef.current === requestId) {
+          setNotes(null);
+          setState("error");
+        }
+      });
+  }, []);
+
+  useEffect(() => {
+    if (!enabled || !version || requestedVersionRef.current === version) {
+      return;
+    }
+    if (hasAuthToken()) {
+      load(version);
+      return;
+    }
+    let attempts = 0;
+    const timer = window.setInterval(() => {
+      attempts += 1;
+      if (hasAuthToken() || attempts >= AUTH_POLL_LIMIT) {
+        window.clearInterval(timer);
+        // Out of patience: load anyway so the panel settles on retry.
+        load(version);
+      }
+    }, AUTH_POLL_MS);
+    return () => window.clearInterval(timer);
+  }, [enabled, version, load]);
+
+  const retry = useCallback(() => {
+    if (version) {
+      requestedVersionRef.current = null;
+      // Bypass the cached remote failure, or retry waits for it to expire.
+      load(version, true);
+    }
+  }, [version, load]);
+
+  // Never hand back another version's notes: state lags `version` by a render.
+  const matchesVersion = notes !== null && notes.version === version;
+  return {
+    state: notes !== null && !matchesVersion ? "loading" : state,
+    notes: matchesVersion ? notes : null,
+    retry,
+  };
+}

studio/frontend/src/hooks/use-sidebar-width.ts

@@ -0,0 +1,21 @@
+// SPDX-License-Identifier: AGPL-3.0-only
+// Copyright 2026-present the Unsloth AI Inc. team. All rights reserved. See /studio/LICENSE.AGPL-3.0
+
+import { createPanelWidthStore } from "./use-panel-width.ts";
+
+/** The previous fixed 17.5rem, at a 16px root font size. */
+export const SIDEBAR_WIDTH_DEFAULT = 280;
+/** Narrowest width that still fits the wordmark. Firefox is the constraint:
+ * it renders the heading ~3px wider than Chromium and WebKit. */
+export const SIDEBAR_WIDTH_MIN = 260;
+export const SIDEBAR_WIDTH_MAX = 480;
+
+const store = createPanelWidthStore({
+  key: "sidebar_width",
+  min: SIDEBAR_WIDTH_MIN,
+  max: SIDEBAR_WIDTH_MAX,
+  fallback: SIDEBAR_WIDTH_DEFAULT,
+});
+
+export const clampSidebarWidth = store.clamp;
+export const useSidebarWidth = store.useWidth;

studio/frontend/src/hooks/use-tauri-update.ts

@@ -21,6 +21,8 @@ export type UpdateStatus =
 export interface UpdateInfo {
   version: string;
   currentVersion: string;
+  // Backend release this build pins; CHANGELOG.md is keyed by it, not the SemVer.
+  pypiVersion?: string;
   body?: string;
   date?: string;
 }
@@ -42,10 +44,17 @@ interface DesktopUpdatePolicy {
 interface ManualUpdateInfo {
   version: string;
   currentVersion: string;
+  pypiVersion?: string | null;
   body?: string;
   date?: string;
 }
 
+/** `pypi_version` from latest.json, which the updater passes through raw. */
+function rawPypiVersion(raw: Record<string, unknown>): string | undefined {
+  const value = raw.pypi_version;
+  return typeof value === "string" && value.length > 0 ? value : undefined;
+}
+
 export interface RetainedUpdateFailure {
   error: string;
   phase: UpdatePhase;
@@ -162,6 +171,7 @@ export function useTauriUpdate(isExternalServer = false) {
       setInfo({
         version: manualUpdate.version,
         currentVersion: manualUpdate.currentVersion,
+        pypiVersion: manualUpdate.pypiVersion ?? undefined,
         body: manualUpdate.body,
         date: manualUpdate.date,
       });
@@ -197,6 +207,7 @@ export function useTauriUpdate(isExternalServer = false) {
           setInfo({
             version: update.version,
             currentVersion: update.currentVersion,
+            pypiVersion: rawPypiVersion(update.rawJson),
             body: update.body,
             date: update.date,
           });
@@ -384,10 +395,13 @@ export function useTauriUpdate(isExternalServer = false) {
     });
   }
 
+  // Install target for Linux packages that cannot self-update.
   const manualReleaseUrl =
     updatePolicy.mode === "manual_linux_package" && info
       ? manualReleasePageUrl(updatePolicy, info.version)
       : null;
+  // Release page for the offered version, on every platform, for the notes link.
+  const releasePageUrl = info ? manualReleasePageUrl(updatePolicy, info.version) : null;
 
   return {
     status,
@@ -401,6 +415,7 @@ export function useTauriUpdate(isExternalServer = false) {
     isExternalServer,
     updatePolicyMode: updatePolicy.mode,
     manualReleaseUrl,
+    releasePageUrl,
     installUpdate,
     retryUpdate,
     skipAndRestart,

studio/frontend/src/i18n/locales/ar.ts

@@ -27,10 +27,18 @@ export const ar = {
     product: "Unsloth Studio",
     accountMenu: "قائمة حساب {name}",
     updateAvailable: "يتوفر تحديث",
+    resize: {
+      collapse: "انقر للطي",
+      expand: "انقر للتوسيع",
+      drag: "اسحب لتغيير الحجم",
+    },
     aria: {
       home: "الصفحة الرئيسية لـ Unsloth",
       closeSidebar: "إغلاق الشريط الجانبي",
       openSidebar: "فتح الشريط الجانبي",
+      resizeSidebar: "تغيير حجم الشريط الجانبي أو طيه",
+      resizeRunSettings: "تغيير حجم إعدادات التشغيل أو إغلاقها",
+      openRunSettings: "فتح إعدادات التشغيل",
       chatOptions: "خيارات المحادثة",
       runOptions: "خيارات التدريب",
     },
@@ -317,6 +325,8 @@ export const ar = {
         diskUsage: "{used} مستخدم / {total}",
         diskFree: "{free} متاح",
         modelsFolder: "مجلد النماذج",
+        modelsFolderKeywords:
+          "النماذج مجلد دليل مسار موقع تنزيلات التنزيل ذاكرة التخزين المؤقت تخزين قرص محرك نقل تغيير models folder path hugging face",
         modelsFolderDescription: "المكان الذي تُخزَّن فيه النماذج المُنزَّلة.",
         openAction: "فتح",
         copyAction: "نسخ المسار",

studio/frontend/src/i18n/locales/de.ts

@@ -27,10 +27,18 @@ export const de = {
     product: "Unsloth Studio",
     accountMenu: "Kontomenü von {name}",
     updateAvailable: "Update verfügbar",
+    resize: {
+      collapse: "Zum Einklappen klicken",
+      expand: "Zum Ausklappen klicken",
+      drag: "Zum Ändern der Größe ziehen",
+    },
     aria: {
       home: "Unsloth Startseite",
       closeSidebar: "Seitenleiste schließen",
       openSidebar: "Seitenleiste öffnen",
+      resizeSidebar: "Seitenleiste anpassen oder einklappen",
+      resizeRunSettings: "Ausführungseinstellungen anpassen oder schließen",
+      openRunSettings: "Ausführungseinstellungen öffnen",
       chatOptions: "Chat-Optionen",
       runOptions: "Trainingslauf-Optionen",
     },
@@ -330,9 +338,23 @@ export const de = {
         diskFree: "{free} frei",
         modelsFolder: "Modell-Ordner",
         modelsFolderDescription:
-          "Wo heruntergeladene Modelle gespeichert werden.",
+          "Wo heruntergeladene Modelle gespeichert werden. Ändern Sie ihn, um Modelle nicht auf dem Systemlaufwerk abzulegen.",
+        modelsFolderKeywords:
+          "Modelle Ordner Verzeichnis Pfad Speicherort Download Downloads Cache Speicher Festplatte Laufwerk verschieben ändern hugging face",
+        futureDownloads: "Nur neue Downloads",
+        environmentManaged:
+          "Wird über die Umgebungsvariable {variable} verwaltet.",
+        locationFree: "{free} frei",
         openAction: "Öffnen",
         copyAction: "Pfad kopieren",
+        changeAction: "Ändern",
+        resetAction: "Standard verwenden",
+        chooseTitle: "Speicherort für Modell-Downloads wählen",
+        chooseAction: "Für künftige Downloads verwenden",
+        cacheSaved: "Speicherort für Modell-Downloads aktualisiert",
+        cacheSaveError:
+          "Der Speicherort für Modell-Downloads konnte nicht geändert werden",
+        cachePickerError: "Die Ordnerauswahl konnte nicht geöffnet werden",
         copied: "Pfad kopiert",
         openError: "Der Ordner konnte nicht geöffnet werden",
         copyError: "Der Pfad konnte nicht kopiert werden",

studio/frontend/src/i18n/locales/en.ts

@@ -24,10 +24,18 @@ export const en = {
     product: "Unsloth Studio",
     accountMenu: "{name} account menu",
     updateAvailable: "Update available",
+    resize: {
+      collapse: "Click to collapse",
+      expand: "Click to expand",
+      drag: "Drag to resize",
+    },
     aria: {
       home: "Unsloth home",
       closeSidebar: "Close sidebar",
       openSidebar: "Open sidebar",
+      resizeSidebar: "Resize or collapse sidebar",
+      resizeRunSettings: "Resize or close run settings",
+      openRunSettings: "Open run settings",
       chatOptions: "Chat options",
       runOptions: "Run options",
     },
@@ -556,8 +564,12 @@ export const en = {
         systemDisk: "System disk",
         diskUsage: "{used} used / {total}",
         diskFree: "{free} free",
-        modelsFolder: "Model downloads",
-        modelsFolderDescription: "Hugging Face cache used for model downloads.",
+        modelsFolder: "Models folder",
+        modelsFolderDescription:
+          "Where downloaded models are stored. Change it to keep models off your system drive.",
+        // Not rendered: extra terms the settings search matches this row on.
+        modelsFolderKeywords:
+          "models folder directory path location download downloads cache storage disk drive move relocate hugging face",
         futureDownloads: "New downloads only",
         environmentManaged: "Managed by the {variable} environment variable.",
         locationFree: "{free} free",

studio/frontend/src/i18n/locales/es.ts

@@ -27,10 +27,18 @@ export const es = {
     product: "Unsloth Studio",
     accountMenu: "Menú de cuenta de {name}",
     updateAvailable: "Actualización disponible",
+    resize: {
+      collapse: "Haz clic para contraer",
+      expand: "Haz clic para expandir",
+      drag: "Arrastra para redimensionar",
+    },
     aria: {
       home: "Inicio de Unsloth",
       closeSidebar: "Cerrar barra lateral",
       openSidebar: "Abrir barra lateral",
+      resizeSidebar: "Redimensionar o contraer la barra lateral",
+      resizeRunSettings: "Redimensionar o cerrar los ajustes de ejecución",
+      openRunSettings: "Abrir los ajustes de ejecución",
       chatOptions: "Opciones de chat",
       runOptions: "Opciones de ejecución",
     },
@@ -328,6 +336,8 @@ export const es = {
         diskUsage: "{used} en uso / {total}",
         diskFree: "{free} libre",
         modelsFolder: "Carpeta de modelos",
+        modelsFolderKeywords:
+          "modelos carpeta directorio ruta ubicacion ubicación descargas descarga cache caché almacenamiento disco unidad mover cambiar models folder path hugging face",
         modelsFolderDescription:
           "Dónde se almacenan los modelos descargados.",
         openAction: "Abrir",

studio/frontend/src/i18n/locales/fr.ts

@@ -27,10 +27,18 @@ export const fr = {
     product: "Unsloth Studio",
     accountMenu: "Menu du compte de {name}",
     updateAvailable: "Mise à jour disponible",
+    resize: {
+      collapse: "Cliquez pour réduire",
+      expand: "Cliquez pour développer",
+      drag: "Faites glisser pour redimensionner",
+    },
     aria: {
       home: "Accueil Unsloth",
       closeSidebar: "Fermer la barre latérale",
       openSidebar: "Ouvrir la barre latérale",
+      resizeSidebar: "Redimensionner ou réduire la barre latérale",
+      resizeRunSettings: "Redimensionner ou fermer les paramètres d'exécution",
+      openRunSettings: "Ouvrir les paramètres d'exécution",
       chatOptions: "Options de discussion",
       runOptions: "Options d'exécution",
     },
@@ -325,6 +333,8 @@ export const fr = {
         diskUsage: "{used} utilisé / {total}",
         diskFree: "{free} libre",
         modelsFolder: "Dossier des modèles",
+        modelsFolderKeywords:
+          "modeles modèles dossier repertoire répertoire chemin emplacement telechargements téléchargements cache stockage disque lecteur deplacer déplacer changer models folder path hugging face",
         modelsFolderDescription: "Emplacement de stockage des modèles téléchargés.",
         openAction: "Ouvrir",
         copyAction: "Copier le chemin",

studio/frontend/src/i18n/locales/hi.ts

@@ -27,10 +27,18 @@ export const hi = {
     product: "Unsloth Studio",
     accountMenu: "{name} खाता मेनू",
     updateAvailable: "अपडेट उपलब्ध है",
+    resize: {
+      collapse: "छोटा करने के लिए क्लिक करें",
+      expand: "विस्तार के लिए क्लिक करें",
+      drag: "आकार बदलने के लिए खींचें",
+    },
     aria: {
       home: "Unsloth होम",
       closeSidebar: "साइडबार बंद करें",
       openSidebar: "साइडबार खोलें",
+      resizeSidebar: "साइडबार का आकार बदलें या छोटा करें",
+      resizeRunSettings: "रन सेटिंग्स का आकार बदलें या बंद करें",
+      openRunSettings: "रन सेटिंग्स खोलें",
       chatOptions: "चैट विकल्प",
       runOptions: "रन विकल्प",
     },
@@ -316,6 +324,8 @@ export const hi = {
         diskUsage: "{used} उपयोग में / {total}",
         diskFree: "{free} खाली",
         modelsFolder: "मॉडल फ़ोल्डर",
+        modelsFolderKeywords:
+          "मॉडल फ़ोल्डर फोल्डर निर्देशिका पथ स्थान डाउनलोड कैश संग्रहण डिस्क ड्राइव स्थानांतरित बदलें models folder path hugging face",
         modelsFolderDescription: "जहां डाउनलोड किए गए मॉडल संग्रहीत होते हैं।",
         openAction: "खोलें",
         copyAction: "पथ कॉपी करें",

studio/frontend/src/i18n/locales/ja.ts

@@ -28,10 +28,18 @@ export const ja = {
     product: "Unsloth Studio",
     accountMenu: "{name} のアカウントメニュー",
     updateAvailable: "アップデートが利用可能です",
+    resize: {
+      collapse: "クリックで折りたたむ",
+      expand: "クリックで展開",
+      drag: "ドラッグでサイズ変更",
+    },
     aria: {
       home: "Unsloth ホーム",
       closeSidebar: "サイドバーを閉じる",
       openSidebar: "サイドバーを開く",
+      resizeSidebar: "サイドバーのサイズ変更または折りたたみ",
+      resizeRunSettings: "実行設定のサイズ変更または閉じる",
+      openRunSettings: "実行設定を開く",
       chatOptions: "チャットオプション",
       runOptions: "実行オプション",
     },
@@ -393,6 +401,8 @@ export const ja = {
         diskUsage: "{used} 使用中 / {total}",
         diskFree: "{free} 空き",
         modelsFolder: "モデルフォルダ",
+        modelsFolderKeywords:
+          "モデル フォルダ ディレクトリ パス 保存先 場所 ダウンロード キャッシュ ストレージ ディスク ドライブ 移動 変更 models folder path hugging face",
         modelsFolderDescription: "ダウンロードしたモデルの保存先。",
         openAction: "開く",
         copyAction: "パスをコピー",

studio/frontend/src/i18n/locales/ko.ts

@@ -27,10 +27,18 @@ export const ko = {
     product: "Unsloth Studio",
     accountMenu: "{name} 계정 메뉴",
     updateAvailable: "업데이트 사용 가능",
+    resize: {
+      collapse: "클릭하여 접기",
+      expand: "클릭하여 펼치기",
+      drag: "드래그하여 크기 조절",
+    },
     aria: {
       home: "Unsloth 홈",
       closeSidebar: "사이드바 닫기",
       openSidebar: "사이드바 열기",
+      resizeSidebar: "사이드바 크기 조절 또는 접기",
+      resizeRunSettings: "실행 설정 크기 조절 또는 닫기",
+      openRunSettings: "실행 설정 열기",
       chatOptions: "채팅 옵션",
       runOptions: "학습 옵션",
     },
@@ -315,6 +323,8 @@ export const ko = {
         diskUsage: "{used} 사용 중 / {total}",
         diskFree: "{free} 여유",
         modelsFolder: "모델 폴더",
+        modelsFolderKeywords:
+          "모델 폴더 디렉터리 디렉토리 경로 위치 저장 다운로드 캐시 저장소 디스크 드라이브 이동 변경 models folder path hugging face",
         modelsFolderDescription: "다운로드한 모델이 저장되는 위치입니다.",
         openAction: "열기",
         copyAction: "경로 복사",

studio/frontend/src/i18n/locales/pt-br.ts

@@ -27,10 +27,18 @@ export const ptBR = {
     product: "Unsloth Studio",
     accountMenu: "Menu de conta {name}",
     updateAvailable: "Atualização disponível",
+    resize: {
+      collapse: "Clique para recolher",
+      expand: "Clique para expandir",
+      drag: "Arraste para redimensionar",
+    },
     aria: {
       home: "Início do Unsloth",
       closeSidebar: "Fechar barra lateral",
       openSidebar: "Abrir barra lateral",
+      resizeSidebar: "Redimensionar ou recolher a barra lateral",
+      resizeRunSettings: "Redimensionar ou fechar as configurações de execução",
+      openRunSettings: "Abrir as configurações de execução",
       chatOptions: "Opções de chat",
       runOptions: "Opções de execução",
     },
@@ -417,6 +425,8 @@ export const ptBR = {
         diskUsage: "{used} usados / {total}",
         diskFree: "{free} livres",
         modelsFolder: "Pasta de modelos",
+        modelsFolderKeywords:
+          "modelos pasta diretorio diretório caminho local localizacao localização downloads baixar cache armazenamento disco unidade mover alterar models folder path hugging face",
         modelsFolderDescription: "Onde os modelos baixados são armazenados.",
         openAction: "Abrir",
         copyAction: "Copiar caminho",

studio/frontend/src/i18n/locales/ru.ts

@@ -27,10 +27,18 @@ export const ru = {
     product: "Unsloth Studio",
     accountMenu: "Меню аккаунта {name}",
     updateAvailable: "Доступно обновление",
+    resize: {
+      collapse: "Нажмите, чтобы свернуть",
+      expand: "Нажмите, чтобы развернуть",
+      drag: "Потяните, чтобы изменить размер",
+    },
     aria: {
       home: "Главная Unsloth",
       closeSidebar: "Закрыть боковую панель",
       openSidebar: "Открыть боковую панель",
+      resizeSidebar: "Изменить размер или свернуть боковую панель",
+      resizeRunSettings: "Изменить размер или закрыть настройки запуска",
+      openRunSettings: "Открыть настройки запуска",
       chatOptions: "Параметры чата",
       runOptions: "Параметры запуска",
     },
@@ -316,6 +324,8 @@ export const ru = {
         diskUsage: "{used} использовано / {total}",
         diskFree: "{free} свободно",
         modelsFolder: "Папка моделей",
+        modelsFolderKeywords:
+          "модели папка каталог путь расположение загрузки кэш хранилище диск перенести изменить models folder path hugging face",
         modelsFolderDescription: "Где хранятся загруженные модели.",
         openAction: "Открыть",
         copyAction: "Копировать путь",

studio/frontend/src/i18n/locales/zh-CN.ts

@@ -27,10 +27,18 @@ export const zhCN = {
     product: "Unsloth Studio",
     accountMenu: "{name} 账号菜单",
     updateAvailable: "有可用更新",
+    resize: {
+      collapse: "点击折叠",
+      expand: "点击展开",
+      drag: "拖动调整大小",
+    },
     aria: {
       home: "Unsloth 首页",
       closeSidebar: "关闭侧边栏",
       openSidebar: "打开侧边栏",
+      resizeSidebar: "调整或折叠侧边栏",
+      resizeRunSettings: "调整或关闭运行设置",
+      openRunSettings: "打开运行设置",
       chatOptions: "聊天选项",
       runOptions: "训练选项",
     },
@@ -408,6 +416,8 @@ export const zhCN = {
         diskUsage: "已用 {used} / {total}",
         diskFree: "{free} 可用",
         modelsFolder: "模型文件夹",
+        modelsFolderKeywords:
+          "模型 文件夹 目录 路径 位置 下载 缓存 存储 磁盘 驱动器 移动 更改 models folder path hugging face",
         modelsFolderDescription: "已下载模型的存储位置。",
         openAction: "打开",
         copyAction: "复制路径",

studio/frontend/src/index.css

@@ -1363,6 +1363,23 @@ html[data-chat-font] .aui-root {
 		cursor: pointer;
 	}
 
+	/* While a panel edge is dragged, keep the resize cursor even as the pointer
+	   travels over buttons and text that would claim their own. */
+	html[data-panel-resizing],
+	html[data-panel-resizing] * {
+		cursor: col-resize !important;
+		user-select: none !important;
+	}
+
+	html[data-panel-resizing]
+		:is(
+			[data-slot="sidebar-inner"],
+			[data-slot="sidebar-inset"],
+			[data-slot="chat-settings-panel"] > div
+		) {
+		pointer-events: none;
+	}
+
 	/* Model selector: pointer cursor on every clickable element. */
 	.unsloth-model-selector-trigger,
 	.unsloth-model-selector-menu button {

studio/frontend/src/lib/changelog-links.ts

@@ -0,0 +1,664 @@
+// SPDX-License-Identifier: AGPL-3.0-only
+// Copyright 2026-present the Unsloth AI Inc. team. All rights reserved. See /studio/LICENSE.AGPL-3.0
+
+/**
+ * A relative link in CHANGELOG.md means "somewhere in the Unsloth repository",
+ * but inside Studio it would resolve against Studio's own origin. Rewriting to
+ * absolute repository URLs makes them behave the way GitHub renders the file.
+ */
+
+import {
+  type CodeSpan,
+  codeSpans,
+  insideSpan,
+} from "@/lib/markdown-code-spans";
+import { commentClosesBelow } from "@/lib/markdown-inline-comments";
+import {
+  EMPTY_LIST_STATE,
+  type ListState,
+  NO_QUOTE,
+  type QuoteState,
+  containerContent,
+  hiddenStructure,
+  indentWidth,
+  itemContent,
+  openLists,
+  quoteDepth,
+  quoteState,
+} from "@/lib/markdown-list-columns";
+
+const LINK_BASE = "https://github.com/unslothai/unsloth/blob/main/";
+const IMAGE_BASE = "https://raw.githubusercontent.com/unslothai/unsloth/main/";
+
+// Inline `](dest)` plus the `[label]: dest` reference form. The destination is
+// either <bracketed> or runs to whitespace or the closing paren.
+const NESTED_LABEL = String.raw`((?:[^[\]\\]|\\.|\[(?:[^[\]\\]|\\.)*\])*)`;
+// Only ASCII punctuation is escapable, so the backslash in `a\ b.md` is an
+// ordinary character of the destination and the space still ends it.
+const ESCAPABLE = String.raw`[!-/:-@[-\`{-~]`;
+const DESTINATION_CHAR = String.raw`\\${ESCAPABLE}|[^\s()]`;
+// A destination may hold balanced parentheses, and a path may nest them, so
+// `[x](((draft)).md)` points at `((draft)).md`. An expression cannot count, so
+// pairs are unrolled to the depth cmark stops at, which is what GitHub renders.
+const MAX_DESTINATION_NESTING = 32;
+
+/** A balanced parenthesised run nested up to `depth` levels deep. */
+function nestedParens(depth: number): string {
+  let group = String.raw`\((?:${DESTINATION_CHAR})*\)`;
+  for (let left = depth - 1; left > 0; left -= 1) {
+    group = String.raw`\((?:${DESTINATION_CHAR}|${group})*\)`;
+  }
+  return group;
+}
+
+const BALANCED_DESTINATION = String.raw`(?:${DESTINATION_CHAR}|${nestedParens(MAX_DESTINATION_NESTING)})*`;
+const PLAIN_DESTINATION = String.raw`(?:${DESTINATION_CHAR})*`;
+// A balanced pair counts only while a `)` or a title still closes the link
+// after it, or swallowing it would invent a link across lines.
+const CLOSES_LINK = String.raw`(?=[ \t]*[)'"])`;
+// A destination that runs out of line has its closer below it, the line being
+// only part of the link. One stopping short of a closer is no destination at all,
+// so `[x](a b.md)` and `[x](a(b.md)` stay plain text and keep the paths they name.
+const CLOSES_OR_ENDS_LINE = String.raw`(?=[ \t]*(?:[)'"]|$))`;
+const INLINE_TARGET = new RegExp(
+  String.raw`(!?)\[${NESTED_LABEL}\]\(\s*(<[^<>\n]*>|${BALANCED_DESTINATION}${CLOSES_LINK}|${PLAIN_DESTINATION}${CLOSES_OR_ENDS_LINE})`,
+  "g",
+);
+const REFERENCE_TARGET = /^( {0,3}\[((?:[^[\]\\]|\\.)*)\]:\s*)(<[^<>\n]*>|\S+)/;
+// `![alt][label]`, `![label][]` and `![label]`: a definition they point at
+// has to resolve to the raw file, not to its page on GitHub.
+const IMAGE_REFERENCE =
+  /!\[((?:[^[\]\\]|\\.)*)\](?:\[((?:[^[\]\\]|\\.)*)\]|(?!\())/g;
+const FENCE = /^ {0,3}(`{3,}|~{3,})(.*)$/;
+// Four columns past the container start indented code, unless a paragraph is
+// open. Inside a list item that is measured from the item's content column, so a
+// link indented under a bullet is prose and still resolves.
+const INDENTED_CODE_INDENT = 4;
+// CommonMark type 1 HTML blocks show their contents verbatim.
+const RAW_HTML_OPEN = /^ {0,3}<(pre|script|style|textarea)(?=[\s>]|$)/i;
+const RAW_HTML_CLOSE = /<\/(pre|script|style|textarea)\s*>/i;
+// Type 6 and 7 blocks are literal too and run to the next blank line, not to a
+// closing tag, so `<details>` holds Markdown only after a blank line. Type 7 (any
+// other complete tag alone on a line) cannot interrupt a paragraph.
+const HTML_BLOCK_OPEN = /^ {0,3}<\/?([a-zA-Z][a-zA-Z0-9-]*)(?=[\s/>]|$)/;
+const HTML_ATTRIBUTE =
+  "(?:\\s+[a-zA-Z_:][a-zA-Z0-9_.:-]*(?:\\s*=\\s*(?:[^\\s\"'=<>`]+|'[^']*'|\"[^\"]*\"))?)";
+const HTML_TAG_ONLY_LINE = new RegExp(
+  `^ {0,3}(?:<[a-zA-Z][a-zA-Z0-9-]*${HTML_ATTRIBUTE}*\\s*/?>|</[a-zA-Z][a-zA-Z0-9-]*\\s*>)\\s*$`,
+);
+const HTML_BLOCK_TAGS = new Set(
+  `address article aside base basefont blockquote body caption center col colgroup
+   dd details dialog dir div dl dt fieldset figcaption figure footer form frame
+   frameset h1 h2 h3 h4 h5 h6 head header hr html iframe legend li link main menu
+   menuitem nav noframes ol optgroup option p param search section summary table
+   tbody td tfoot th thead title tr track ul`.split(/\s+/),
+);
+// Lines that are blocks in their own right, so no paragraph is open after.
+const BLOCK_LINE =
+  /^ {0,3}(?:#{1,6}([ \t]|$)|(?:\*[ \t]*){3,}$|(?:-[ \t]*){3,}$|(?:_[ \t]*){3,}$|>|=+[ \t]*$)/;
+// A definition is a block of its own but may not interrupt a paragraph, so it
+// ends the one above only when there is none to continue. It opens none either,
+// or consecutive definitions could never start (spec 0.31.2 section 4.7). Same
+// rule as `_LINK_DEFINITION` in the backend's `after_paragraph`.
+const LINK_DEFINITION = /^ {0,3}\[(?:[^[\]\\]|\\.)+\]:/;
+const LINE_ENDINGS = /\r\n?/g;
+// A scheme, a protocol-relative host, or a fragment: already absolute enough.
+// `//` needs a host after it, so `///docs` stays a repository path.
+const ABSOLUTE = /^(?:[a-zA-Z][a-zA-Z0-9+.-]*:|\/\/[^/]|#)/;
+
+const COMMENT_OPEN = "<!--";
+const COMMENT_CLOSE = "-->";
+const COMMENT_BLOCK_OPEN = /^ {0,3}<!--/;
+
+/**
+ * `line` with its commented spans blanked, and whether a comment block is still
+ * open below it. Commented content renders as nothing, so it holds no fence,
+ * block or code span. Lengths are preserved so offsets still line up.
+ *
+ * Only a comment that starts a line opens a block (CommonMark type 2), and only
+ * that runs on to the line holding `-->`, tail included. One written mid-sentence
+ * is inline raw HTML belonging to its paragraph, so its `-->` may arrive on a
+ * later line and only the text up to it is hidden. `closesBelow` says one does;
+ * without it the opener is ordinary text, so a note merely mentioning `<!--` must
+ * not hide the links below it.
+ *
+ * "Starts a line" is read inside the container, so `blockOpen` comes from the
+ * item's content rather than the raw line.
+ */
+function maskComments(
+  line: string,
+  inComment: boolean,
+  runOn: boolean,
+  closesBelow: boolean,
+  blockOpen: boolean,
+): [string, boolean, boolean] {
+  if (inComment) {
+    // The closing line belongs to the block, tail included.
+    return [" ".repeat(line.length), !line.includes(COMMENT_CLOSE), false];
+  }
+  if (runOn) {
+    const closed = line.indexOf(COMMENT_CLOSE);
+    if (closed < 0) {
+      return [" ".repeat(line.length), false, true];
+    }
+    // Only up to the closer: the tail is the paragraph's own text again.
+    const resumed = closed + COMMENT_CLOSE.length;
+    return maskInline(line, resumed, closesBelow);
+  }
+  if (blockOpen) {
+    // `<!-->` and `<!--->` are complete comments, so the closer may overlap the
+    // opener; searching past it would blank the rest of the file.
+    return [" ".repeat(line.length), !line.includes(COMMENT_CLOSE), false];
+  }
+  return maskInline(line, 0, closesBelow);
+}
+
+/** `maskComments` from `from`, where no comment block is open. */
+function maskInline(
+  line: string,
+  from: number,
+  closesBelow: boolean,
+): [string, boolean, boolean] {
+  let out = " ".repeat(from);
+  let index = from;
+  // Scanned only once an opener turns up. Spans are ordered and disjoint and each
+  // opener sits at or past the last, so the search resumes rather than restarts.
+  let spans: CodeSpan[] | null = null;
+  let cursor = 0;
+  while (index < line.length) {
+    const start = line.indexOf(COMMENT_OPEN, index);
+    if (start < 0) {
+      return [out + line.slice(index), false, false];
+    }
+    spans ??= codeSpans(line);
+    while (cursor < spans.length && (spans[cursor]?.end ?? 0) <= start) {
+      cursor += 1;
+    }
+    // A delimiter inside inline code is literal, not a comment opener.
+    const span = spans[cursor];
+    if (span !== undefined && span.start <= start) {
+      out += line.slice(index, span.end);
+      index = span.end;
+      continue;
+    }
+    // `<!-->` and `<!--->` are complete comments, so the closer may overlap.
+    const close = line.indexOf(COMMENT_CLOSE, start + 2);
+    if (close < 0) {
+      if (closesBelow) {
+        // The paragraph carries the comment on, so the line from the opener is
+        // inside it, and so is the line below.
+        return [
+          out + line.slice(index, start) + " ".repeat(line.length - start),
+          false,
+          true,
+        ];
+      }
+      // Nothing closes it at all, so the renderer shows it as ordinary text.
+      return [out + line.slice(index), false, false];
+    }
+    out += line.slice(index, start);
+    out += " ".repeat(close + COMMENT_CLOSE.length - start);
+    index = close + COMMENT_CLOSE.length;
+  }
+  return [out, false, false];
+}
+
+/**
+ * Whether `line` is written outside the container an open block belongs to. A
+ * fence and an HTML block hold no lazy continuation line, so content left of the
+ * item, or outside the quote, ends the block with its container. A raw block or
+ * comment inside a list item ends on a blank line too: the item takes the break,
+ * so what follows is a block of the item's own.
+ */
+function leavesContainer(
+  line: string,
+  quotes: number,
+  column: number,
+  blockQuotes: number,
+  rawInItem: boolean,
+): boolean {
+  if (quotes < blockQuotes) {
+    return true;
+  }
+  if (!line.trim()) {
+    return rawInItem;
+  }
+  return column > 0 && indentWidth(line) < column;
+}
+
+/** True if `line` starts a CommonMark type 6 or type 7 HTML block. */
+function opensHtmlBlock(line: string, afterParagraph: boolean): boolean {
+  const named = HTML_BLOCK_OPEN.exec(line);
+  if (named && HTML_BLOCK_TAGS.has((named[1] ?? "").toLowerCase())) {
+    return true;
+  }
+  return !afterParagraph && HTML_TAG_ONLY_LINE.test(line);
+}
+
+/** A reference label as CommonMark compares them. */
+function label(text: string): string {
+  return text.trim().replace(/\s+/g, " ").toLowerCase();
+}
+
+const NEEDS_BRACKETS = /[()\s]/;
+// `\(` in a destination is a literal paren. Only ASCII punctuation is escapable,
+// so the backslash in `docs\alpha.md` is part of the path and has to survive.
+const ESCAPE = new RegExp(String.raw`\\(${ESCAPABLE})`, "g");
+// A URL parser reads a backslash as a path separator, so `docs\a.md` would
+// resolve to `docs/a.md`. Encode it first, the way a renderer normalises it.
+const BACKSLASH = /\\/g;
+// Only spaces and tabs may follow a closing fence.
+const NON_SPACE = /[^ \t]/;
+const LEADING_SLASHES = /^\/+/;
+
+function absolute(target: string, image: boolean): string {
+  const base = image ? IMAGE_BASE : LINK_BASE;
+  const trimmed = target.trim().replace(ESCAPE, "$1");
+  if (!trimmed || ABSOLUTE.test(trimmed)) {
+    return target;
+  }
+  try {
+    // A leading slash means the repository root, not the site root, so append
+    // it to the base instead of replacing the base path.
+    const resolved = new URL(
+      trimmed.replace(LEADING_SLASHES, "").replace(BACKSLASH, "%5C"),
+      base,
+    ).toString();
+    // `../` can climb out of the repository: leave those alone.
+    return resolved.startsWith(base) ? resolved : target;
+  } catch {
+    return target;
+  }
+}
+
+/** True when `index` is escaped by an odd run of backslashes. */
+function isEscaped(line: string, index: number): boolean {
+  let slashes = 0;
+  while (line[index - 1 - slashes] === "\\") {
+    slashes += 1;
+  }
+  return slashes % 2 === 1;
+}
+
+function unwrap(target: string): string {
+  return target.startsWith("<") && target.endsWith(">")
+    ? target.slice(1, -1)
+    : target;
+}
+
+/** The destination as it goes back into the line. */
+function wrap(resolved: string, original: string): string {
+  const bracketed = original.startsWith("<") && original.endsWith(">");
+  return bracketed || (resolved !== original && NEEDS_BRACKETS.test(resolved))
+    ? `<${resolved}>`
+    : resolved;
+}
+
+/** Rewrites one line's link and image targets, leaving code spans alone. */
+function rewriteLine(
+  line: string,
+  imageLabels: Set<string>,
+  spans: CodeSpan[],
+  base: number,
+  isDefinition: boolean,
+): string {
+  const reference = isDefinition ? REFERENCE_TARGET.exec(line) : null;
+  if (reference) {
+    const target = reference[3] ?? "";
+    const resolved = absolute(
+      unwrap(target),
+      imageLabels.has(label(reference[2] ?? "")),
+    );
+    const rest = line.slice(reference[0].length);
+    return `${reference[1]}${wrap(resolved, target)}${rest}`;
+  }
+
+  INLINE_TARGET.lastIndex = 0;
+  return line.replace(INLINE_TARGET, (match, bang, text, target, offset) => {
+    // `\\[` is a literal bracket, so the expression is not a link.
+    const opener = offset + (bang ? 1 : 0);
+    if (insideSpan(spans, base + offset) || isEscaped(line, opener)) {
+      return match;
+    }
+    // `\\!` is a literal mark, so what follows is a link, not an image.
+    const image = bang === "!" && !isEscaped(line, offset);
+    const resolved = absolute(unwrap(target), image);
+    // A badge nests an image inside a link, so the label is rewritten too.
+    const inner = text.includes("](")
+      ? rewriteLine(text, imageLabels, codeSpans(text), 0, false)
+      : text;
+    return `${bang}[${inner}](${wrap(resolved, target)}`;
+  });
+}
+
+interface Classified {
+  // Lines the renderer shows as Markdown, by index.
+  text: number[];
+  // Same lines, blanked where the renderer shows code, for span scanning.
+  masked: string;
+  // Lines where a `[label]: dest` definition can start.
+  definition: Set<number>;
+  // Document ranges the renderer hides inside HTML comments.
+  comments: CodeSpan[];
+}
+
+/**
+ * Sorts lines into Markdown and code, masking the code so a span cannot pair
+ * across it. Offsets are preserved, so a mask span sits where it does in the doc.
+ */
+function classify(lines: string[]): Classified {
+  const text: number[] = [];
+  const definition = new Set<number>();
+  const masked: string[] = [];
+  let openFence: string | null = null;
+  let inRawHtml = false;
+  let inHtmlBlock = false;
+  // Where the open block was written: the content column of the item it belongs
+  // to, 0 at document level, plus the blockquotes it sits inside. Only one is ever
+  // open, and none holds a lazy continuation line, so a line left of the item or
+  // outside the quote ends the block with its container.
+  let blockColumn = 0;
+  let blockQuotes = 0;
+  let inComment = false;
+  // True while an inline comment opened above runs on into this line, carried by
+  // the paragraph holding it.
+  let runOn = false;
+  const closesBelow = commentClosesBelow(lines);
+  let inCode = false;
+  let afterParagraph = false;
+  let quote: QuoteState = NO_QUOTE;
+  let lists: ListState = EMPTY_LIST_STATE;
+  const comments: CodeSpan[] = [];
+  let offset = 0;
+
+  // The line as list tracking sees it: blank wherever nothing renders. Taken
+  // with the paragraph state from the line above, as the renderer would.
+  const track = (structural: string, above: QuoteState): void => {
+    lists = openLists(structural, lists, afterParagraph, above.quoted);
+  };
+  // Where a block just opened sits, read after the opener closed the items it
+  // is dedented out of, so it belongs to the container it is really in.
+  const startBlock = (quotes: number): void => {
+    blockColumn = lists.columns.at(-1) ?? 0;
+    blockQuotes = quotes;
+  };
+  const endBlock = (): void => {
+    blockColumn = 0;
+    blockQuotes = 0;
+  };
+
+  lines.forEach((original, index) => {
+    const start = offset;
+    offset += original.length + 1;
+    // The quote state from the line above, which is what list tracking asks
+    // about. Only plain text below rewrites it, so every block returning early
+    // leaves no quoted paragraph open behind it.
+    const above = quote;
+    quote = NO_QUOTE;
+    // A fence, comment or HTML block runs only to the end of the container it was
+    // written in, so a line dedented out of that item or outside that quote
+    // closes both.
+    const quotes = quoteDepth(original);
+    let inBlock = openFence !== null || inRawHtml || inHtmlBlock || inComment;
+    if (
+      inBlock &&
+      leavesContainer(
+        original,
+        quotes,
+        blockColumn,
+        blockQuotes,
+        (inRawHtml || inComment) && blockColumn > 0 && blockQuotes === 0,
+      )
+    ) {
+      openFence = null;
+      inRawHtml = false;
+      inHtmlBlock = false;
+      inComment = false;
+      endBlock();
+      inBlock = false;
+    }
+    // Read from the container the line is written in, so a fence three columns
+    // past a nested bullet or behind a quote marker still opens one. A block
+    // already open keeps only its own quote stripped, or a deeper marker in it
+    // would read as a closer.
+    const container = containerContent(
+      original,
+      lists,
+      inBlock ? blockQuotes : quotes,
+    );
+    // A comment cannot open a fence and a fence hides a comment opener, so resolve
+    // them in that order or a hidden delimiter opens a phantom fence. An opener is
+    // read past a marker on the same line too, since a fence written as an item's
+    // first content opens inside it. Only an opener: fenced content is literal and
+    // a closer carries no marker.
+    const fenceSource = inComment
+      ? null
+      : FENCE.exec(
+          openFence === null
+            ? itemContent(container, afterParagraph)
+            : container,
+        );
+    if (inRawHtml) {
+      track("", above);
+      inRawHtml = !RAW_HTML_CLOSE.test(container);
+      if (!inRawHtml) {
+        endBlock();
+      }
+      masked.push(" ".repeat(original.length));
+      afterParagraph = false;
+      return;
+    }
+    if (inHtmlBlock) {
+      track("", above);
+      // Only a blank line ends a type 6 or 7 block, so nothing inside one is a
+      // fence or a link. A bare quote marker holds nothing, so it ends one too.
+      inHtmlBlock = !!container.trim();
+      if (!inHtmlBlock) {
+        endBlock();
+      }
+      masked.push(" ".repeat(original.length));
+      afterParagraph = false;
+      return;
+    }
+    const fence = fenceSource;
+    if (fence) {
+      // A fence renders as nothing, but its indent still closes an item.
+      track(original, above);
+      const marker = fence[1] ?? "";
+      if (openFence === null) {
+        // A backtick fence's info string may not contain a backtick.
+        openFence =
+          marker[0] !== "`" || !(fence[2] ?? "").includes("`") ? marker : null;
+        if (openFence === null) {
+          text.push(index);
+          masked.push(original);
+          afterParagraph = true;
+          return;
+        }
+        startBlock(quotes);
+      } else if (
+        // A closer matches the opening character and carries nothing after it.
+        marker[0] === openFence[0] &&
+        marker.length >= openFence.length &&
+        !NON_SPACE.test(fence[2] ?? "")
+      ) {
+        openFence = null;
+        endBlock();
+      }
+      masked.push(" ".repeat(original.length));
+      afterParagraph = false;
+      return;
+    }
+    if (openFence !== null) {
+      track("", above);
+      // Fenced content is literal, so a comment opener in it is not one.
+      masked.push(" ".repeat(original.length));
+      return;
+    }
+    // A block already open owns this line, so it is content rather than a block
+    // written at the column it happens to start in.
+    const hidden = inComment;
+    const carried = runOn;
+    // A comment is an HTML block too, so one written as a list item's first
+    // content opens inside that item exactly as a fence does: read past a marker
+    // on the same line and from its container's column, not the line's margin.
+    const opensComment =
+      !(hidden || carried) &&
+      COMMENT_BLOCK_OPEN.test(itemContent(container, afterParagraph));
+    // Only now, outside every fence, does a comment hide what follows.
+    const [line, stillInComment, stillRunOn] = maskComments(
+      original,
+      inComment,
+      runOn,
+      closesBelow[index + 1] ?? false,
+      opensComment,
+    );
+    inComment = stillInComment;
+    runOn = stillRunOn;
+    // A line an inline comment runs on into is still a line of the paragraph
+    // that carries it: only its text is hidden, never its block structure.
+    const structure = carried ? original : line;
+    // The same container reading as above, now the comments are masked. A comment
+    // blanks its own line, so that line is read as written: the block renders as
+    // nothing, but the item it is the content of still opens.
+    const source = opensComment ? original : line;
+    const visible = containerContent(source, lists, quotes);
+    // An HTML block written as a list item's first content opens inside that item,
+    // as a fence does, so an opener is read past a marker on the same line. The
+    // marker survives into the structural line, so its item is still tracked.
+    const content = itemContent(visible, afterParagraph);
+    const marker =
+      content === visible
+        ? ""
+        : source.slice(0, source.length - content.length);
+    // Taken before an HTML opener is hidden: it renders as nothing, but its indent
+    // still closes a list item it sits left of. A comment or a <pre> keeps only its
+    // column and marker, since the text it hides is not Markdown and opens no list.
+    const opensRaw = !carried && RAW_HTML_OPEN.test(content);
+    track(
+      !(hidden || carried) && (opensRaw || !line.trim())
+        ? hiddenStructure(original, marker)
+        : structure,
+      above,
+    );
+    // Read once the opener has closed the items it is dedented out of, so the
+    // comment block belongs to the item it is really written inside.
+    if (inComment !== hidden) {
+      if (inComment) {
+        startBlock(quotes);
+      } else {
+        endBlock();
+      }
+    }
+    for (let at = 0; at < line.length; at += 1) {
+      if (line[at] === " " && original[at] !== " ") {
+        const from = at;
+        while (at < line.length && line[at] === " " && original[at] !== " ") {
+          at += 1;
+        }
+        comments.push({ start: start + from, end: start + at, content: "" });
+      }
+    }
+    if (opensRaw) {
+      inRawHtml = !RAW_HTML_CLOSE.test(content.replace(RAW_HTML_OPEN, ""));
+      if (inRawHtml) {
+        startBlock(quotes);
+      }
+      masked.push(" ".repeat(line.length));
+      afterParagraph = false;
+      return;
+    }
+    if (!carried && content.trim() && opensHtmlBlock(content, afterParagraph)) {
+      inHtmlBlock = true;
+      startBlock(quotes);
+      masked.push(" ".repeat(line.length));
+      afterParagraph = false;
+      return;
+    }
+    const blank = !structure.trim();
+    // Measured from the innermost open item's content column, not the margin:
+    // four spaces under "- Details:" is a paragraph, not a code block.
+    const column = lists.columns.at(-1) ?? 0;
+    const indented = indentWidth(structure) - column >= INDENTED_CODE_INDENT;
+    // Indented code starts only outside a paragraph and runs to a dedent.
+    if (inCode) {
+      inCode = blank || indented;
+    } else {
+      inCode = !afterParagraph && !blank && indented;
+    }
+    if (inCode) {
+      masked.push(" ".repeat(line.length));
+      afterParagraph = false;
+      return;
+    }
+    // A definition cannot interrupt a paragraph.
+    if (!afterParagraph) {
+      definition.add(index);
+    }
+    text.push(index);
+    masked.push(line);
+    afterParagraph =
+      !blank &&
+      !BLOCK_LINE.test(structure) &&
+      (afterParagraph || !LINK_DEFINITION.test(structure));
+    quote = quoteState(structure, above.inQuote);
+  });
+
+  return { text, masked: masked.join("\n"), definition, comments };
+}
+
+/** Absolute repository URLs for every relative link and image in `markdown`. */
+export function resolveChangelogLinks(markdown: string): string {
+  // The desktop updater body arrives with CRLF, which would hide fences.
+  const lines = markdown.replace(LINE_ENDINGS, "\n").split("\n");
+  const { text, masked, definition, comments } = classify(lines);
+  // Scanned over the whole document, so a span may cross a line break. Commented
+  // ranges join them: the renderer shows neither, so a link in one is not
+  // followable and rewriting it would only mutate hidden text.
+  const spans = [...codeSpans(masked), ...comments].sort(
+    (a, b) => a.start - b.start,
+  );
+
+  // Offset of each line in the document, to place matches inside it.
+  const offsets: number[] = [];
+  let cursor = 0;
+  for (const line of lines) {
+    offsets.push(cursor);
+    cursor += line.length + 1;
+  }
+
+  // Only images resolve against the raw host, so collect the image labels
+  // before rewriting any definition.
+  const imageLabels = new Set<string>();
+  for (const index of text) {
+    const line = lines[index] ?? "";
+    IMAGE_REFERENCE.lastIndex = 0;
+    for (
+      let match = IMAGE_REFERENCE.exec(line);
+      match !== null;
+      match = IMAGE_REFERENCE.exec(line)
+    ) {
+      // An escaped mark makes it a link, so its definition stays a page URL.
+      if (
+        insideSpan(spans, (offsets[index] ?? 0) + match.index) ||
+        isEscaped(line, match.index)
+      ) {
+        continue;
+      }
+      const explicit = match[2] ?? "";
+      imageLabels.add(label(explicit.trim() ? explicit : (match[1] ?? "")));
+    }
+  }
+
+  const rewritten = [...lines];
+  for (const index of text) {
+    rewritten[index] = rewriteLine(
+      lines[index] ?? "",
+      imageLabels,
+      spans,
+      offsets[index] ?? 0,
+      definition.has(index),
+    );
+  }
+  return rewritten.join("\n");
+}

studio/frontend/src/lib/markdown-code-spans.ts

@@ -0,0 +1,123 @@
+// SPDX-License-Identifier: AGPL-3.0-only
+// Copyright 2026-present the Unsloth AI Inc. team. All rights reserved. See /studio/LICENSE.AGPL-3.0
+
+/**
+ * CommonMark code spans: a backtick run closes only on an equal-length run.
+ * That needs lookbehind, which older Safari rejects, so runs are scanned by hand.
+ */
+
+export interface CodeSpan {
+  // Offsets of the whole span, delimiters included.
+  start: number;
+  end: number;
+  // Between the delimiters, with the one space of padding removed.
+  content: string;
+}
+
+function runLength(text: string, index: number): number {
+  let end = index;
+  while (text[end] === "`") {
+    end += 1;
+  }
+  return end - index;
+}
+
+/** True when `index` is escaped by an odd run of backslashes. */
+function escaped(text: string, index: number): boolean {
+  let slashes = 0;
+  while (text[index - 1 - slashes] === "\\") {
+    slashes += 1;
+  }
+  return slashes % 2 === 1;
+}
+
+/** CommonMark drops one space of padding, so `` ` a ` `` renders as "a". */
+function stripPadding(content: string): string {
+  if (
+    content.length > 1 &&
+    content.startsWith(" ") &&
+    content.endsWith(" ") &&
+    content.trim() !== ""
+  ) {
+    return content.slice(1, -1);
+  }
+  return content;
+}
+
+/** Every code span in `text`, in order. Unclosed runs are ordinary text. */
+export function codeSpans(text: string): CodeSpan[] {
+  const spans: CodeSpan[] = [];
+  let index = 0;
+
+  while (index < text.length) {
+    if (text[index] !== "`" || escaped(text, index)) {
+      index += 1;
+      continue;
+    }
+    const ticks = runLength(text, index);
+    const contentStart = index + ticks;
+
+    let cursor = contentStart;
+    let closed = false;
+    while (cursor < text.length) {
+      // Escapes do not apply inside a span, so a run after a backslash closes it.
+      if (text[cursor] !== "`") {
+        cursor += 1;
+        continue;
+      }
+      const candidate = runLength(text, cursor);
+      if (candidate === ticks) {
+        spans.push({
+          start: index,
+          end: cursor + ticks,
+          content: stripPadding(text.slice(contentStart, cursor)),
+        });
+        index = cursor + ticks;
+        closed = true;
+        break;
+      }
+      cursor += candidate;
+    }
+    if (!closed) {
+      // Nothing closes this run: it is literal text, carry on after it.
+      index = contentStart;
+    }
+  }
+  return spans;
+}
+
+/** Replaces every code span with `park(content)`, leaving the rest as is. */
+export function parkCodeSpans(
+  text: string,
+  park: (content: string) => string,
+): string {
+  const spans = codeSpans(text);
+  if (spans.length === 0) {
+    return text;
+  }
+  let out = "";
+  let cursor = 0;
+  for (const span of spans) {
+    out += text.slice(cursor, span.start) + park(span.content);
+    cursor = span.end;
+  }
+  return out + text.slice(cursor);
+}
+
+/** True when `index` falls inside one of `spans`, which are in order. */
+export function insideSpan(spans: CodeSpan[], index: number): boolean {
+  let low = 0;
+  let high = spans.length - 1;
+  while (low <= high) {
+    const mid = (low + high) >> 1;
+    const span = spans[mid];
+    if (span === undefined || index < span.start) {
+      high = mid - 1;
+    } else if (index >= span.end) {
+      low = mid + 1;
+    } else {
+      return true;
+    }
+  }
+  return false;
+}

studio/frontend/src/lib/markdown-inline-comments.ts

@@ -0,0 +1,62 @@
+// SPDX-License-Identifier: AGPL-3.0-only
+// Copyright 2026-present the Unsloth AI Inc. team. All rights reserved. See /studio/LICENSE.AGPL-3.0
+
+/**
+ * An HTML comment written mid-sentence is inline raw HTML, not a block, so it
+ * belongs to its paragraph: the `-->` may arrive on a later line of that same
+ * paragraph and everything between renders as nothing, while past the paragraph
+ * the `<!--` is ordinary text. Both changelog scanners share that answer here.
+ *
+ * The backend needs none of it: a heading closes the paragraph it sits under, so
+ * no heading can ever land inside one of these comments.
+ */
+
+import { interruptsParagraph } from "@/lib/markdown-list-columns";
+
+const COMMENT_CLOSE = "-->";
+// A line that cannot be more of the paragraph above it: blank, or a block that
+// may interrupt one. Leading punctuation is not one: `-->` alone is the ordinary
+// multiline close and a continuation may open with emphasis, so reading either as
+// a break leaves the comment unclosed and its text on show. Indented code and link
+// definitions are absent: neither may interrupt a paragraph (spec 0.31.2 4.4, 4.7).
+const BLANK = /^[ \t]*$/;
+const ATX_HEADING = /^ {0,3}#{1,6}([ \t]|$)/;
+const FENCE = /^ {0,3}(?:`{3,}|~{3,})/;
+const THEMATIC_BREAK =
+  /^ {0,3}(?:(?:\*[ \t]*){3,}|(?:-[ \t]*){3,}|(?:_[ \t]*){3,})$/;
+// A row of `=` or `-` alone makes the paragraph above it a setext heading, ending it.
+const SETEXT_UNDERLINE = /^ {0,3}(?:=+|-+)[ \t]*$/;
+// A tag, comment or declaration at the start of a line. HTML block types 1 to 6
+// interrupt a paragraph; type 7 does not, but reading one as a break only leaves
+// the opener as plain text, which is what a leading `<` has always meant here.
+const HTML_LINE = /^ {0,3}</;
+
+/** Whether `line` starts a block of its own rather than continuing a paragraph. */
+function startsBlock(line: string): boolean {
+  return (
+    BLANK.test(line) ||
+    ATX_HEADING.test(line) ||
+    FENCE.test(line) ||
+    THEMATIC_BREAK.test(line) ||
+    SETEXT_UNDERLINE.test(line) ||
+    HTML_LINE.test(line) ||
+    // Blockquote, or a list item with content: the rule the other scanners share.
+    interruptsParagraph(line)
+  );
+}
+
+/**
+ * For each line, whether a `-->` is reachable without leaving the paragraph it
+ * starts in. Read at `index + 1` it answers whether an inline comment opened on
+ * `index` and left unclosed there is a comment at all.
+ */
+export function commentClosesBelow(lines: string[]): boolean[] {
+  const closes: boolean[] = new Array(lines.length + 1).fill(false);
+  for (let at = lines.length - 1; at >= 0; at -= 1) {
+    const line = lines[at] ?? "";
+    closes[at] =
+      !startsBlock(line) &&
+      (line.includes(COMMENT_CLOSE) || (closes[at + 1] ?? false));
+  }
+  return closes;
+}

studio/frontend/src/lib/markdown-list-columns.ts

@@ -0,0 +1,357 @@
+// SPDX-License-Identifier: AGPL-3.0-only
+// Copyright 2026-present the Unsloth AI Inc. team. All rights reserved. See /studio/LICENSE.AGPL-3.0
+
+/**
+ * CommonMark measures a block's indentation from its container, not the left
+ * margin: four spaces at document level and four under a bullet mean different
+ * things. Tracking the open items lets both changelog scanners ask "is this
+ * indented code?" the way a renderer would.
+ *
+ * Ported from `_open_lists` in studio/backend/utils/changelog.py so the three
+ * scanners classify a line the same way.
+ */
+
+/** The open list items, innermost last, by the column their content starts. */
+export interface ListState {
+  columns: number[];
+  // True while the innermost item has had no content since its marker.
+  emptyItem: boolean;
+}
+
+export const EMPTY_LIST_STATE: ListState = { columns: [], emptyItem: false };
+
+// The marker needs whitespace after it, so `2.0` is a version, not an item.
+const LIST_ITEM = /^[ \t]*([-*+]|\d{1,9}[.)])([ \t]+|$)/;
+const THEMATIC_BREAK =
+  /^ {0,3}(?:(?:\*[ \t]*){3,}|(?:-[ \t]*){3,}|(?:_[ \t]*){3,})$/;
+const BLOCK_QUOTE = /^ {0,3}>/;
+const QUOTE_MARKER = /^ {0,3}>[ \t]?/;
+// Blocks that are not paragraph text, so they cannot continue one lazily.
+const PARAGRAPH_TEXT = /^ {0,3}(?![-*+>]([ \t]|$)|\d{1,9}[.)]([ \t]|$))\S/;
+// Blocks that break into an open paragraph, closing it rather than continuing
+// it. A link reference definition is not one of them.
+const INTERRUPTS =
+  /^ {0,3}(?:#{1,6}([ \t]|$)|(?:\*[ \t]*){3,}$|(?:-[ \t]*){3,}$|(?:_[ \t]*){3,}$)/;
+const FENCE = /^ {0,3}(?:`{3,}|~{3,})/;
+const HTML_BLOCK_OPEN = /^ {0,3}<\/?([a-zA-Z][a-zA-Z0-9-]*)(?=[\s/>]|$)/;
+const HTML_BLOCK_TAGS = new Set(
+  `address article aside base basefont blockquote body caption center col colgroup
+   dd details dialog dir div dl dt fieldset figcaption figure footer form frame
+   frameset h1 h2 h3 h4 h5 h6 head header hr html iframe legend li link main menu
+   menuitem nav noframes ol optgroup option p param search section summary table
+   tbody td tfoot th thead title tr track ul`.split(/\s+/),
+);
+// Content indented more than this after a marker is an indented code block, so
+// the item's content starts one column past the marker instead.
+const MAX_ITEM_PADDING = 4;
+// Columns past its container at which a line becomes an indented code block.
+const INDENTED_CODE = 4;
+// Stands in for a line the renderer hides. `#` is a block of its own, so list
+// tracking reads it like a comment: never a marker, never a lazy continuation.
+const HIDDEN_BLOCK = "#";
+const LEADING_SPACE = /^[ \t]*/;
+
+/**
+ * `line` as list tracking sees it once the renderer hides its text. A comment or
+ * raw HTML block renders nothing but is still a block at its own column, so it
+ * closes the items it sits left of. Only the indentation survives: what the block
+ * hides is not Markdown and must not open a list. `marker` is the part opening
+ * the item the block is content of, which survives too. Ported from
+ * `_hidden_structure` on the backend.
+ */
+export function hiddenStructure(line: string, marker = ""): string {
+  if (marker) {
+    return `${marker}${HIDDEN_BLOCK}`;
+  }
+  const indent = LEADING_SPACE.exec(line)?.[0] ?? "";
+  return line.trim() ? `${indent}${HIDDEN_BLOCK}` : "";
+}
+
+/** Columns of leading whitespace, counting a tab to the next stop of four. */
+export function indentWidth(line: string): number {
+  let width = 0;
+  for (const char of line) {
+    if (char === " ") {
+      width += 1;
+    } else if (char === "\t") {
+      width += 4 - (width % 4);
+    } else {
+      break;
+    }
+  }
+  return width;
+}
+
+/**
+ * Whether `line` starts a block that can break into an open paragraph. A quote
+ * marker always can; a list item only with content, an ordered one only at 1.
+ * Anything else is text of the paragraph it appears to interrupt.
+ */
+export function interruptsParagraph(line: string): boolean {
+  if (BLOCK_QUOTE.test(line)) {
+    return true;
+  }
+  const item = THEMATIC_BREAK.test(line) ? null : LIST_ITEM.exec(line);
+  if (item === null) {
+    return false;
+  }
+  const marker = item[1] ?? "";
+  if (!line.slice(item[0].length).trim()) {
+    return false;
+  }
+  const ordered = marker.endsWith(".") || marker.endsWith(")");
+  return !ordered || marker.slice(0, -1) === "1";
+}
+
+/**
+ * Whether a marker-shaped `line` is really text of the paragraph above. Only a
+ * marker inside the paragraph's own item interrupts it; one to the left closes
+ * that item and opens a sibling. A quote owns the paragraph its lines hold, so a
+ * marker outside the quote opens a list of its own.
+ */
+export function lazyMarker(
+  line: string,
+  state: ListState,
+  afterParagraph: boolean,
+  quoted: boolean,
+): boolean {
+  const item = THEMATIC_BREAK.test(line) ? null : LIST_ITEM.exec(line);
+  const columns = state.columns;
+  const inside =
+    columns.length === 0 || indentWidth(line) >= (columns.at(-1) ?? 0);
+  return (
+    item !== null &&
+    afterParagraph &&
+    !quoted &&
+    inside &&
+    !interruptsParagraph(line)
+  );
+}
+
+/** `columns` with every item whose content starts past `indent` closed. */
+function dropDeeper(columns: number[], indent: number): number[] {
+  let open = columns.length;
+  while (open > 0 && (columns[open - 1] ?? 0) > indent) {
+    open -= 1;
+  }
+  return open === columns.length ? columns : columns.slice(0, open);
+}
+
+/** `line` with up to `columns` columns of leading whitespace removed. */
+function stripIndent(line: string, columns: number): string {
+  let width = 0;
+  let index = 0;
+  while (index < line.length && width < columns) {
+    const char = line[index];
+    if (char !== " " && char !== "\t") {
+      break;
+    }
+    width += char === " " ? 1 : 4 - (width % 4);
+    index += 1;
+  }
+  return line.slice(index);
+}
+
+/**
+ * Whether `line` can continue a paragraph it is indented out of. Only plain text
+ * can: a heading, fence, break or HTML block starts a block of its own, closing
+ * the item instead. An underline is not one: it may never be lazy, so `===` left
+ * of an open item is more of the item's paragraph. Nor is a definition, a block
+ * of its own that may not interrupt a paragraph. A row of dashes still closes the
+ * item: `INTERRUPTS` reads three or more as the thematic break they are.
+ */
+function mayBeLazy(line: string): boolean {
+  const named = HTML_BLOCK_OPEN.exec(line);
+  // Types 1 to 6 interrupt a paragraph, so a `<div>` left of an open item closes
+  // it. Type 7 cannot, and is deliberately excluded.
+  const htmlBlock =
+    named !== null && HTML_BLOCK_TAGS.has((named[1] ?? "").toLowerCase());
+  return (
+    PARAGRAPH_TEXT.test(line) &&
+    !INTERRUPTS.test(line) &&
+    !FENCE.test(line) &&
+    !htmlBlock
+  );
+}
+
+/**
+ * Whether `line` reads as more of a paragraph open in its container, measured
+ * from `column` where that container's content starts: four columns past it the
+ * line is indented code, which may not interrupt a paragraph, so indentation
+ * alone never closes the one above.
+ */
+export function continuesParagraph(line: string, column: number): boolean {
+  const inner = stripIndent(line, column);
+  return indentWidth(inner) >= INDENTED_CODE || mayBeLazy(inner);
+}
+
+/** `line` with up to `depth` blockquote markers removed, and how many went. */
+function stripQuotes(line: string, depth: number): [string, number] {
+  let rest = line;
+  let removed = 0;
+  let marker = removed < depth ? QUOTE_MARKER.exec(rest) : null;
+  while (marker !== null) {
+    rest = rest.slice(marker[0].length);
+    removed += 1;
+    marker = removed < depth ? QUOTE_MARKER.exec(rest) : null;
+  }
+  return [rest, removed];
+}
+
+/** What a blockquote line holds, with its markers stripped. */
+function quoteContent(line: string): string {
+  return stripQuotes(line, Number.POSITIVE_INFINITY)[0];
+}
+
+/** How many blockquotes `line` is written inside. */
+export function quoteDepth(line: string): number {
+  return stripQuotes(line, Number.POSITIVE_INFINITY)[1];
+}
+
+/**
+ * `line` as the container it is written in sees it, with `quotes` blockquote
+ * markers and the open item's content column removed. CommonMark measures a block
+ * from its container, not the margin (spec 0.31.2 sections 5.1, 5.2), so `> ~~~`
+ * and a fence under a nested bullet are openers despite sitting more than three
+ * columns in.
+ */
+export function containerContent(
+  line: string,
+  state: ListState,
+  quotes: number,
+): string {
+  const [inner] = stripQuotes(line, quotes);
+  if (quotes > 0) {
+    // A list inside a quote is the quote's own; this tracker follows document
+    // level only, so its columns do not apply here.
+    return inner;
+  }
+  const columns = dropDeeper(state.columns, indentWidth(inner));
+  return stripIndent(inner, columns.at(-1) ?? 0);
+}
+
+/**
+ * `line` read from the content column of a list item that opens on it. A block
+ * written as an item's first content sits inside that item, so ``- ``` `` opens a
+ * fence even though its marker is not within three columns of the container (spec
+ * 0.31.2 section 5.2). Padding is capped the way `openLists` caps it, or
+ * ``-     ``` `` would read as a fence rather than the indented code it is. A
+ * marker the paragraph above swallows opens no item, so its line is returned
+ * whole, as is one four columns past its container.
+ */
+export function itemContent(line: string, afterParagraph: boolean): string {
+  if (
+    indentWidth(line) >= INDENTED_CODE ||
+    (afterParagraph && !interruptsParagraph(line))
+  ) {
+    return line;
+  }
+  const item = THEMATIC_BREAK.test(line) ? null : LIST_ITEM.exec(line);
+  if (item === null) {
+    return line;
+  }
+  const padding = indentWidth(item[2] ?? "");
+  // Over-indented content starts one column past the marker; the rest of the
+  // padding is the content's own indentation.
+  const over = padding > MAX_ITEM_PADDING ? padding - 1 : 0;
+  return `${" ".repeat(over)}${line.slice(item[0].length)}`;
+}
+
+/** Whether a blockquote owns the paragraph the line below could continue. */
+export interface QuoteState {
+  // True while a quoted paragraph is open, so plain text below is more of it.
+  inQuote: boolean;
+  // True whenever that paragraph is the quote's rather than the document's.
+  quoted: boolean;
+}
+
+export const NO_QUOTE: QuoteState = { inQuote: false, quoted: false };
+
+/**
+ * The quote state after `line`, given the state after the line above and the
+ * content column of the item `line` sits in. A quote owns the paragraph its own
+ * lines hold, so a marker written outside the quote opens a list of its own
+ * rather than reading as more of that paragraph. Ported from `in_quote` tracking
+ * in changelog.py.
+ */
+export function quoteState(
+  line: string,
+  inQuote: boolean,
+  column = 0,
+): QuoteState {
+  if (BLOCK_QUOTE.test(line)) {
+    // An empty quote holds no paragraph, so the line below starts a new one.
+    return { inQuote: mayBeLazy(quoteContent(line)), quoted: true };
+  }
+  const open = inQuote && continuesParagraph(line, column);
+  return { inQuote: open, quoted: open };
+}
+
+/**
+ * `columns` with every item `line` is written to the left of closed. Read inside
+ * the container the item sits in, not from the margin: a line that only looks
+ * dedented there is lazy text of the item's paragraph, leaving the item open.
+ */
+function closeDedented(
+  columns: number[],
+  line: string,
+  indent: number,
+  afterParagraph: boolean,
+): number[] {
+  let open = columns.length;
+  while (open > 0 && (columns[open - 1] ?? 0) > indent) {
+    const outer = open > 1 ? (columns[open - 2] ?? 0) : 0;
+    if (afterParagraph && continuesParagraph(line, outer)) {
+      break;
+    }
+    open -= 1;
+  }
+  return open === columns.length ? columns : columns.slice(0, open);
+}
+
+/**
+ * The list items still open after `line`. A dedented line closes an item unless
+ * it is a lazy paragraph continuation. A new marker nests under a deeper column
+ * and replaces a sibling. `quoted` marks a paragraph the blockquote above owns:
+ * a marker outside the quote is not text of it, so it opens a list of its own.
+ */
+export function openLists(
+  line: string,
+  state: ListState,
+  afterParagraph: boolean,
+  quoted = false,
+): ListState {
+  let columns = state.columns;
+  if (!line.trim()) {
+    // A blank line leaves the list open, unless the item is still empty: an
+    // item may begin with one blank line, and later content is outside it.
+    return {
+      columns: state.emptyItem ? columns.slice(0, -1) : columns,
+      emptyItem: false,
+    };
+  }
+  const indent = indentWidth(line);
+  const item = THEMATIC_BREAK.test(line) ? null : LIST_ITEM.exec(line);
+  const empty = item !== null && !line.slice(item[0].length).trim();
+  if (lazyMarker(line, state, afterParagraph, quoted)) {
+    // A lazy continuation or an underline, so the open items are untouched.
+    return state;
+  }
+  columns = closeDedented(columns, line, indent, afterParagraph);
+  // Four columns past its container the marker is an indented code block, or
+  // lazy text of the paragraph above it, so it opens no list of its own.
+  if (item === null || indent - (columns.at(-1) ?? 0) >= INDENTED_CODE) {
+    return { columns, emptyItem: false };
+  }
+  const marker = item[1] ?? "";
+  let padding = indentWidth(item[2] ?? "");
+  if (padding === 0 || padding > MAX_ITEM_PADDING) {
+    // An empty or over-indented item still holds one column of content.
+    padding = 1;
+  }
+  // A sibling marker replaces the item it lines up with.
+  return {
+    columns: [...dropDeeper(columns, indent), indent + marker.length + padding],
+    emptyItem: empty,
+  };
+}

studio/frontend/tests/sidebar-width.test.ts

@@ -0,0 +1,72 @@
+// SPDX-License-Identifier: AGPL-3.0-only
+// Copyright 2026-present the Unsloth AI Inc. team. All rights reserved. See /studio/LICENSE.AGPL-3.0
+
+import assert from "node:assert/strict";
+import test from "node:test";
+import { readFile } from "node:fs/promises";
+
+// Every localStorage key written by a panel width store.
+const PANEL_WIDTH_KEYS = ["sidebar_width", "chat_settings_width"];
+
+// The store reads window at import time, so stub it before importing.
+const stubWindow = {
+  innerWidth: 1440,
+  localStorage: {
+    getItem: () => null,
+    setItem: () => {},
+  },
+  addEventListener: () => {},
+  removeEventListener: () => {},
+};
+(globalThis as { window?: unknown }).window = stubWindow;
+
+const {
+  clampSidebarWidth,
+  SIDEBAR_WIDTH_DEFAULT,
+  SIDEBAR_WIDTH_MAX,
+  SIDEBAR_WIDTH_MIN,
+} = await import("../src/hooks/use-sidebar-width.ts");
+
+test("clamps to the absolute range on a roomy window", () => {
+  stubWindow.innerWidth = 1440;
+  assert.equal(clampSidebarWidth(320), 320);
+  assert.equal(clampSidebarWidth(SIDEBAR_WIDTH_MAX + 200), SIDEBAR_WIDTH_MAX);
+  assert.equal(clampSidebarWidth(10), SIDEBAR_WIDTH_MIN);
+  assert.equal(clampSidebarWidth(Number.NaN), SIDEBAR_WIDTH_DEFAULT);
+});
+
+test("caps at 40% of a narrow window", () => {
+  stubWindow.innerWidth = 800;
+  assert.equal(clampSidebarWidth(SIDEBAR_WIDTH_MAX), 320);
+  assert.equal(clampSidebarWidth(300), 300);
+});
+
+test("the floor still wins when 40% falls below it", () => {
+  stubWindow.innerWidth = 500;
+  assert.equal(clampSidebarWidth(SIDEBAR_WIDTH_MAX), SIDEBAR_WIDTH_MIN);
+});
+
+test("re-evaluates the cap per call, so a resize can re-clamp", () => {
+  stubWindow.innerWidth = 1440;
+  assert.equal(clampSidebarWidth(SIDEBAR_WIDTH_MAX), SIDEBAR_WIDTH_MAX);
+  stubWindow.innerWidth = 900;
+  assert.equal(clampSidebarWidth(SIDEBAR_WIDTH_MAX), 360);
+  stubWindow.innerWidth = 1440;
+  assert.equal(clampSidebarWidth(SIDEBAR_WIDTH_MAX), SIDEBAR_WIDTH_MAX);
+});
+
+// The reset action promises to clear every stored preference, so a persisted
+// panel width that is missing from the list survives the reload.
+test("persisted panel widths are cleared by the preference reset", async () => {
+  const source = await readFile(
+    new URL("../src/features/settings/tabs/general-tab.tsx", import.meta.url),
+    "utf8",
+  );
+  const keys = source.slice(
+    source.indexOf("const PREFS_KEYS"),
+    source.indexOf("];", source.indexOf("const PREFS_KEYS")),
+  );
+  for (const key of PANEL_WIDTH_KEYS) {
+    assert.ok(keys.includes(`"${key}"`), `${key} missing from PREFS_KEYS`);
+  }
+});

studio/install_node_prebuilt.py

@@ -707,18 +707,55 @@ def existing_install_usable(install_dir: Path, host: HostInfo) -> bool:
     return npm_major is not None and npm_major >= NPM_MIN_MAJOR
 
 
+def _replace_with_retry(
+    src: Path,
+    dst: Path,
+    *,
+    attempts: int = 8,
+) -> None:
+    """os.replace, retried against transient Windows sharing violations.
+
+    A directory rename fails with WinError 5/32 while any process holds a handle inside
+    it, and Defender or the indexer routinely does right after extraction (seen in CI on
+    a fresh install, with no existing directory to conflict with). Handles clear in a
+    second or two, so a bounded backoff turns the failure into a pause; other errors
+    raise immediately rather than stalling on a real problem.
+    """
+    delay = 0.25
+    for attempt in range(attempts):
+        try:
+            os.replace(src, dst)
+            return
+        except OSError as exc:
+            transient = os.name == "nt" and getattr(exc, "winerror", None) in (5, 32, 145)
+            if not transient or attempt == attempts - 1:
+                raise
+            log(
+                f"rename blocked ({exc.winerror}), retrying in {delay:.2f}s "
+                f"-- a scanner is likely still holding the extracted files"
+            )
+            time.sleep(delay)
+            delay = min(delay * 2, 4.0)
+
+
 def _swap_into_place(extracted_root: Path, install_dir: Path) -> None:
     """Atomically replace install_dir with extracted_root (same filesystem)."""
     install_dir.parent.mkdir(parents = True, exist_ok = True)
     backup: Path | None = None
     if install_dir.exists():
         backup = install_dir.parent / f".{install_dir.name}.old-{os.getpid()}"
-        os.replace(install_dir, backup)
+        _replace_with_retry(install_dir, backup)
     try:
-        os.replace(extracted_root, install_dir)
+        _replace_with_retry(extracted_root, install_dir)
     except OSError:
+        # The forward rename retries ~16s, ample time for a scanner to grab the backup too.
+        # A plain os.replace would then raise over the original error and leave no
+        # install_dir at all, so the rollback gets the same backoff and never masks it.
         if backup is not None and not install_dir.exists():
-            os.replace(backup, install_dir)
+            try:
+                _replace_with_retry(backup, install_dir)
+            except OSError as rollback_exc:
+                log(f"could not restore the previous Node install from {backup}: {rollback_exc}")
         raise
     if backup is not None:
         shutil.rmtree(backup, ignore_errors = True)

studio/setup.ps1

@@ -869,12 +869,22 @@ function Ensure-BuildToolsForLlamaSourceBuild {
     }
 }
 
-# Detect the VC++ 2015-2022 Redistributable that the prebuilt llama-server and
-# PyTorch need (they link VCRUNTIME140_1.dll etc., which the Universal CRT lacks).
-# Signal is System32\vcruntime140_1.dll (VS 2019+), registry as fallback.
+# Machine arch: PROCESSOR_ARCHITECTURE describes this PROCESS, so an emulated x64 shell on
+# ARM64 reports AMD64; PROCESSOR_ARCHITEW6432 is ARM64 in exactly that case.
+function Get-HostMachineArch {
+    $osArch = ""
+    try { $osArch = [System.Runtime.InteropServices.RuntimeInformation]::OSArchitecture.ToString() } catch { }
+    foreach ($s in @([string]$env:PROCESSOR_ARCHITEW6432, [string]$env:PROCESSOR_ARCHITECTURE, $osArch)) {
+        if ($s.ToLowerInvariant() -eq "arm64") { return "arm64" }
+    }
+    return "other"
+}
+
+# Detect the VC++ 2015-2022 Redistributable prebuilt llama-server and PyTorch need (they
+# link VCRUNTIME140_1.dll, absent from the Universal CRT). Registry first: Runtimes\x64 is
+# the only x64-specific proof; System32\vcruntime140_1.dll is arch-blind and on ARM64 may
+# be the ARM64-only package, unloadable under x64 emulation.
 function Test-VCRedistInstalled {
-    $sys = $env:SystemRoot
-    if ($sys -and (Test-Path (Join-Path $sys 'System32\vcruntime140_1.dll'))) { return $true }
     foreach ($k in @(
         'HKLM:\SOFTWARE\Microsoft\VisualStudio\14.0\VC\Runtimes\x64',
         'HKLM:\SOFTWARE\WOW6432Node\Microsoft\VisualStudio\14.0\VC\Runtimes\x64'
@@ -884,10 +894,14 @@ function Test-VCRedistInstalled {
             if ($r.Installed -eq 1 -and [int]$r.Major -ge 14 -and [int]$r.Minor -ge 20) { return $true }
         } catch { }
     }
+    if ((Get-HostMachineArch) -eq "arm64") { return $false }
+    $sys = $env:SystemRoot
+    if ($sys -and (Test-Path (Join-Path $sys 'System32\vcruntime140_1.dll'))) { return $true }
     return $false
 }
 
-# Install the VC++ 2015-2022 runtime if missing (non-fatal; usually a no-op).
+# Install the VC++ 2015-2022 runtime if missing (non-fatal; usually a no-op). Unlike CMake
+# and Build Tools torch cannot import without it, and winget is absent on LTSC/Server images.
 function Ensure-VCRedist {
     if (Test-VCRedistInstalled) { step "vcredist" "present"; return }
     Write-Host "Microsoft Visual C++ Redistributable (2015-2022) is missing; the prebuilt llama.cpp and PyTorch need it. Installing the runtime..." -ForegroundColor Yellow
@@ -897,6 +911,45 @@ function Ensure-VCRedist {
             Refresh-Environment
         } catch { substep "VCRedist install failed: $($_.Exception.Message)" "Yellow" }
     }
+    if (-not (Test-VCRedistInstalled)) {
+        # Evergreen link; /quiet /norestart so it never blocks or reboots an unattended run.
+        # Always the x64 package, deliberately: Microsoft ships it as the Arm64X superset of
+        # both ARM64 and X64 binaries and documents it as the one for ARM64 devices, while
+        # the arm64 package is ARM64-only (learn.microsoft.com/cpp/windows/latest-supported-vc-redist).
+        # PROCESSOR_ARCHITECTURE is wrong twice here: it reports the process, and the runtime
+        # must match the interpreter loading the DLLs, an emulated x64 Python not yet created.
+        $url = "https://aka.ms/vs/17/release/vc_redist.x64.exe"
+        $dst = Join-Path ([System.IO.Path]::GetTempPath()) "vc_redist.x64.exe"
+        substep "winget unavailable or failed; downloading the runtime directly..."
+        # Windows PowerShell 5.1 on an old image can carry a .NET default protocol set that
+        # predates TLS 1.2, which aka.ms refuses -- exactly the no-winget host this fallback
+        # exists for. SystemDefault (0) means "let the OS choose" and already covers TLS 1.2+,
+        # so only an explicit legacy set is upgraded, and it is restored afterwards.
+        $_prevProtocol = $null
+        try {
+            $_cur = [System.Net.ServicePointManager]::SecurityProtocol
+            if ([int]$_cur -ne 0 -and ([int]$_cur -band [int][System.Net.SecurityProtocolType]::Tls12) -eq 0) {
+                [System.Net.ServicePointManager]::SecurityProtocol = $_cur -bor [System.Net.SecurityProtocolType]::Tls12
+                $_prevProtocol = $_cur
+            }
+        } catch { $_prevProtocol = $null }
+        try {
+            Invoke-WebRequest -Uri $url -OutFile $dst -UseBasicParsing -TimeoutSec 300
+            $p = Start-Process -FilePath $dst -ArgumentList '/quiet', '/norestart' -Wait -PassThru
+            # 3010 = success, reboot required; usable either way.
+            if ($p.ExitCode -notin @(0, 3010)) {
+                substep "VC++ runtime installer exited $($p.ExitCode)" "Yellow"
+            }
+            Refresh-Environment
+        } catch {
+            substep "Direct VC++ runtime download failed: $($_.Exception.Message)" "Yellow"
+        } finally {
+            if ($null -ne $_prevProtocol) {
+                try { [System.Net.ServicePointManager]::SecurityProtocol = $_prevProtocol } catch { }
+            }
+            Remove-Item -LiteralPath $dst -Force -ErrorAction SilentlyContinue
+        }
+    }
     if (Test-VCRedistInstalled) { step "vcredist" "installed" }
     else {
         substep "Could not install the VC++ Redistributable automatically." "Yellow"
@@ -1650,11 +1703,42 @@ if ($LongPathsEnabled) {
 }
 
 # ============================================
-# 1b. Git (required by pip for git+https:// deps and by npm)
+# 1b. Git (only required for --local / source installs)
 # ============================================
+# Was fatal as "required by pip and npm", but the consumer path uses neither: the
+# unsloth-zoo git+https URL is STUDIO_LOCAL_INSTALL only, node is a pinned prebuilt, and the
+# frontend lockfile has no VCS deps. Being fatal blocked clean no-winget Windows boxes.
 $HasGit = $null -ne (Get-Command git -ErrorAction SilentlyContinue)
 if (-not $HasGit) {
-    Write-Host "Git not found -- installing via winget..." -ForegroundColor Yellow
+    # Fatal only where git is used: --local and the opt-in llama.cpp source build. A local
+    # llama.cpp dir overrides those opt-ins, but only once it holds a reusable binary:
+    # pointing at the canonical install location with nothing built there falls through to
+    # the normal install, so an explicit source build still needs git. The automatic
+    # fallback after a failed prebuilt download is not knowable here; Phase 4 handles it.
+    $gitNeeded = ($env:STUDIO_LOCAL_INSTALL -eq '1')
+    $_localLlamaDir = if ($env:UNSLOTH_LOCAL_LLAMA_CPP_DIR) { $env:UNSLOTH_LOCAL_LLAMA_CPP_DIR.Trim() } else { "" }
+    $_localLlamaBuilt = $false
+    if ($_localLlamaDir) {
+        # Same layout candidates as the reuse check in Phase 4.
+        foreach ($_c in @("llama-server.exe", "build\bin\llama-server.exe", "build\bin\Release\llama-server.exe")) {
+            if (Test-Path -LiteralPath (Join-Path $_localLlamaDir $_c)) { $_localLlamaBuilt = $true; break }
+        }
+    }
+    if (-not $_localLlamaBuilt) {
+        $_prForce = if ($env:UNSLOTH_LLAMA_PR_FORCE) { $env:UNSLOTH_LLAMA_PR_FORCE.Trim() } else { $DefaultLlamaPrForce }
+        $_llamaSrc = $DefaultLlamaSource -replace '\.git$', ''
+        # Same tag resolution as Phase 4. "master" is a branch, never a release, so the
+        # prebuilt lookup always misses and Phase 4 rebuilds it from source.
+        $_llamaTag = if ($env:UNSLOTH_LLAMA_TAG) { $env:UNSLOTH_LLAMA_TAG } else { $DefaultLlamaTag }
+        if ($_llamaTag -eq "master") { $gitNeeded = $true }
+        if ($env:UNSLOTH_LLAMA_FORCE_COMPILE -eq '1') { $gitNeeded = $true }
+        if (-not [string]::IsNullOrWhiteSpace($env:UNSLOTH_LLAMA_PR)) { $gitNeeded = $true }
+        # Same positive-integer predicate as the PR_FORCE promotion below: 0 or non-numeric
+        # never forces a source build, so it must not demand git.
+        if ($_prForce -match '^\d+$' -and [int]$_prForce -gt 0) { $gitNeeded = $true }
+        if ($_llamaSrc -ne "https://github.com/ggml-org/llama.cpp") { $gitNeeded = $true }
+    }
+    Write-Host "Git not found -- attempting install via winget..." -ForegroundColor Yellow
     $HasWinget = $null -ne (Get-Command winget -ErrorAction SilentlyContinue)
     if ($HasWinget) {
         try {
@@ -1664,11 +1748,18 @@ if (-not $HasGit) {
         } catch { }
     }
     if (-not $HasGit) {
-        Write-Host "[ERROR] Git is required but could not be installed automatically." -ForegroundColor Red
-        Write-Host "        Install Git from https://git-scm.com/download/win and re-run." -ForegroundColor Red
-        Exit-SetupFailure "Git is required but could not be installed automatically"
+        if ($gitNeeded) {
+            Write-Host "[ERROR] Git is required for --local and llama.cpp source-build installs but could not be installed." -ForegroundColor Red
+            Write-Host "        --local clones unsloth-zoo, and a source build clones llama.cpp." -ForegroundColor Red
+            Write-Host "        Install Git from https://git-scm.com/download/win and re-run." -ForegroundColor Red
+            Exit-SetupFailure "Git is required for --local / source-build installs but could not be installed"
+        }
+        step "git" "not found (not required)" "Yellow"
+        substep "Unsloth installs prebuilt binaries and wheels, so git is not needed."
+        substep "Install it only for --local/source installs: https://git-scm.com/download/win"
+    } else {
+        step "git" "$(git --version)"
     }
-    step "git" "$(git --version)"
 } else {
     step "git" "$(git --version)"
 }
@@ -3275,18 +3366,32 @@ $PyTorchWhlBase = if ($env:UNSLOTH_PYTORCH_MIRROR) { $env:UNSLOTH_PYTORCH_MIRROR
 $TorchInstallIndexUrl = if ($ROCmIndexUrl) { "$PyTorchWhlBase/cpu" } elseif ($PinnedTorchIndexUrl) { $PinnedTorchIndexUrl } else { "$PyTorchWhlBase/$CuTag" }
 
 if (-not $NoTorchMode) {
+# Windows on ARM has win_arm64 torch and torchvision wheels but no torchaudio on any index,
+# so every branch below drops it. Ask the interpreter uv resolves for, not
+# PROCESSOR_ARCHITECTURE, which describes the host process. Inside the no-torch guard
+# because all three uses are, and no-torch installs nothing to skip.
+$_setupPlatform = ""
+try {
+    $_setupPlatform = (& python -c "import sysconfig; print(sysconfig.get_platform())" 2>$null | Out-String).Trim().ToLowerInvariant()
+} catch { $_setupPlatform = "" }
+$WinArm64NoAudio = ($_setupPlatform -eq "win-arm64")
+if ($WinArm64NoAudio) { substep "windows on arm: skipping torchaudio (no win_arm64 wheel upstream)" }
+
 $ROCmCpuFallback = $false
 if ($ROCmIndexUrl) {
     substep "installing PyTorch (AMD ROCm, $ROCmGfxArch)..."
     if ($ROCmTorchSpec -ne "torch") {
         substep "  enforcing $ROCmTorchSpec $ROCmVisionSpec $ROCmAudioSpec (known _grouped_mm bug in older wheels)" "Cyan"
     }
+    # Built above the verbose branch: a splat assigned inside it is unset on the other.
+    $_rocmTrio = @($ROCmTorchSpec, $ROCmVisionSpec, $ROCmAudioSpec)
+    if ($WinArm64NoAudio) { $_rocmTrio = @($ROCmTorchSpec, $ROCmVisionSpec) }
     if ($script:UnslothVerbose) {
-        Fast-Install $ROCmTorchSpec $ROCmVisionSpec $ROCmAudioSpec --force-reinstall --index-url $ROCmIndexUrl | ForEach-Object { Redact-InstallOutput "$_" } | Out-Host
+        Fast-Install @_rocmTrio --force-reinstall --index-url $ROCmIndexUrl | ForEach-Object { Redact-InstallOutput "$_" } | Out-Host
         $torchInstallExit = $LASTEXITCODE
         $output = ""
     } else {
-        $output = Fast-Install $ROCmTorchSpec $ROCmVisionSpec $ROCmAudioSpec --force-reinstall --index-url $ROCmIndexUrl | Out-String
+        $output = Fast-Install @_rocmTrio --force-reinstall --index-url $ROCmIndexUrl | Out-String
         $torchInstallExit = $LASTEXITCODE
     }
     if ($torchInstallExit -ne 0) {
@@ -3322,12 +3427,14 @@ if (-not $ROCmIndexUrl -and ($CuTag -eq "cpu" -or $ROCmCpuFallback)) {
         $cpuVisionSpec = "torchvision>=0.19,<0.27.0"
         $cpuAudioSpec  = "torchaudio>=2.4,<2.12.0"
     }
+    $_torchTrio = @($cpuTorchSpec, $cpuVisionSpec, $cpuAudioSpec)
+    if ($WinArm64NoAudio) { $_torchTrio = @($cpuTorchSpec, $cpuVisionSpec) }
     if ($script:UnslothVerbose) {
-        Fast-Install $cpuTorchSpec $cpuVisionSpec $cpuAudioSpec @cpuForce --index-url $TorchInstallIndexUrl | ForEach-Object { Redact-InstallOutput "$_" } | Out-Host
+        Fast-Install @_torchTrio @cpuForce --index-url $TorchInstallIndexUrl | ForEach-Object { Redact-InstallOutput "$_" } | Out-Host
         $torchInstallExit = $LASTEXITCODE
         $output = ""
     } else {
-        $output = Fast-Install $cpuTorchSpec $cpuVisionSpec $cpuAudioSpec @cpuForce --index-url $TorchInstallIndexUrl | Out-String
+        $output = Fast-Install @_torchTrio @cpuForce --index-url $TorchInstallIndexUrl | Out-String
         $torchInstallExit = $LASTEXITCODE
     }
     if ($torchInstallExit -ne 0) {
@@ -3354,12 +3461,16 @@ if (-not $ROCmIndexUrl -and ($CuTag -eq "cpu" -or $ROCmCpuFallback)) {
         $cudaVisionSpec = "torchvision>=0.19,<0.26.0"
         $cudaAudioSpec = "torchaudio>=2.4,<2.11.0"
     }
+    # A custom pin whose leaf is not cpu (a corporate /simple mirror) lands an ARM64 host
+    # here, so this branch drops torchaudio too.
+    $_cudaTrio = @($cudaTorchSpec, $cudaVisionSpec, $cudaAudioSpec)
+    if ($WinArm64NoAudio) { $_cudaTrio = @($cudaTorchSpec, $cudaVisionSpec) }
     if ($script:UnslothVerbose) {
-        Fast-Install $cudaTorchSpec $cudaVisionSpec $cudaAudioSpec @cudaForce --index-url $TorchInstallIndexUrl | ForEach-Object { Redact-InstallOutput "$_" } | Out-Host
+        Fast-Install @_cudaTrio @cudaForce --index-url $TorchInstallIndexUrl | ForEach-Object { Redact-InstallOutput "$_" } | Out-Host
         $torchInstallExit = $LASTEXITCODE
         $output = ""
     } else {
-        $output = Fast-Install $cudaTorchSpec $cudaVisionSpec $cudaAudioSpec @cudaForce --index-url $TorchInstallIndexUrl | Out-String
+        $output = Fast-Install @_cudaTrio @cudaForce --index-url $TorchInstallIndexUrl | Out-String
         $torchInstallExit = $LASTEXITCODE
     }
     if ($torchInstallExit -ne 0) {
@@ -4048,6 +4159,7 @@ $BuildDir = Join-Path $LlamaCppDir "build"
 $LlamaServerBin = Join-Path $BuildDir "bin\Release\llama-server.exe"
 
 $HasCmakeForBuild = $null -ne (Get-Command cmake -ErrorAction SilentlyContinue)
+$HasGitForBuild = $null -ne (Get-Command git -ErrorAction SilentlyContinue)
 
 # Check if existing llama-server matches current GPU mode. A CUDA-built binary
 # on a now-CPU-only machine (or vice versa) needs to be rebuilt.
@@ -4073,9 +4185,27 @@ if (Test-Path -LiteralPath $LlamaServerBin) {
 $WillBuildLlamaFromSource = $NeedLlamaSourceBuild -and `
     -not ((Test-Path -LiteralPath $LlamaServerBin) -and -not $NeedRebuild -and $RequestedLlamaTag -ne "master")
 if ($WillBuildLlamaFromSource) {
-    Ensure-BuildToolsForLlamaSourceBuild
-    # refresh so the chain below sees a newly installed cmake
-    $HasCmakeForBuild = $null -ne (Get-Command cmake -ErrorAction SilentlyContinue)
+    if (-not $HasGitForBuild) {
+        # Phase 1 keeps git optional, so only the automatic fallback after a failed prebuilt
+        # download arrives here without it. Last chance to install: Invoke-SetupCommand
+        # returns 0 for command-not-found, so a git-less clone misreports as a cmake failure.
+        if ($null -ne (Get-Command winget -ErrorAction SilentlyContinue)) {
+            try {
+                Invoke-SetupCommand { winget install Git.Git --source winget --accept-package-agreements --accept-source-agreements } | Out-Null
+                Refresh-Environment
+            } catch { }
+        }
+        $HasGitForBuild = $null -ne (Get-Command git -ErrorAction SilentlyContinue)
+    }
+    # Git first, then the toolchain: Ensure-BuildToolsForLlamaSourceBuild exits setup when
+    # Build Tools cannot be installed, so running it first made the degraded path below
+    # unreachable on a no-winget box, and elsewhere spent a multi-GB download on a clone
+    # that cannot happen.
+    if ($HasGitForBuild) {
+        Ensure-BuildToolsForLlamaSourceBuild
+        # refresh so the chain below sees a newly installed cmake
+        $HasCmakeForBuild = $null -ne (Get-Command cmake -ErrorAction SilentlyContinue)
+    }
 }
 
 if ($LocalLlamaCppLinked) {
@@ -4093,6 +4223,16 @@ if ($LocalLlamaCppLinked) {
     # up new model architecture support (e.g. Gemma 4).
     Write-Host ""
     step "llama.cpp" "already built"
+} elseif (-not $HasGitForBuild) {
+    # Before cmake: the toolchain install is skipped without git, so cmake may be missing
+    # purely as a consequence. Degrade rather than abort; the opt-in source triggers already
+    # required git in Phase 1, so only the automatic fallback lands here.
+    Write-Host ""
+    step "llama.cpp" "build skipped (git not available)" "Yellow"
+    substep "The prebuilt download failed and a source build clones llama.cpp." "Yellow"
+    substep "GGUF inference and export will not be available." "Yellow"
+    substep "Install Git from https://git-scm.com/download/win and re-run setup." "Yellow"
+    $script:LlamaCppDegraded = $true
 } elseif (-not $HasCmakeForBuild) {
     Write-Host ""
     if (-not $HasNvidiaSmi) {

studio/src-tauri/src/desktop_update_policy.rs

@@ -27,6 +27,8 @@ pub(crate) struct DesktopUpdatePolicy {
 pub(crate) struct ManualUpdateInfo {
     version: String,
     current_version: String,
+    // Backend release this desktop build pins; CHANGELOG.md is keyed by it.
+    pypi_version: Option<String>,
     body: Option<String>,
     date: Option<String>,
 }
@@ -34,8 +36,12 @@ pub(crate) struct ManualUpdateInfo {
 #[derive(Debug, serde::Deserialize)]
 struct ChannelMetadata {
     version: String,
-    body: Option<String>,
-    date: Option<String>,
+    // latest.json publishes Tauri's `notes`/`pub_date`; aliases keep older metadata working.
+    pypi_version: Option<String>,
+    #[serde(alias = "body")]
+    notes: Option<String>,
+    #[serde(alias = "date")]
+    pub_date: Option<String>,
     platforms: HashMap<String, ChannelPlatform>,
 }
 
@@ -99,8 +105,9 @@ pub(crate) async fn check_desktop_manual_update() -> Result<Option<ManualUpdateI
     Ok(Some(ManualUpdateInfo {
         version: latest_version,
         current_version: current_version.to_string(),
-        body: metadata.body,
-        date: metadata.date,
+        pypi_version: metadata.pypi_version,
+        body: metadata.notes,
+        date: metadata.pub_date,
     }))
 }
 

tests/python/test_bitsandbytes_kernel_readiness.py

@@ -155,7 +155,10 @@ def test_the_ctypes_binds_are_gated_on_the_same_verdict():
         "if bnb is None or not native_kernels_ready(bnb, DEVICE_TYPE):" in source
     ), "the ctypes bind block must take the _bnb_required branch on a dead library too"
     guarded = source.split("if bnb is None or not native_kernels_ready(bnb, DEVICE_TYPE):")[1]
-    assert "bnb.functional.lib" in guarded, "the binds must sit under that guard"
+    # Anchor on the symbol, not the module alias: #7580 renamed the binding from
+    # `bnb.functional.lib` to `bnb_functional.lib`, which is exactly the kind of rename
+    # this assertion should survive.
+    assert "lib.cdequantize_blockwise_fp32" in guarded, "the binds must sit under that guard"
 
 
 def test_the_kernel_check_reads_the_submodule_not_the_parent_attribute():

tests/python/test_cross_platform_parity.py

@@ -454,9 +454,12 @@ class TestKnown211SetParity:
             "$_pinCuLeaf" not in text
         ), "install.ps1 must bound companions on every index (no cu-family exemption)"
         # The bounded companions must actually be passed to the install command.
-        assert re.search(
-            r'"torch>=2\.4,<2\.11\.0" \$_pinVisionSpec \$_pinAudioSpec --default-index \$TorchIndexUrl',
-            text,
+        # Specs are splatted, so check both halves: the list is built, and it is passed.
+        assert (
+            '$_torchSpecs = @("torch>=2.4,<2.11.0", $_pinVisionSpec, $_pinAudioSpec)' in text
+        ), "install.ps1 custom-pin install must build the bounded spec list"
+        assert (
+            "@_torchSpecs --default-index $TorchIndexUrl" in text
         ), "install.ps1 custom-pin install must pass the bounded companion specs to uv"
 
     def test_gfx_allowlist_matches_across_installers(self):
@@ -704,9 +707,13 @@ class TestPinnedIndexClearsUvEnvParity:
         assert (
             "if ($TorchIndexPinned -and -not (Test-CudaFamilyLeaf $CuTag)) {" in text
         ), "the custom-leaf trio bounds must be gated on a pinned non-cu-family leaf"
+        # Specs are splatted, so check both halves: the list is built, and it is passed.
         assert (
-            "Fast-Install $cudaTorchSpec $cudaVisionSpec $cudaAudioSpec" in text
-        ), "setup.ps1's CUDA branch must install via the bounded spec variables"
+            "$_cudaTrio = @($cudaTorchSpec, $cudaVisionSpec, $cudaAudioSpec)" in text
+        ), "setup.ps1's CUDA branch must build the trio from the bounded spec variables"
+        assert (
+            "Fast-Install @_cudaTrio @cudaForce" in text
+        ), "setup.ps1's CUDA branch must install the trio it built"
 
     def test_setup_ps1_bounds_pinned_cpu_torch(self):
         """setup.ps1's CPU branch must bound the trio under an explicit pin (parity with
@@ -724,8 +731,11 @@ class TestPinnedIndexClearsUvEnvParity:
             "if ($TorchIndexPinned) {" in text
         ), "the CPU trio bounds must be gated on an explicit pin"
         assert (
-            "Fast-Install $cpuTorchSpec $cpuVisionSpec $cpuAudioSpec @cpuForce" in text
-        ), "setup.ps1's CPU branch must install via the spec variables"
+            "$_torchTrio = @($cpuTorchSpec, $cpuVisionSpec, $cpuAudioSpec)" in text
+        ), "setup.ps1's CPU branch must build the trio from the spec variables"
+        assert (
+            "Fast-Install @_torchTrio @cpuForce" in text
+        ), "setup.ps1's CPU branch must install the trio it built"
         # The ceilings mirror the Python repair spec exactly.
         stack = STACK_PY.read_text(encoding = "utf-8")
         spec_block = re.search(r"_CUDA_TORCH_PKG_SPEC[^(]*\(\s*(.*?)\)", stack, re.DOTALL)

tests/python/test_windows_arm64_python_choice.py

@@ -0,0 +1,143 @@
+# SPDX-License-Identifier: AGPL-3.0-only
+# Copyright 2026-present the Unsloth AI Inc. team. All rights reserved.
+
+"""Windows on ARM: install.ps1 must not settle for a native ARM64 interpreter.
+
+pyarrow (via datasets) and hf-transfer publish no win_arm64 wheels, so an ARM64
+Python source-builds both and dies minutes into the run. The resolver prefers an
+x64 build of the requested minor and bootstraps one otherwise; the case pinned
+here is the recovery path, where nothing can be downloaded but an x64 build of a
+lower-priority supported minor is already installed.
+"""
+
+from __future__ import annotations
+
+import os
+import re
+import shutil
+import subprocess
+from pathlib import Path
+
+import pytest
+
+
+REPO_ROOT = Path(__file__).resolve().parents[2]
+INSTALL_PS1 = REPO_ROOT / "install.ps1"
+
+
+def _extract(pattern: str, source: str) -> str:
+    match = re.search(pattern, source, flags = re.DOTALL)
+    assert match is not None, f"install.ps1 block not found: {pattern}"
+    return match.group(0)
+
+
+def _resolver_script(installed: list[tuple[str, str]], can_download: bool) -> str:
+    """Both production functions verbatim, over a fake set of interpreters.
+
+    Extracted rather than reimplemented so the test cannot drift away from the
+    text install.ps1 actually runs. `installed` is (minor, arch) in py-launcher
+    order, so the first entry for a minor is what a bare `py -3.13` resolves to.
+    The fake interpreters are named `*.exe` and invoked through the call operator,
+    which resolves a string to a function, so no real binary is needed.
+    """
+    source = INSTALL_PS1.read_text(encoding = "utf-8")
+    finder = _extract(r"    function Find-CompatiblePython \{.*?\n    \}\n", source)
+    installer = _extract(r"    function Install-X64Python \{.*?\n    \}\n", source)
+
+    names = [f"Py{minor.replace('.', '')}{arch}.exe" for minor, arch in installed]
+    table = ", ".join(
+        f'@{{ Minor = "{minor}"; Arch = "{arch}"; Name = "{name}" }}'
+        for (minor, arch), name in zip(installed, names)
+    )
+    downloaded = (
+        '@{ Version = "3.13"; Path = "Downloaded.exe"; Arch = "x86_64" }'
+        if can_download
+        else "$null"
+    )
+    version_stubs = "\n".join(
+        f"function {name} {{ param([Parameter(ValueFromRemainingArguments = $true)]$Rest)\n"
+        f'    if ($Rest -contains "--version") {{ return "Python {minor}.0" }}\n'
+        f'    return "{name}" }}'
+        for (minor, _arch), name in zip(installed, names)
+    )
+    return f"""
+$ErrorActionPreference = "Stop"
+$PythonVersion = "3.13"
+$script:WingetAvailable = $false
+$script:CondaSkipPattern = 'conda'
+$Interpreters = @({table})
+{version_stubs}
+# `py -0p` lists every registration; `py -3.x` runs the launcher's preferred build
+# for that minor, which on an ARM64 host is normally the native one.
+function FakePy {{
+    param([Parameter(ValueFromRemainingArguments = $true)]$Rest)
+    if ($Rest -contains "-0p") {{
+        return @($Interpreters | ForEach-Object {{ "  -V:$($_.Minor) *        $($_.Name)" }})
+    }}
+    $minor = ([string]$Rest[0]).TrimStart('-')
+    $hit = @($Interpreters | Where-Object {{ $_.Minor -eq $minor }})
+    if ($hit.Count -eq 0) {{ return "" }}
+    if ($Rest -contains "--version") {{ return "Python $minor.0" }}
+    return $hit[0].Name
+}}
+function substep {{ param($a, $b) }}
+function Get-HostMachineArch {{ return "arm64" }}
+function Get-Command {{
+    param([Parameter(Position = 0)][string]$Name,
+          [Parameter(ValueFromRemainingArguments = $true)]$Rest)
+    if ($Name -eq "py") {{ return @([pscustomobject]@{{ Source = "FakePy" }}) }}
+    return @()
+}}
+function Test-Path {{ param([Parameter(ValueFromRemainingArguments = $true)]$Rest) return $true }}
+function Test-IsCondaPython {{ param([string]$Exe) return $false }}
+function Get-PythonPlatformTag {{
+    param([string]$Exe)
+    foreach ($i in $Interpreters) {{
+        if ($i.Name -eq $Exe) {{
+            if ($i.Arch -eq "x86_64") {{ return "win-amd64" }} else {{ return "win-arm64" }}
+        }}
+    }}
+    return "win-amd64"
+}}
+function Refresh-SessionPath {{ }}
+function Install-PythonFromPythonOrg {{ param([string]$Arch = "") return {downloaded} }}
+{finder}
+{installer}
+# The caller's ARM64 swap, condensed to what decides the interpreter.
+$found = Find-CompatiblePython
+if ($found -and $found.Arch -ne "x86_64") {{
+    $x64 = Install-X64Python
+    if ($x64) {{ $found = $x64 }}
+}}
+if ($found) {{ Write-Output "$($found.Version)|$($found.Arch)" }} else {{ Write-Output "none" }}
+"""
+
+
+def _pwsh(script: str) -> str:
+    result = subprocess.run(
+        ["pwsh", "-NoProfile", "-NonInteractive", "-Command", script],
+        check = True,
+        capture_output = True,
+        text = True,
+        env = os.environ.copy(),
+    )
+    return result.stdout.strip()
+
+
+@pytest.mark.skipif(shutil.which("pwsh") is None, reason = "PowerShell is unavailable")
+@pytest.mark.parametrize(
+    ("installed", "can_download", "expected"),
+    [
+        # An x64 build of the requested minor wins outright, downloads irrelevant.
+        ([("3.13", "arm64"), ("3.13", "x86_64")], False, "3.13|x86_64"),
+        # Requested minor is ARM64-only: bootstrap x64 rather than take the native one.
+        ([("3.13", "arm64")], True, "3.13|x86_64"),
+        # Offline, but an x64 build of a lower-priority minor is here. Use it: the native
+        # 3.13 cannot resolve pyarrow or hf-transfer, and this one can.
+        ([("3.13", "arm64"), ("3.11", "x86_64")], False, "3.11|x86_64"),
+        # ARM64 everywhere: still returned, and the caller warns.
+        ([("3.13", "arm64"), ("3.11", "arm64")], False, "3.13|arm64"),
+    ],
+)
+def test_arm64_host_prefers_an_x64_interpreter(installed, can_download, expected):
+    assert _pwsh(_resolver_script(installed, can_download)) == expected