diff --git a/.github/scripts/clean-machine-assert.sh b/.github/scripts/clean-machine-assert.sh
new file mode 100755
index 0000000000..d96a6c8540
--- /dev/null
+++ b/.github/scripts/clean-machine-assert.sh
@@ -0,0 +1,127 @@
+#!/usr/bin/env bash
+# SPDX-License-Identifier: AGPL-3.0-only
+# Copyright 2026-present the Unsloth AI Inc. team. All rights reserved.
+#
+# Assert the clean-machine contract after an install attempt.
+#
+#   absent   The toolchain really was absent for the whole run. Guards against a
+#            leg that "passed" only because masking silently failed, or because
+#            the installer quietly installed Xcode CLT behind our back.
+#   notools  The trace recorded no compiler/git/brew invocation (trace mode).
+#   nobuild  The install log shows no source build (no sdist, no cmake, no
+#            "Building wheel"). This is the wheels-only contract.
+#
+# Usage: bash .github/scripts/clean-machine-assert.sh absent notools nobuild
+set -uo pipefail
+
+LOG="${INSTALL_LOG:-logs/install.log}"
+TRACE="${UNSLOTH_TOOL_TRACE:-}"
+rc=0
+
+fail() { echo "::error::$*"; rc=1; }
+ok()   { echo "[assert] OK  $*"; }
+
+for check in "$@"; do
+  case "$check" in
+
+    absent)
+      # Deliberately NOT a `command -v` check. On a real virgin Mac /usr/bin/git and
+      # /usr/bin/cc EXIST as Xcode CLT stubs, so `command -v git` SUCCEEDS -- running
+      # it is what fails ("xcrun: error: invalid active developer path"). Asserting on
+      # `command -v` would therefore be unfaithful and would fail on a correctly masked
+      # runner. The honest invariant is: the tool must not WORK.
+      if xcode-select -p >/dev/null 2>&1; then
+        fail "xcode-select -p still resolves to $(xcode-select -p 2>/dev/null); not a clean Mac"
+      else
+        ok "xcode-select -p fails (the gate a virgin Mac hits)"
+      fi
+      for tool in git cc clang cmake; do
+        command -v "$tool" >/dev/null 2>&1 || { ok "$tool not on PATH"; continue; }
+        if "$tool" --version >/dev/null 2>&1; then
+          fail "toolchain still usable: '$tool --version' succeeded ($(command -v "$tool")); masking failed"
+        else
+          ok "$tool present but non-functional (CLT stub), as on a clean Mac"
+        fi
+      done
+      # brew is a plain binary with no stub, so absence from PATH is the right test.
+      if command -v brew >/dev/null 2>&1; then
+        fail "Homebrew still on PATH at $(command -v brew); masking failed"
+      else
+        ok "brew absent"
+      fi
+      ;;
+
+    notools)
+      if [ -z "$TRACE" ] || [ ! -f "$TRACE" ]; then
+        fail "notools requested but no trace file (\$UNSLOTH_TOOL_TRACE=$TRACE)"
+      else
+        # git is legitimate under --local (it installs unsloth-zoo from a git URL);
+        # UNSLOTH_ALLOW_TOOLS lets that leg allow-list it explicitly.
+        allow="${UNSLOTH_ALLOW_TOOLS:-}"
+        hits=""
+        while IFS=$'\t' read -r tool rest; do
+          [ -n "$tool" ] || continue
+          case " $allow " in *" $tool "*) continue ;; esac
+          # `xcode-select -p` ASKS whether a toolchain is selected; it cannot build
+          # anything. The installer has to ask in order to tell the user whether a
+          # source build is available, and the whole point of the fix is that it then
+          # carries on without one. Treating the question as toolchain USE would fail
+          # the very leg that proves the toolchain was never used. `--install`, which
+          # pops the CLT installer, stays a hit.
+          if [ "$tool" = "xcode-select" ]; then
+            case "$rest" in
+              -p|--print-path|-v|--version|"") continue ;;
+            esac
+          fi
+          hits="$hits $tool"
+        done < "$TRACE"
+        if [ -n "$hits" ]; then
+          fail "installer invoked toolchain:$(echo "$hits" | tr ' ' '\n' | sort -u | tr '\n' ' ')"
+          echo "---- tool trace ----"; sort -u "$TRACE" | head -50
+        else
+          ok "no compiler/git/brew invocation recorded"
+        fi
+      fi
+      ;;
+
+    nobuild)
+      # "Built an sdist" is NOT the same as "needed a compiler". Four packages on the
+      # macOS path are sdist-only PURE PYTHON projects that build fine with no
+      # toolchain (verified by resolving each against cp313/macos-arm64):
+      #   openai-whisper, argbind, randomname  -- no version ever ships a wheel
+      #   antlr4-python3-runtime==4.9.3        -- pinned below the 4.13.2 wheel
+      # Failing on those would be a false alarm, so the contract asserted here is
+      # "nothing that needs a COMPILER was built", with that allowlist subtracted.
+      # UNSLOTH_ALLOW_SDIST can extend it.
+      _allow="openai-whisper argbind randomname antlr4-python3-runtime ${UNSLOTH_ALLOW_SDIST:-}"
+      if [ ! -f "$LOG" ]; then
+        fail "nobuild requested but $LOG is missing"
+      else
+        _built="$(grep -oiE "building wheel for [a-z0-9._-]+" "$LOG" 2>/dev/null \
+                  | sed -E 's/.* for //' | tr 'A-Z' 'a-z' | sort -u || true)"
+        _bad=""
+        for pkg in $_built; do
+          case " $_allow " in *" $pkg "*) continue ;; esac
+          _bad="$_bad $pkg"
+        done
+        if [ -n "$_bad" ]; then
+          fail "built from source:$_bad -- these must resolve to wheels on a clean machine"
+        else
+          [ -n "$_built" ] && say_built="$(echo "$_built" | tr '\n' ' ')" || say_built="none"
+          ok "no non-allowlisted source build (built: $say_built)"
+        fi
+        # Independent of package names: a compiler error means a toolchain was needed.
+        if grep -qiE "error: command '(cc|gcc|clang|cl)' failed|no such file or directory: 'cc'|clang: error|cargo: not found|error: linker \`cc\` not found" "$LOG"; then
+          fail "compiler invocation appears in the install log"
+          grep -iE "error: command '(cc|gcc|clang|cl)' failed|clang: error" "$LOG" | head -10
+        fi
+      fi
+      ;;
+
+    *)
+      fail "unknown check '$check'"
+      ;;
+  esac
+done
+
+exit "$rc"
diff --git a/.github/scripts/clean-machine-env.sh b/.github/scripts/clean-machine-env.sh
new file mode 100755
index 0000000000..c1e838d35a
--- /dev/null
+++ b/.github/scripts/clean-machine-env.sh
@@ -0,0 +1,165 @@
+#!/usr/bin/env bash
+# SPDX-License-Identifier: AGPL-3.0-only
+# Copyright 2026-present the Unsloth AI Inc. team. All rights reserved.
+#
+# Simulate a virgin developer machine on a GitHub-hosted runner, so the installer
+# is exercised the way a real user's brand-new Mac / PC exercises it.
+#
+# Two modes, because "the tool is absent" and "the installer never called the tool"
+# CANNOT be simulated by the same mechanism:
+#
+#   mask   Make the toolchain genuinely ABSENT. Scrubs PATH down to the OS
+#          defaults and (with --remove) moves the real toolchain aside. After
+#          this, `command -v git` correctly FAILS, which is what a clean Mac does.
+#          A failing "poison shim" on PATH would do the opposite -- `command -v`
+#          finds it and reports the tool as present -- so shims are NOT used here.
+#
+#   trace  Leave the toolchain working, but route it through logging wrappers that
+#          record the invocation and then exec the real binary. Proves whether the
+#          installer ever REACHES for a compiler/git, without changing behaviour.
+#
+# Writes shell exports to $CLEAN_ENV_FILE (default ./clean-machine.env) for the
+# caller to `source`. Nothing is exported globally, so other workflow steps
+# (checkout, upload-artifact) keep a normal environment.
+#
+# Usage:
+#   bash .github/scripts/clean-machine-env.sh mask [--remove]
+#   bash .github/scripts/clean-machine-env.sh trace
+#   source ./clean-machine.env
+set -uo pipefail
+
+MODE="${1:-}"
+REMOVE=0
+[ "${2:-}" = "--remove" ] && REMOVE=1
+
+case "$MODE" in
+  mask|trace) ;;
+  *) echo "usage: $0 {mask|trace} [--remove]" >&2; exit 2 ;;
+esac
+
+OS="$(uname -s)"
+WORK="${CLEAN_MACHINE_DIR:-$PWD/.clean-machine}"
+ENV_FILE="${CLEAN_ENV_FILE:-$PWD/clean-machine.env}"
+TRACE="$WORK/tool-invocations.log"
+BIN="$WORK/bin"
+RESTORE="$WORK/restore.sh"
+mkdir -p "$BIN"
+: > "$TRACE"
+: > "$ENV_FILE"
+printf '#!/usr/bin/env bash\n# Undo clean-machine-env.sh --remove. Safe to run twice.\nset -uo pipefail\n' > "$RESTORE"
+chmod +x "$RESTORE"
+
+# The toolchain we care about: a consumer install must need none of it.
+TOOLS="xcode-select xcrun clang clang++ cc c++ gcc g++ git cmake make brew ninja cargo rustc"
+
+note() { echo "[clean-machine] $*"; }
+
+# ── PATH scrub ────────────────────────────────────────────────────────────────
+# Keep only OS-default system dirs. Drops Homebrew, the hosted Python toolcache,
+# setup-* shims, pipx, cargo, and every other preinstalled developer dir.
+scrub_path() {
+  local keep out=""
+  if [ "$OS" = "Darwin" ]; then
+    keep="/usr/bin:/bin:/usr/sbin:/sbin"
+  else
+    keep="/usr/local/sbin:/usr/local/bin:/usr/sbin:/usr/bin:/sbin:/bin"
+  fi
+  local IFS=":"
+  for d in $keep; do
+    [ -d "$d" ] && out="${out:+$out:}$d"
+  done
+  echo "$out"
+}
+
+# ── mask ──────────────────────────────────────────────────────────────────────
+if [ "$MODE" = "mask" ]; then
+  NEWPATH="$(scrub_path)"
+  {
+    echo "export PATH='$NEWPATH'"
+    # DEVELOPER_DIR must be UNSET, not pointed at a fake path: `xcode-select -p`
+    # honours DEVELOPER_DIR and prints it verbatim with exit 0, so setting it to a
+    # nonexistent dir makes the probe SUCCEED -- the exact opposite of a clean Mac,
+    # where DEVELOPER_DIR is unset and the missing /var/db/xcode_select_link is what
+    # makes `xcode-select -p` fail.
+    echo "unset DEVELOPER_DIR || true"
+    echo "unset SDKROOT CC CXX CFLAGS CXXFLAGS LDFLAGS CMAKE_GENERATOR CMAKE_PREFIX_PATH || true"
+    echo "export HOMEBREW_NO_AUTO_UPDATE=1"
+    echo "export UNSLOTH_CLEAN_MACHINE=1"
+  } >> "$ENV_FILE"
+
+  if [ "$REMOVE" = "1" ] && [ "$OS" = "Darwin" ]; then
+    # Best-effort real removal. Each step is independent and recorded in
+    # restore.sh so an `if: always()` step can put the runner back.
+    # /var/db/xcode_select_link is exactly what `xcode-select -p` reads, so
+    # removing it reproduces a virgin Mac's gate precisely. `xcode-select --reset`
+    # is NOT enough: it can reselect a full Xcode.app.
+    if [ -e /var/db/xcode_select_link ]; then
+      if sudo rm -f /var/db/xcode_select_link 2>/dev/null; then
+        note "removed /var/db/xcode_select_link"
+        echo "sudo xcode-select --switch /Library/Developer/CommandLineTools 2>/dev/null || true" >> "$RESTORE"
+      else
+        note "WARN could not remove /var/db/xcode_select_link"
+      fi
+    fi
+    # Moving the CLT dir aside turns /usr/bin/{cc,clang,git} into dead shims, so
+    # the run also proves the install needs no compiler at all.
+    if [ -d /Library/Developer/CommandLineTools ]; then
+      if sudo mv /Library/Developer/CommandLineTools /Library/Developer/CommandLineTools.masked 2>/dev/null; then
+        note "moved CommandLineTools aside"
+        echo "sudo mv /Library/Developer/CommandLineTools.masked /Library/Developer/CommandLineTools 2>/dev/null || true" >> "$RESTORE"
+      else
+        note "WARN could not move CommandLineTools"
+      fi
+    fi
+    # Xcode.app must go too. With the select link removed AND CommandLineTools moved,
+    # `xcode-select -p` does not fail -- it falls through to whatever Xcode bundle the
+    # runner image ships (observed: /Applications/Xcode_16.4.app/Contents/Developer),
+    # which re-arms /usr/bin/git and /usr/bin/cc and silently un-cleans the machine.
+    # A rename is instant regardless of bundle size: same filesystem, no copy.
+    for app in /Applications/Xcode*.app; do
+      [ -d "$app" ] || continue
+      if sudo mv "$app" "${app}.masked" 2>/dev/null; then
+        note "moved $(basename "$app") aside"
+        echo "sudo mv '${app}.masked' '$app' 2>/dev/null || true" >> "$RESTORE"
+      else
+        note "WARN could not move $app"
+      fi
+    done
+    for brewdir in /opt/homebrew /usr/local/Homebrew; do
+      if [ -d "$brewdir" ]; then
+        if sudo mv "$brewdir" "${brewdir}.masked" 2>/dev/null; then
+          note "moved $brewdir aside"
+          echo "sudo mv '${brewdir}.masked' '$brewdir' 2>/dev/null || true" >> "$RESTORE"
+        else
+          note "WARN could not move $brewdir"
+        fi
+      fi
+    done
+  fi
+fi
+
+# ── trace ─────────────────────────────────────────────────────────────────────
+if [ "$MODE" = "trace" ]; then
+  for tool in $TOOLS; do
+    real="$(command -v "$tool" 2>/dev/null || true)"
+    [ -n "$real" ] || continue
+    # Wrapper logs the call then execs the REAL binary, so behaviour is unchanged
+    # and the trace answers "did the installer reach for this?" honestly.
+    cat > "$BIN/$tool" <<WRAP
+#!/bin/sh
+printf '%s\t%s\n' "$tool" "\$*" >> "$TRACE"
+exec "$real" "\$@"
+WRAP
+    chmod +x "$BIN/$tool"
+  done
+  {
+    echo "export PATH='$BIN:$PATH'"
+    echo "export UNSLOTH_TOOL_TRACE='$TRACE'"
+    echo "export UNSLOTH_CLEAN_MACHINE=trace"
+  } >> "$ENV_FILE"
+fi
+
+note "mode=$MODE remove=$REMOVE"
+note "env file: $ENV_FILE"
+note "trace:    $TRACE"
+note "restore:  $RESTORE"
diff --git a/.github/workflows/clean-machine-install-ci.yml b/.github/workflows/clean-machine-install-ci.yml
new file mode 100644
index 0000000000..acfe56e48f
--- /dev/null
+++ b/.github/workflows/clean-machine-install-ci.yml
@@ -0,0 +1,528 @@
+# SPDX-License-Identifier: AGPL-3.0-only
+# Copyright 2026-present the Unsloth AI Inc. team. All rights reserved.
+
+# Proves Unsloth installs on a machine that has never seen a developer toolchain.
+#
+# Why this exists: studio-mac-install-matrix.yml runs `install.sh --local --no-torch`
+# on runners that already have Xcode CLT selected AND actions/setup-python
+# preinstalled, so the macOS dependency gate in install.sh never fires there -- and
+# `--local` is precisely the mode that legitimately needs git. A brand-new Mac
+# therefore hits a hard `exit 1` that no CI job covered.
+#
+# Hosted runners are developer machines, so each job simulates absence rather than
+# being virgin. Two modes, because they answer different questions and cannot be
+# done by the same mechanism (see .github/scripts/clean-machine-env.sh):
+#   mask  -> the toolchain is genuinely unusable; does the install still work?
+#   trace -> the toolchain works but is logged; does the installer ever call it?
+# Linux is the exception: containers are genuinely clean.
+
+name: Clean machine install
+
+on:
+  pull_request:
+    paths:
+      - 'install.sh'
+      - 'install.ps1'
+      - 'studio/setup.sh'
+      - 'studio/setup.ps1'
+      - 'studio/install_python_stack.py'
+      - '.github/scripts/clean-machine-*.sh'
+      - '.github/workflows/clean-machine-install-ci.yml'
+  push:
+    branches: [main]
+    paths:
+      - 'install.sh'
+      - 'install.ps1'
+      - '.github/workflows/clean-machine-install-ci.yml'
+  workflow_dispatch:
+    inputs:
+      installer_source:
+        description: 'published = curl unsloth.ai/install.sh, tree = the checked-out script'
+        type: choice
+        options: [tree, published]
+        default: tree
+
+concurrency:
+  group: ${{ github.workflow }}-${{ github.ref }}
+  cancel-in-progress: true
+
+permissions:
+  contents: read
+
+env:
+  # Keep every install inside the workspace so a leg cannot inherit another's state.
+  UNSLOTH_STUDIO_HOME: ${{ github.workspace }}/.studio-home
+  # No wildcard bind -> no ifconfig.me / check-host.net calls on the startup path.
+  UNSLOTH_STUDIO_DISABLE_PUBLIC_CHECK: '1'
+
+jobs:
+  # ── macOS: the reported failure ────────────────────────────────────────────
+  macos:
+    name: mac ${{ matrix.os }} / ${{ matrix.mode }} / ${{ matrix.delivery }}${{ matrix.flags && format(' {0}', matrix.flags) || '' }}
+    runs-on: ${{ matrix.os }}
+    timeout-minutes: 40
+    continue-on-error: ${{ matrix.experimental }}
+    # Explicit legs rather than a full cross-product: the interesting dimensions are
+    # (does the toolchain exist) x (how the script is delivered), not every pairing.
+    strategy:
+      fail-fast: false
+      matrix:
+        include:
+          # The reported failure, in the shape users run it. Default install (torch
+          # included) because that is what a consumer actually gets.
+          - {os: macos-14, mode: mask,  delivery: pipe,  flags: '',           experimental: false}
+          - {os: macos-14, mode: mask,  delivery: file,  flags: '',           experimental: false}
+          # What the desktop app runs: no tty, stdin closed, TAURI markers on.
+          - {os: macos-14, mode: mask,  delivery: tauri, flags: '',           experimental: false}
+          # Toolchain present but logged: does the installer ever reach for it?
+          - {os: macos-14, mode: trace, delivery: file,  flags: '',           experimental: false}
+          # --no-torch is the one macOS path that can still want a compiler
+          # (sentencepiece has no guaranteed cp313 arm64 wheel), so probe it apart
+          # from the default path instead of letting it mask the gate under test.
+          - {os: macos-14, mode: mask,  delivery: file,  flags: '--no-torch', experimental: true}
+          # OS-version dimension.
+          - {os: macos-15, mode: mask,  delivery: pipe,  flags: '',           experimental: false}
+          - {os: macos-26, mode: mask,  delivery: file,  flags: '',           experimental: true}
+          # Intel pins python 3.12, not 3.13 -- informational only.
+          - {os: macos-15-intel, mode: mask, delivery: file, flags: '',       experimental: true}
+
+    steps:
+      # checkout FIRST: it needs a working git, which masking then takes away.
+      - uses: actions/checkout@de0fac2e4500dabe0009e67214ff5f5447ce83dd  # v6.0.2
+        with:
+          persist-credentials: false
+
+      # Deliberately no actions/setup-python: install.sh must bring its own
+      # uv-managed CPython, exactly as it must on a user's machine.
+
+      - name: Record the pre-masking toolchain
+        run: |
+          {
+            echo "xcode-select -p : $(xcode-select -p 2>&1 || true)"
+            echo "git             : $(command -v git || echo none)"
+            echo "brew            : $(command -v brew || echo none)"
+            echo "cmake           : $(command -v cmake || echo none)"
+            echo "python3         : $(command -v python3 || echo none)"
+          } | tee runner-baseline.txt
+
+      - name: Simulate a clean machine (${{ matrix.mode }})
+        run: |
+          mkdir -p logs
+          if [ "${{ matrix.mode }}" = "mask" ]; then
+            bash .github/scripts/clean-machine-env.sh mask --remove
+          else
+            bash .github/scripts/clean-machine-env.sh trace
+          fi
+
+      - name: Verify the simulation actually took effect
+        if: matrix.mode == 'mask'
+        run: |
+          set -a; . ./clean-machine.env; set +a
+          bash .github/scripts/clean-machine-assert.sh absent
+
+      - name: Install
+        id: install
+        env:
+          GH_TOKEN: ${{ secrets.GITHUB_TOKEN }}
+          # Withheld on PR: this step runs checked-out PR code.
+          HF_TOKEN: ${{ github.event_name != 'pull_request' && secrets.HF_TOKEN || '' }}
+        run: |
+          set -a; . ./clean-machine.env; set +a
+          set -o pipefail
+          rc=0
+          FLAGS="${{ matrix.flags }}"
+          case "${{ matrix.delivery }}" in
+            file)
+              # Plain file execution: isolates "installer logic broken" from
+              # "curl-pipe delivery broken".
+              bash install.sh $FLAGS 2>&1 | tee logs/install.log || rc=$?
+              ;;
+            pipe)
+              # The shape users actually run. install.sh is ~150KB of top-level
+              # statements, so an early `exit` leaves the writer with a closed
+              # pipe -> `curl: (56)`. Piping a local file reproduces that
+              # faithfully without depending on unsloth.ai being current.
+              # On pull_request/push this input is empty, which correctly falls through to
+          # the checked-out ref -- only an explicit dispatch tests unsloth.ai.
+          if [ "${{ inputs.installer_source }}" = "published" ]; then
+                curl -fsSL https://unsloth.ai/install.sh | sh -s -- $FLAGS 2>&1 | tee logs/install.log || rc=$?
+              else
+                # `sh -s --` with no further args would pass an empty positional,
+                # so only add the separator when there are flags to pass.
+                if [ -n "$FLAGS" ]; then
+                  cat install.sh | sh -s -- $FLAGS 2>&1 | tee logs/install.log || rc=$?
+                else
+                  cat install.sh | sh 2>&1 | tee logs/install.log || rc=$?
+                fi
+              fi
+              ;;
+            tauri)
+              # Exactly how the desktop app invokes it: no tty, stdin closed.
+              # --tauri rejects a custom UNSLOTH_STUDIO_HOME outright (the desktop app
+              # still uses the legacy ~/.unsloth/studio root), so the workspace-scoped
+              # value every other leg relies on has to go here or the installer exits
+              # before it does any work. The runner is ephemeral, so the real home is
+              # as disposable as the override.
+              env -u UNSLOTH_STUDIO_HOME \
+                bash install.sh --tauri $FLAGS < /dev/null 2>&1 | tee logs/install.log || rc=$?
+              ;;
+          esac
+          echo "install_rc=$rc" >> "$GITHUB_OUTPUT"
+          echo "installer exit code: $rc"
+          # The pipe legs are the ones that expose curl:(56); surface it explicitly
+          # rather than leaving it buried in a 4000-line log.
+          if grep -qE "curl: \(5[36]\)|Failure writing output to destination" logs/install.log; then
+            echo "::warning::curl reported a broken pipe -- an early exit killed the reader"
+          fi
+          exit "$rc"
+
+      - name: Assert no source build and no toolchain use
+        if: always() && steps.install.outcome == 'success'
+        run: |
+          set -a; . ./clean-machine.env; set +a
+          checks="nobuild"
+          [ "${{ matrix.mode }}" = "trace" ] && checks="$checks notools"
+          bash .github/scripts/clean-machine-assert.sh $checks
+
+      - name: Assert llama.cpp loads
+        if: steps.install.outcome == 'success'
+        run: |
+          set -a; . ./clean-machine.env; set +a
+          # The tauri leg cannot honour UNSLOTH_STUDIO_HOME (see the Install step), so
+          # it installed into the legacy root and that is where to look.
+          if [ "${{ matrix.delivery }}" = "tauri" ]; then
+            HOME_DIR="$HOME/.unsloth/studio"
+          else
+            HOME_DIR="$UNSLOTH_STUDIO_HOME"
+          fi
+          STUDIO_HOME="$HOME_DIR" bash .github/scripts/assert-llama-loads.sh
+
+      - name: Restore the runner
+        if: always()
+        run: bash .clean-machine/restore.sh || true
+
+      - name: Upload logs
+        if: always()
+        uses: actions/upload-artifact@043fb46d1a93c77aae656e7c1c64a875d1fc6a0a  # v7.0.1
+        with:
+          name: clean-mac-${{ matrix.os }}-${{ matrix.mode }}-${{ matrix.delivery }}
+          path: |
+            logs/
+            runner-baseline.txt
+            clean-machine.env
+            .clean-machine/tool-invocations.log
+          retention-days: 7
+          if-no-files-found: warn
+
+  # ── Linux: genuinely clean, via containers ────────────────────────────────
+  linux:
+    name: linux ${{ matrix.label }}
+    runs-on: ${{ matrix.runner }}
+    container: ${{ matrix.image }}
+    timeout-minutes: 40
+    continue-on-error: ${{ matrix.experimental }}
+    # Container jobs default to `sh -e`, which is dash: `set -o pipefail` is an
+    # "Illegal option" there and kills the step before the installer even starts.
+    defaults:
+      run:
+        shell: bash
+    strategy:
+      fail-fast: false
+      matrix:
+        include:
+          # Root + apt available: install.sh's _smart_apt_install should self-heal
+          # from a base image with no curl, git, gcc or cmake at all.
+          - label: ubuntu2404-root
+            image: ubuntu:24.04
+            runner: ubuntu-latest
+            experimental: false
+          - label: ubuntu2404-arm-root
+            image: ubuntu:24.04
+            runner: ubuntu-24.04-arm
+            experimental: false
+          # No elevation: today this hard-fails at install.sh:856-861. Expected
+          # failure -- the point is to pin the message and prove it is actionable
+          # rather than a bare `curl: (56)`.
+          - label: ubuntu2404-nonroot
+            image: ubuntu:24.04
+            runner: ubuntu-latest
+            experimental: true
+          # Non-apt: today this hard-fails at install.sh:2034. Expected failure;
+          # forces the decision on whether dnf/pacman/zypper get supported.
+          - label: fedora41
+            image: fedora:41
+            runner: ubuntu-latest
+            experimental: true
+
+    steps:
+      - name: Describe the container's starting state
+        run: |
+          for t in curl wget git gcc cc cmake make python3 sudo; do
+            printf '%-8s %s\n' "$t" "$(command -v $t 2>/dev/null || echo ABSENT)"
+          done | tee /tmp/container-baseline.txt
+
+      # The advertised `curl | sh` cannot even start on an image without curl, so
+      # the bootstrap transport is provisioned separately from the installer's own
+      # dependencies. Everything else stays absent.
+      - name: Provision only the bootstrap transport
+        run: |
+          if command -v apt-get >/dev/null 2>&1; then
+            apt-get update -qq && apt-get install -y -qq --no-install-recommends ca-certificates curl
+          elif command -v dnf >/dev/null 2>&1; then
+            dnf install -y -q ca-certificates curl
+          fi
+
+      # No actions/checkout here on purpose: it requires git, and a container with git
+      # preinstalled is not the clean machine under test. Fetch the two files we need
+      # over the transport provisioned above -- and fetch the INSTALLER from the same
+      # ref, so these legs can validate a fix instead of only the published script.
+      - name: Fetch installer + assert script for this ref
+        run: |
+          mkdir -p logs .github/scripts
+          raw="https://raw.githubusercontent.com/${GITHUB_REPOSITORY}/${GITHUB_SHA}"
+          curl -fsSL "$raw/.github/scripts/clean-machine-assert.sh" -o .github/scripts/clean-machine-assert.sh
+          # On pull_request/push this input is empty, which correctly falls through to
+          # the checked-out ref -- only an explicit dispatch tests unsloth.ai.
+          if [ "${{ inputs.installer_source }}" = "published" ]; then
+            curl -fsSL https://unsloth.ai/install.sh -o install.sh
+            echo "installer: published (unsloth.ai)"
+          else
+            curl -fsSL "$raw/install.sh" -o install.sh
+            echo "installer: this ref (${GITHUB_SHA})"
+          fi
+          wc -l install.sh
+
+      - name: Create an unprivileged user
+        if: matrix.label == 'ubuntu2404-nonroot'
+        run: |
+          useradd -m tester
+          # No sudo installed and not root -> exercises the "cannot elevate" branch.
+          chown -R tester logs install.sh
+
+      - name: Install (root)
+        if: matrix.label != 'ubuntu2404-nonroot'
+        run: |
+          set -o pipefail
+          rc=0
+          # Piped, because that is the advertised command and the shape that turns an
+          # early exit into curl:(56).
+          cat install.sh | sh 2>&1 | tee logs/install.log || rc=$?
+          echo "installer exit code: $rc"
+          exit "$rc"
+
+      - name: Install (unprivileged, expected to fail cleanly)
+        if: matrix.label == 'ubuntu2404-nonroot'
+        run: |
+          set -o pipefail
+          rc=0
+          su tester -c 'cat install.sh | sh' > logs/install.log 2>&1 || rc=$?
+          echo "installer exit code: $rc"
+          tail -40 logs/install.log
+          # It may legitimately fail; what must NOT happen is an unexplained exit or a
+          # bare broken-pipe error standing in for a real diagnosis.
+          if [ "$rc" != "0" ] && ! grep -qiE "sudo is not available|apt-get install|missing:|permission" logs/install.log; then
+            echo "::error::unprivileged install failed with no actionable message"
+            exit 1
+          fi
+
+      - name: Assert no source build
+        if: always()
+        run: |
+          if [ -f .github/scripts/clean-machine-assert.sh ]; then
+            INSTALL_LOG=logs/install.log bash .github/scripts/clean-machine-assert.sh nobuild
+          else
+            echo "::warning::assert script unavailable (fetch step did not run)"
+          fi
+
+      - name: Upload logs
+        if: always()
+        uses: actions/upload-artifact@043fb46d1a93c77aae656e7c1c64a875d1fc6a0a  # v7.0.1
+        with:
+          name: clean-linux-${{ matrix.label }}
+          path: |
+            logs/
+            /tmp/container-baseline.txt
+          retention-days: 7
+          if-no-files-found: warn
+
+  # ── WSL ───────────────────────────────────────────────────────────────────
+  # install.sh carries ~126 lines of WSL-specific logic (the `linux|wsl` dependency
+  # branch, UNSLOTH_WSL_REROUTED, the Strix Halo reroute to 24.04), and none of it
+  # had ever run in CI -- tests/sh/test_strixhalo_wsl_reroute.sh extracts functions
+  # and mocks the environment, which cannot catch anything about a real WSL.
+  #
+  # No third-party action: the official Ubuntu WSL rootfs plus `wsl --import` is
+  # deterministic, checksum-verifiable, and avoids adding a supply-chain dependency
+  # to a repo that audits its lockfiles.
+  wsl:
+    name: wsl ubuntu-24.04
+    runs-on: windows-latest
+    timeout-minutes: 50
+    continue-on-error: true
+
+    steps:
+      - uses: actions/checkout@de0fac2e4500dabe0009e67214ff5f5447ce83dd  # v6.0.2
+        with:
+          persist-credentials: false
+
+      - name: Import a fresh Ubuntu 24.04 WSL distro
+        shell: pwsh
+        run: |
+          # WSL2 is present on windows-2022+ runner images; only a distro is missing.
+          wsl --set-default-version 2
+          $url = 'https://cloud-images.ubuntu.com/wsl/releases/24.04/current/ubuntu-noble-wsl-amd64-24.04lts.rootfs.tar.gz'
+          $expected = '2a790896740b14d637dbdc583cce1ba081ac53b9e9cdb46dc09a2f73abbd9934'
+          New-Item -ItemType Directory -Force -Path wsl-dist, logs | Out-Null
+          Invoke-WebRequest -Uri $url -OutFile wsl-dist/rootfs.tar.gz -UseBasicParsing -TimeoutSec 900
+          $actual = (Get-FileHash wsl-dist/rootfs.tar.gz -Algorithm SHA256).Hash.ToLower()
+          if ($actual -ne $expected) {
+            Write-Host "::error::rootfs checksum mismatch: got $actual"
+            exit 1
+          }
+          wsl --import unsloth-ci "$PWD/wsl-dist/instance" "$PWD/wsl-dist/rootfs.tar.gz" --version 2
+          wsl -d unsloth-ci -- uname -a
+          # A freshly imported rootfs is genuinely bare: no curl, no git, no compiler.
+          # That is the clean machine, not a simulation of one.
+          wsl -d unsloth-ci -- sh -c 'for t in curl wget git gcc cmake python3 sudo; do printf "%-8s %s\n" "$t" "$(command -v $t || echo ABSENT)"; done'
+
+      - name: Install inside WSL, piped exactly as documented
+        shell: pwsh
+        run: |
+          # Only ca-certificates + curl, because the advertised one-liner cannot even
+          # start without a transport. Everything else must come from the installer.
+          wsl -d unsloth-ci -u root -- sh -c 'apt-get update -qq && apt-get install -y -qq --no-install-recommends ca-certificates curl' 2>&1 | Tee-Object -FilePath logs/wsl-bootstrap.log
+          # Copy the script in rather than reaching across /mnt/c: a DrvFs path brings
+          # Windows file permissions and CRLF risk with it, and neither is what a real
+          # WSL user's install looks like.
+          $wslPath = (wsl -d unsloth-ci -- wslpath -a "$($env:GITHUB_WORKSPACE -replace '\\','/')/install.sh").Trim()
+          Write-Host "installer source in WSL: $wslPath"
+          wsl -d unsloth-ci -u root -- cp "$wslPath" /root/install.sh
+          # Feed it through a pipe: same shape as `curl ... | sh`, so an early exit
+          # still exposes the broken-pipe problem, but the script under test is this
+          # ref rather than whatever production currently serves.
+          wsl -d unsloth-ci -u root -- sh -c 'cd /root && cat install.sh | sh' 2>&1 | Tee-Object -FilePath logs/wsl-install.log
+          Write-Host "installer exit: $LASTEXITCODE"
+
+      - name: Did it detect WSL, and did it end up usable?
+        if: always()
+        shell: pwsh
+        run: |
+          # The platform line proves the wsl branch was taken rather than plain linux.
+          Select-String -Path logs/wsl-install.log -Pattern 'platform|\[TAURI:DIAG\]|wsl' -ErrorAction SilentlyContinue |
+            Select-Object -First 10
+          wsl -d unsloth-ci -u root -- sh -c 'test -x "$HOME/.unsloth/studio/unsloth_studio/bin/unsloth" && "$HOME/.unsloth/studio/unsloth_studio/bin/unsloth" --version || echo "no CLI installed"' 2>&1 |
+            Tee-Object -FilePath logs/wsl-verify.log
+
+      - name: Tear the distro down
+        if: always()
+        shell: pwsh
+        run: wsl --unregister unsloth-ci 2>&1 | Out-Null; exit 0
+
+      - name: Upload logs
+        if: always()
+        uses: actions/upload-artifact@043fb46d1a93c77aae656e7c1c64a875d1fc6a0a  # v7.0.1
+        with:
+          name: clean-wsl-ubuntu2404
+          path: logs/
+          retention-days: 7
+          if-no-files-found: warn
+
+  # ── Windows ───────────────────────────────────────────────────────────────
+  windows:
+    name: win ${{ matrix.os }} / winget=${{ matrix.winget }}
+    runs-on: ${{ matrix.os }}
+    timeout-minutes: 45
+    continue-on-error: ${{ matrix.experimental }}
+    strategy:
+      fail-fast: false
+      matrix:
+        include:
+          - os: windows-latest
+            winget: 'visible'
+            experimental: false
+          # The no-winget path (LTSC / Server / managed corporate machines) falls
+          # back to python.org + astral.sh and is completely untested today. It is
+          # also the path where Ensure-VCRedist silently does not run, which leaves
+          # torch unable to load -- hence the explicit `import torch` assert below.
+          - os: windows-latest
+            winget: 'masked'
+            experimental: false
+          - os: windows-11-arm
+            winget: 'visible'
+            experimental: true
+
+    steps:
+      - uses: actions/checkout@de0fac2e4500dabe0009e67214ff5f5447ce83dd  # v6.0.2
+        with:
+          persist-credentials: false
+
+      # No actions/setup-python here either: install.ps1 must bootstrap Python.
+
+      - name: Simulate a clean machine
+        shell: pwsh
+        run: |
+          New-Item -ItemType Directory -Force -Path logs | Out-Null
+          # Drop preinstalled Python, git, CMake, VS/LLVM and the WindowsApps
+          # aliases from PATH. A full Visual Studio uninstall is not realistic in
+          # CI (registry + vswhere discovery, slow, may need a reboot), so PATH and
+          # env scrubbing is the honest approximation -- recorded as such.
+          $drop = @('hostedtoolcache\windows\Python', 'WindowsApps', '\Git\',
+                    'CMake', 'Microsoft Visual Studio', 'BuildTools', 'LLVM',
+                    'MSYS', 'mingw', 'Strawberry')
+          $kept = ($env:PATH -split ';') | Where-Object {
+            $p = $_; $p -and -not ($drop | Where-Object { $p -like "*$_*" })
+          }
+          if ('${{ matrix.winget }}' -eq 'masked') {
+            $kept = $kept | Where-Object { $_ -notlike '*WinGet*' -and $_ -notlike '*Microsoft\WindowsApps*' }
+          }
+          $newPath = ($kept -join ';')
+          "PATH=$newPath" | Out-File -FilePath $env:GITHUB_ENV -Append -Encoding utf8
+          foreach ($v in 'VSINSTALLDIR','VCINSTALLDIR','WindowsSdkDir','INCLUDE','LIB','LIBPATH') {
+            "$v=" | Out-File -FilePath $env:GITHUB_ENV -Append -Encoding utf8
+          }
+          Write-Host "kept PATH entries: $($kept.Count)"
+
+      - name: Verify the simulation took effect
+        shell: pwsh
+        run: |
+          foreach ($t in 'python','git','cmake','cl') {
+            $f = Get-Command $t -ErrorAction SilentlyContinue
+            Write-Host ("{0,-8} {1}" -f $t, $(if ($f) { $f.Source } else { 'ABSENT' }))
+          }
+          if ('${{ matrix.winget }}' -eq 'masked' -and (Get-Command winget -ErrorAction SilentlyContinue)) {
+            Write-Host '::error::winget still resolvable; masking failed'
+            exit 1
+          }
+
+      - name: Install
+        id: install
+        shell: pwsh
+        run: |
+          $ErrorActionPreference = 'Continue'
+          & ./install.ps1 -SkipTorch *>&1 | Tee-Object -FilePath logs/install.log
+          $rc = $LASTEXITCODE
+          Write-Host "installer exit code: $rc"
+          exit $rc
+
+      - name: Assert torch loads (the VCRedist contract)
+        if: steps.install.outcome == 'success'
+        shell: pwsh
+        run: |
+          # The prebuilt llama-server and PyTorch both link the VC++ runtime.
+          # Ensure-VCRedist only runs when winget exists, so on the masked leg this
+          # is the assertion that catches a silently broken install.
+          $py = Join-Path $env:UNSLOTH_STUDIO_HOME 'unsloth_studio\Scripts\python.exe'
+          if (-not (Test-Path $py)) { $py = (Get-Command python -ErrorAction SilentlyContinue).Source }
+          if (-not $py) { Write-Host '::error::no python from the install'; exit 1 }
+          & $py -c "import ctypes.util, sys; print('VCRUNTIME140:', ctypes.util.find_library('vcruntime140'))"
+          & $py -c "import torch; print('torch', torch.__version__)"
+          if ($LASTEXITCODE -ne 0) { Write-Host '::error::torch failed to import (VC++ runtime missing?)'; exit 1 }
+
+      - name: Upload logs
+        if: always()
+        uses: actions/upload-artifact@043fb46d1a93c77aae656e7c1c64a875d1fc6a0a  # v7.0.1
+        with:
+          name: clean-win-${{ matrix.os }}-${{ matrix.winget }}
+          path: logs/
+          retention-days: 7
+          if-no-files-found: warn
diff --git a/.github/workflows/desktop-app-clean-machine-ci.yml b/.github/workflows/desktop-app-clean-machine-ci.yml
new file mode 100644
index 0000000000..246e423dcc
--- /dev/null
+++ b/.github/workflows/desktop-app-clean-machine-ci.yml
@@ -0,0 +1,354 @@
+# SPDX-License-Identifier: AGPL-3.0-only
+# Copyright 2026-present the Unsloth AI Inc. team. All rights reserved.
+
+# Installs and launches the SHIPPED desktop app on a machine stripped of developer
+# tooling, on all three platforms.
+#
+# studio-tauri-smoke.yml compiles the Tauri crate; release-desktop.yml produces the
+# bundles. Neither takes a published artifact, puts it on a clean machine, and checks
+# that it starts -- which is exactly the gap the reported failures fell through: both
+# came from the packaged app running its bundled
+# Contents/Resources/install.sh, a path no CI job exercised.
+#
+# What "runs" means here, given hosted runners have no interactive desktop session:
+#   - the bundle installs / mounts / extracts
+#   - the binary is present, of the right architecture, and passes the OS gatekeeper
+#     checks a user would hit (macOS quarantine + codesign, Windows installer exit)
+#   - the process starts and STAYS UP past its preflight (it does not exit or crash),
+#     which is where an unhappy app dies
+#   - it writes tauri.log, and that log shows the preflight disposition -- the same
+#     field that read `ManagedReady` over an unbootable venv in the bug report
+# Linux gets the strongest check: a real webview under Xvfb.
+
+name: Desktop app clean machine
+
+on:
+  # Also on PRs that touch this job or the machine-stripping scripts. workflow_dispatch
+  # alone is not enough to validate a change to the job itself: dispatch resolves the
+  # workflow from the DEFAULT branch, so a new or edited file on a feature branch can
+  # never be dispatched, and the job would first run only after merging blind.
+  pull_request:
+    paths:
+      - '.github/workflows/desktop-app-clean-machine-ci.yml'
+      - '.github/scripts/clean-machine-env.sh'
+      - '.github/scripts/clean-machine-assert.sh'
+  workflow_dispatch:
+    inputs:
+      release_tag:
+        description: 'Release tag in the desktop release repo'
+        type: string
+        default: 'desktop-v0.1.50-beta'
+      release_repo:
+        description: 'owner/name hosting the desktop release'
+        type: string
+        default: 'unsloth-test/unsloth-test'
+      strip_toolchain:
+        description: 'Strip developer tooling before installing'
+        type: boolean
+        default: true
+  schedule:
+    # Nightly, so a broken published bundle is caught without anyone asking.
+    - cron: '17 5 * * *'
+
+concurrency:
+  group: ${{ github.workflow }}-${{ github.ref }}
+  cancel-in-progress: true
+
+permissions:
+  contents: read
+
+env:
+  REL_REPO: ${{ inputs.release_repo || 'unsloth-test/unsloth-test' }}
+  REL_TAG: ${{ inputs.release_tag || 'desktop-v0.1.50-beta' }}
+  UNSLOTH_STUDIO_HOME: ${{ github.workspace }}/.studio-home
+  UNSLOTH_STUDIO_DISABLE_PUBLIC_CHECK: '1'
+
+jobs:
+  # ── macOS: .dmg, Apple Silicon ────────────────────────────────────────────
+  macos:
+    name: desktop macOS ${{ matrix.os }}
+    runs-on: ${{ matrix.os }}
+    timeout-minutes: 45
+    continue-on-error: ${{ matrix.experimental }}
+    strategy:
+      fail-fast: false
+      matrix:
+        include:
+          - {os: macos-14, experimental: false}
+          - {os: macos-15, experimental: false}
+          - {os: macos-26, experimental: true}
+
+    steps:
+      - uses: actions/checkout@de0fac2e4500dabe0009e67214ff5f5447ce83dd  # v6.0.2
+        with:
+          persist-credentials: false
+
+      - name: Download the shipped .dmg
+        env:
+          GH_TOKEN: ${{ secrets.GITHUB_TOKEN }}
+        run: |
+          mkdir -p dl logs
+          gh release download "$REL_TAG" --repo "$REL_REPO" \
+            --pattern '*aarch64.dmg' --dir dl
+          ls -la dl
+
+      - name: Strip the developer toolchain
+        if: ${{ inputs.strip_toolchain != false }}
+        run: |
+          bash .github/scripts/clean-machine-env.sh mask --remove
+          set -a; . ./clean-machine.env; set +a
+          bash .github/scripts/clean-machine-assert.sh absent
+
+      - name: Mount and install
+        run: |
+          DMG="$(ls dl/*.dmg | head -1)"
+          # A real download is quarantined; Gatekeeper treats it differently from a
+          # locally built bundle, and that difference is a genuine failure mode.
+          xattr -w com.apple.quarantine \
+            "0081;$(printf %x $(date +%s));Safari;" "$DMG" 2>/dev/null || true
+          hdiutil attach "$DMG" -nobrowse -quiet -mountpoint /Volumes/UnslothCI
+          APP="$(ls -d /Volumes/UnslothCI/*.app | head -1)"
+          echo "app bundle: $APP"
+          cp -R "$APP" /Applications/
+          hdiutil detach /Volumes/UnslothCI -quiet
+          ls -la /Applications | grep -i unsloth
+
+      - name: Inspect the bundle (arch, signature, Gatekeeper)
+        run: |
+          APP="$(ls -d /Applications/*Unsloth*.app | head -1)"
+          BIN="$APP/Contents/MacOS/$(/usr/libexec/PlistBuddy -c 'Print :CFBundleExecutable' "$APP/Contents/Info.plist")"
+          file "$BIN"
+          lipo -archs "$BIN" || true
+          # Report rather than gate: an unnotarised beta is expected to fail
+          # assessment, but a user WILL hit this, so it must be visible.
+          codesign -dv --verbose=2 "$APP" 2>&1 | head -20 || true
+          spctl -a -vvv -t install "$APP" 2>&1 | head -5 || \
+            echo "::warning::Gatekeeper assessment failed -- users see 'cannot be opened' unless notarised"
+          # The bundled installer is what actually failed for users.
+          test -f "$APP/Contents/Resources/install.sh" \
+            && echo "bundled install.sh present" \
+            || echo "::error::no bundled install.sh in the app"
+
+      - name: Launch and prove it stays up
+        run: |
+          set -a; [ -f ./clean-machine.env ] && . ./clean-machine.env; set +a
+          APP="$(ls -d /Applications/*Unsloth*.app | head -1)"
+          BIN="$APP/Contents/MacOS/$(/usr/libexec/PlistBuddy -c 'Print :CFBundleExecutable' "$APP/Contents/Info.plist")"
+          "$BIN" > logs/app-stdout.log 2>&1 &
+          APP_PID=$!
+          # 90s: long enough to clear preflight and start the bundled installer.
+          for i in $(seq 1 90); do
+            kill -0 "$APP_PID" 2>/dev/null || break
+            sleep 1
+          done
+          if kill -0 "$APP_PID" 2>/dev/null; then
+            echo "app still running after 90s (pid $APP_PID)"
+            kill -TERM "$APP_PID" 2>/dev/null || true
+          else
+            wait "$APP_PID" 2>/dev/null; rc=$?
+            echo "::error::desktop app exited early with rc=$rc"
+            tail -50 logs/app-stdout.log || true
+            exit 1
+          fi
+
+      - name: What did its own log say?
+        if: always()
+        run: |
+          for f in "$UNSLOTH_STUDIO_HOME/tauri.log" "$HOME/.unsloth/studio/tauri.log"; do
+            [ -f "$f" ] || continue
+            echo "=== $f ==="
+            cp "$f" logs/ 2>/dev/null || true
+            tail -60 "$f"
+            # The two fields the bug report turned on.
+            grep -E "disposition=|can_auto_repair=|Xcode Command Line|ModuleNotFoundError" "$f" || true
+          done
+
+      - name: Restore the runner
+        if: always()
+        run: bash .clean-machine/restore.sh || true
+
+      - name: Upload logs
+        if: always()
+        uses: actions/upload-artifact@043fb46d1a93c77aae656e7c1c64a875d1fc6a0a  # v7.0.1
+        with:
+          name: desktop-macos-${{ matrix.os }}
+          path: logs/
+          retention-days: 7
+          if-no-files-found: warn
+
+  # ── Linux: .deb and .AppImage, with a real webview under Xvfb ────────────
+  linux:
+    name: desktop linux ${{ matrix.kind }}
+    runs-on: ubuntu-22.04
+    timeout-minutes: 45
+    continue-on-error: ${{ matrix.experimental }}
+    strategy:
+      fail-fast: false
+      matrix:
+        include:
+          - {kind: deb, experimental: false}
+          - {kind: appimage, experimental: false}
+
+    steps:
+      - uses: actions/checkout@de0fac2e4500dabe0009e67214ff5f5447ce83dd  # v6.0.2
+        with:
+          persist-credentials: false
+
+      - name: Download the shipped bundle
+        env:
+          GH_TOKEN: ${{ secrets.GITHUB_TOKEN }}
+        run: |
+          mkdir -p dl logs
+          pat='*.deb'; [ "${{ matrix.kind }}" = "appimage" ] && pat='*.AppImage'
+          gh release download "$REL_TAG" --repo "$REL_REPO" --pattern "$pat" --dir dl
+          ls -la dl
+
+      - name: Install with NO dev tooling, only runtime libs
+        run: |
+          # Deliberately not build-essential/cmake/git: a user installing a .deb has
+          # none of that. WebKit + Xvfb are runtime requirements of the app itself,
+          # and apt pulls the .deb's declared deps -- if that list is wrong, this
+          # step is what catches it.
+          sudo apt-get update -qq
+          sudo apt-get install -y -qq --no-install-recommends xvfb
+          if [ "${{ matrix.kind }}" = "deb" ]; then
+            sudo apt-get install -y ./dl/*.deb || {
+              echo "::error::the .deb does not declare its runtime dependencies correctly"
+              exit 1
+            }
+            BIN="$(dpkg -L "$(dpkg-deb -f dl/*.deb Package)" | grep -E '/usr/bin/' | head -1)"
+          else
+            sudo apt-get install -y -qq --no-install-recommends libfuse2 \
+              libwebkit2gtk-4.1-0 libgtk-3-0 libayatana-appindicator3-1 || true
+            chmod +x dl/*.AppImage
+            BIN="$(ls dl/*.AppImage | head -1)"
+          fi
+          echo "BIN=$BIN" >> "$GITHUB_ENV"
+          echo "binary: $BIN"
+
+      - name: Launch under Xvfb and prove it stays up
+        run: |
+          # Linux is the one platform where a hosted runner can give the app a real
+          # display, so this is the strongest "does the UI actually come up" check
+          # available without self-hosted hardware.
+          xvfb-run -a --server-args="-screen 0 1440x900x24" \
+            "$BIN" > logs/app-stdout.log 2>&1 &
+          APP_PID=$!
+          for i in $(seq 1 90); do
+            kill -0 "$APP_PID" 2>/dev/null || break
+            sleep 1
+          done
+          if kill -0 "$APP_PID" 2>/dev/null; then
+            echo "app still running after 90s"
+            kill -TERM "$APP_PID" 2>/dev/null || true
+          else
+            wait "$APP_PID" 2>/dev/null; rc=$?
+            echo "::error::desktop app exited early with rc=$rc"
+            tail -60 logs/app-stdout.log || true
+            exit 1
+          fi
+
+      - name: What did its own log say?
+        if: always()
+        run: |
+          for f in "$UNSLOTH_STUDIO_HOME/tauri.log" "$HOME/.unsloth/studio/tauri.log"; do
+            [ -f "$f" ] || continue
+            echo "=== $f ==="; cp "$f" logs/ 2>/dev/null || true; tail -60 "$f"
+            grep -E "disposition=|can_auto_repair=|ModuleNotFoundError" "$f" || true
+          done
+
+      - name: Upload logs
+        if: always()
+        uses: actions/upload-artifact@043fb46d1a93c77aae656e7c1c64a875d1fc6a0a  # v7.0.1
+        with:
+          name: desktop-linux-${{ matrix.kind }}
+          path: logs/
+          retention-days: 7
+          if-no-files-found: warn
+
+  # ── Windows: NSIS setup.exe, silent install ──────────────────────────────
+  windows:
+    name: desktop windows
+    runs-on: windows-latest
+    timeout-minutes: 45
+    continue-on-error: true
+
+    steps:
+      - uses: actions/checkout@de0fac2e4500dabe0009e67214ff5f5447ce83dd  # v6.0.2
+        with:
+          persist-credentials: false
+
+      - name: Download the shipped installer
+        shell: bash
+        env:
+          GH_TOKEN: ${{ secrets.GITHUB_TOKEN }}
+        run: |
+          mkdir -p dl logs
+          gh release download "$REL_TAG" --repo "$REL_REPO" --pattern '*setup.exe' --dir dl
+          ls -la dl
+
+      - name: Strip developer tooling from PATH
+        if: ${{ inputs.strip_toolchain != false }}
+        shell: pwsh
+        run: |
+          $drop = @('hostedtoolcache\windows\Python', 'WindowsApps', '\Git\', 'CMake',
+                    'Microsoft Visual Studio', 'BuildTools', 'LLVM', 'MSYS', 'mingw')
+          $kept = ($env:PATH -split ';') | Where-Object {
+            $p = $_; $p -and -not ($drop | Where-Object { $p -like "*$_*" })
+          }
+          "PATH=$($kept -join ';')" | Out-File -FilePath $env:GITHUB_ENV -Append -Encoding utf8
+
+      - name: Silent install
+        shell: pwsh
+        run: |
+          $exe = (Get-ChildItem dl/*setup.exe | Select-Object -First 1).FullName
+          # /S is the NSIS silent switch. A user double-clicks, but an installer that
+          # cannot run unattended also cannot be scripted or MDM-deployed.
+          $p = Start-Process -FilePath $exe -ArgumentList '/S' -Wait -PassThru
+          Write-Host "installer exit: $($p.ExitCode)"
+          if ($p.ExitCode -ne 0) { Write-Host "::error::silent install failed"; exit 1 }
+          $found = Get-ChildItem -Path "$env:LOCALAPPDATA","$env:ProgramFiles" -Recurse `
+                     -Filter '*Unsloth*.exe' -ErrorAction SilentlyContinue |
+                   Select-Object -First 1
+          if (-not $found) { Write-Host '::error::no installed executable found'; exit 1 }
+          Write-Host "installed: $($found.FullName)"
+          "APP_EXE=$($found.FullName)" | Out-File -FilePath $env:GITHUB_ENV -Append -Encoding utf8
+
+      - name: Launch and prove it stays up
+        shell: pwsh
+        run: |
+          $p = Start-Process -FilePath $env:APP_EXE -PassThru `
+                 -RedirectStandardOutput logs/app-stdout.log `
+                 -RedirectStandardError logs/app-stderr.log
+          for ($i = 0; $i -lt 90; $i++) { if ($p.HasExited) { break }; Start-Sleep -Seconds 1 }
+          if ($p.HasExited) {
+            Write-Host "::error::desktop app exited early with rc=$($p.ExitCode)"
+            Get-Content logs/app-stdout.log, logs/app-stderr.log -Tail 40 -ErrorAction SilentlyContinue
+            exit 1
+          }
+          Write-Host "app still running after 90s"
+          Stop-Process -Id $p.Id -Force -ErrorAction SilentlyContinue
+
+      - name: What did its own log say?
+        if: always()
+        shell: pwsh
+        run: |
+          foreach ($f in @("$env:UNSLOTH_STUDIO_HOME\tauri.log",
+                           "$env:USERPROFILE\.unsloth\studio\tauri.log")) {
+            if (Test-Path $f) {
+              Write-Host "=== $f ==="
+              Copy-Item $f logs/ -ErrorAction SilentlyContinue
+              Get-Content $f -Tail 60
+              Select-String -Path $f -Pattern 'disposition=|can_auto_repair=|ModuleNotFoundError' `
+                -ErrorAction SilentlyContinue
+            }
+          }
+
+      - name: Upload logs
+        if: always()
+        uses: actions/upload-artifact@043fb46d1a93c77aae656e7c1c64a875d1fc6a0a  # v7.0.1
+        with:
+          name: desktop-windows
+          path: logs/
+          retention-days: 7
+          if-no-files-found: warn