From b7fa2c8718371cd2f60e54a0bc8580a74d50b51b Mon Sep 17 00:00:00 2001
From: Daniel Han <danielhanchen@gmail.com>
Date: Mon, 27 Apr 2026 00:08:07 +0000
Subject: [PATCH] comments: condense multiline blocks added by this PR

Across the 27-cycle review process, comments accumulated as multiline
blocks explaining each fix's history (cycle numbers, prior bugs,
reviewer rationale). Compress every block to 1-2 lines that capture
just the WHY, dropping cycle references and history that belongs in
the PR description / commit log instead.

Net: 268 deletions / 124 insertions (-144 lines) of comments only.
Behavior unchanged. Verified: bash -n, pwsh parser, python ast.parse,
cargo check all pass.
---
 install.ps1                                  |  91 +++++-------
 install.sh                                   | 138 ++++++-------------
 studio/backend/core/inference/llama_cpp.py   |  22 +--
 studio/backend/main.py                       |   9 +-
 studio/backend/run.py                        |  11 +-
 studio/backend/utils/models/model_config.py  |   1 -
 studio/backend/utils/paths/storage_roots.py  |  19 +--
 studio/backend/utils/transformers_version.py |   1 -
 studio/setup.ps1                             |  21 +--
 studio/setup.sh                              |  19 +--
 studio/src-tauri/src/desktop_auth.rs         |   6 +-
 studio/src-tauri/src/install.rs              |   6 +-
 studio/src-tauri/src/process.rs              |   9 +-
 studio/src-tauri/src/update.rs               |   5 +-
 unsloth_cli/commands/studio.py               |  34 ++---
 15 files changed, 124 insertions(+), 268 deletions(-)

diff --git a/install.ps1 b/install.ps1
index 9db4856034..8d8338aeed 100644
--- a/install.ps1
+++ b/install.ps1
@@ -70,10 +70,8 @@ function Install-UnslothStudio {
     # Resolve install destinations. Priority: env vars, then USERPROFILE-redirect, then default.
     $envOverride = if ($env:UNSLOTH_STUDIO_HOME) { $env:UNSLOTH_STUDIO_HOME } elseif ($env:STUDIO_HOME) { $env:STUDIO_HOME } else { $null }
 
-    # Custom Studio roots are not supported in Tauri-mode installs because
-    # the desktop app still resolves the legacy %USERPROFILE%\.unsloth\studio
-    # path. Pass through when the override resolves to that legacy default
-    # (the desktop app already uses it); fail fast otherwise.
+    # Custom Studio roots are not supported with --tauri (desktop app still
+    # resolves %USERPROFILE%\.unsloth\studio). Pass through if override == legacy.
     if ($TauriMode -and $envOverride) {
         $_tauriOverride = $envOverride
         if ($_tauriOverride -eq "~" -or $_tauriOverride -like "~/*" -or $_tauriOverride -like "~\*") {
@@ -86,8 +84,7 @@ function Install-UnslothStudio {
         try {
             $_legacyTauriRoot = [System.IO.Path]::GetFullPath($_legacyTauriRoot)
         } catch {}
-        # Strip trailing separators so a legacy override with a trailing
-        # backslash or slash still matches the legacy root.
+        # Strip trailing separators so ".../studio\" matches ".../studio".
         $_trimSeps = @(
             [System.IO.Path]::DirectorySeparatorChar,
             [System.IO.Path]::AltDirectorySeparatorChar
@@ -106,35 +103,29 @@ function Install-UnslothStudio {
     $defaultProfile = $null
     try { $defaultProfile = [Environment]::GetFolderPath("UserProfile") } catch {}
 
-    # Default DataDir uses LOCALAPPDATA. Guard the lookup: in service / CI
-    # contexts LOCALAPPDATA may be unset, and Join-Path under
-    # $ErrorActionPreference='Stop' would otherwise abort the installer.
+    # LOCALAPPDATA may be unset in service / CI contexts; Join-Path would abort
+    # under ErrorActionPreference=Stop without this guard.
     $defaultDataDir = if ($env:LOCALAPPDATA -and -not [string]::IsNullOrWhiteSpace($env:LOCALAPPDATA)) {
         Join-Path $env:LOCALAPPDATA "Unsloth Studio"
     } else { $null }
 
     if ($envOverride) {
-        # Expand a leading '~' to $HOME / $env:USERPROFILE because env-var
-        # values are not subject to tilde expansion in any shell.
+        # Tilde expansion: env vars aren't subject to it when quoted on assignment.
         if ($envOverride -eq "~" -or $envOverride -like "~/*" -or $envOverride -like "~\*") {
             $envOverride = (Join-Path $env:USERPROFILE $envOverride.Substring(1).TrimStart('/','\'))
         }
         try {
-            # New-Item has no -LiteralPath in PowerShell 5.1 and -Path treats
-            # square brackets as wildcards. Use the .NET API so a custom root
-            # like C:\workspaces\studio[abc] is handled literally.
+            # .NET API: New-Item -Path treats brackets as wildcards and has no
+            # -LiteralPath in PS 5.1, so a root like C:\studio[abc] would fail.
             [System.IO.Directory]::CreateDirectory($envOverride) | Out-Null
             $StudioHome = (Resolve-Path -LiteralPath $envOverride).Path
         } catch {
             Write-Host "ERROR: STUDIO_HOME=$envOverride cannot be created or accessed." -ForegroundColor Red
             exit 1
         }
-        # Default ToString() form already produces a unique GUID string.
         $probe = Join-Path $StudioHome (".unsloth-write-probe-" + [guid]::NewGuid())
         try {
-            # WriteAllText is literal-path safe and closes the file handle
-            # before the Remove-Item below; New-Item -Path would fail on
-            # bracketed roots (wildcard expansion) just like the dir case.
+            # WriteAllText: literal-path safe + closes handle so Remove-Item works.
             [System.IO.File]::WriteAllText($probe, "")
             Remove-Item -LiteralPath $probe -Force -ErrorAction SilentlyContinue
         } catch {
@@ -415,8 +406,7 @@ function Install-UnslothStudio {
             # This prevents runtime variable expansion for paths containing '$'.
             $SingleQuotedExePath = $UnslothExePath -replace "'", "''"
 
-            # $StudioDataDir was resolved at install start (default = LOCALAPPDATA\Unsloth Studio,
-            # or $StudioHome\share when UNSLOTH_STUDIO_HOME / STUDIO_HOME is set).
+            # $StudioDataDir = LOCALAPPDATA\Unsloth Studio, or $StudioHome\share in env-mode.
             if (-not $StudioDataDir -or [string]::IsNullOrWhiteSpace($StudioDataDir)) {
                 substep "DataDir path unavailable; skipped shortcut creation" "Yellow"
                 return
@@ -457,18 +447,14 @@ function Install-UnslothStudio {
                 [System.IO.Directory]::CreateDirectory($appDir) | Out-Null
             }
 
-            # Persist UNSLOTH_STUDIO_HOME inside the generated launcher when
-            # in env-override mode. Lets fresh shells launch Studio without
-            # the user re-exporting the env var. Default installs get an
-            # empty string here so behavior matches today exactly.
+            # Env-mode: persist UNSLOTH_STUDIO_HOME (and llama path) in the
+            # launcher so fresh shells don't need to re-export. Default installs
+            # get an empty prefix so behavior matches pre-PR exactly.
             $studioHomeExport = if ($StudioRedirectMode -eq 'env') {
-                # Mirror setup.ps1: when an env override happens to equal the
-                # legacy default, llama.cpp still lives at ~/.unsloth/llama.cpp.
-                # Keep the persisted UNSLOTH_LLAMA_CPP_PATH consistent with that.
+                # When override == legacy default, llama.cpp stays at
+                # ~/.unsloth/llama.cpp (one shared build). Canonicalize the
+                # legacy side so the comparison survives path normalization.
                 $_legacyStudio = Join-Path $env:USERPROFILE ".unsloth\studio"
-                # Canonicalize the legacy side (when it exists) to match the
-                # resolved $StudioHome from the env-override path. This keeps
-                # the legacy-equality check stable across path normalization.
                 if (Test-Path -LiteralPath $_legacyStudio -PathType Container) {
                     $_legacyStudio = (Resolve-Path -LiteralPath $_legacyStudio).Path
                 }
@@ -479,9 +465,7 @@ function Install-UnslothStudio {
                 }
                 $_sq = $StudioHome -replace "'", "''"
                 $_llama = $_llamaPath -replace "'", "''"
-                # UNSLOTH_LLAMA_CPP_PATH is a pre-existing user-controlled
-                # llama.cpp directory override. Only default it when the
-                # caller has not already set one in their environment.
+                # UNSLOTH_LLAMA_CPP_PATH is a pre-existing user override; only default if unset.
                 "`$env:UNSLOTH_STUDIO_HOME = '$_sq'`nif (-not `$env:UNSLOTH_LLAMA_CPP_PATH) {`n    `$env:UNSLOTH_LLAMA_CPP_PATH = '$_llama'`n}`n"
             } else { "" }
 
@@ -707,10 +691,8 @@ shell.Run cmd, 0, False
                 }
             }
 
-            # Env-override installs are workspace-scoped: skip persistent
-            # Desktop / Start Menu .lnk shortcuts that would point at a
-            # path the user may later delete. The launcher scripts and
-            # icon written above ARE kept regardless of mode.
+            # Env-mode: skip persistent Desktop / Start Menu .lnk shortcuts
+            # that may point at a deleted workspace; launcher + icon stay.
             if ($StudioRedirectMode -eq 'env') {
                 substep "wrote launcher at $launcherPs1 (persistent shortcuts skipped in env-override mode)"
                 return
@@ -909,8 +891,7 @@ shell.Run cmd, 0, False
     # a version string back to a conda interpreter.
     Write-TauriLog "STEP" "Creating virtual environment"
     if (-not (Test-Path -LiteralPath $StudioHome)) {
-        # New-Item has no -LiteralPath parameter; use the .NET API to honor
-        # bracket characters in custom Studio roots.
+        # .NET API: New-Item -Path treats brackets as wildcards.
         [System.IO.Directory]::CreateDirectory($StudioHome) | Out-Null
     }
 
@@ -946,11 +927,9 @@ shell.Run cmd, 0, False
         $StudioRedirectMode -ne 'env' `
         -and (Test-Path -LiteralPath (Join-Path $env:USERPROFILE "unsloth_studio\Scripts\python.exe"))
     ) {
-        # CWD-relative venv from old install.ps1 -- migrate to absolute path.
-        # Skip in env-override mode: workspace-scoped installs must not
-        # move the user's pre-existing default-install venv away from
-        # %USERPROFILE%, which would break their legacy default install
-        # and contaminate the workspace root.
+        # CWD-relative venv from old install.ps1 -> migrate to absolute path.
+        # Skip in env-mode so we don't relocate the default-install venv into
+        # the workspace root.
         $CwdVenv = Join-Path $env:USERPROFILE "unsloth_studio"
         substep "found CWD-relative Studio environment, migrating to $VenvDir..."
         Move-Item -LiteralPath $CwdVenv -Destination $VenvDir -Force
@@ -1225,9 +1204,8 @@ shell.Run cmd, 0, False
     # Use 'studio setup' (not 'studio update') because 'update' pops
     # SKIP_STUDIO_BASE, which would cause redundant package reinstallation
     # and bypass the fast-path version check from PR #4667.
-    # Only propagate UNSLOTH_STUDIO_HOME for actual env-override installs;
-    # otherwise default-install setups would mistakenly take the env path
-    # (placing llama.cpp under $StudioHome\llama.cpp instead of legacy).
+    # Propagate UNSLOTH_STUDIO_HOME only for env-override installs; otherwise
+    # an inherited value would put llama.cpp in the wrong place.
     $previousUnslothStudioHome = $env:UNSLOTH_STUDIO_HOME
     $hadPreviousUnslothStudioHome = ($null -ne $previousUnslothStudioHome)
     if ($StudioRedirectMode -eq 'env') {
@@ -1314,10 +1292,8 @@ shell.Run cmd, 0, False
             Write-Host "       Launch unsloth studio directly via '$UnslothExe' until the next successful install." -ForegroundColor Yellow
         }
     }
-    # Only add to PATH when the launcher actually exists on disk.
-    # Skip persistent registry PATH modification when env-override is active:
-    # the workspace path may be deleted, and we should not pollute the user's
-    # persistent PATH with it. Caller is expected to add $StudioHome\bin manually.
+    # Add to PATH only when launcher exists. Env-mode: session-only export,
+    # no registry change (workspace path may be deleted later).
     $pathAdded = $false
     if (Test-Path -LiteralPath $ShimExe) {
         if ($StudioRedirectMode -eq 'env') {
@@ -1332,9 +1308,8 @@ shell.Run cmd, 0, False
     }
     Refresh-SessionPath  # sync current session with registry
 
-    # Re-prepend the env-override shim AFTER Refresh-SessionPath, otherwise
-    # a previously-installed legacy User PATH entry would win precedence
-    # (Refresh rebuilds Path as Machine > User > current $env:Path).
+    # Re-prepend env-mode shim AFTER Refresh-SessionPath; otherwise a legacy
+    # User PATH entry (Machine > User > current $env:Path) would win.
     if ($StudioRedirectMode -eq 'env' -and (Test-Path -LiteralPath $ShimExe)) {
         $env:Path = "$ShimDir;$env:Path"
     }
@@ -1345,9 +1320,7 @@ shell.Run cmd, 0, False
         return
     }
 
-    # New-StudioShortcuts itself gates the persistent Desktop / Start
-    # Menu .lnk shortcuts based on $StudioRedirectMode; the launcher
-    # script and icon are always written so env-mode shims still resolve.
+    # New-StudioShortcuts gates the .lnk shortcuts on env-mode internally.
     New-StudioShortcuts -UnslothExePath $UnslothExe
 
     # Launch studio automatically in interactive terminals;
@@ -1358,9 +1331,7 @@ shell.Run cmd, 0, False
     } else {
         step "launch" "manual commands:"
         if ($StudioRedirectMode -eq 'env') {
-            # Env-override mode skips persistent registry PATH update, so
-            # `unsloth` may not resolve in a fresh shell. Print the
-            # absolute shim path so callers can launch directly.
+            # Env-mode skips registry PATH; print the absolute shim path.
             $_shim = Join-Path $StudioHome "bin\unsloth.exe"
             substep "& `"$_shim`" studio -H 0.0.0.0 -p 8888"
             substep "or activate env first:"
diff --git a/install.sh b/install.sh
index 5e42b4f58d..54e060dfc5 100755
--- a/install.sh
+++ b/install.sh
@@ -71,13 +71,8 @@ if [ "$_VERBOSE" = true ]; then
     export UNSLOTH_VERBOSE=1
 fi
 
-# Custom Studio roots are not supported in Tauri-mode installs because the
-# desktop app still resolves the legacy ~/.unsloth/studio path. Producing
-# a custom-root --tauri install would yield a desktop app that cannot
-# locate the freshly installed binary or auth secret. Fail fast for real
-# custom roots; pass through when the override resolves to the legacy
-# default ($HOME/.unsloth/studio), since that is exactly what the desktop
-# app already uses.
+# Custom Studio roots are not supported with --tauri (desktop app still
+# resolves ~/.unsloth/studio). Pass through if the override == legacy default.
 if [ "$TAURI_MODE" = true ]; then
     _tauri_override="${UNSLOTH_STUDIO_HOME:-${STUDIO_HOME:-}}"
     if [ -n "$_tauri_override" ]; then
@@ -85,25 +80,20 @@ if [ "$TAURI_MODE" = true ]; then
             "~") _tauri_override="$HOME" ;;
             "~/"*) _tauri_override="$HOME/${_tauri_override#'~/'}" ;;
         esac
-        # Resolve symlinks/relative paths if the dir exists, else use as-is.
-        # CDPATH= prevents `cd` from echoing the resolved path on stdout when
-        # the user has CDPATH set in their environment. -P resolves symlinks.
+        # Canonicalize both sides (CDPATH=, -P) so a CDPATH-set env or
+        # symlinked $HOME doesn't break the legacy-equality comparison.
         if [ -d "$_tauri_override" ]; then
             _tauri_override_abs=$(CDPATH= cd -P -- "$_tauri_override" 2>/dev/null && pwd -P) \
                 || _tauri_override_abs="$_tauri_override"
         else
             _tauri_override_abs="$_tauri_override"
         fi
-        # Strip trailing separators so a legacy override with a trailing
-        # slash (".../studio/") still matches the legacy root (".../studio").
+        # Strip trailing separators so ".../studio/" matches ".../studio".
         while [ "$_tauri_override_abs" != "/" ] \
             && [ "${_tauri_override_abs%/}" != "$_tauri_override_abs" ]; do
             _tauri_override_abs=${_tauri_override_abs%/}
         done
         _tauri_legacy_root="$HOME/.unsloth/studio"
-        # Apply the same physical-path canonicalization to the legacy root
-        # so a symlinked $HOME (e.g. /home/alice -> /u/alice) doesn't make
-        # the comparison fail when both sides point at the same directory.
         if [ -d "$_tauri_legacy_root" ]; then
             _tauri_legacy_root=$(CDPATH= cd -P -- "$_tauri_legacy_root" 2>/dev/null && pwd -P) \
                 || _tauri_legacy_root="$HOME/.unsloth/studio"
@@ -220,14 +210,11 @@ tauri_log() {
 
 PYTHON_VERSION=""  # resolved after platform detection
 
-# Resolve install destinations. Priority: env vars, then HOME-redirect, then default.
-# Best-effort HOME-redirect detection: skipped on hosts without getent/dscl.
+# Resolve install destinations: env override, HOME-redirect (best-effort
+# via getent/dscl), or default.
 _resolve_studio_destinations() {
     _override="${UNSLOTH_STUDIO_HOME:-${STUDIO_HOME:-}}"
-    # Expand leading ~ / ~/path to $HOME because env vars are not subject to
-    # tilde expansion when set with quotes around the value. Quote the
-    # ~/ inside the prefix-removal so the shell does not tilde-expand it
-    # back to $HOME/ before matching.
+    # Tilde expansion: env vars are not subject to it when quoted on assignment.
     case "$_override" in
         "~") _override="$HOME" ;;
         "~/"*) _override="$HOME/${_override#'~/'}" ;;
@@ -235,8 +222,6 @@ _resolve_studio_destinations() {
     if [ -n "$_override" ]; then
         mkdir -p -- "$_override" 2>/dev/null || { echo "ERROR: STUDIO_HOME=$_override cannot be created." >&2; exit 1; }
         [ -w "$_override" ] || { echo "ERROR: STUDIO_HOME=$_override is not writable." >&2; exit 1; }
-        # CDPATH= prevents `cd` from echoing a CDPATH-prefixed path on stdout
-        # if the user has CDPATH set; -P / pwd -P canonicalizes symlinks.
         STUDIO_HOME="$(CDPATH= cd -P -- "$_override" && pwd -P)" || exit 1
         DATA_DIR="$STUDIO_HOME/share"
         _LOCAL_BIN="$STUDIO_HOME/bin"
@@ -381,10 +366,8 @@ create_studio_shortcuts() {
     mkdir -p "$_css_data_dir"
 
     # ── Write launcher script ──
-    # Heredoc is single-quoted (no $-expansion at write time). The
-    # @@DATA_DIR@@ placeholder below is substituted via sed after the
-    # heredoc is written so the runtime launcher reads studio.conf
-    # from the same DATA_DIR install.sh resolved.
+    # Single-quoted heredoc; @@DATA_DIR@@ is substituted via sed below so
+    # the runtime launcher reads studio.conf from the resolved DATA_DIR.
     cat > "$_css_launcher" << 'LAUNCHER_EOF'
 #!/usr/bin/env bash
 # Unsloth Studio Launcher
@@ -638,33 +621,20 @@ else
 fi
 LAUNCHER_EOF
 
-    # Substitute @@DATA_DIR@@. Default and HOME-redirect installs keep the
-    # legacy runtime form (DATA_DIR="$HOME/.local/share/unsloth") so a later
-    # shell with a different $HOME still resolves DATA_DIR correctly --
-    # byte-identical to pre-PR. Only env-mode installs bake the resolved
-    # absolute path because their root is fixed at install time.
-    # Portable in-place edit: redirect to tempfile, then mv. Avoids the
-    # GNU-vs-BSD-vs-BusyBox `sed -i` divergence (per Gemini review feedback).
+    # Default / HOME-redirect installs replace the placeholder line with the
+    # legacy literal (DATA_DIR="$HOME/.local/share/unsloth") so a later shell
+    # with a different $HOME still resolves correctly -- byte-identical to
+    # pre-PR. Env-mode installs bake the resolved absolute path because their
+    # root is fixed at install time.
     if [ "$_STUDIO_HOME_REDIRECT" = "env" ]; then
-        # Two-stage escape so path metacharacters survive sed and shell
-        # single-quoted embedding. Verified end-to-end with apostrophes,
-        # spaces, &, |, $; do not "simplify" to fewer/more backslashes.
-        #  1) ' -> '\''  for safe single-quote shell embedding.
-        #     The shell pattern "s/'/'\\''/g" passes "s/'/'\''/g" to sed
-        #     (\\ -> \). sed's replacement '\'' contains a literal
-        #     backslash-quote-quote, producing the canonical close-quote /
-        #     escaped-quote / open-quote sequence on output. Result:
-        #     `a b's` -> `a b'\''s`.
-        #  2) For the value to land inside a sed s|...|VALUE|g call below,
-        #     escape \, &, and | (the chosen delimiter) so they survive sed
-        #     replacement. Result of stage 2: `a b'\''s` -> `a b'\\''s`.
+        # Two-stage escape: (1) `'` -> `'\''` for shell single-quote embedding,
+        # (2) backslash/&/| escape so the value survives the s|...|VALUE| sed
+        # below. Verified end-to-end with apostrophes, spaces, &, |, $.
         _sq_escaped=$(printf '%s' "$DATA_DIR" | sed "s/'/'\\\\''/g")
         _sed_safe=$(printf '%s' "$_sq_escaped" | sed 's/[\\&|]/\\&/g')
         sed "s|@@DATA_DIR@@|$_sed_safe|g" "$_css_launcher" > "$_css_launcher.tmp" \
             && mv "$_css_launcher.tmp" "$_css_launcher"
     else
-        # Replace the placeholder line entirely with the legacy literal
-        # so the launcher reads $HOME at runtime, not install time.
         sed "s|DATA_DIR='@@DATA_DIR@@'|DATA_DIR=\"\$HOME/.local/share/unsloth\"|" \
             "$_css_launcher" > "$_css_launcher.tmp" \
             && mv "$_css_launcher.tmp" "$_css_launcher"
@@ -672,30 +642,16 @@ LAUNCHER_EOF
 
     chmod +x "$_css_launcher"
 
-    # Write the exe path to a separate conf file sourced by the launcher.
-    # Single-quote wrapping with the standard `'\''` escape (shell pattern
-    # "s/'/'\\''/g" -> sed "s/'/'\''/g"; replacement `'\''` produces
-    # close-quote, backslash-quote, open-quote on output). No sed templating
-    # is applied to studio.conf, so no second-stage backslash/&/| escaping
-    # is needed here.
+    # studio.conf: exe path + (env-mode only) persisted env vars so fresh
+    # shells launch the right install without re-exporting.
     _css_quoted_exe=$(printf '%s' "$_css_exe" | sed "s/'/'\\\\''/g")
     {
         printf '%s\n' "UNSLOTH_EXE='$_css_quoted_exe'"
-        # Persist UNSLOTH_STUDIO_HOME for env-override installs so the launcher,
-        # CLI, and backend pick up the same root in fresh shells where the user
-        # did not re-export the env var. Also persist UNSLOTH_LLAMA_CPP_PATH so
-        # unsloth-zoo's import-time LLAMA_CPP_DEFAULT_DIR binding finds the
-        # custom-root build. Default installs do NOT get these lines so the
-        # legacy ~/.unsloth/studio + ~/.unsloth/llama.cpp resolution stands.
         if [ "$_STUDIO_HOME_REDIRECT" = "env" ]; then
-            # Mirror setup.sh's legacy-equality check: when an env override
-            # happens to point at the legacy default, llama.cpp still lives
-            # at ~/.unsloth/llama.cpp (one shared build across legacy
-            # installs) -- keep UNSLOTH_LLAMA_CPP_PATH consistent with that.
-            # $STUDIO_HOME is canonicalized (cycle 24) but $HOME/.unsloth/studio
-            # is still logical. Canonicalize the legacy side too so a symlinked
-            # $HOME doesn't make the comparison fail when both point at the
-            # same dir.
+            # When an override resolves to the legacy default, llama.cpp
+            # still lives at ~/.unsloth/llama.cpp (one shared build).
+            # Canonicalize the legacy side so a symlinked $HOME doesn't
+            # break the comparison.
             _css_legacy_studio="$HOME/.unsloth/studio"
             if [ -d "$_css_legacy_studio" ]; then
                 _css_legacy_studio=$(CDPATH= cd -P -- "$_css_legacy_studio" 2>/dev/null && pwd -P) \
@@ -709,9 +665,8 @@ LAUNCHER_EOF
             _css_quoted_home=$(printf '%s' "$STUDIO_HOME" | sed "s/'/'\\\\''/g")
             _css_quoted_llama=$(printf '%s' "$_css_llama_path" | sed "s/'/'\\\\''/g")
             printf '%s\n' "export UNSLOTH_STUDIO_HOME='$_css_quoted_home'"
-            # UNSLOTH_LLAMA_CPP_PATH is a pre-existing custom-llama.cpp-dir
-            # override the Python backend / unsloth-zoo respect. Only default
-            # it when the caller has not already set one in their shell.
+            # UNSLOTH_LLAMA_CPP_PATH is a pre-existing user-controlled
+            # llama.cpp dir override; only default it if unset.
             printf '%s\n' 'if [ -z "${UNSLOTH_LLAMA_CPP_PATH:-}" ]; then'
             printf '%s\n' "    export UNSLOTH_LLAMA_CPP_PATH='$_css_quoted_llama'"
             printf '%s\n' 'fi'
@@ -762,11 +717,9 @@ LAUNCHER_EOF
     fi
 
     # ── Platform-specific shortcuts ──
-    # Env-override installs are workspace-scoped: skip persistent
-    # desktop / Start-Menu / dock launchers that would point at a path
-    # the user may later delete. The runtime launcher + studio.conf +
-    # icon written above are still essential for the env-mode shim and
-    # ARE kept regardless of mode.
+    # Env-mode installs are workspace-scoped: skip persistent desktop /
+    # Start-Menu / dock launchers that may point at a deleted workspace.
+    # Runtime launcher + studio.conf + icon are still written above.
     if [ "$_STUDIO_HOME_REDIRECT" = "env" ]; then
         substep "wrote launcher at $_css_launcher (persistent shortcuts skipped in env-override mode)"
         return 0
@@ -849,12 +802,9 @@ DESKTOP_EOF
 </plist>
 PLIST_EOF
 
-        # Executable stub
-        # The stub embeds the resolved launcher path. Use a single-quoted
-        # heredoc + post-write sed substitution + single-quoted shell
-        # embedding so any path metacharacters ($, ", `, &, |, \, ') in
-        # $_css_data_dir do not expand at .app launch time. Same pattern
-        # as the launch-studio.sh @@DATA_DIR@@ substitution above.
+        # Executable stub: same single-quoted-heredoc + sed-substitute
+        # pattern as launch-studio.sh so $-vars in $_css_data_dir don't
+        # expand at .app launch time.
         _css_sq_dir=$(printf '%s' "$_css_data_dir" | sed "s/'/'\\\\''/g")
         _css_sed_dir=$(printf '%s' "$_css_sq_dir" | sed 's/[\\&|]/\\&/g')
         cat > "$_css_macos_dir/launch-studio" << 'STUB_EOF'
@@ -1807,10 +1757,8 @@ _SKIP_FRONTEND=0
 if [ "$TAURI_MODE" = true ]; then
     _SKIP_FRONTEND=1
 fi
-# Helper: prepend UNSLOTH_STUDIO_HOME=$STUDIO_HOME to "$@" only for actual
-# env-override installs. Avoids word-splitting on whitespace paths -- a
-# string-form '_STUDIO_ENV_FOR_SETUP="UNSLOTH_STUDIO_HOME=$STUDIO_HOME"'
-# would split '/tmp/space path' into separate argv entries.
+# Prepend UNSLOTH_STUDIO_HOME=$STUDIO_HOME to "$@" for env-override installs
+# without word-splitting on whitespace paths.
 _run_setup_with_studio_home() {
     if [ "$_STUDIO_HOME_REDIRECT" = "env" ]; then
         UNSLOTH_STUDIO_HOME="$STUDIO_HOME" "$@"
@@ -1844,9 +1792,8 @@ else
 fi
 
 # ── Make 'unsloth' available via $_LOCAL_BIN (resolved earlier) ──
-# When STUDIO_HOME / UNSLOTH_STUDIO_HOME is used, $_LOCAL_BIN is workspace-scoped
-# ($STUDIO_HOME/bin) and we skip the shell-rc PATH append so we do not pollute
-# the user's profile with a path that may be deleted with the workspace.
+# Env-mode: $_LOCAL_BIN is $STUDIO_HOME/bin; skip shell-rc PATH append so we
+# don't pollute the user's profile with a workspace-scoped path.
 mkdir -p "$_LOCAL_BIN"
 ln -sf "$VENV_DIR/bin/unsloth" "$_LOCAL_BIN/unsloth"
 
@@ -1879,9 +1826,8 @@ case ":$PATH:" in
 esac
 
 # Non-Tauri installs keep shortcuts even if setup reports failure.
-# create_studio_shortcuts itself gates the persistent desktop/menu
-# launchers based on $_STUDIO_HOME_REDIRECT; the runtime launcher +
-# studio.conf + icon are always written so env-mode shims still resolve.
+# create_studio_shortcuts gates persistent menu shortcuts on env-mode;
+# launcher + studio.conf + icon are always written.
 if [ "$TAURI_MODE" != true ]; then
     create_studio_shortcuts "$VENV_ABS_BIN/unsloth" "$OS"
 fi
@@ -1925,15 +1871,11 @@ if [ -t 1 ]; then
     exit "$_LAUNCH_EXIT"
 else
     step "launch" "manual commands:"
-    # Single-quote-escape paths so values with spaces / apostrophes /
-    # metacharacters round-trip through copy-paste from a non-TTY install log.
+    # Single-quote-escape so paths with spaces / apostrophes copy-paste cleanly.
     _li_shim_q="'$(printf '%s' "${_LOCAL_BIN}/unsloth" | sed "s/'/'\\\\''/g")'"
     _li_act_q="'$(printf '%s' "${VENV_DIR}/bin/activate" | sed "s/'/'\\\\''/g")'"
     if [ "$_STUDIO_HOME_REDIRECT" = "env" ]; then
-        # In env-override mode we deliberately skip the persistent shell
-        # rc PATH append, so a fresh shell will not have `unsloth` on PATH
-        # unless the caller re-exports UNSLOTH_STUDIO_HOME. Print the
-        # absolute shim path and the activate-then-run alternative.
+        # Env-mode skips the rc PATH append, so print the absolute shim path.
         substep "$_li_shim_q studio -H 0.0.0.0 -p 8888"
         substep "or activate env first:"
         substep "source $_li_act_q"
diff --git a/studio/backend/core/inference/llama_cpp.py b/studio/backend/core/inference/llama_cpp.py
index 057d737aea..199b14af5a 100644
--- a/studio/backend/core/inference/llama_cpp.py
+++ b/studio/backend/core/inference/llama_cpp.py
@@ -491,14 +491,10 @@ class LlamaCppBackend:
                 if win_bin.is_file():
                     return str(win_bin)
 
-        # 2-4. Mirror setup.sh / setup.ps1's install layout:
-        #   - In env-override mode (custom Studio root != legacy default),
-        #     llama.cpp is installed under $STUDIO_HOME/llama.cpp.
-        #   - Otherwise (default install or HOME redirect), llama.cpp is
-        #     installed at ~/.unsloth/llama.cpp (sibling of the Studio dir).
-        # Default-mode searches must NOT look at $STUDIO_HOME/llama.cpp,
-        # to avoid picking a stale partial install from a previous failed
-        # install over the real legacy binary.
+        # 2-4. Match installer layout: env-mode -> $STUDIO_HOME/llama.cpp;
+        # default/HOME-redirect -> ~/.unsloth/llama.cpp (sibling of studio).
+        # Default mode skips $STUDIO_HOME/llama.cpp so a stale partial install
+        # there cannot shadow the real legacy binary.
         legacy_llama = Path.home() / ".unsloth" / "llama.cpp"
         try:
             from utils.paths.storage_roots import studio_root as _sr  # noqa: WPS433
@@ -511,7 +507,6 @@ class LlamaCppBackend:
                 search_roots = [_resolved_sr / "llama.cpp", legacy_llama]
         except (ImportError, OSError, ValueError):
             search_roots = [legacy_llama]
-        # De-dupe while preserving order (defensive in case both resolve equal).
         _seen: set[str] = set()
         for unsloth_home in [
             r for r in search_roots if str(r) not in _seen and not _seen.add(str(r))
@@ -2084,12 +2079,9 @@ class LlamaCppBackend:
             #                      (binary must be *under* one of these)
             install_roots: list[Path] = []
 
-            # Resolved Studio root (covers env-override custom installs).
-            # Mirror _find_llama_server_binary: only treat $STUDIO_HOME/llama.cpp
-            # as Studio-owned when STUDIO_HOME is a real env override, not the
-            # legacy default. In default-mode installs llama.cpp is a sibling
-            # of studio (~/.unsloth/llama.cpp), and ~/.unsloth/studio/llama.cpp
-            # may be owned by a different tool or a stale partial install.
+            # Env-mode custom root (mirrors _find_llama_server_binary). Default
+            # mode excluded so we don't kill llama-server from another tool
+            # running under ~/.unsloth/studio/llama.cpp.
             try:
                 from utils.paths.storage_roots import studio_root as _sr  # noqa: WPS433
 
diff --git a/studio/backend/main.py b/studio/backend/main.py
index 365a4be812..0b9fbdd283 100644
--- a/studio/backend/main.py
+++ b/studio/backend/main.py
@@ -23,12 +23,9 @@ if _backend_dir not in sys.path:
 # See: https://github.com/python/cpython/issues/102396
 import _platform_compat  # noqa: F401
 
-# Custom-root env propagation BEFORE any unsloth/unsloth-zoo import: when
-# main.py is launched directly via `uvicorn main:app` from a custom-root
-# venv, neither unsloth_cli nor run.py runs, so UNSLOTH_LLAMA_CPP_PATH
-# stays unset and unsloth-zoo's import-time LLAMA_CPP_DEFAULT_DIR binding
-# falls back to the legacy ~/.unsloth/llama.cpp. Mirror run.py's logic:
-# only export when the resolved root is a real custom override.
+# Direct `uvicorn main:app` launches bypass run.py, so re-export here too
+# (mirrors run.py). Required BEFORE the unsloth-zoo import below, since
+# its LLAMA_CPP_DEFAULT_DIR binding is import-time.
 from utils.paths.storage_roots import studio_root as _studio_root
 
 _LEGACY_STUDIO_ROOT = (_Path.home() / ".unsloth" / "studio").resolve()
diff --git a/studio/backend/run.py b/studio/backend/run.py
index e6035e705b..f6c7208278 100644
--- a/studio/backend/run.py
+++ b/studio/backend/run.py
@@ -159,17 +159,14 @@ def _find_free_port(host: str, start: int, max_attempts: int = 20) -> int:
     )
 
 
-# Resolved via the shared helper so custom installs land in the right place.
 from utils.paths.storage_roots import studio_root as _studio_root
 
 _PID_FILE = _studio_root() / "studio.pid"
 
-# When the backend is launched directly (bypassing unsloth_cli, which
-# normally re-exports these env vars), make sure unsloth-zoo's import-time
-# LLAMA_CPP_DEFAULT_DIR binding still picks up the custom-root build. Only
-# set when the resolved root is a real custom override -- legacy default
-# installs must NOT export, since the installers treat any non-empty
-# UNSLOTH_STUDIO_HOME as env-override mode.
+# Direct backend launches bypass the CLI's env re-export; do it here for
+# real custom roots so unsloth-zoo's import-time LLAMA_CPP_DEFAULT_DIR
+# picks up the custom build. Skip for legacy-default to avoid flipping
+# default-mode installs into env-override.
 _LEGACY_STUDIO_ROOT = (Path.home() / ".unsloth" / "studio").resolve()
 try:
     _STUDIO_ROOT_RESOLVED = _studio_root().resolve()
diff --git a/studio/backend/utils/models/model_config.py b/studio/backend/utils/models/model_config.py
index ce9fe4fe6d..9d04ec09d6 100644
--- a/studio/backend/utils/models/model_config.py
+++ b/studio/backend/utils/models/model_config.py
@@ -499,7 +499,6 @@ _VLM_MODEL_TYPES = {
 
 # Pre-computed .venv_t5 paths and backend dir for subprocess version switching.
 # Vision check uses 5.5.0 (newest, recognizes all architectures).
-# Use the shared resolver so custom-root installs find their own venv.
 from utils.paths.storage_roots import studio_root as _studio_root  # noqa: E402
 
 _VENV_T5_DIR = str(_studio_root() / ".venv_t5_550")
diff --git a/studio/backend/utils/paths/storage_roots.py b/studio/backend/utils/paths/storage_roots.py
index f1a3038871..e52fdcd946 100644
--- a/studio/backend/utils/paths/storage_roots.py
+++ b/studio/backend/utils/paths/storage_roots.py
@@ -11,14 +11,9 @@ import tempfile
 
 
 def _infer_studio_home_from_venv() -> Path | None:
-    """If running from an installer-managed unsloth_studio venv, return the
-    parent dir as STUDIO_HOME.
-
-    Fallback for fresh shells after a custom install where the installer
-    wrote to a workspace path but the user did not re-export the env var.
-    Narrowed via installer-sentinel check (share/studio.conf or bin shim)
-    so a developer venv that happens to be named ``unsloth_studio`` is not
-    misidentified as a custom Studio root.
+    """Return parent dir of sys.prefix as STUDIO_HOME if running from an
+    installer-managed unsloth_studio venv. Sentinel-gated (share/studio.conf
+    or bin shim) so a developer venv named unsloth_studio is not misidentified.
     """
     try:
         prefix = Path(sys.prefix).resolve()
@@ -36,12 +31,10 @@ def _infer_studio_home_from_venv() -> Path | None:
 
 
 def studio_root() -> Path:
-    """Resolve the Studio install root.
+    """Studio install root.
 
-    Priority: UNSLOTH_STUDIO_HOME env, STUDIO_HOME env (alias), sys.prefix
-    inference, legacy ~/.unsloth/studio. Backwards-compatible: identical
-    to the legacy default when no env var is set and we are not running
-    from the venv.
+    Priority: UNSLOTH_STUDIO_HOME, STUDIO_HOME, sys.prefix inference,
+    legacy ~/.unsloth/studio.
     """
     override = os.environ.get("UNSLOTH_STUDIO_HOME") or os.environ.get("STUDIO_HOME")
     if override:
diff --git a/studio/backend/utils/transformers_version.py b/studio/backend/utils/transformers_version.py
index 5b683fd4d2..1a5a6d668c 100644
--- a/studio/backend/utils/transformers_version.py
+++ b/studio/backend/utils/transformers_version.py
@@ -94,7 +94,6 @@ TRANSFORMERS_DEFAULT_VERSION = "4.57.6"
 TRANSFORMERS_5_VERSION = TRANSFORMERS_550_VERSION
 
 # Pre-installed directories — created by setup.sh / setup.ps1.
-# Use the shared resolver so custom-root installs find their own venvs.
 from utils.paths.storage_roots import studio_root as _studio_root  # noqa: E402
 
 _VENV_T5_530_DIR = str(_studio_root() / ".venv_t5_530")
diff --git a/studio/setup.ps1 b/studio/setup.ps1
index 2dd52d36bb..0e6969ce8a 100644
--- a/studio/setup.ps1
+++ b/studio/setup.ps1
@@ -1455,11 +1455,8 @@ if (-not $PythonCmd) {
 
 substep "Using $PythonCmd ($(& $PythonCmd --version 2>&1))"
 
-# The venv must already exist (created by install.ps1).
-# This script (setup.ps1 / "unsloth studio update") only updates packages.
-# UNSLOTH_STUDIO_HOME / STUDIO_HOME (alias) override the install root,
-# mirroring install.ps1. install.ps1 exports UNSLOTH_STUDIO_HOME when
-# invoking the studio update.
+# The venv must already exist (created by install.ps1); this script only
+# updates packages. UNSLOTH_STUDIO_HOME / STUDIO_HOME override the root.
 $_studioOverride = if ($env:UNSLOTH_STUDIO_HOME) { $env:UNSLOTH_STUDIO_HOME } elseif ($env:STUDIO_HOME) { $env:STUDIO_HOME } else { $null }
 if ($_studioOverride) {
     if ($_studioOverride -eq "~" -or $_studioOverride -like "~/*" -or $_studioOverride -like "~\*") {
@@ -1728,8 +1725,7 @@ if ($stackExit -ne 0) {
 # ── Pre-install transformers 5.x into .venv_t5_530/ and .venv_t5_550/ ──
 # Runs outside the deps fast-path gate so that upgrades from the legacy
 # single .venv_t5 are always migrated to the tiered layout.
-# T5 sidecar venvs live next to the main venv under the resolved $StudioHome
-# so custom-root installs are self-contained.
+# T5 sidecar venvs live under the resolved $StudioHome so custom installs are self-contained.
 $VenvT5_530Dir = Join-Path $StudioHome ".venv_t5_530"
 $VenvT5_550Dir = Join-Path $StudioHome ".venv_t5_550"
 $VenvT5Legacy = Join-Path $StudioHome ".venv_t5"
@@ -1822,15 +1818,12 @@ step "transformers" "5.5.0 pre-installed"
 # ==========================================================================
 #  PHASE 3.4: Prefer prebuilt llama.cpp bundles before source build
 # ==========================================================================
-# Only nest llama.cpp under $StudioHome when the resolved Studio root is
-# a real override (not the legacy default). Compare resolved paths so a
-# stale UNSLOTH_STUDIO_HOME pointing at the legacy default does not
+# Nest llama.cpp under $StudioHome only for real env-overrides, never the
+# legacy default. Stale UNSLOTH_STUDIO_HOME pointing at legacy must not
 # accidentally relocate llama.cpp.
 $LegacyStudioHome = Join-Path $env:USERPROFILE ".unsloth\studio"
-# Canonicalize BOTH sides. $StudioHome is the resolved env-override path
-# in env-mode (line 1474) but the bare logical path in default mode
-# (line 1480). Canonicalizing on the fly handles a junctioned/symlinked
-# %USERPROFILE% the same in both modes.
+# Canonicalize both sides so a junctioned/symlinked %USERPROFILE% behaves
+# the same in env-mode (resolved) and default mode (logical $StudioHome).
 $_studioHomeCanon = $StudioHome
 if (Test-Path -LiteralPath $_studioHomeCanon -PathType Container) {
     $_studioHomeCanon = (Resolve-Path -LiteralPath $_studioHomeCanon).Path
diff --git a/studio/setup.sh b/studio/setup.sh
index affcc5683a..48f1e925c1 100755
--- a/studio/setup.sh
+++ b/studio/setup.sh
@@ -399,18 +399,14 @@ if [ -d "$SCRIPT_DIR/backend/core/data_recipe/oxc-validator" ] && command -v npm
 fi
 
 # ── Python venv + deps ──
-# UNSLOTH_STUDIO_HOME / STUDIO_HOME (alias) override the install root, mirroring
-# install.sh. install.sh exports UNSLOTH_STUDIO_HOME when invoking this script.
+# UNSLOTH_STUDIO_HOME / STUDIO_HOME override the install root (mirrors install.sh).
 _studio_override="${UNSLOTH_STUDIO_HOME:-${STUDIO_HOME:-}}"
-# Expand a leading ~ / ~/path because env vars are not subject to tilde
-# expansion when set with quotes around the value.
 case "$_studio_override" in
     "~") _studio_override="$HOME" ;;
     "~/"*) _studio_override="$HOME/${_studio_override#'~/'}" ;;
 esac
 if [ -n "$_studio_override" ]; then
     mkdir -p -- "$_studio_override"
-    # CDPATH= prevents CDPATH-prefixed echo; -P canonicalizes symlinks.
     STUDIO_HOME="$(CDPATH= cd -P -- "$_studio_override" && pwd -P)" || exit 1
 else
     STUDIO_HOME="$HOME/.unsloth/studio"
@@ -570,16 +566,11 @@ fi
 fi
 
 # ── 7. Prefer prebuilt llama.cpp bundles before any source build path ──
-# Only nest llama.cpp under $STUDIO_HOME when the resolved Studio root is a
-# real override (not the legacy default). Comparing resolved paths instead
-# of env-var presence avoids regressing default installs that incidentally
-# inherit UNSLOTH_STUDIO_HOME from a parent process or the CLI.
+# Nest llama.cpp under $STUDIO_HOME only for real env-overrides, never the
+# legacy default. Compare canonicalized paths so STUDIO_HOME (logical in
+# default mode, canonical in env mode) and the legacy side line up under
+# symlinked $HOME.
 _LEGACY_STUDIO_HOME="$HOME/.unsloth/studio"
-# Canonicalize BOTH sides under symlinked $HOME. STUDIO_HOME is logical
-# in default-mode (line 416 sets it from the bare $HOME path) and
-# canonical in env-mode (line 413 uses pwd -P). Canonicalizing on the
-# fly here means default-mode under symlinked $HOME still recognizes
-# the legacy default and keeps llama.cpp at ~/.unsloth/llama.cpp.
 _studio_home_canon="$STUDIO_HOME"
 if [ -d "$_studio_home_canon" ]; then
     _studio_home_canon=$(CDPATH= cd -P -- "$_studio_home_canon" 2>/dev/null && pwd -P) \
diff --git a/studio/src-tauri/src/desktop_auth.rs b/studio/src-tauri/src/desktop_auth.rs
index 3f35e16466..6bb256c14c 100644
--- a/studio/src-tauri/src/desktop_auth.rs
+++ b/studio/src-tauri/src/desktop_auth.rs
@@ -194,10 +194,8 @@ async fn provision_desktop_auth() -> Result<(), String> {
         cmd.env_remove("PYTHONPATH");
     }
 
-    // Tauri does not honor UNSLOTH_STUDIO_HOME / STUDIO_HOME yet; scrub so the
-    // provisioning subprocess writes to the legacy ~/.unsloth/studio root that
-    // matches what the Rust auth code reads. UNSLOTH_LLAMA_CPP_PATH is a
-    // pre-existing backend-only llama.cpp directory override and is kept.
+    // Tauri uses the legacy root regardless of UNSLOTH_STUDIO_HOME / STUDIO_HOME.
+    // Scrub so provisioning writes match what the Rust auth code reads.
     cmd.env_remove("UNSLOTH_STUDIO_HOME");
     cmd.env_remove("STUDIO_HOME");
     #[cfg(windows)]
diff --git a/studio/src-tauri/src/install.rs b/studio/src-tauri/src/install.rs
index f8a12b5d3e..173f88a4c4 100644
--- a/studio/src-tauri/src/install.rs
+++ b/studio/src-tauri/src/install.rs
@@ -192,10 +192,8 @@ fn spawn_script(
         cmd.env_remove("PYTHONPATH");
     }
 
-    // Tauri only does default-root installs. install.sh / install.ps1 reject
-    // UNSLOTH_STUDIO_HOME / STUDIO_HOME under --tauri; scrub them from the
-    // spawned installer so an inherited shell-set value cannot trip the guard.
-    // UNSLOTH_LLAMA_CPP_PATH is unrelated to the Studio root and kept as-is.
+    // Tauri only does default-root installs; install.sh / install.ps1 reject
+    // these under --tauri. Scrub so an inherited value can't trip the guard.
     cmd.env_remove("UNSLOTH_STUDIO_HOME");
     cmd.env_remove("STUDIO_HOME");
 
diff --git a/studio/src-tauri/src/process.rs b/studio/src-tauri/src/process.rs
index 67cef43a10..a05a7bd6ee 100644
--- a/studio/src-tauri/src/process.rs
+++ b/studio/src-tauri/src/process.rs
@@ -280,12 +280,9 @@ pub fn start_backend(
         cmd.env_remove("PYTHONPATH");
     }
 
-    // The Tauri desktop app does not honor UNSLOTH_STUDIO_HOME / STUDIO_HOME yet;
-    // it always uses ~/.unsloth/studio. Scrub these from the spawned Python
-    // backend so it cannot diverge from the Rust-resolved Studio root when the
-    // user's shell happens to have them set. Keep UNSLOTH_LLAMA_CPP_PATH: that
-    // is a pre-existing custom-llama.cpp-directory override the Python backend
-    // and unsloth-zoo intentionally support, independent of the Studio root.
+    // Tauri uses the legacy root regardless of UNSLOTH_STUDIO_HOME / STUDIO_HOME;
+    // scrub so the spawned Python backend can't diverge. UNSLOTH_LLAMA_CPP_PATH
+    // is a pre-existing user-controlled llama.cpp dir override; keep it.
     cmd.env_remove("UNSLOTH_STUDIO_HOME");
     cmd.env_remove("STUDIO_HOME");
 
diff --git a/studio/src-tauri/src/update.rs b/studio/src-tauri/src/update.rs
index 8dc4ebbb6d..c138aef0d4 100644
--- a/studio/src-tauri/src/update.rs
+++ b/studio/src-tauri/src/update.rs
@@ -58,9 +58,8 @@ fn spawn_update(
         cmd.env_remove("PYTHONPATH");
     }
 
-    // Tauri still manages the legacy ~/.unsloth/studio root; scrub the custom-
-    // root env vars so 'unsloth studio update' updates the same install the
-    // desktop app uses, not an unrelated custom root inherited from the shell.
+    // Tauri manages the legacy root; scrub so 'unsloth studio update' targets
+    // the same install the desktop app uses, not an inherited custom root.
     cmd.env_remove("UNSLOTH_STUDIO_HOME");
     cmd.env_remove("STUDIO_HOME");
 
diff --git a/unsloth_cli/commands/studio.py b/unsloth_cli/commands/studio.py
index 593d5f4e1f..d11a7a6374 100644
--- a/unsloth_cli/commands/studio.py
+++ b/unsloth_cli/commands/studio.py
@@ -21,17 +21,12 @@ import typer
 studio_app = typer.Typer(help = "Unsloth Studio commands.")
 
 
-# UNSLOTH_STUDIO_HOME / STUDIO_HOME (alias) override the install root, matching
-# install.sh / install.ps1. Falls back to sys.prefix inference (so direct
-# invocations of <STUDIO_HOME>/bin/unsloth still resolve correctly even after
-# the installer's env var has expired), then to the legacy ~/.unsloth/studio.
-# Returns (path, is_custom): is_custom=True only when the resolved root is a
-# real override; we use this to decide whether to re-export the env var to
-# child processes.
+# Resolve install root: UNSLOTH_STUDIO_HOME / STUDIO_HOME, then sys.prefix
+# inference (so a direct call to <root>/bin/unsloth resolves after the
+# installer's env var has expired), then legacy ~/.unsloth/studio.
 def _looks_like_installer_managed_studio_home(candidate: Path) -> bool:
-    """Heuristic: only treat a directory as an installer-managed Studio root
-    if it carries installer-written sentinels (studio.conf or the bin shim).
-    Avoids over-matching on a dev venv that happens to be named unsloth_studio.
+    """Sentinel check (studio.conf or bin shim) so a dev venv named
+    unsloth_studio is not misidentified as a custom Studio root.
     """
     shim_name = "unsloth.exe" if platform.system() == "Windows" else "unsloth"
     return (candidate / "share" / "studio.conf").is_file() or (
@@ -58,21 +53,16 @@ def _resolve_studio_home() -> tuple[Path, bool]:
 
 
 STUDIO_HOME, _STUDIO_HOME_IS_CUSTOM = _resolve_studio_home()
-# Re-export only for actual custom roots so child processes (setup script,
-# backend run.py) inherit it. Default installs MUST NOT re-export the env
-# var, because setup.sh / setup.ps1 treat its presence as "env-override
-# mode" and would relocate llama.cpp / DATA_DIR away from legacy paths.
-# UNSLOTH_LLAMA_CPP_PATH is also setdefault for custom roots so
-# unsloth-zoo's import-time LLAMA_CPP_DEFAULT_DIR binding picks up the
-# correct build dir for GGUF export.
+# Re-export only for real custom roots; default installs must NOT export
+# (setup.sh/setup.ps1 treat any non-empty UNSLOTH_STUDIO_HOME as env-mode).
+# UNSLOTH_LLAMA_CPP_PATH is set so unsloth-zoo's import-time
+# LLAMA_CPP_DEFAULT_DIR binding finds the custom build for GGUF export.
 if _STUDIO_HOME_IS_CUSTOM:
-    # Use truthy-check rather than setdefault so a blank env var (e.g.
-    # UNSLOTH_STUDIO_HOME=) doesn't suppress the inferred custom root.
+    # Truthy-check (not setdefault) so a blank UNSLOTH_STUDIO_HOME= doesn't
+    # suppress the inferred custom root.
     if not os.environ.get("UNSLOTH_STUDIO_HOME"):
         os.environ["UNSLOTH_STUDIO_HOME"] = str(STUDIO_HOME)
-    # Mirror setup.sh / setup.ps1's legacy-equality check: when an env
-    # override happens to equal the legacy default, llama.cpp still lives
-    # at ~/.unsloth/llama.cpp (one shared build across legacy installs).
+    # When override == legacy default, llama.cpp stays at ~/.unsloth/llama.cpp.
     _legacy_studio = (Path.home() / ".unsloth" / "studio").resolve()
     if STUDIO_HOME.resolve() == _legacy_studio:
         _llama_dir = Path.home() / ".unsloth" / "llama.cpp"