install.ps1: remove the torch overrides temp file from the outer finally

New-UnslothTorchOverridesFile writes a uv --overrides file that also folds in the
caller's inherited UV_OVERRIDE lines, which can carry authenticated direct URLs.
The in-flow Remove-Item calls only run on the normal path, so a terminating error
or Ctrl-C between the GetTempFileName and those removals left the file in %TEMP%.

install.sh already removes its twin (_UNSLOTH_TORCH_OVERRIDES) from
_cleanup_install_temporaries on both the EXIT and the signal traps, and empties the
variable beforehand so an inherited value never reaches the rm. Mirror both halves
here: reset $script:TorchOverridesFile to $null ahead of the outer try (under
irm | iex the script scope is the caller's session) and sweep it in the finally.
The block writes nothing to the success or error stream, so a Ctrl-C cannot
truncate it.

tests/studio/test_unsloth_torch_override.ps1 is the Windows twin of
tests/sh/test_unsloth_torch_override.sh: it asserts the guarded with-deps installs,
the removal sites and the null reset, and behaviourally runs the extracted finally
body against a live temp file holding a credential-bearing override line.
Before this change 17 passed, 5 failed; after, 22 passed, 0 failed.

install.ps1

@@ -2782,6 +2782,10 @@ exit 0
     }
 }
 
+# $null so a value left by an earlier run in the same session never reaches the finally
+# below: under `irm | iex` the script scope IS the caller's session. Twin of install.sh's
+# `_UNSLOTH_TORCH_OVERRIDES=""` ahead of its traps -- only a path this run created is removed.
+$script:TorchOverridesFile = $null
 try {
     Install-UnslothStudio @args
 } finally {
@@ -2789,4 +2793,12 @@ try {
     # session outlives the installer, so a terminating exception that bypasses the in-flow
     # clears must not leave an abandoned exact pin for a later `studio setup` / `update`.
     Remove-Item Env:UNSLOTH_KEPT_TORCH -ErrorAction SilentlyContinue
+    # Same for the generated uv overrides temp file (twin of install.sh's
+    # _cleanup_install_temporaries): it copies the caller's inherited UV_OVERRIDE contents, so a
+    # terminating error between its creation and the in-flow removal would leave those
+    # requirements sitting in %TEMP%. Only paths this script created are ever set here.
+    if ($script:TorchOverridesFile) {
+        Remove-Item -LiteralPath $script:TorchOverridesFile -Force -ErrorAction SilentlyContinue
+        $script:TorchOverridesFile = $null
+    }
 }

tests/studio/test_unsloth_torch_override.ps1

@@ -0,0 +1,134 @@
+#!/usr/bin/env pwsh
+# SPDX-License-Identifier: AGPL-3.0-only
+# Copyright 2026-present the Unsloth AI Inc. team. All rights reserved. See /studio/LICENSE.AGPL-3.0
+# Windows twin of tests/sh/test_unsloth_torch_override.sh: install.ps1's torch-trio
+# --overrides guard (New-UnslothTorchOverridesFile) on the Step-2 unsloth installs.
+# The generated file also folds in the caller's UV_OVERRIDE lines, which can carry
+# authenticated direct URLs, so it must never outlive the run: install.sh removes its
+# twin from the EXIT/signal traps and install.ps1 must do the same from the outer
+# finally. Pure text/AST assertions plus one behavioural cleanup check -- no venv needed.
+# Run: pwsh -NoProfile -File tests/studio/test_unsloth_torch_override.ps1
+
+$ErrorActionPreference = "Stop"
+$installPath = [System.IO.Path]::Combine($PSScriptRoot, "..", "..", "install.ps1")
+$installPath = (Resolve-Path $installPath).Path
+$installText = Get-Content -Raw $installPath
+
+# --- Parse install.ps1 (also serves as a syntax gate) ---
+$tokens = $null; $errors = $null
+$ast = [System.Management.Automation.Language.Parser]::ParseFile($installPath, [ref]$tokens, [ref]$errors)
+if ($errors) { $errors | ForEach-Object { $_.ToString() }; throw "install.ps1 has parse errors" }
+
+$failures = 0
+function Check($name, $cond) {
+    if ($cond) { Write-Host "  PASS  $name" }
+    else { Write-Host "  FAIL  $name" -ForegroundColor Red; $script:failures++ }
+}
+
+# Text of every Invoke-InstallCommandRetry statement carrying $label. A with-deps
+# path has two: the overrides-guarded call and the no-torch-installed fallback.
+function Get-InstallBlocks([string]$label) {
+    $calls = $ast.FindAll({ param($n)
+        $n -is [System.Management.Automation.Language.CommandAst] -and
+        $n.Extent.Text -like "*-Label `"$label`" *" -and
+        $n.GetCommandName() -eq "Invoke-InstallCommandRetry"
+    }, $true)
+    if ($calls.Count -eq 0) { throw "no Invoke-InstallCommandRetry found for '$label'" }
+    return @($calls | ForEach-Object { $_.Extent.Text })
+}
+
+Write-Host "New-UnslothTorchOverridesFile"
+$fnAst = $ast.FindAll({ param($n)
+    $n -is [System.Management.Automation.Language.FunctionDefinitionAst] -and
+    $n.Name -eq "New-UnslothTorchOverridesFile"
+}, $true)
+Check "helper defined exactly once" ($fnAst.Count -eq 1)
+$fnText = $fnAst[0].Extent.Text
+Check "helper returns null under --no-torch" ($fnText -match 'if \(\$SkipTorch\) \{ return \$null \}')
+Check "helper folds in caller UV_OVERRIDE files" ($fnText -match '\$env:UV_OVERRIDE')
+
+Write-Host "with-deps unsloth installs pass --overrides"
+foreach ($label in @("install unsloth (local)", "install unsloth")) {
+    $blocks = Get-InstallBlocks $label
+    $guarded = @($blocks | Where-Object { $_ -match '--overrides \$script:TorchOverridesFile' })
+    Check "'$label' has one overrides-guarded call and one plain fallback" (
+        $blocks.Count -eq 2 -and $guarded.Count -eq 1)
+}
+
+Write-Host "the --no-deps no-torch installs carry no overrides"
+foreach ($label in @("install unsloth (no-torch)", "install unsloth (migrated no-torch)")) {
+    $blocks = Get-InstallBlocks $label
+    Check "'$label' has no --overrides" (@($blocks | Where-Object { $_ -match '--overrides' }).Count -eq 0)
+}
+
+Write-Host "the generated temp file never outlives the run"
+$removals = [regex]::Matches($installText, 'Remove-Item -LiteralPath \$script:TorchOverridesFile -Force')
+# One in-flow removal per with-deps install, plus the outer-finally sweep.
+Check "in-flow removal after each with-deps install, plus a final sweep" ($removals.Count -eq 3)
+$outer = @($ast.FindAll({ param($n)
+    $n -is [System.Management.Automation.Language.TryStatementAst] -and
+    $n.Body.Extent.Text -match 'Install-UnslothStudio @args'
+}, $true))
+Check "outer try/finally around Install-UnslothStudio found" ($outer.Count -eq 1)
+$finallyText = $outer[0].Finally.Extent.Text
+Check "outer finally removes the overrides temp file" ($finallyText -match 'Remove-Item -LiteralPath \$script:TorchOverridesFile -Force')
+Check "outer finally still clears UNSLOTH_KEPT_TORCH" ($finallyText -match 'Remove-Item Env:UNSLOTH_KEPT_TORCH')
+# install.sh empties _UNSLOTH_TORCH_OVERRIDES before arming its traps so an inherited
+# value can never be rm'd; under `irm | iex` the script scope is the caller's session,
+# so the same reset must precede the outer try.
+Check "overrides path reset to null before the outer try" (
+    $installText -match '(?m)^\$script:TorchOverridesFile = \$null\r?\ntry \{\r?\n\s*Install-UnslothStudio @args')
+
+Write-Host "outer finally actually deletes the file after a terminating error"
+# Behavioural: run the real finally body with a live temp file holding a credential-
+# bearing inherited override line, exactly as an interrupted install would leave it.
+$leakFile = [System.IO.Path]::GetTempFileName()
+Set-Content -LiteralPath $leakFile -Encoding ascii -Value @(
+    "torch==2.11.0+cu128",
+    "private-pkg @ https://svc:TOKEN123@pkgs.corp.example/private-1.0-py3-none-any.whl")
+$script:TorchOverridesFile = $leakFile
+$env:UNSLOTH_KEPT_TORCH = "2.11.0"
+# Strip the `finally { ... }` wrapper and run the statements themselves; Invoke-Expression
+# evaluates in this scope, so the block's $script: writes land where the installer's would.
+$finallyBody = ($finallyText.Trim() -replace '(?s)^\{', '') -replace '(?s)\}$', ''
+try {
+    try { throw "simulated terminating error mid-install" }
+    finally { Invoke-Expression $finallyBody }
+} catch { }
+Check "temp overrides file removed" (-not (Test-Path -LiteralPath $leakFile))
+Check "kept-torch handoff still cleared" ($null -eq $env:UNSLOTH_KEPT_TORCH)
+Check "tracked path reset so a rerun cannot re-remove it" ($null -eq $script:TorchOverridesFile)
+Remove-Item -LiteralPath $leakFile -Force -ErrorAction SilentlyContinue
+
+Write-Host "the inherited-override filter drops the torch trio in any casing"
+# PowerShell's -notmatch is case-insensitive unless written -cnotmatch, so a caller
+# override spelled `Torch<2.11` is dropped and the generated exact pin wins.
+$filterPattern = $null
+if ($fnText -match '\$_ -notmatch ''([^'']+)''') { $filterPattern = $Matches[1] }
+Check "filter pattern extracted from the helper" ($null -ne $filterPattern)
+$inherited = @(
+    "# comment survives",
+    "Torch<2.11",
+    "TORCHVISION>=0.19",
+    "TorchAudio==2.1",
+    "torch<2.11.0",
+    "torchvision==0.25.0",
+    "torchaudio!=2.11.0",
+    "torchmetrics==1.0",
+    "transformers>=4.57.6",
+    "anyio<4.14.0"
+)
+$merged = @("torch==2.11.0+cu128") + @($inherited | Where-Object { $_ -notmatch $filterPattern })
+$trio = @($merged | Where-Object { $_ -match '^(torch|torchvision|torchaudio)([\s<>=!~;@[]|$)' })
+Check "exactly one trio requirement survives (the generated pin)" ($trio.Count -eq 1)
+Check "the survivor is the generated exact pin" ($trio[0] -eq "torch==2.11.0+cu128")
+foreach ($keep in @("torchmetrics==1.0", "transformers>=4.57.6", "anyio<4.14.0", "# comment survives")) {
+    Check "unrelated inherited override preserved: $keep" ($merged -contains $keep)
+}
+
+Write-Host ""
+if ($failures -gt 0) {
+    Write-Host "FAILED: $failures check(s)" -ForegroundColor Red
+    exit 1
+}
+Write-Host "All checks passed."