ci: keep Windows PowerShell alive on the ARM64 runner image

.github/workflows/release.yml

@@ -592,6 +592,9 @@ jobs:
       - name: Package native ARM64 ZIP
         shell: pwsh
         run: ./scripts/package-release.ps1 -Version $env:PACKAGE_VERSION -Architecture arm64 -OutputDirectory dist -TargetDirectory target
+      - name: Keep Windows PowerShell alive on the ARM64 runner image
+        shell: pwsh
+        run: ./scripts/conformance/windows_arm64_module_path.ps1
       - name: Run ARM64 Windows conformance
         shell: pwsh
         env:

.github/workflows/windows-arm64-diagnostics.yml

@@ -13,6 +13,7 @@ on:
       - .github/workflows/windows-arm64-diagnostics.yml
       - scripts/conformance/conpty_smoke.py
       - scripts/conformance/explicit_command_boot.py
+      - scripts/conformance/windows_arm64_module_path.ps1
 
 permissions:
   contents: read
@@ -68,6 +69,18 @@ jobs:
         if: always()
         shell: pwsh
         run: python scripts/conformance/windows_standard_user.py scripts/conformance/explicit_command_boot.py diagnostic-runtime/pebrel.exe diagnostic-output/explicit-commands.json
+      - name: Apply the ARM64 image module-path workaround
+        if: always()
+        shell: pwsh
+        run: ./scripts/conformance/windows_arm64_module_path.ps1
+      - name: Explicit -e commands after the workaround
+        if: always()
+        shell: pwsh
+        run: python scripts/conformance/windows_standard_user.py scripts/conformance/explicit_command_boot.py diagnostic-runtime/pebrel.exe diagnostic-output/explicit-commands-fixed.json
+      - name: Conformance after the workaround
+        if: always()
+        shell: pwsh
+        run: python scripts/conformance/windows_standard_user.py scripts/conformance/run.py --app diagnostic-runtime/pebrel.exe --platform windows-aarch64 --output diagnostic-output/fixed/windows-arm64-report.json
       - uses: actions/upload-artifact@v4
         if: always()
         with:

scripts/conformance/conpty_smoke.py

@@ -246,7 +246,7 @@ def run_case(
         first_output_ms = round((time.monotonic() - started) * 1000)
     result["first_output_ms"] = first_output_ms
     result["output_bytes"] = len(output)
-    result["output_head"] = output[:400].decode("utf-8", "replace")
+    result["output_head"] = output[:2000].decode("utf-8", "replace")
     kernel.CloseHandle(process.hThread)
     kernel.CloseHandle(process.hProcess)
     kernel.DeleteProcThreadAttributeList(attributes)

scripts/conformance/explicit_command_boot.py

@@ -221,6 +221,11 @@ if app_env is not None:
                  f"Get-Module -ListAvailable PSReadLine | ForEach-Object {{ $_.Version.ToString() + ' ' + $_.Path }}; Write-Output {MARKER}"],
             ),
         }
+        variants["windows-default-import-utility-verbose"] = (
+            windows_default,
+            ["powershell.exe", "-NoLogo", "-NoProfile", "-Command",
+             f"Import-Module Microsoft.PowerShell.Utility -Verbose; Write-Output {MARKER}"],
+        )
         for index, entry in enumerate(app_entries):
             variants[f"app-entries-without-{index}"] = ([e for e in app_entries if e != entry], POWERSHELL_51)
         for name, (entries, command) in variants.items():
@@ -231,7 +236,7 @@ if app_env is not None:
                 library, subprocess.list2cmdline(command), 0, REPLAY_WAIT, done_marker=MARKER.encode(), env=env, cwd=None
             )
             summary = {k: result.get(k) for k in ("error", "first_output_ms", "marker_ms", "output_bytes")}
-            summary["output_head"] = str(result.get("output_head", ""))[:300]
+            summary["output_head"] = str(result.get("output_head", ""))[:1500]
             summary["entries"] = entries
             print("psmodulepath", name, "PASS" if result.get("marker_ms") is not None else "SILENT", json.dumps(summary)[:400], flush=True)
             report.setdefault("psmodulepath_variants", {})[name] = summary  # type: ignore[index]

scripts/conformance/windows_arm64_module_path.ps1

@@ -0,0 +1,23 @@
+# Work around the windows-11-arm runner image: Windows PowerShell 5.1 there
+# renders nothing (not even `Write-Output`) when its PSModulePath is the
+# registry value alone, and recovers as soon as the PowerShell 7 module
+# directories that the runner's pwsh step shell injects come first. Pebrel
+# rebuilds child environments from the registry (the stock console host rule), so
+# the injected entries never reach the default tab; putting them into the
+# user-level registry value keeps the rebuild faithful and PS 5.1 alive.
+# Evidence: .github/workflows/windows-arm64-diagnostics.yml bisect, 2026-09-22.
+[CmdletBinding()]
+param()
+
+$ErrorActionPreference = 'Stop'
+$pwsh7 = @(
+    (Join-Path $HOME 'Documents\PowerShell\Modules'),
+    (Join-Path $env:ProgramFiles 'PowerShell\Modules'),
+    (Join-Path $env:ProgramFiles 'PowerShell\7\Modules')
+)
+$machine = [Environment]::GetEnvironmentVariable('PSModulePath', 'Machine')
+$user = [Environment]::GetEnvironmentVariable('PSModulePath', 'User')
+$entries = @($pwsh7) + @(($user, $machine) -join ';' -split ';' | Where-Object { $_ })
+$value = ($entries | Select-Object -Unique) -join ';'
+[Environment]::SetEnvironmentVariable('PSModulePath', $value, 'User')
+"User PSModulePath: $value"