pwsh.exe hardcoded in 6 places - CLI completely unusable on Windows 11 with only PowerShell 5.1 (closed #411 is still broken in v0.0.417)

[guidegdm]

Describe the bug

Issue #411 was closed as "not_planned" in Oct 2025, but the bug is still present and getting worse — it now blocks the CLI from running any shell command at all on Windows machines that ship only with Windows PowerShell 5.1 (powershell.exe).

The error on every single command:

<exited with error: PowerShell 6+ (pwsh) is not available. Please install it from https://aka.ms/powershell (https://aka.ms/powershell). Error: Error: Command failed: pwsh.exe --version 'pwsh.exe' is not recognized as an internal or external command, operable program or file.

Affected version

0.0.417 (also reproducible on 0.0.415, 0.0.414 — any recent version)

Root cause (with exact locations in index.js)

pwsh.exe is hardcoded in 6 places in ~/.copilot/pkg/universal/{version}/index.js.
All 6 must be changed to powershell.exe for the CLI to work on Windows PowerShell 5.1:

#	Pattern	Location
1	process.platform==="win32"?"pwsh.exe":"pwsh"	Shell type detection
(xds function)
2	l?"pwsh.exe":"bash"	PTY spawn (class constructor)
3	Start-Process -FilePath "pwsh.exe"
tryExecuteDetachedCommandWindows (inner PS command)
4	ths("pwsh.exe",["-NoProfile","-Command",I]
tryExecuteDetachedCommandWindows (outer spawn)
5	"pwsh.exe --version"	ensureShellIsSupported version check
6	(one remaining — likely in installer/zip extraction path)	TBD

Proposed fix

Use powershell.exe as the fallback when pwsh.exe is not found:

// Before
process.platform === "win32" ? "pwsh.exe" : "pwsh"

// After — detect what's available
process.platform === "win32" ? (hasExe("pwsh.exe") ? "pwsh.exe" :
"powershell.exe") : "pwsh"

Or simpler: just use powershell.exe (works on both PS 5.1 and PS 7+, both ship  
it).

Why "not_planned" is the wrong call

- Windows 11 ships only with powershell.exe by default. No pwsh.
- powershell.exe is available on every Windows machine going back to Windows 7.
- The CLI already works perfectly once patched — there is no functional dependency on PS 6+.
- This blocks 100% of Windows users on default installs from using the CLI at all.
- Related open issue: #1086

Workaround (until fixed)

Patch ~/.copilot/pkg/universal/{version}/index.js — replace all pwsh.exe → powershell.exe. 
Must be re-applied after each winget upgrade GitHub.Copilot.

[guidegdm]

+1 — and the problem is worse than a one-time fix

I'm hitting all of the same issues described here, plus a compounding set of workflow problems that make the CLI nearly unusable day-to-day on Windows:

1. Auto-updates silently revert the pwsh.exe workaround every single day Every time Copilot CLI auto-updates, the hardcoded pwsh.exe path is restored, breaking shell commands again. There is no setting to persist a custom shell path. The only fix — manually replacing the binary — gets wiped on the next update. This is a daily manual task just to keep the tool functional.

2. No way to specify a shell path in config There should be a user-configurable setting (e.g. shellPath in settings or an env var like COPILOT_CLI_SHELL) so the shell binary can be overridden without touching internal files, and without being reverted on update.

3. Terminal restart / VS Code window reload kills the session entirely When a fix requires restarting the terminal or reloading the VS Code window (which it currently does after each update reverts the binary), the entire Copilot CLI session is lost. Sessions are not persistent across restarts, so all context is gone.

4. Context bank is not reliably auto-updated The CLI is supposed to automatically update the context bank based on session rules, but this is inconsistent — sometimes it does, sometimes it doesn't. Users coming from tools like Claude CLI expect this to work reliably without manually prompting it each session.

Requested fixes:

• Fall back to powershell.exe when pwsh.exe is not found (or detect shell automatically)
• Add a configurable shellPath setting that persists across updates
• Make session context persistent across terminal restarts
• Fix context bank auto-update to be consistent and rule-driven

This is a regression that actively breaks daily workflows. Please reopen or link #411 and treat this as a blocking issue for Windows users.