On Windows, `spawn()` with `detached: true` sets the
CREATE_NEW_PROCESS_GROUP flag in CreateProcess. In certain terminal
contexts — notably VSCode's integrated terminal (ConPTY), Windows
Terminal, and some MSYS2/Git Bash configurations — this flag conflicts
with the parent process group hierarchy and causes a synchronous EINVAL
from libuv, making *every* bash/async_bash/bg_shell command fail
immediately with `spawn EINVAL`.
The bg-shell extension already guards against this with
`detached: process.platform !== "win32"` (process-manager.ts:109),
but three other spawn sites were missed:
- `packages/pi-coding-agent/src/core/tools/bash.ts` (bash tool)
- `packages/pi-coding-agent/src/core/bash-executor.ts` (RPC executor)
- `src/resources/extensions/async-jobs/async-bash-tool.ts` (async_bash)
This commit aligns all spawn sites with the bg-shell pattern.
Additionally fixes two related issues:
1. `killProcessTree()` in shell.ts used `detached: true` on its own
`taskkill` spawn call — unnecessary and potentially problematic
in the same terminal contexts. Removed.
2. `killTree()` in async-bash-tool.ts used Unix-only
`process.kill(-pid)` with no Windows fallback. On Windows, negative
PIDs (process group kill) are not supported, so orphaned child
processes could survive timeout kills. Now uses `taskkill /F /T`
on Windows, matching the bg-shell and shell.ts implementations.
Includes a regression test that statically verifies no spawn site
uses unconditional `detached: true`, plus a smoke test confirming
the platform-guarded pattern works on all platforms.
Reproduction: Run GSD v2.42-v2.51 inside VSCode on Windows 11 with
Git Bash as the shell. Any bash tool call fails with `spawn EINVAL`.
The error is 100% reproducible and affects all shell operations
(bash, async_bash, bg_shell start).
Co-authored-by: Matt Haynes <matt@auroraventures.io>
Co-authored-by: Claude Opus 4.6 <noreply@anthropic.com>
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