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fix(windows): prevent EINVAL by disabling detached process groups on Win32 (#2744)

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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>
This commit is contained in:
Matt Haynes 2026-03-26 16:08:03 -06:00 • committed by GitHub
parent 543710b5a9
commit c557aea8de
5 changed files with 133 additions and 14 deletions
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6
packages/pi-coding-agent/src/core/bash-executor.ts
View file

@ -87,8 +87,12 @@ export function executeBash(command: string, options?: BashExecutorOptions & { l
} else {
({ shell, args } = getShellConfig());
}
// On Windows, detached: true sets CREATE_NEW_PROCESS_GROUP which can
// cause EINVAL in VSCode/ConPTY terminal contexts. The bg-shell
// extension already guards this (process-manager.ts); align here.
// Process-tree cleanup uses taskkill /F /T on Windows regardless.
const child: ChildProcess = spawn(shell, [...args, sanitizeCommand(command)], {
detached: true,
detached: process.platform !== "win32",
env: getShellEnv(),
stdio: ["ignore", "pipe", "pipe"],
});

101
packages/pi-coding-agent/src/core/tools/bash-spawn-windows.test.ts Normal file
View file

@ -0,0 +1,101 @@
/**
* bash-spawn-windows.test.ts — Regression test for Windows spawn EINVAL.
*
* Verifies that bash tool spawn options disable `detached: true` on Windows
* to prevent EINVAL errors in ConPTY / VSCode terminal contexts.
*
* Background:
* On Windows, `spawn()` with `detached: true` sets the
* CREATE_NEW_PROCESS_GROUP flag in CreateProcess. In certain terminal
* contexts (VSCode integrated terminal, ConPTY, Windows Terminal) this
* flag conflicts with the parent process group and causes a synchronous
* EINVAL from libuv. The bg-shell extension already guards against this
* with `detached: process.platform !== "win32"` (process-manager.ts);
* this test ensures all other spawn sites are aligned.
*
* See: gsd-build/gsd-2#XXXX
*/
import test from "node:test";
import assert from "node:assert/strict";
import { spawn } from "node:child_process";
// Verify the spawn option pattern used across the codebase.
// This is a static/structural test — it reads the source files and asserts
// they use the platform-guarded detached flag.
import { readFileSync } from "node:fs";
import { join, dirname } from "node:path";
import { fileURLToPath } from "node:url";
const __dirname = dirname(fileURLToPath(import.meta.url));
const SPAWN_FILES = [
join(__dirname, "bash.ts"),
join(__dirname, "..", "bash-executor.ts"),
join(__dirname, "..", "..", "utils", "shell.ts"),
];
test("spawn calls use platform-guarded detached flag (no unconditional detached: true)", () => {
for (const file of SPAWN_FILES) {
const content = readFileSync(file, "utf-8");
const lines = content.split("\n");
for (let i = 0; i < lines.length; i++) {
const line = lines[i]!;
// Skip comments
if (line.trim().startsWith("//") || line.trim().startsWith("*")) continue;
// Check for unconditional `detached: true`
if (/detached:\s*true\b/.test(line)) {
assert.fail(
`${file}:${i + 1} has unconditional 'detached: true' — ` +
`must use 'detached: process.platform !== "win32"' ` +
`to prevent EINVAL on Windows (ConPTY / VSCode terminal)`,
);
}
}
}
});
test("killProcessTree does not use detached: true for taskkill on Windows", () => {
const shellFile = join(__dirname, "..", "..", "utils", "shell.ts");
const content = readFileSync(shellFile, "utf-8");
// Find the taskkill spawn call and ensure it doesn't have detached: true
const taskkillRegion = content.match(/spawn\("taskkill"[\s\S]*?\}\)/);
if (taskkillRegion) {
assert.ok(
!/detached:\s*true/.test(taskkillRegion[0]),
"taskkill spawn should not use detached: true — " +
"it can cause EINVAL on Windows and is unnecessary for a utility process",
);
}
});
// Smoke test: spawn with platform-guarded detached flag actually works
test("spawn with detached: process.platform !== 'win32' succeeds", async () => {
const { promise, resolve, reject } = Promise.withResolvers<void>();
const child = spawn(
process.platform === "win32" ? "cmd" : "sh",
process.platform === "win32" ? ["/c", "echo ok"] : ["-c", "echo ok"],
{
detached: process.platform !== "win32",
stdio: ["ignore", "pipe", "pipe"],
},
);
let output = "";
child.stdout?.on("data", (d: Buffer) => { output += d.toString(); });
child.on("error", reject);
child.on("close", (code) => {
try {
assert.equal(code, 0, "spawn should succeed");
assert.ok(output.trim().includes("ok"), `Expected 'ok' in output, got: ${output}`);
resolve();
} catch (e) {
reject(e);
}
});
await promise;
});

6
packages/pi-coding-agent/src/core/tools/bash.ts
View file

@ -158,9 +158,13 @@ const defaultBashOperations: BashOperations = {
return;
}
// On Windows, detached: true sets CREATE_NEW_PROCESS_GROUP which can
// cause EINVAL in VSCode/ConPTY terminal contexts. The bg-shell
// extension already guards this (process-manager.ts); align here.
// Process-tree cleanup uses taskkill /F /T on Windows regardless.
const child = spawn(shell, [...args, command], {
cwd,
detached: true,
detached: process.platform !== "win32",
env: env ?? getShellEnv(),
stdio: ["ignore", "pipe", "pipe"],
});

1
packages/pi-coding-agent/src/utils/shell.ts
View file

@ -192,7 +192,6 @@ export function killProcessTree(pid: number): void {
try {
spawn("taskkill", ["/F", "/T", "/PID", String(pid)], {
stdio: "ignore",
detached: true,
});
} catch {
// Ignore errors if taskkill fails

33
src/resources/extensions/async-jobs/async-bash-tool.ts
View file

@ -14,7 +14,7 @@ import {
DEFAULT_MAX_LINES,
} from "@gsd/pi-coding-agent";
import { Type } from "@sinclair/typebox";
import { spawn } from "node:child_process";
import { spawn, spawnSync } from "node:child_process";
import { createWriteStream } from "node:fs";
import { tmpdir } from "node:os";
import { join } from "node:path";
@ -38,17 +38,24 @@ function getTempFilePath(): string {
}
/**
* Kill a process and its children. Uses process group kill on Unix.
* Kill a process and its children (cross-platform).
* Uses process group kill on Unix; taskkill /F /T on Windows.
*/
function killTree(pid: number): void {
try {
// Kill the process group (negative PID)
process.kill(-pid, "SIGTERM");
} catch {
if (process.platform === "win32") {
try {
process.kill(pid, "SIGTERM");
spawnSync("taskkill", ["/F", "/T", "/PID", String(pid)], {
timeout: 5_000,
stdio: "ignore",
});
} catch {
// Already exited
try { process.kill(pid, "SIGTERM"); } catch { /* already exited */ }
}
} else {
try {
process.kill(-pid, "SIGTERM");
} catch {
try { process.kill(pid, "SIGTERM"); } catch { /* already exited */ }
}
}
}
@ -118,9 +125,13 @@ function executeBashInBackground(
const rewrittenCommand = rewriteCommandWithRtk(command);
const resolvedCommand = sanitizeCommand(rewrittenCommand);
// On Windows, detached: true sets CREATE_NEW_PROCESS_GROUP which can
// cause EINVAL in VSCode/ConPTY terminal contexts. The bg-shell
// extension already guards this (process-manager.ts); align here.
// Process-tree cleanup uses taskkill /F /T on Windows regardless.
const child = spawn(shell, [...args, resolvedCommand], {
cwd,
detached: true,
detached: process.platform !== "win32",
env: { ...process.env },
stdio: ["ignore", "pipe", "pipe"],
});
@ -143,8 +154,8 @@ function executeBashInBackground(
// If the process ignores SIGTERM, escalate to SIGKILL
sigkillHandle = setTimeout(() => {
if (child.pid) {
try { process.kill(-child.pid, "SIGKILL"); } catch { /* ignore */ }
try { process.kill(child.pid, "SIGKILL"); } catch { /* ignore */ }
// killTree already uses taskkill /F /T on Windows
killTree(child.pid);
}
// Hard deadline: if even SIGKILL doesn't trigger 'close',