Fix Windows Pi shim spawning

.github/workflows/release.yml

@@ -267,6 +267,37 @@ jobs:
           # 3. annotate: exercises annotate server startup with a real file.
           Test-PlannotatorServer "plannotator annotate" "19501" "/api/plan" @("annotate", "README.md")
 
+  pi-extension-ai-runtime-windows:
+    needs: test
+    # Exercises the Pi extension's Node/jiti server mirror on Windows with an
+    # npm-style `pi` shim pair. The binary smoke above covers the compiled Bun
+    # CLI, but the published Pi extension uses this separate Node path.
+    name: Pi extension AI runtime (Windows)
+    runs-on: windows-latest
+    steps:
+      - uses: actions/checkout@de0fac2e4500dabe0009e67214ff5f5447ce83dd # v6.0.2
+
+      - uses: oven-sh/setup-bun@0c5077e51419868618aeaa5fe8019c62421857d6 # v2.2.0
+        with:
+          bun-version: 1.3.11
+
+      - uses: actions/setup-node@53b83947a5a98c8d113130e565377fae1a50d02f # v6.3.0
+        with:
+          node-version: 24
+
+      - name: Install dependencies
+        run: bun install
+
+      - name: Generate Pi extension shared copies
+        shell: bash
+        run: bash apps/pi-extension/vendor.sh
+
+      - name: Build Pi AI runtime smoke
+        run: bun build scripts/smoke-pi-extension-ai-runtime.ts --target=node --outfile "$env:RUNNER_TEMP/pi-ai-runtime-smoke.mjs"
+
+      - name: Run Pi AI runtime smoke
+        run: node "$env:RUNNER_TEMP/pi-ai-runtime-smoke.mjs"
+
   install-script-smoke:
     needs: build
     runs-on: ${{ matrix.os }}
@@ -423,6 +454,7 @@ jobs:
     needs:
       - build
       - smoke-binaries
+      - pi-extension-ai-runtime-windows
       - install-script-smoke
     if: startsWith(github.ref, 'refs/tags/')
     runs-on: ubuntu-latest
@@ -489,6 +521,7 @@ jobs:
     needs:
       - build
       - smoke-binaries
+      - pi-extension-ai-runtime-windows
       - install-script-smoke
     runs-on: ubuntu-latest
     permissions:

.github/workflows/test.yml

@@ -31,6 +31,37 @@ jobs:
       - name: Run tests
         run: bun test
 
+  pi-extension-ai-runtime-windows:
+    # Exercises the Pi extension's Node/jiti server mirror on Windows with an
+    # npm-style `pi` shim pair. This catches regressions where `where pi`
+    # resolves the extensionless shim before pi.cmd and the Ask AI provider
+    # crashes before the plan review UI opens.
+    name: Pi extension AI runtime (Windows)
+    runs-on: windows-latest
+    steps:
+      - uses: actions/checkout@de0fac2e4500dabe0009e67214ff5f5447ce83dd # v6.0.2
+
+      - uses: oven-sh/setup-bun@0c5077e51419868618aeaa5fe8019c62421857d6 # v2.2.0
+        with:
+          bun-version: latest
+
+      - uses: actions/setup-node@53b83947a5a98c8d113130e565377fae1a50d02f # v6.3.0
+        with:
+          node-version: 24
+
+      - name: Install dependencies
+        run: bun install
+
+      - name: Generate Pi extension shared copies
+        shell: bash
+        run: bash apps/pi-extension/vendor.sh
+
+      - name: Build Pi AI runtime smoke
+        run: bun build scripts/smoke-pi-extension-ai-runtime.ts --target=node --outfile "$env:RUNNER_TEMP/pi-ai-runtime-smoke.mjs"
+
+      - name: Run Pi AI runtime smoke
+        run: node "$env:RUNNER_TEMP/pi-ai-runtime-smoke.mjs"
+
   install-cmd-windows:
     # End-to-end integration test for scripts/install.cmd on real cmd.exe.
     # The unit tests in scripts/install.test.ts are file-content string checks

apps/pi-extension/server/ai-runtime.ts

@@ -2,6 +2,7 @@ import { execFileSync } from "node:child_process";
 import type { IncomingMessage, ServerResponse } from "node:http";
 import { Readable } from "node:stream";
 
+import { resolveCommandFromWhichOutput } from "../generated/ai/providers/command-path.js";
 import { json, toWebRequest } from "./helpers.js";
 
 export interface PiAIRuntime {
@@ -21,10 +22,7 @@ function whichCmd(cmd: string): string | null {
 			encoding: "utf-8",
 			stdio: ["pipe", "pipe", "pipe"],
 		});
-		return output
-			.split(/\r?\n/)
-			.map((line) => line.trim())
-			.find(Boolean) ?? null;
+		return resolveCommandFromWhichOutput(output);
 	} catch {
 		return null;
 	}

apps/pi-extension/vendor.sh

@@ -39,7 +39,7 @@ for f in index types provider session-manager endpoints context base-session; do
   printf '// @generated — DO NOT EDIT. Source: packages/ai/%s.ts\n' "$f" | cat - "$src" > "generated/ai/$f.ts"
 done
 
-for f in claude-agent-sdk codex-sdk opencode-sdk pi-sdk pi-sdk-node pi-events; do
+for f in claude-agent-sdk codex-sdk opencode-sdk command-path pi-sdk pi-sdk-node pi-events; do
   src="../../packages/ai/providers/$f.ts"
   printf '// @generated — DO NOT EDIT. Source: packages/ai/providers/%s.ts\n' "$f" | cat - "$src" > "generated/ai/providers/$f.ts"
 done

packages/ai/ai.test.ts

@@ -13,6 +13,13 @@ import type {
   AIMessage,
   AIContext,
 } from "./types.ts";
+import {
+  buildWindowsCommandScriptSpawnCommand,
+  killWindowsProcessTree,
+  resolveCommandFromWhichOutput,
+  resolveWindowsCommandShim,
+  shouldSpawnViaShell,
+} from "./providers/command-path.ts";
 
 // ---------------------------------------------------------------------------
 // Helpers — mock provider/session for testing
@@ -71,6 +78,110 @@ function mockProvider(name = "mock"): AIProvider {
   };
 }
 
+// ---------------------------------------------------------------------------
+// Command path helpers
+// ---------------------------------------------------------------------------
+
+describe("command path helpers", () => {
+  test("resolveWindowsCommandShim prefers a sibling .cmd for npm shims", () => {
+    const raw = String.raw`C:\Users\Andrew\AppData\Roaming\npm\pi`;
+    const resolved = resolveWindowsCommandShim(
+      raw,
+      "win32",
+      (path) => path === `${raw}.cmd`,
+    );
+
+    expect(resolved).toBe(`${raw}.cmd`);
+  });
+
+  test("resolveCommandFromWhichOutput skips extensionless Windows shims", () => {
+    const raw = String.raw`C:\Users\Andrew\AppData\Roaming\npm\pi`;
+    const resolved = resolveCommandFromWhichOutput(
+      `${raw}\r\n${raw}.cmd\r\n`,
+      "win32",
+      () => false,
+    );
+
+    expect(resolved).toBe(`${raw}.cmd`);
+  });
+
+  test("resolveCommandFromWhichOutput preserves the first non-Windows result", () => {
+    expect(
+      resolveCommandFromWhichOutput("/usr/local/bin/pi\n/usr/bin/pi\n", "darwin"),
+    ).toBe("/usr/local/bin/pi");
+  });
+
+  test("shouldSpawnViaShell only flags Windows command scripts", () => {
+    expect(
+      shouldSpawnViaShell(
+        String.raw`C:\Users\Andrew\AppData\Roaming\npm\pi.cmd`,
+        "win32",
+      ),
+    ).toBe(true);
+    expect(shouldSpawnViaShell(String.raw`C:\tools\pi.exe`, "win32")).toBe(false);
+    expect(shouldSpawnViaShell("/usr/local/bin/pi.cmd", "darwin")).toBe(false);
+  });
+
+  test("buildWindowsCommandScriptSpawnCommand wraps command scripts for Bun.spawn", () => {
+    const command = buildWindowsCommandScriptSpawnCommand(
+      String.raw`C:\Users\Andrew Ramos\AppData\Roaming\npm\pi.cmd`,
+      ["--mode", "rpc"],
+      "win32",
+      String.raw`C:\Windows\System32\cmd.exe`,
+    );
+
+    expect(command).toEqual([
+      String.raw`C:\Windows\System32\cmd.exe`,
+      "/d",
+      "/s",
+      "/c",
+      String.raw`"C:\Users\Andrew Ramos\AppData\Roaming\npm\pi.cmd" --mode rpc`,
+    ]);
+  });
+
+  test("buildWindowsCommandScriptSpawnCommand ignores native executables", () => {
+    expect(
+      buildWindowsCommandScriptSpawnCommand(
+        String.raw`C:\tools\pi.exe`,
+        ["--mode", "rpc"],
+        "win32",
+      ),
+    ).toBeNull();
+  });
+
+  test("killWindowsProcessTree invokes taskkill with tree flags on Windows", () => {
+    const calls: Array<{
+      command: string;
+      args: string[];
+      options: { stdio: "ignore"; windowsHide: boolean };
+    }> = [];
+    const killed = killWindowsProcessTree(1234, "win32", (command, args, options) => {
+      calls.push({ command, args, options });
+      return { status: 0 };
+    });
+
+    expect(killed).toBe(true);
+    expect(calls).toEqual([
+      {
+        command: "taskkill",
+        args: ["/pid", "1234", "/t", "/f"],
+        options: { stdio: "ignore", windowsHide: true },
+      },
+    ]);
+  });
+
+  test("killWindowsProcessTree skips non-Windows platforms", () => {
+    let called = false;
+    const killed = killWindowsProcessTree(1234, "darwin", () => {
+      called = true;
+      return { status: 0 };
+    });
+
+    expect(killed).toBe(false);
+    expect(called).toBe(false);
+  });
+});
+
 // ---------------------------------------------------------------------------
 // SessionManager
 // ---------------------------------------------------------------------------

packages/ai/package.json

@@ -12,6 +12,7 @@
     "./endpoints": "./endpoints.ts",
     "./providers/claude-agent-sdk": "./providers/claude-agent-sdk.ts",
     "./providers/codex-sdk": "./providers/codex-sdk.ts",
+    "./providers/command-path": "./providers/command-path.ts",
     "./providers/pi-sdk": "./providers/pi-sdk.ts",
     "./providers/opencode-sdk": "./providers/opencode-sdk.ts",
     "./providers/pi-sdk-node": "./providers/pi-sdk-node.ts"

packages/ai/providers/command-path.ts

@@ -0,0 +1,115 @@
+import { spawnSync } from "node:child_process";
+import { existsSync } from "node:fs";
+
+type Platform = NodeJS.Platform;
+type ExistsFn = (path: string) => boolean;
+type TaskkillFn = (
+	command: string,
+	args: string[],
+	options: { stdio: "ignore"; windowsHide: boolean },
+) => { status: number | null; error?: Error };
+
+const WINDOWS_EXECUTABLE_EXTENSIONS = [".cmd", ".exe", ".bat", ".com"] as const;
+const WINDOWS_SHELL_EXTENSIONS = new Set([".cmd", ".bat"]);
+
+function trimCommandPath(commandPath: string): string {
+	return commandPath.trim();
+}
+
+function getKnownWindowsExtension(commandPath: string): string | null {
+	const match = trimCommandPath(commandPath).match(/\.(cmd|exe|bat|com)$/i);
+	return match ? `.${match[1].toLowerCase()}` : null;
+}
+
+export function resolveWindowsCommandShim(
+	commandPath: string,
+	platform: Platform = process.platform,
+	exists: ExistsFn = existsSync,
+): string {
+	const candidate = trimCommandPath(commandPath);
+	if (!candidate || platform !== "win32" || getKnownWindowsExtension(candidate)) {
+		return candidate;
+	}
+
+	for (const ext of WINDOWS_EXECUTABLE_EXTENSIONS) {
+		const pathWithExtension = `${candidate}${ext}`;
+		if (exists(pathWithExtension)) return pathWithExtension;
+	}
+
+	return candidate;
+}
+
+export function resolveCommandFromWhichOutput(
+	output: string,
+	platform: Platform = process.platform,
+	exists: ExistsFn = existsSync,
+): string | null {
+	const candidates = output
+		.split(/\r?\n/)
+		.map(trimCommandPath)
+		.filter(Boolean);
+
+	if (candidates.length === 0) return null;
+	if (platform !== "win32") return candidates[0] ?? null;
+
+	for (const candidate of candidates) {
+		const resolved = resolveWindowsCommandShim(candidate, platform, exists);
+		if (getKnownWindowsExtension(resolved)) return resolved;
+	}
+
+	return resolveWindowsCommandShim(candidates[0] ?? "", platform, exists) || null;
+}
+
+export function shouldSpawnViaShell(
+	commandPath: string,
+	platform: Platform = process.platform,
+): boolean {
+	if (platform !== "win32") return false;
+	const ext = getKnownWindowsExtension(commandPath);
+	return ext ? WINDOWS_SHELL_EXTENSIONS.has(ext) : false;
+}
+
+function quoteWindowsShellArg(arg: string): string {
+	if (!arg || /[\s"&()^|<>]/.test(arg)) {
+		return `"${arg.replace(/"/g, '\\"')}"`;
+	}
+	return arg;
+}
+
+export function buildWindowsCommandScriptSpawnCommand(
+	commandPath: string,
+	args: string[],
+	platform: Platform = process.platform,
+	comspec: string | undefined = process.env.ComSpec,
+): string[] | null {
+	if (!shouldSpawnViaShell(commandPath, platform)) return null;
+
+	return [
+		comspec || "cmd.exe",
+		"/d",
+		"/s",
+		"/c",
+		[commandPath, ...args].map(quoteWindowsShellArg).join(" "),
+	];
+}
+
+export function killWindowsProcessTree(
+	pid: number | null | undefined,
+	platform: Platform = process.platform,
+	runTaskkill: TaskkillFn = spawnSync as TaskkillFn,
+): boolean {
+	if (
+		platform !== "win32" ||
+		typeof pid !== "number" ||
+		!Number.isFinite(pid) ||
+		pid <= 0
+	) {
+		return false;
+	}
+
+	const result = runTaskkill("taskkill", ["/pid", String(pid), "/t", "/f"], {
+		stdio: "ignore",
+		windowsHide: true,
+	});
+	return !result.error && result.status === 0;
+}