Fix worktree setup scripts losing PATH (#1908)

* fix(worktree): preserve PATH for lifecycle scripts

Lifecycle command strings were running through login shells, which could rewrite PATH before setup commands saw the daemon environment. Use the shared stable script-shell helper without login startup files, and route related project-authored command strings through it.

* fix(worktree): ignore Bash startup env hook

Project command strings should not source shell startup hooks before they see Paseo's supplied environment. Strip BASH_ENV from lifecycle, loop verify, and ACP string-command shells and pin the behavior in setup tests.

* fix(worktree): resolve Bash through PATH

* fix(worktree): preserve Windows cmd command strings

* test(acp): expect Windows cmd terminal strings

docs/development.md

@@ -178,6 +178,15 @@ defaults. The default rotation is `10m` x `3` files everywhere.
 `worktree.setup` and `worktree.teardown` accept either a multiline shell script or an array
 of commands. Both run sequentially.
 
+Lifecycle commands run in the worktree through a stable script shell: `bash`
+resolved from `PATH` on macOS/Linux, and PowerShell with `-NoProfile` on
+Windows. They inherit the daemon environment plus Paseo's lifecycle variables;
+login and interactive shell startup files are not loaded, and Bash's `BASH_ENV`
+hook is unset. Daemon-run loop verify checks and ACP single-string terminal
+commands use the same non-login Bash behavior on macOS/Linux, but preserve their
+existing `cmd.exe /c` string semantics on Windows. Service scripts are separate:
+they launch in a terminal and receive the service environment described below.
+
 ```json
 {
   "worktree": {

packages/server/src/server/agent/providers/acp-agent.test.ts

@@ -46,6 +46,7 @@ import { transformPiModels } from "./pi/agent.js";
 import type { AgentStreamEvent } from "../agent-sdk-types.js";
 import type { AgentCapabilityFlags, AgentPersistenceHandle } from "../agent-sdk-types.js";
 import { createTestLogger } from "../../../test-utils/test-logger.js";
+import { buildStringCommandShellInvocation } from "../../../utils/string-command-shell.js";
 import { asInternals } from "../../test-utils/class-mocks.js";
 import * as spawnUtils from "../../../utils/spawn.js";
 
@@ -540,7 +541,10 @@ describe("ACPAgentSession terminal tools", () => {
     const child = createTerminalChildStub();
     const spawn = vi.spyOn(spawnUtils, "spawnProcess").mockReturnValue(child);
     const session = createSession();
-    const shell = spawnUtils.platformShell();
+    const shell = buildStringCommandShellInvocation({
+      command: "git -C /repo status --short",
+      windowsShell: "cmd",
+    });
 
     await session.createTerminal({
       sessionId: "session-1",
@@ -549,12 +553,50 @@ describe("ACPAgentSession terminal tools", () => {
     });
 
     expect(spawn).toHaveBeenCalledWith(
-      shell.command,
-      [...shell.flag, "git -C /repo status --short"],
-      expect.objectContaining({ cwd: "/repo" }),
+      shell.shell,
+      shell.args,
+      expect.objectContaining({
+        cwd: "/repo",
+        envOverlay: expect.objectContaining({ BASH_ENV: undefined }),
+        shell: false,
+      }),
     );
   });
 
+  test("preserves cmd semantics for single-string terminal commands on Windows", async () => {
+    const originalPlatform = process.platform;
+    Object.defineProperty(process, "platform", {
+      value: "win32",
+      configurable: true,
+    });
+    try {
+      const child = createTerminalChildStub();
+      const spawn = vi.spyOn(spawnUtils, "spawnProcess").mockReturnValue(child);
+      const session = createSession();
+
+      await session.createTerminal({
+        sessionId: "session-1",
+        command: "echo %TEMP% && echo ok",
+        cwd: "C:\\repo",
+      });
+
+      expect(spawn).toHaveBeenCalledWith(
+        "cmd.exe",
+        ["/c", "echo %TEMP% && echo ok"],
+        expect.objectContaining({
+          cwd: "C:\\repo",
+          envOverlay: expect.objectContaining({ BASH_ENV: undefined }),
+          shell: false,
+        }),
+      );
+    } finally {
+      Object.defineProperty(process, "platform", {
+        value: originalPlatform,
+        configurable: true,
+      });
+    }
+  });
+
   test("preserves explicit terminal argv", async () => {
     const child = createTerminalChildStub();
     const spawn = vi.spyOn(spawnUtils, "spawnProcess").mockReturnValue(child);

packages/server/src/server/agent/providers/acp-agent.ts

@@ -102,7 +102,11 @@ import {
 } from "../provider-launch-config.js";
 import { renderPromptAttachmentAsText } from "../prompt-attachments.js";
 import { appendOrReplaceGrowingAssistantMessage, runProviderTurn } from "./provider-runner.js";
-import { platformShell, spawnProcess } from "../../../utils/spawn.js";
+import {
+  buildStringCommandShellInvocation,
+  createStringCommandShellEnvOverlay,
+} from "../../../utils/string-command-shell.js";
+import { spawnProcess } from "../../../utils/spawn.js";
 import {
   type DiagnosticEntry,
   toDiagnosticErrorMessage,
@@ -181,7 +185,7 @@ function toACPRequestError(error: unknown): Error {
 function resolveTerminalCommand(
   command: string,
   args?: string[],
-): { command: string; args: string[] } {
+): { command: string; args: string[]; shell?: boolean } {
   if (args && args.length > 0) {
     return { command, args };
   }
@@ -190,8 +194,8 @@ function resolveTerminalCommand(
     return { command, args: [] };
   }
 
-  const shell = platformShell();
-  return { command: shell.command, args: [...shell.flag, command] };
+  const shell = buildStringCommandShellInvocation({ command, windowsShell: "cmd" });
+  return { command: shell.shell, args: shell.args, shell: false };
 }
 
 function formatDurationMs(startedAt: number): string {
@@ -2159,12 +2163,15 @@ export class ACPAgentSession implements AgentSession, ACPClient {
       (params.env ?? []).map((entry: EnvVariable) => [entry.name, entry.value]),
     );
     const terminalCommand = resolveTerminalCommand(params.command, params.args);
+    const commandEnvOverlays =
+      terminalCommand.shell === false ? [env, createStringCommandShellEnvOverlay()] : [env];
     const child = spawnProcess(terminalCommand.command, terminalCommand.args, {
       cwd: params.cwd ?? this.config.cwd,
       ...createProviderEnvSpec({
         runtimeSettings: this.runtimeSettings,
-        overlays: [env],
+        overlays: commandEnvOverlays,
       }),
+      shell: terminalCommand.shell,
       stdio: ["ignore", "pipe", "pipe"],
     });
 

packages/server/src/server/loop-service.ts

@@ -14,7 +14,11 @@ import type {
   AgentTimelineItem,
   AgentProvider,
 } from "./agent/agent-sdk-types.js";
-import { execCommand, platformShell } from "../utils/spawn.js";
+import {
+  buildStringCommandShellInvocation,
+  createStringCommandShellEnvOverlay,
+} from "../utils/string-command-shell.js";
+import { execCommand } from "../utils/spawn.js";
 import type {
   ProviderSnapshotManager,
   ResolvedProviderCreateConfig,
@@ -266,10 +270,15 @@ async function runVerifyCheck(options: {
 }): Promise<LoopVerifyCheckResult> {
   const startedAt = nowIso();
   try {
-    const shell = platformShell();
-    const result = await execCommand(shell.command, [...shell.flag, options.command], {
+    const shell = buildStringCommandShellInvocation({
+      command: options.command,
+      windowsShell: "cmd",
+    });
+    const result = await execCommand(shell.shell, shell.args, {
       cwd: options.cwd,
+      envOverlay: createStringCommandShellEnvOverlay(),
       maxBuffer: MAX_VERIFY_OUTPUT_BYTES,
+      shell: false,
     });
     return {
       command: options.command,

packages/server/src/utils/spawn.ts

@@ -113,19 +113,3 @@ export async function execCommand(
     windowsHide: true,
   }) as Promise<ExecCommandResult>;
 }
-
-export function platformShell(): { command: string; flag: string[] } {
-  if (process.platform === "win32") {
-    return { command: "cmd.exe", flag: ["/c"] };
-  }
-
-  return { command: "/bin/sh", flag: ["-lc"] };
-}
-
-export function platformBash(): { command: string; flag: string[] } {
-  if (process.platform === "win32") {
-    return { command: "cmd.exe", flag: ["/c"] };
-  }
-
-  return { command: "/bin/bash", flag: ["-lc"] };
-}

packages/server/src/utils/string-command-shell.test.ts

@@ -1,21 +1,76 @@
-import { describe, expect, it } from "vitest";
+import { execFileSync, spawnSync } from "node:child_process";
+import { chmodSync, mkdirSync, mkdtempSync, rmSync, writeFileSync } from "node:fs";
+import { tmpdir } from "node:os";
+import { delimiter, join } from "node:path";
+import { afterEach, describe, expect, it } from "vitest";
 
-import { buildStringCommandShellInvocation } from "./string-command-shell.js";
+import {
+  buildStringCommandShellInvocation,
+  createStringCommandShellEnv,
+} from "./string-command-shell.js";
+
+function hasBashOnPath(): boolean {
+  const result = spawnSync("bash", ["-c", "true"], { stdio: "ignore" });
+  return !result.error && result.status === 0;
+}
 
 describe("buildStringCommandShellInvocation", () => {
-  it("uses bash login-command semantics on unix platforms", () => {
+  const tempDirs: string[] = [];
+
+  afterEach(() => {
+    for (const tempDir of tempDirs) {
+      rmSync(tempDir, { recursive: true, force: true });
+    }
+    tempDirs.length = 0;
+  });
+
+  it("uses bash script semantics on unix platforms", () => {
     expect(
       buildStringCommandShellInvocation({
         command: 'echo "hello"',
         platform: "darwin",
       }),
     ).toEqual({
-      shell: "/bin/bash",
-      args: ["-lc", 'echo "hello"'],
+      shell: "bash",
+      args: ["-c", 'echo "hello"'],
     });
   });
 
-  it("uses powershell command semantics on windows", () => {
+  it.skipIf(process.platform === "win32" || !hasBashOnPath())(
+    "preserves the supplied PATH when login profiles rewrite it",
+    () => {
+      const home = mkdtempSync(join(tmpdir(), "paseo-shell-home-"));
+      tempDirs.push(home);
+      const binDir = join(home, "bin");
+      mkdirSync(binDir);
+
+      const shimPath = join(binDir, "paseo-shim");
+      writeFileSync(shimPath, "#!/bin/sh\nprintf 'shim:%s\\n' \"$1\"\n");
+      chmodSync(shimPath, 0o755);
+      writeFileSync(join(home, ".bash_profile"), "export PATH=/usr/bin:/bin\n");
+      const bashEnvPath = join(home, "bash-env");
+      writeFileSync(bashEnvPath, "export PATH=/usr/bin:/bin\n");
+
+      const invocation = buildStringCommandShellInvocation({
+        command: "command -v paseo-shim >/dev/null && paseo-shim ok",
+      });
+      const env: NodeJS.ProcessEnv = {
+        ...process.env,
+        HOME: home,
+        PATH: `${binDir}${delimiter}${process.env.PATH ?? "/usr/bin:/bin"}`,
+        BASH_ENV: bashEnvPath,
+      };
+
+      const stdout = execFileSync(invocation.shell, invocation.args, {
+        encoding: "utf8",
+        env: createStringCommandShellEnv(env),
+      });
+
+      expect(stdout.trim()).toBe("shim:ok");
+    },
+  );
+
+  it("uses powershell command semantics on windows by default", () => {
     expect(
       buildStringCommandShellInvocation({
         command: "Write-Output 'hello'",
@@ -33,4 +88,17 @@ describe("buildStringCommandShellInvocation", () => {
       ],
     });
   });
+
+  it("can preserve cmd command semantics on windows", () => {
+    expect(
+      buildStringCommandShellInvocation({
+        command: "echo %TEMP% && echo ok",
+        platform: "win32",
+        windowsShell: "cmd",
+      }),
+    ).toEqual({
+      shell: "cmd.exe",
+      args: ["/c", "echo %TEMP% && echo ok"],
+    });
+  });
 });

packages/server/src/utils/string-command-shell.ts

@@ -1,6 +1,7 @@
 export interface BuildStringCommandShellInvocationOptions {
   command: string;
   platform?: NodeJS.Platform;
+  windowsShell?: "powershell" | "cmd";
 }
 
 export interface StringCommandShellInvocation {
@@ -8,12 +9,31 @@ export interface StringCommandShellInvocation {
   args: string[];
 }
 
+export function createStringCommandShellEnv(env: NodeJS.ProcessEnv): NodeJS.ProcessEnv {
+  const sanitized = { ...env };
+  delete sanitized.BASH_ENV;
+  return sanitized;
+}
+
+export function createStringCommandShellEnvOverlay(): Record<string, string | undefined> {
+  return { BASH_ENV: undefined };
+}
+
 export function buildStringCommandShellInvocation(
   options: BuildStringCommandShellInvocationOptions,
 ): StringCommandShellInvocation {
   const platform = options.platform ?? process.platform;
 
+  // Project-authored command strings use a stable script shell. The caller supplies
+  // the environment; shell startup files should not rewrite it behind our back.
   if (platform === "win32") {
+    if (options.windowsShell === "cmd") {
+      return {
+        shell: "cmd.exe",
+        args: ["/c", options.command],
+      };
+    }
+
     return {
       shell: "powershell",
       args: [
@@ -28,7 +48,7 @@ export function buildStringCommandShellInvocation(
   }
 
   return {
-    shell: "/bin/bash",
-    args: ["-lc", options.command],
+    shell: "bash",
+    args: ["-c", options.command],
   };
 }

packages/server/src/utils/worktree-shell-selection.test.ts

@@ -1,9 +1,12 @@
+import { type ChildProcess } from "node:child_process";
+import { EventEmitter } from "node:events";
 import { mkdirSync, mkdtempSync, rmSync, writeFileSync } from "node:fs";
 import { tmpdir } from "node:os";
 import { join } from "node:path";
 import { afterEach, beforeEach, describe, expect, it, vi } from "vitest";
 
 const execFileMock = vi.hoisted(() => vi.fn());
+const spawnProcessMock = vi.hoisted(() => vi.fn());
 
 vi.mock("child_process", async () => {
   const actual = await vi.importActual<typeof import("child_process")>("child_process");
@@ -13,11 +16,34 @@ vi.mock("child_process", async () => {
   };
 });
 
+vi.mock("./spawn.js", async () => {
+  const actual = await vi.importActual<typeof import("./spawn.js")>("./spawn.js");
+  return {
+    ...actual,
+    spawnProcess: spawnProcessMock,
+  };
+});
+
+function emitSuccessfulClose(child: ChildProcess): void {
+  child.emit("close", 0);
+}
+
+function createSpawnChildStub(): ChildProcess {
+  const child = new EventEmitter() as ChildProcess;
+  Object.assign(child, {
+    stdout: new EventEmitter(),
+    stderr: new EventEmitter(),
+  });
+  queueMicrotask(() => emitSuccessfulClose(child));
+  return child;
+}
+
 describe("worktree shell selection", () => {
   const originalPlatform = process.platform;
 
   beforeEach(() => {
     execFileMock.mockReset();
+    spawnProcessMock.mockReset();
     execFileMock.mockImplementation(
       (
         _file: string,
@@ -29,6 +55,7 @@ describe("worktree shell selection", () => {
         return {};
       },
     );
+    spawnProcessMock.mockImplementation(createSpawnChildStub);
   });
 
   afterEach(() => {
@@ -46,6 +73,8 @@ describe("worktree shell selection", () => {
     });
 
     const worktreePath = mkdtempSync(join(tmpdir(), "worktree-shell-selection-"));
+    const originalBashEnv = process.env.BASH_ENV;
+    process.env.BASH_ENV = "should-not-leak";
     try {
       mkdirSync(join(worktreePath, ".git"), { recursive: true });
       writeFileSync(
@@ -79,7 +108,74 @@ describe("worktree shell selection", () => {
         expect.objectContaining({ cwd: worktreePath }),
         expect.any(Function),
       );
+      const execOptions = execFileMock.mock.calls[0]?.[2] as { env?: NodeJS.ProcessEnv };
+      expect(execOptions.env?.BASH_ENV).toBeUndefined();
     } finally {
+      if (originalBashEnv === undefined) {
+        delete process.env.BASH_ENV;
+      } else {
+        process.env.BASH_ENV = originalBashEnv;
+      }
+      rmSync(worktreePath, { recursive: true, force: true });
+    }
+  });
+
+  it("routes streamed setup command execution through powershell on win32", async () => {
+    Object.defineProperty(process, "platform", {
+      value: "win32",
+      configurable: true,
+    });
+
+    const worktreePath = mkdtempSync(join(tmpdir(), "worktree-shell-selection-"));
+    const originalBashEnv = process.env.BASH_ENV;
+    process.env.BASH_ENV = "should-not-leak";
+    try {
+      writeFileSync(
+        join(worktreePath, "paseo.json"),
+        JSON.stringify({
+          worktree: {
+            setup: ["Write-Output 'setup'"],
+          },
+        }),
+        "utf8",
+      );
+
+      const { runWorktreeSetupCommands } = await import("./worktree.js");
+      await runWorktreeSetupCommands({
+        worktreePath,
+        branchName: "main",
+        cleanupOnFailure: false,
+        runtimeEnv: {
+          PASEO_SOURCE_CHECKOUT_PATH: worktreePath,
+          PASEO_ROOT_PATH: worktreePath,
+          PASEO_WORKTREE_PATH: worktreePath,
+          PASEO_BRANCH_NAME: "main",
+          PASEO_WORKTREE_PORT: "12345",
+        },
+        onEvent: () => {},
+      });
+
+      expect(spawnProcessMock).toHaveBeenCalledTimes(1);
+      expect(spawnProcessMock).toHaveBeenCalledWith(
+        "powershell",
+        [
+          "-NoProfile",
+          "-NonInteractive",
+          "-ExecutionPolicy",
+          "Bypass",
+          "-Command",
+          "Write-Output 'setup'",
+        ],
+        expect.objectContaining({ cwd: worktreePath, shell: false }),
+      );
+      const spawnOptions = spawnProcessMock.mock.calls[0]?.[2] as { env?: NodeJS.ProcessEnv };
+      expect(spawnOptions.env?.BASH_ENV).toBeUndefined();
+    } finally {
+      if (originalBashEnv === undefined) {
+        delete process.env.BASH_ENV;
+      } else {
+        process.env.BASH_ENV = originalBashEnv;
+      }
       rmSync(worktreePath, { recursive: true, force: true });
     }
   });

packages/server/src/utils/worktree.posix.test.ts

@@ -33,8 +33,9 @@ import {
   realpathSync,
   writeFileSync,
   readFileSync,
+  chmodSync,
 } from "fs";
-import { dirname, join } from "path";
+import { delimiter, dirname, join } from "path";
 import { tmpdir } from "os";
 import net from "node:net";
 
@@ -637,6 +638,68 @@ describe.skipIf(isPlatform("win32"))("worktree POSIX-only", () => {
       );
     });
 
+    it("runs setup commands with the daemon PATH instead of login profile PATH", async () => {
+      const home = join(tempDir, "host-home");
+      const binDir = join(tempDir, "daemon-bin");
+      mkdirSync(home);
+      mkdirSync(binDir);
+
+      const shimPath = join(binDir, "paseo-shim");
+      writeFileSync(shimPath, "#!/bin/sh\nprintf 'shim:%s\\n' \"$1\"\n");
+      chmodSync(shimPath, 0o755);
+      writeFileSync(join(home, ".bash_profile"), "export PATH=/usr/bin:/bin\n");
+      const bashEnvPath = join(home, "bash-env");
+      writeFileSync(bashEnvPath, "export PATH=/usr/bin:/bin\n");
+      writeFileSync(
+        join(repoDir, "paseo.json"),
+        JSON.stringify({
+          worktree: {
+            setup: "command -v paseo-shim >/dev/null && paseo-shim ok > setup-path.log",
+          },
+        }),
+      );
+
+      const originalHome = process.env.HOME;
+      const originalPath = process.env.PATH;
+      const originalBashEnv = process.env.BASH_ENV;
+      process.env.HOME = home;
+      process.env.PATH = `${binDir}${delimiter}${originalPath ?? "/usr/bin:/bin"}`;
+      process.env.BASH_ENV = bashEnvPath;
+
+      try {
+        await runWorktreeSetupCommands({
+          worktreePath: repoDir,
+          branchName: "main",
+          cleanupOnFailure: false,
+          runtimeEnv: {
+            PASEO_SOURCE_CHECKOUT_PATH: repoDir,
+            PASEO_ROOT_PATH: repoDir,
+            PASEO_WORKTREE_PATH: repoDir,
+            PASEO_BRANCH_NAME: "main",
+            PASEO_WORKTREE_PORT: "12345",
+          },
+        });
+      } finally {
+        if (originalHome === undefined) {
+          delete process.env.HOME;
+        } else {
+          process.env.HOME = originalHome;
+        }
+        if (originalPath === undefined) {
+          delete process.env.PATH;
+        } else {
+          process.env.PATH = originalPath;
+        }
+        if (originalBashEnv === undefined) {
+          delete process.env.BASH_ENV;
+        } else {
+          process.env.BASH_ENV = originalBashEnv;
+        }
+      }
+
+      expect(readFileSync(join(repoDir, "setup-path.log"), "utf8").trim()).toBe("shim:ok");
+    });
+
     it("treats blank lifecycle strings as empty", () => {
       writeFileSync(
         join(repoDir, "paseo.json"),

packages/server/src/utils/worktree.ts

@@ -6,7 +6,10 @@ import { join, basename, dirname, isAbsolute, resolve, sep } from "path";
 import net from "node:net";
 import { createHash } from "node:crypto";
 import stripAnsi from "strip-ansi";
-import { buildStringCommandShellInvocation } from "./string-command-shell.js";
+import {
+  buildStringCommandShellInvocation,
+  createStringCommandShellEnv,
+} from "./string-command-shell.js";
 import { readPaseoConfigJson, resolvePaseoConfigPath } from "./paseo-config-file.js";
 export {
   PaseoConfigRawSchema,
@@ -489,6 +492,7 @@ async function execSetupCommandStreamed(options: {
     const child = spawnProcess(shellInvocation.shell, shellInvocation.args, {
       cwd: options.cwd,
       env: options.env,
+      shell: false,
       stdio: ["ignore", "pipe", "pipe"],
     });
 
@@ -607,7 +611,7 @@ export async function runWorktreeSetupCommands(options: {
       branchName: options.branchName,
       ...(options.repoRootPath ? { repoRootPath: options.repoRootPath } : {}),
     }));
-  const setupEnv = createExternalProcessEnv(process.env, runtimeEnv);
+  const setupEnv = createStringCommandShellEnv(createExternalProcessEnv(process.env, runtimeEnv));
 
   const results: WorktreeSetupCommandResult[] = [];
   for (const [index, cmd] of setupCommands.entries()) {
@@ -715,17 +719,19 @@ export async function runWorktreeTeardownCommands(options: {
     options.branchName ?? (await resolveBranchNameForWorktreePath(options.worktreePath));
   const worktreePort = readPaseoWorktreeRuntimePort(options.worktreePath);
 
-  const teardownEnv: NodeJS.ProcessEnv = createExternalProcessEnv(process.env, {
-    // Source checkout path is the original git repo root (shared across worktrees), not the
-    // worktree itself. This allows lifecycle scripts to copy or clean resources using paths
-    // from the source checkout.
-    PASEO_SOURCE_CHECKOUT_PATH: repoRootPath,
-    // Backward-compatible alias.
-    PASEO_ROOT_PATH: repoRootPath,
-    PASEO_WORKTREE_PATH: options.worktreePath,
-    PASEO_BRANCH_NAME: branchName,
-    ...(worktreePort !== null ? { PASEO_WORKTREE_PORT: String(worktreePort) } : {}),
-  });
+  const teardownEnv: NodeJS.ProcessEnv = createStringCommandShellEnv(
+    createExternalProcessEnv(process.env, {
+      // Source checkout path is the original git repo root (shared across worktrees), not the
+      // worktree itself. This allows lifecycle scripts to copy or clean resources using paths
+      // from the source checkout.
+      PASEO_SOURCE_CHECKOUT_PATH: repoRootPath,
+      // Backward-compatible alias.
+      PASEO_ROOT_PATH: repoRootPath,
+      PASEO_WORKTREE_PATH: options.worktreePath,
+      PASEO_BRANCH_NAME: branchName,
+      ...(worktreePort !== null ? { PASEO_WORKTREE_PORT: String(worktreePort) } : {}),
+    }),
+  );
 
   const results: WorktreeTeardownCommandResult[] = [];
   for (const cmd of teardownCommands) {