fix: isolate Bun startup for external lanes

plugins/pstack/skills/poteto-mode/scripts/omp/parent.ts

@@ -60,11 +60,9 @@ export default function parent(pi: Extension): void {
       const output = join(directory, "output.txt");
       const receipt = join(directory, "receipt.json");
       writeFileSync(prompt, args.prompt, { mode: 0o600 });
-      const bun = Bun.which("bun");
-      if (!bun) throw new Error("pstack_task requires Bun on PATH");
       const runner = process.env.PSTACK_OMP_RUNNER;
       if (!runner) throw new Error("Start OMP through pstack-omp to dispatch workers");
-      const child = Bun.spawn([bun, runner,
+      const child = Bun.spawn([runner,
         "--parent", "omp", "--provider", "omp", "--model", choice.model,
         "--effort", choice.effort, "--mode", args.mode, "--cwd", args.cwd,
         "--prompt", prompt, "--output", output, "--receipt", receipt, "--label", args.role,

plugins/pstack/skills/poteto-mode/scripts/runner/entry.ts

@@ -0,0 +1,5 @@
+#!/usr/bin/env bun
+export {};
+const startedAt = Date.now();
+const { main } = await import("./cli.ts");
+process.exitCode = await main(process.argv.slice(2), startedAt);

plugins/pstack/skills/poteto-mode/scripts/runner/pstack-runner

@@ -1,4 +1,4 @@
-#!/usr/bin/env bun
-const startedAt = Date.now();
-const { main } = await import("./cli.ts");
-process.exitCode = await main(process.argv.slice(2), startedAt);
+#!/bin/sh
+unset BUN_OPTIONS NODE_OPTIONS
+case $0 in */*) dir=${0%/*} ;; *) dir=. ;; esac
+exec bun --no-env-file --config=/dev/null "$dir/entry.ts" "$@"

plugins/pstack/skills/poteto-mode/scripts/runner/run.test.ts

@@ -550,7 +550,7 @@ describe("runLane", () => {
     const transientMarker = join(scratch, "grok-cancel-unauth.pid");
     const preflightLog = join(scratch, "grok-cancel-unauth.log");
     const input = options("grok", "grok-preflight-retry-cancelled");
-    const runner = Bun.spawn([process.execPath, ...runnerArgs(input)], {
+    const runner = Bun.spawn(runnerArgs(input), {
       cwd: scratch,
       env: {
         ...process.env,
@@ -609,7 +609,7 @@ describe("runLane", () => {
   it("does not spawn the model when preflight exhausts the wrapper deadline", async () => {
     const modelStarted = join(scratch, "deadline-model.started");
     const input = { ...options("claude", "preflight-deadline"), timeoutMs: 300 };
-    const runner = Bun.spawn([process.execPath, ...runnerArgs(input)], {
+    const runner = Bun.spawn(runnerArgs(input), {
       cwd: scratch,
       env: {
         ...process.env,
@@ -634,7 +634,7 @@ describe("runLane", () => {
 
   it("lets a delayed wrapper lane finish when timeout is omitted", async () => {
     const input = options("claude", "unbounded-default");
-    const runner = Bun.spawn([process.execPath, ...runnerArgs(input)], {
+    const runner = Bun.spawn(runnerArgs(input), {
       cwd: scratch,
       env: { ...process.env, FAKE_MODEL_DELAY_MS: "400" },
       stdout: "pipe",
@@ -657,7 +657,7 @@ describe("runLane", () => {
       ...options("claude", "long-runtime-deadline"),
       timeoutMs: 2_147_483_648,
     };
-    const runner = Bun.spawn([process.execPath, ...runnerArgs(input)], {
+    const runner = Bun.spawn(runnerArgs(input), {
       cwd: scratch,
       env: { ...process.env, FAKE_MODEL_DELAY_MS: "100" },
       stdout: "pipe",
@@ -720,7 +720,7 @@ describe("runLane", () => {
   it("bounds a descendant-held pipe by the explicit deadline without fabricating a signal", async () => {
     const descendantPidPath = join(scratch, "deadline-descendant.pid");
     const input = { ...options("claude", "deadline-drain"), timeoutMs: 700 };
-    const runner = Bun.spawn([process.execPath, ...runnerArgs(input)], {
+    const runner = Bun.spawn(runnerArgs(input), {
       cwd: scratch,
       env: {
         ...process.env,
@@ -751,7 +751,7 @@ describe("runLane", () => {
   it("does not claim a signal was sent to an already signal-reaped child", async () => {
     const descendantPidPath = join(scratch, "signalled-descendant.pid");
     const input = { ...options("claude", "signalled-drain"), timeoutMs: 700 };
-    const runner = Bun.spawn([process.execPath, ...runnerArgs(input)], {
+    const runner = Bun.spawn(runnerArgs(input), {
       cwd: scratch,
       env: {
         ...process.env,
@@ -782,7 +782,7 @@ describe("runLane", () => {
     const descendantPidPath = join(scratch, "cancel-descendant.pid");
     const modelExiting = join(scratch, "cancel-model.exiting");
     const input = options("claude", "cancel-drain");
-    const runner = Bun.spawn([process.execPath, ...runnerArgs(input)], {
+    const runner = Bun.spawn(runnerArgs(input), {
       cwd: scratch,
       env: {
         ...process.env,
@@ -815,7 +815,7 @@ describe("runLane", () => {
 
   it("clears a losing long-deadline timer when the shipped wrapper succeeds", async () => {
     const input = { ...options("claude", "long-deadline"), timeoutMs: 60_000 };
-    const runner = Bun.spawn([process.execPath, ...runnerArgs(input)], {
+    const runner = Bun.spawn(runnerArgs(input), {
       cwd: scratch,
       env: { ...process.env },
       stdout: "pipe",
@@ -838,7 +838,6 @@ describe("runLane", () => {
     cpSync(join(import.meta.dir, "../omp"), join(scratch, "omp"), { recursive: true });
     cpSync(join(import.meta.dir, "../harnesses.ts"), join(scratch, "harnesses.ts"));
     const runner = Bun.spawn([
-      process.execPath,
       join(isolatedRunner, "pstack-runner"),
       ...runnerArgs(input).slice(1),
     ], {
@@ -872,7 +871,7 @@ describe("runLane", () => {
     const input = { ...options("codex", "repeated-cancel"), timeoutMs: 60_000 };
     const started = join(scratch, "repeated-child.started");
     const terminated = join(scratch, "repeated-child.terminated");
-    const runner = Bun.spawn([process.execPath, ...runnerArgs(input)], {
+    const runner = Bun.spawn(runnerArgs(input), {
       cwd: scratch,
       env: {
         ...process.env,
@@ -913,7 +912,7 @@ describe("runLane", () => {
       FAKE_STARTED_PATH: started,
       FAKE_TERMINATED_PATH: terminated,
     };
-    const runner = Bun.spawn([process.execPath, ...runnerArgs(input)], {
+    const runner = Bun.spawn(runnerArgs(input), {
       cwd: scratch,
       env,
       stdout: "pipe",
@@ -935,7 +934,7 @@ describe("runLane", () => {
       error: { message: "launcher received SIGTERM; signal was sent to child" },
     });
 
-    const samePaths = Bun.spawn([process.execPath, ...runnerArgs(input)], {
+    const samePaths = Bun.spawn(runnerArgs(input), {
       cwd: scratch,
       env: { ...process.env },
       stdout: "pipe",
@@ -984,7 +983,7 @@ describe("runLane", () => {
   it("terminalizes catchable failures after reserving output paths", async () => {
     const unreadable = options("claude", "unreadable-prompt");
     chmodSync(unreadable.promptPath, 0o000);
-    const unreadableRunner = Bun.spawn([process.execPath, ...runnerArgs(unreadable)], {
+    const unreadableRunner = Bun.spawn(runnerArgs(unreadable), {
       cwd: scratch,
       env: { ...process.env },
       stdout: "pipe",
@@ -1005,7 +1004,7 @@ describe("runLane", () => {
       error: { message: "launcher failed after reserving output paths" },
     });
 
-    const samePaths = Bun.spawn([process.execPath, ...runnerArgs(unreadable)], {
+    const samePaths = Bun.spawn(runnerArgs(unreadable), {
       cwd: scratch,
       env: { ...process.env },
       stdout: "pipe",
@@ -1019,7 +1018,7 @@ describe("runLane", () => {
 
     const spawnFailure = options("claude", "spawn-failure");
     const modelStarted = join(scratch, "spawn-failure-model.started");
-    const spawnRunner = Bun.spawn([process.execPath, ...runnerArgs(spawnFailure)], {
+    const spawnRunner = Bun.spawn(runnerArgs(spawnFailure), {
       cwd: scratch,
       env: {
         ...process.env,

plugins/pstack/skills/poteto-mode/scripts/runner/startup.test.ts

@@ -0,0 +1,65 @@
+import { afterEach, describe, expect, it } from "bun:test";
+import { chmodSync, existsSync, mkdtempSync, mkdirSync, readFileSync, rmSync, writeFileSync } from "node:fs";
+import { tmpdir } from "node:os";
+import { dirname, join } from "node:path";
+
+const directories: string[] = [];
+afterEach(() => {
+  for (const directory of directories.splice(0)) rmSync(directory, { recursive: true, force: true });
+});
+
+describe("runner startup isolation", () => {
+  for (const source of ["bun options", "node options", "dotenv", "bunfig", "combined"] as const) {
+    it(`ignores ${source} while preserving exported child variables`, () => {
+      const cwd = mkdtempSync(join(tmpdir(), "pstack startup "));
+      directories.push(cwd);
+      const bin = join(cwd, "bin");
+      mkdirSync(bin);
+      const marker = join(cwd, "preload-ran");
+      const preload = join(cwd, "preload.cjs");
+      writeFileSync(preload, `require("node:fs").writeFileSync(${JSON.stringify(marker)}, "executed");`);
+      const executable = join(bin, "codex");
+      writeFileSync(executable, `#!/bin/sh
+if [ "$1" = login ]; then
+  echo 'Logged in using ChatGPT'
+  exit 0
+fi
+env > "$PSTACK_TEST_ENV"
+echo '{"type":"item.completed","item":{"type":"agent_message","text":"STARTUP_OK"}}'
+echo '{"type":"turn.completed","usage":{"input_tokens":1,"output_tokens":1}}'
+`);
+      chmodSync(executable, 0o755);
+      if (source === "dotenv" || source === "combined") writeFileSync(join(cwd, ".env"), "PSTACK_DOTENV_SENTINEL=project-only\n");
+      if (source === "bunfig" || source === "combined") writeFileSync(join(cwd, "bunfig.toml"), `preload = [${JSON.stringify(preload)}]\n`);
+      const prompt = join(cwd, "prompt.md");
+      writeFileSync(prompt, "Return STARTUP_OK.");
+      const output = join(cwd, "output.txt");
+      const receipt = join(cwd, "receipt.json");
+      const dump = join(cwd, "child.env");
+      const env = {
+        ...process.env,
+        PATH: `${bin}:${dirname(process.execPath)}:/usr/bin:/bin`,
+        PSTACK_TEST_ENV: dump,
+        OPENAI_API_KEY: "synthetic-exported-key",
+        CODEX_THREAD_ID: "synthetic-parent-identity",
+        BUN_OPTIONS: source === "bun options" || source === "combined" ? `--preload=${JSON.stringify(preload)}` : "",
+        NODE_OPTIONS: source === "node options" || source === "combined" ? `--require=${JSON.stringify(preload)}` : "",
+      };
+      const result = Bun.spawnSync([
+        join(import.meta.dir, "pstack-runner"),
+        "--parent", "claude", "--provider", "codex", "--model", "gpt-5.6-sol", "--effort", "max",
+        "--mode", "read-only", "--cwd", cwd, "--prompt", prompt, "--output", output, "--receipt", receipt,
+      ], { cwd, env });
+      expect(result.exitCode).toBe(0);
+      expect(readFileSync(output, "utf8")).toContain("STARTUP_OK");
+      expect(JSON.parse(readFileSync(receipt, "utf8"))).toMatchObject({ status: "complete", parent: "claude", provider: "codex" });
+      expect(existsSync(marker)).toBe(false);
+      const childEnv = readFileSync(dump, "utf8");
+      expect(childEnv).not.toContain("PSTACK_DOTENV_SENTINEL=");
+      expect(childEnv).not.toContain("BUN_OPTIONS=");
+      expect(childEnv).not.toContain("NODE_OPTIONS=");
+      expect(childEnv).toContain("OPENAI_API_KEY=synthetic-exported-key\n");
+      expect(childEnv).toContain("CODEX_THREAD_ID=synthetic-parent-identity\n");
+    });
+  }
+});

tests/omp-live.py

@@ -100,7 +100,7 @@ def do_POST(self):
             if scenario == 'missing-model':
                 selected = 'pstack-test/missing'
             effort = 'max' if scenario == 'unsupported-effort' else 'off' if scenario == 'non-reasoning' else 'high'
-            argv = [bun, str(scripts / 'runner/pstack-runner'), '--parent', 'omp', '--provider', 'omp',
+            argv = [str(scripts / 'runner/pstack-runner'), '--parent', 'omp', '--provider', 'omp',
                     '--model', selected, '--effort', effort, '--mode',
                     'isolated-write' if scenario in ('outside-write', 'inside-write') else 'read-only',
                     '--cwd', str(work), '--prompt', str(root / 'prompt'), '--output', str(output), '--receipt', str(receipt)]