Fix/js exec worker resolution

[engelberger]

Fix js-exec failing on both Bun and Node.js

Fixes #159

Problem

js-exec commands hang for exactly maxJsTimeoutMs (default 10s) and exit with code 124 on every invocation, regardless of input complexity. Even js-exec -c "console.log(42)" fails.

Affected runtimes: Bun (all versions), Node.js LTS (intermittently, due to bug #1)

Root Cause

Two independent bugs compound to break js-exec:

Bug 1: Worker URL resolves to the wrong file after esbuild bundling

js-exec.ts references the worker via:

const workerPath = fileURLToPath(new URL("./worker.js", import.meta.url));

After esbuild bundles js-exec.ts into dist/bin/chunks/js-exec-XXXX.js, the relative ./worker.js resolves to dist/bin/chunks/worker.js at runtime -- which is the Python worker (copied there by build:worker). The js-exec worker exists as dist/bin/chunks/js-exec-worker.js but is never loaded.

The Python worker expects workerData (passed at new Worker(path, { workerData }) constructor time). The js-exec protocol sends input via postMessage(). Since workerData is undefined, the Python worker does nothing and hangs until the timeout fires.

Diagram of the name collision:

build:worker script copies:
  python3/worker.js  --> dist/bin/chunks/worker.js          <-- Python protocol
  js-exec/worker.js  --> dist/bin/chunks/js-exec-worker.js  <-- js-exec protocol

js-exec.ts references:
  new URL("./worker.js", import.meta.url)
  --> resolves to: dist/bin/chunks/worker.js (Python!)

Bug 2: Static import of stripTypeScriptTypes crashes Bun workers

worker.ts line 12:

import { stripTypeScriptTypes } from "node:module";

stripTypeScriptTypes is a Node.js 23.2+ experimental API. Bun's node:module does not export this symbol. Since this is a static ESM named import, it causes a link-time error that crashes the worker thread before any code runs:

SyntaxError: Export named 'stripTypeScriptTypes' not found in module 'node:module'.

Fix

Change 1: Rename worker output to avoid name collision (js-exec.ts + package.json)

- const workerPath = fileURLToPath(new URL("./worker.js", import.meta.url));
+ const workerPath = fileURLToPath(new URL("./js-exec-worker.js", import.meta.url));

The build:worker script already produces js-exec-worker.js in the chunks directories. This change makes the source reference match.

The build script is also updated to output esbuild to js-exec-worker.js directly (instead of worker.js with a rename), keeping the source and build output consistent.

Change 2: Dynamic require with fallback (worker.ts)

- import { stripTypeScriptTypes } from "node:module";
+ let stripTypeScriptTypes: (code: string) => string;
+ try {
+   const nodeModule = require("node:module");
+   stripTypeScriptTypes = nodeModule.stripTypeScriptTypes ?? ((code: string) => code);
+ } catch {
+   stripTypeScriptTypes = (code: string) => code;
+ }

Uses require() instead of await import() because Bun Worker threads load bundled .js files in a script context where top-level await is not supported (produces "await is only valid in async functions").

When stripTypeScriptTypes is unavailable (Bun, older Node.js), the fallback returns the source code unmodified. TypeScript type stripping (.ts/.mts files, --strip-types flag) becomes unavailable, but plain JavaScript execution works normally -- which is the common case.

Verification

All tests run against the built dist/ output (not source), matching what npm consumers receive.

Node.js v25.4.0

Test	Result
js-exec -c "console.log(42)"	exit=0, stdout="42"
require("fs").readFileSync	exit=0, stdout="{\"k\":1}"
[1,2,3].reduce((a,b)=>a+b)	exit=0, stdout="6"
.ts file auto-detection	exit=0, stdout="42" (stripTypeScriptTypes works)

Bun 1.3.11

Test	Result
js-exec -c "console.log(42)"	exit=0, stdout="42"
require("fs").readFileSync	exit=0, stdout="{\"k\":1}"
[1,2,3].reduce((a,b)=>a+b)	exit=0, stdout="6"
fs.writeFileSync cross-call persistence	exit=0, stdout="hi"

Before this fix: 0% success rate (exit=124 timeout on every call).
After this fix: 100% success rate on both runtimes.

Files Changed

File	Lines	Description
src/commands/js-exec/js-exec.ts	+1/-1	Worker URL: ./worker.js -> ./js-exec-worker.js
src/commands/js-exec/worker.ts	+10/-1	Static import -> require() with try/catch fallback
package.json	+1/-1	build:worker: esbuild output to js-exec-worker.js
.gitignore	+1	Add generated js-exec-worker.js

Notes

• The fix is backward compatible: on Node.js 23.2+, stripTypeScriptTypes is loaded normally via the dynamic import path
• No new dependencies added
• The Python worker (worker.js) path and behavior are unchanged
• On Bun, .ts/.mts execution will show the raw TypeScript source (type annotations are not stripped). This could be documented or addressed separately with a Bun-native TS strip implementation
• Uses require() instead of await import() because Bun Worker threads load bundled .js files in a script context where top-level await is not supported

[vercel]

@engelberger is attempting to deploy a commit to the Vercel Labs Team on Vercel.

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[vercel]

Additional Suggestions:

1. The js-exec worker output path was renamed to js-exec-worker.js in the build script but three other files still reference the old path worker.js, causing pnpm check:worker-sync (part of pnpm validate) to fail.

2. biome.json excludes the old worker path src/commands/js-exec/worker.js instead of the actual build output src/commands/js-exec/js-exec-worker.js, so the generated bundle will be linted and cause lint errors.