Sandbox route: forEach(async) fire-and-forget can run code before multi-file writes finish

[chirag127]

Problem

Multi-file fragments can execute before all files are written to the sandbox — a race condition in app/api/sandbox/route.ts.

Location

app/api/sandbox/route.ts:52-56:

if (fragment.code && Array.isArray(fragment.code)) {
  fragment.code.forEach(async (file) => {
    await sbx.files.write(file.file_path, file.file_content)
    console.log(`Copied file to ${file.file_path} in ${sbx.sandboxId}`)
  })
}

Array.prototype.forEach ignores the promises returned by the async callback. The outer POST handler continues to sbx.runCode(...) / URL return at line 62+ without awaiting the writes.

Steps

1. Generate a multi-file fragment (Next.js/Vue template producing 2+ files).
2. POST to /api/sandbox with fragment.code as an array.
3. Sandbox may run/serve before later files are on disk.

Expected

All files persisted before execution/URL return.

Actual

Fire-and-forget writes; ordering depends on E2B SDK internal timing.

Fix

Replace with await Promise.all(fragment.code.map(file => sbx.files.write(...))).

Environment

@e2b/code-interpreter@^1.0.2, next@^14.2.35, Node per repo package.json.

Thanks for maintaining e2b-dev/fragments!

[mishushakov]

please submit pull request