fix: await thenables to support cross-realm promises

[pi0]

Replace result instanceof Promise with a thenable check (typeof result.then === "function") in callHooks, so hooks returning a Promise from a different realm (e.g. jiti/vm contexts) are awaited correctly instead of silently dropped.

Reported by @brandonroberts in nitrojs/nitro#4203 ❤️

Summary by CodeRabbit

• Bug Fixes
  • Improved handling of asynchronous results from external or sandboxed execution contexts so async operations are reliably detected and awaited, preserving correct execution order.
• Tests
  • Added a regression test covering cross-context async behavior and adjusted a bundle-size benchmark to reflect updated measurements.

[coderabbitai]

Caution

Review failed

The head commit changed during the review from 0032ac3 to 031c2e1.

📝 Walkthrough

Walkthrough

callHooks in src/utils.ts now detects thenables via result && typeof result.then === "function" and wraps them with Promise.resolve(...) before chaining. Tests were added to validate cross-realm thenable behavior and a bundle size assertion was tweaked.

Changes

Cohort / File(s)	Summary
Async Detection Enhancement src/utils.ts	Replaced result instanceof Promise check with thenable detection (typeof result.then === "function") and normalize returned thenables with Promise.resolve(...) before continuing hook chain.
Cross-Realm Hook Testing test/hookable.test.ts	Added regression test using node:vm to create hooks in a separate realm and assert that foreign thenables are detected and awaited, preserving hook execution order.
Bundle Size Assertion test/bundle.test.ts	Loosened bundle size upper bound from < 630 to < 642 bytes for new HookableCore() benchmark test; gzip size assertion unchanged.

Estimated code review effort

🎯 3 (Moderate) | ⏱️ ~20 minutes

Poem

🐰 A thenable whisper from a distant VM shore,
It promises motion yet is seen no more,
Not by instanceof, but by .then it’s known—
The rabbit hops, awaits, and watches hooks be sewn. ✨

🚥 Pre-merge checks | ✅ 2 | ❌ 1

❌ Failed checks (1 warning)

Check name	Status	Explanation	Resolution
Docstring Coverage	⚠️ Warning	Docstring coverage is 0.00% which is insufficient. The required threshold is 80.00%.	Write docstrings for the functions missing them to satisfy the coverage threshold.

✅ Passed checks (2 passed)

Check name	Status	Explanation
Description Check	✅ Passed	Check skipped - CodeRabbit’s high-level summary is enabled.
Title check	✅ Passed	The title accurately describes the main change: replacing instanceof Promise with thenable detection to support cross-realm promises.

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✨ Finishing Touches

📝 Generate docstrings

• Create stacked PR
• Commit on current branch

🧪 Generate unit tests (beta)

• Create PR with unit tests
• Commit unit tests in branch fix/cross-realm-thenable

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