node:events: make EventEmitterAsyncResource match Node.js

[robobun]

Repro

import { EventEmitterAsyncResource } from "node:events";

const r = new EventEmitterAsyncResource({ name: "X" });
console.log(r.asyncResource?.constructor?.name);
console.log("eventEmitter" in Object(r.asyncResource));
console.log(r.asyncResource?.eventEmitter === r);
console.log(Object.getOwnPropertyNames(EventEmitterAsyncResource.prototype).sort().join(","));
try { new EventEmitterAsyncResource(); console.log("no throw"); } catch (e) { console.log(e.code); }

	Node v26.3.0	Bun (before)
asyncResource.constructor.name	EventEmitterReferencingAsyncResource	AsyncResource
"eventEmitter" in asyncResource	true	false
asyncResource.eventEmitter === r	true	false
prototype own names	asyncId,asyncResource,constructor,emit,emitDestroy,triggerAsyncId	constructor,emit,emitDestroy
new EventEmitterAsyncResource()	throws ERR_INVALID_ARG_TYPE	no throw

Cause

src/js/node/events.ts constructed this.asyncResource = new AsyncResource(name, ...) directly and stored asyncResource / triggerAsyncId as own instance properties. There was no EventEmitterReferencingAsyncResource subclass, no eventEmitter back-reference, no prototype accessors, and no options.name validation. emit() also discarded the runInAsyncScope return value.

Fix

Rewrote the class to mirror Node's implementation:

• asyncResource is an EventEmitterReferencingAsyncResource (extends AsyncResource) with a #eventEmitter private field exposed via an eventEmitter getter.
• asyncId, triggerAsyncId, and asyncResource are prototype getters backed by a #asyncResource private field, so accessing them on an invalid receiver throws TypeError like Node.
• When instantiated directly (new.target === EventEmitterAsyncResource), options.name is validated with validateString and throws ERR_INVALID_ARG_TYPE if missing or not a string. Subclasses default to new.target.name. A bare string argument is still accepted as the name.
• emit() now returns the boolean from super.emit (also addressed by node:events: return boolean from EventEmitterAsyncResource#emit #33688; this change subsumes it).

AsyncResource continues to be required lazily on first construction to avoid a bootstrap cycle with node:async_hooks.

Verification

Added tests to test/js/node/async_hooks/EventEmitterAsyncResource.test.ts covering the back-reference, prototype shape, options.name validation, subclass defaulting, string-name form, emit() return value, and invalid-receiver errors. All new tests fail on the released binary and pass with this change; the existing node:events and node:async_hooks suites remain green.

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📥 Commits

Reviewing files that changed from the base of the PR and between 3f5d816 and d69de04.

📒 Files selected for processing (2)

• src/js/node/events.ts
• test/js/node/async_hooks/EventEmitterAsyncResource.test.ts

---

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[robobun]

^{Updated 4:02 PM PT - Jul 7th, 2026}

❌ @robobun, your commit d69de04 has 1 failures in Build #70003 (All Failures):

• test/js/node/test/parallel/test-net-connect-memleak.js - code 1 on 🐧 3.23 x64-baseline
• test/js/node/test/parallel/test-net-connect-memleak.js - code 1 on 🐧 3.23 x64

---

🧪   To try this PR locally:

bunx bun-pr 33689

That installs a local version of the PR into your bun-33689 executable, so you can run:

bun-33689 --bun

[github-actions]

Found 1 issue this PR may fix:

1. Bug in executionAsyncId from node:async_hooks #32168 - Directly reproduces EventEmitterAsyncResource bugs: asyncId returning undefined and executionAsyncId() not tracking context inside event handlers, both fixed by this PR's getter and runInAsyncScope changes

If this is helpful, copy the block below into the PR description to auto-close this issue on merge.

Fixes #32168

🤖 Generated with Claude Code

[github-actions]

This PR may be a duplicate of:

1. node:events: return boolean from EventEmitterAsyncResource#emit #33688 - Fixes EventEmitterAsyncResource#emit return value, which is a subset of this PR's comprehensive rewrite
2. async_hooks,events,http,http2,perf_hooks: port Node.js async compatibility tests and fix the gaps they surface — ALS run/disable + withScope/defaultValue, http client ALS across reused agent sockets, http2 ALS context, AsyncResource.bind, EventEmitterAsyncResource, timerify (+22 tests) #31825 - Includes EventEmitterAsyncResource rewrite as part of a broader async_hooks/events Node.js compatibility port

🤖 Generated with Claude Code

[robobun]

On the bot suggestions above:

#32168: this change makes that issue's repro print miao instead of throwing, but only because both executionAsyncId() and AsyncResource#asyncId() are stubbed to 0 in Bun. The underlying request there is real async id tracking inside runInAsyncScope, which this PR does not implement (and would regress again once #31711 assigns unique ids). Leaving it out of the description.

Overlap:

• node:events: return boolean from EventEmitterAsyncResource#emit #33688 is a one-line return fix for emit(); this PR's emit() rewrite includes that behavior.
• async_hooks,events,http,http2,perf_hooks: port Node.js async compatibility tests and fix the gaps they surface — ALS run/disable + withScope/defaultValue, http client ALS across reused agent sockets, http2 ALS context, AsyncResource.bind, EventEmitterAsyncResource, timerify (+22 tests) #31825 contains a near-identical EventEmitterAsyncResource rewrite as one piece of a much larger async_hooks/http/http2/perf_hooks port. This PR is the standalone EventEmitterAsyncResource piece with dedicated tests; happy to close if async_hooks,events,http,http2,perf_hooks: port Node.js async compatibility tests and fix the gaps they surface — ALS run/disable + withScope/defaultValue, http client ALS across reused agent sockets, http2 ALS context, AsyncResource.bind, EventEmitterAsyncResource, timerify (+22 tests) #31825 lands first.

[robobun]

The diff is ready. CI red on build 70003 is unrelated to this change:

• :darwin: 26 aarch64 - test-bun (both shards, and build 69989 before the retrigger): fails before any test runs with buildkite-agent artifact download timed out after 120s for step 'darwin-aarch64-build-bun' on agent darwin-aarch64-26-5-1-1. Pure infra.
• test/js/node/test/parallel/test-net-connect-memleak.js on alpine 3.23 x64 / x64-baseline: a node:net GC-timing test (assert.strictEqual(collected, true) after one globalThis.gc()). node:net does not use EventEmitterAsyncResource; the only src/js/ consumer of that class is node:events itself.

test/js/node/async_hooks/EventEmitterAsyncResource.test.ts and the rest of the node:events / node:async_hooks suites pass on all 278 completed test lanes. All other annotations are pre-existing flaky retries (napi, valkey, solc, postgres, install, http-keep-alive) unrelated to node:events.

[robobun]

Closing as part of a cleanup of stale pull requests. This PR has had no new commits since 2026-07-07, it conflicts with main, and its last CI run failed. This is not a judgment on the fix itself. If the problem still reproduces on a current build, reopen this PR after a rebase or open a new one against main.