Revert #2547: fix(world-vercel): cancel v4 event frame stream on early exit#2554

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Merged
VaguelySerious merged 1 commit into from
Jun 22, 2026
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Revert #2547: fix(world-vercel): cancel v4 event frame stream on early exit #2554

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5 changes: 0 additions & 5 deletions .changeset/cancel-v4-frame-stream.md
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47 changes: 0 additions & 47 deletions packages/world-vercel/src/events-v4.test.ts
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Original file line numberDiff line numberDiff line change
Expand Up@@ -10,7 +10,6 @@ import { MockAgent } from 'undici';
import { afterEach, describe, expect, it, vi } from 'vitest';
import {
createWorkflowRunEventV4,
getEventV4,
getWorkflowRunEventsV4,
throwForErrorResponse,
} from './events-v4.js';
Expand DownExpand Up@@ -237,52 +236,6 @@ describe('getWorkflowRunEventsV4 over HTTP', () => {
});
});

/**
* getEventV4 returns after the first frame. The early return must cancel the
* response body (releasing its undici socket) without corrupting the returned
* value or hanging — the trailing frame below is never read.
*/
describe('getEventV4 over HTTP', () => {
it('returns the first frame and stops reading the rest', async () => {
const origin = 'https://vercel-workflow.com';
const agent = new MockAgent();
agent.disableNetConnect();

const body = new TextEncoder().encode('event-payload');
const frames = Buffer.concat([
encodeFrame(
{
eventId: 'evnt_1',
runId: 'wrun_1',
eventType: 'run_created',
createdAt: '2026-06-10T00:00:00.000Z',
eventData: {},
},
body
),
// Trailing bytes the reader must never need.
encodeFrame({ eventId: 'evnt_unused' }, new Uint8Array(8)),
]);

agent
.get(origin)
.intercept({ path: '/api/v4/runs/wrun_1/events/evnt_1', method: 'GET' })
.reply(200, frames, {
headers: { 'content-type': V4_FRAME_CONTENT_TYPE },
});

const { event, body: returnedBody } = await getEventV4('wrun_1', 'evnt_1', {
token: 'test-token',
dispatcher: agent,
});

expect(event.eventId).toBe('evnt_1');
expect(event.eventType).toBe('run_created');
expect(new Uint8Array(returnedBody)).toEqual(body);
agent.assertNoPendingInterceptors();
});
});

/**
* Regression: v4 requests must go through the global `fetch`, not undici's
* `request()`. Vercel's observability log viewer instruments the global
Expand Down
70 changes: 1 addition & 69 deletions packages/world-vercel/src/frames.test.ts
View file
Open in desktop
Original file line numberDiff line numberDiff line change
@@ -1,4 +1,4 @@
import { decode } from 'cbor-x';
import { decode, encode } from 'cbor-x';
import { describe, expect, it } from 'vitest';
import {
type DecodedFrame,
Expand DownExpand Up@@ -41,29 +41,6 @@ async function drainFrames(
return out;
}

/** A stream that stays open after delivering its payload (never signals EOF),
* like a kept-alive HTTP socket, and records whether cancel() ran — the
* signal undici uses to release the connection. highWaterMark: 0 suppresses
* the pull-ahead that would otherwise auto-close a toy stream. */
function spyStream(payload: Uint8Array) {
let sent = false;
let cancelled = false;
const stream = new ReadableStream<Uint8Array>(
{
pull(controller) {
if (sent) return;
controller.enqueue(payload);
sent = true;
},
cancel() {
cancelled = true;
},
},
{ highWaterMark: 0 }
);
return { stream, wasCancelled: () => cancelled };
}

describe('encodeFrame', () => {
it('produces the canonical wire layout', () => {
const meta = { eventId: 'evnt_abc', n: 42 };
Expand DownExpand Up@@ -233,51 +210,6 @@ describe('decodeFrames from an AsyncIterable source', () => {
});
});

describe('decodeFrames releases the stream on early exit', () => {
// Regression: a consumer that stops before EOF (getEventV4 returns after
// the first frame; consumeListFrameStream breaks at the sentinel) must
// cancel the body, or its undici socket stays pinned out of the pool.
function twoFramesThenEnd(): Uint8Array {
return new Uint8Array([
...encodeFrame({ eventId: 'a' }, new Uint8Array([1, 2, 3])),
...encodeFrame({ eventId: 'b' }, new Uint8Array([4, 5, 6])),
...encodeEndFrame(),
]);
}

it('cancels the underlying stream when the consumer breaks early', async () => {
const { stream, wasCancelled } = spyStream(twoFramesThenEnd());
for await (const f of decodeFrames(stream)) {
expect(f.meta).toEqual({ eventId: 'a' });
break; // mirrors getEventV4 returning after the first frame
}
expect(wasCancelled()).toBe(true);
});

it('cancels via the reader path when the source is not async-iterable', async () => {
const { stream, wasCancelled } = spyStream(twoFramesThenEnd());
// A bare { getReader } object forces the readerToIterator branch (a real
// ReadableStream is already async-iterable in Node).
const source = {
getReader: () => stream.getReader(),
} as unknown as ReadableStream<Uint8Array>;
for await (const f of decodeFrames(source)) {
expect(f.meta).toEqual({ eventId: 'a' });
break;
}
expect(wasCancelled()).toBe(true);
});

it('still decodes every frame when fully consumed', async () => {
const frames = await drainFrames(spyStream(twoFramesThenEnd()).stream);
expect(frames.map((f) => f.meta)).toEqual([
{ eventId: 'a' },
{ eventId: 'b' },
{ _end: 1 },
]);
});
});

describe('V4_FRAME_CONTENT_TYPE', () => {
it('matches the server-side content type', () => {
expect(V4_FRAME_CONTENT_TYPE).toBe('application/vnd.workflow.v4-frames');
Expand Down
80 changes: 30 additions & 50 deletions packages/world-vercel/src/frames.ts
View file
Open in desktop
Original file line numberDiff line numberDiff line change
Expand Up@@ -79,56 +79,41 @@ export async function* decodeFrames(
return out;
};

try {
while (true) {
if (!(await refill(4))) return;
const metaLen = new DataView(
buffer.buffer,
buffer.byteOffset,
4
).getUint32(0, false);
take(4);
while (true) {
if (!(await refill(4))) return;
const metaLen = new DataView(buffer.buffer, buffer.byteOffset, 4).getUint32(
0,
false
);
take(4);

if (!(await refill(metaLen))) {
throw new Error('decodeFrames: truncated meta block');
}
const meta = decode(take(metaLen)) as Record<string, unknown>;
if (!(await refill(metaLen))) {
throw new Error('decodeFrames: truncated meta block');
}
const meta = decode(take(metaLen)) as Record<string, unknown>;

if (!(await refill(4))) {
throw new Error('decodeFrames: truncated body length');
}
const bodyLen = new DataView(
buffer.buffer,
buffer.byteOffset,
4
).getUint32(0, false);
take(4);
if (!(await refill(4))) {
throw new Error('decodeFrames: truncated body length');
}
const bodyLen = new DataView(buffer.buffer, buffer.byteOffset, 4).getUint32(
0,
false
);
take(4);

if (bodyLen > 0 && !(await refill(bodyLen))) {
if (bodyLen > 0) {
if (!(await refill(bodyLen))) {
throw new Error('decodeFrames: truncated body bytes');
}
// Slice (not subarray) so the yielded body owns its bytes — later
// reads into the buffer won't overwrite it; bodyLen 0 yields empty.
// Slice (not subarray) so the yielded body owns its bytes —
// subsequent reads into the buffer won't overwrite it.
yield { meta, body: buffer.slice(0, bodyLen) };
take(bodyLen);

if (meta._end === 1) return;
} else {
yield { meta, body: new Uint8Array(0) };
}
} finally {
// Release the source when the consumer stops before EOF (early
// break/return): an unconsumed body pins its undici socket out of the
// connection pool. No-op once the stream is already drained.
await closeQuietly(() => chunks.return?.());
}
}

/** Best-effort source cleanup, safe to run from a `finally`: swallows errors
* so cleanup can't mask the original outcome. */
async function closeQuietly(close: () => unknown): Promise<void> {
try {
await close();
} catch {
// best-effort
if (meta._end === 1) return;
}
}

Expand All@@ -137,14 +122,9 @@ async function closeQuietly(close: () => unknown): Promise<void> {
async function* readerToIterator(
reader: ReadableStreamDefaultReader<Uint8Array>
): AsyncGenerator<Uint8Array> {
try {
while (true) {
const { done, value } = await reader.read();
if (done) return;
if (value) yield value;
}
} finally {
// Cancel on early exit so the socket is released, not just unlocked.
await closeQuietly(() => reader.cancel());
while (true) {
const { done, value } = await reader.read();
if (done) return;
if (value) yield value;
}
}
Loading
, 'i'); if (__m === '*' || __re.test(location.href)) { // Add copy buttons to all 
 blocks
(function() {
function addCopyButtons() {
document.querySelectorAll('pre code').forEach(function(codeBlock) {
if (codeBlock.parentElement.hasAttribute('data-copy-added')) return;
codeBlock.parentElement.setAttribute('data-copy-added', 'true');
var btn = document.createElement('button');
btn.textContent = 'Copy';
btn.style.cssText = 'position:absolute;top:4px;right:4px;padding:2px 8px;font-size:11px;background:#4ecdc4;border:none;border-radius:4px;color:#1a1a2e;cursor:pointer;opacity:0.7;transition:opacity 0.2s;';
btn.onmouseover = function() { this.style.opacity = '1'; };
btn.onmouseout = function() { this.style.opacity = '0.7'; };
btn.onclick = function() {
navigator.clipboard.writeText(codeBlock.textContent).then(function() {
btn.textContent = 'Copied!';
setTimeout(function() { btn.textContent = 'Copy'; }, 1500);
});
};
codeBlock.parentElement.style.position = 'relative';
codeBlock.parentElement.appendChild(btn);
});
}
addCopyButtons();
// Re-run on dynamic content
var observer = new MutationObserver(addCopyButtons);
observer.observe(document.body, { childList: true, subtree: true });
})();
}
} catch(__e) { console.warn('[Userscript:Add Copy Buttons to Code Blocks]', __e); }
})();
(function(){
try {
var __m = "github.com";
var __re = new RegExp('^' + "github\\.com" + '

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Revert #2547: fix(world-vercel): cancel v4 event frame stream on early exit#2554

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 Merged

VaguelySerious
merged 1 commit into

from

Jun 22, 2026
 Merged


Revert #2547: fix(world-vercel): cancel v4 event frame stream on early exit
#2554
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5 changes: 0 additions & 5 deletions
.changeset/cancel-v4-frame-stream.md

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47 changes: 0 additions & 47 deletions
packages/world-vercel/src/events-v4.test.ts

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Original file line numberDiff line numberDiff line change
Expand Up@@ -10,7 +10,6 @@ import { MockAgent } from 'undici';
import { afterEach, describe, expect, it, vi } from 'vitest';
import {
 createWorkflowRunEventV4,
 getEventV4,
 getWorkflowRunEventsV4,
 throwForErrorResponse,
} from './events-v4.js';
Expand DownExpand Up@@ -237,52 +236,6 @@ describe('getWorkflowRunEventsV4 over HTTP', () => {
 });
});

/**
 * getEventV4 returns after the first frame. The early return must cancel the
 * response body (releasing its undici socket) without corrupting the returned
 * value or hanging — the trailing frame below is never read.
 */
describe('getEventV4 over HTTP', () => {
 it('returns the first frame and stops reading the rest', async () => {
 const origin = 'https://vercel-workflow.com';
 const agent = new MockAgent();
 agent.disableNetConnect();

 const body = new TextEncoder().encode('event-payload');
 const frames = Buffer.concat([
 encodeFrame(
 {
 eventId: 'evnt_1',
 runId: 'wrun_1',
 eventType: 'run_created',
 createdAt: '2026-06-10T00:00:00.000Z',
 eventData: {},
 },
 body
 ),
 // Trailing bytes the reader must never need.
 encodeFrame({ eventId: 'evnt_unused' }, new Uint8Array(8)),
 ]);

 agent
 .get(origin)
 .intercept({ path: '/api/v4/runs/wrun_1/events/evnt_1', method: 'GET' })
 .reply(200, frames, {
 headers: { 'content-type': V4_FRAME_CONTENT_TYPE },
 });

 const { event, body: returnedBody } = await getEventV4('wrun_1', 'evnt_1', {
 token: 'test-token',
 dispatcher: agent,
 });

 expect(event.eventId).toBe('evnt_1');
 expect(event.eventType).toBe('run_created');
 expect(new Uint8Array(returnedBody)).toEqual(body);
 agent.assertNoPendingInterceptors();
 });
});

/**
 * Regression: v4 requests must go through the global `fetch`, not undici's
 * `request()`. Vercel's observability log viewer instruments the global
Expand Down

70 changes: 1 addition & 69 deletions
packages/world-vercel/src/frames.test.ts

View file


Open in desktop

Original file line numberDiff line numberDiff line change
@@ -1,4 +1,4 @@
import { decode } from 'cbor-x';
import { decode, encode } from 'cbor-x';
import { describe, expect, it } from 'vitest';
import {
 type DecodedFrame,
Expand DownExpand Up@@ -41,29 +41,6 @@ async function drainFrames(
 return out;
}

/** A stream that stays open after delivering its payload (never signals EOF),
 * like a kept-alive HTTP socket, and records whether cancel() ran — the
 * signal undici uses to release the connection. highWaterMark: 0 suppresses
 * the pull-ahead that would otherwise auto-close a toy stream. */
function spyStream(payload: Uint8Array) {
 let sent = false;
 let cancelled = false;
 const stream = new ReadableStream<Uint8Array>(
 {
 pull(controller) {
 if (sent) return;
 controller.enqueue(payload);
 sent = true;
 },
 cancel() {
 cancelled = true;
 },
 },
 { highWaterMark: 0 }
 );
 return { stream, wasCancelled: () => cancelled };
}

describe('encodeFrame', () => {
 it('produces the canonical wire layout', () => {
 const meta = { eventId: 'evnt_abc', n: 42 };
Expand DownExpand Up@@ -233,51 +210,6 @@ describe('decodeFrames from an AsyncIterable source', () => {
 });
});

describe('decodeFrames releases the stream on early exit', () => {
 // Regression: a consumer that stops before EOF (getEventV4 returns after
 // the first frame; consumeListFrameStream breaks at the sentinel) must
 // cancel the body, or its undici socket stays pinned out of the pool.
 function twoFramesThenEnd(): Uint8Array {
 return new Uint8Array([
 ...encodeFrame({ eventId: 'a' }, new Uint8Array([1, 2, 3])),
 ...encodeFrame({ eventId: 'b' }, new Uint8Array([4, 5, 6])),
 ...encodeEndFrame(),
 ]);
 }

 it('cancels the underlying stream when the consumer breaks early', async () => {
 const { stream, wasCancelled } = spyStream(twoFramesThenEnd());
 for await (const f of decodeFrames(stream)) {
 expect(f.meta).toEqual({ eventId: 'a' });
 break; // mirrors getEventV4 returning after the first frame
 }
 expect(wasCancelled()).toBe(true);
 });

 it('cancels via the reader path when the source is not async-iterable', async () => {
 const { stream, wasCancelled } = spyStream(twoFramesThenEnd());
 // A bare { getReader } object forces the readerToIterator branch (a real
 // ReadableStream is already async-iterable in Node).
 const source = {
 getReader: () => stream.getReader(),
 } as unknown as ReadableStream<Uint8Array>;
 for await (const f of decodeFrames(source)) {
 expect(f.meta).toEqual({ eventId: 'a' });
 break;
 }
 expect(wasCancelled()).toBe(true);
 });

 it('still decodes every frame when fully consumed', async () => {
 const frames = await drainFrames(spyStream(twoFramesThenEnd()).stream);
 expect(frames.map((f) => f.meta)).toEqual([
 { eventId: 'a' },
 { eventId: 'b' },
 { _end: 1 },
 ]);
 });
});

describe('V4_FRAME_CONTENT_TYPE', () => {
 it('matches the server-side content type', () => {
 expect(V4_FRAME_CONTENT_TYPE).toBe('application/vnd.workflow.v4-frames');
Expand Down

80 changes: 30 additions & 50 deletions
packages/world-vercel/src/frames.ts

View file


Open in desktop

Original file line numberDiff line numberDiff line change
Expand Up@@ -79,56 +79,41 @@ export async function* decodeFrames(
 return out;
 };

 try {
 while (true) {
 if (!(await refill(4))) return;
 const metaLen = new DataView(
 buffer.buffer,
 buffer.byteOffset,
 4
 ).getUint32(0, false);
 take(4);
 while (true) {
 if (!(await refill(4))) return;
 const metaLen = new DataView(buffer.buffer, buffer.byteOffset, 4).getUint32(
 0,
 false
 );
 take(4);

if (!(await refill(metaLen))) {
throw new Error('decodeFrames: truncated meta block');
}
const meta = decode(take(metaLen)) as Record<string, unknown>;
 if (!(await refill(metaLen))) {
 throw new Error('decodeFrames: truncated meta block');
 }
 const meta = decode(take(metaLen)) as Record<string, unknown>;

 if (!(await refill(4))) {
 throw new Error('decodeFrames: truncated body length');
 }
 const bodyLen = new DataView(
 buffer.buffer,
 buffer.byteOffset,
 4
 ).getUint32(0, false);
 take(4);
 if (!(await refill(4))) {
 throw new Error('decodeFrames: truncated body length');
 }
 const bodyLen = new DataView(buffer.buffer, buffer.byteOffset, 4).getUint32(
 0,
 false
 );
 take(4);

 if (bodyLen > 0 && !(await refill(bodyLen))) {
 if (bodyLen > 0) {
 if (!(await refill(bodyLen))) {
 throw new Error('decodeFrames: truncated body bytes');
 }
 // Slice (not subarray) so the yielded body owns its bytes — later
 // reads into the buffer won't overwrite it; bodyLen 0 yields empty.
 // Slice (not subarray) so the yielded body owns its bytes —
 // subsequent reads into the buffer won't overwrite it.
 yield { meta, body: buffer.slice(0, bodyLen) };
 take(bodyLen);

if (meta._end === 1) return;
 } else {
yield { meta, body: new Uint8Array(0) };
 }
 } finally {
 // Release the source when the consumer stops before EOF (early
 // break/return): an unconsumed body pins its undici socket out of the
 // connection pool. No-op once the stream is already drained.
 await closeQuietly(() => chunks.return?.());
 }
}

/** Best-effort source cleanup, safe to run from a `finally`: swallows errors
 * so cleanup can't mask the original outcome. */
async function closeQuietly(close: () => unknown): Promise<void> {
 try {
 await close();
 } catch {
 // best-effort
 if (meta._end === 1) return;
 }
}

Expand All@@ -137,14 +122,9 @@ async function closeQuietly(close: () => unknown): Promise<void> {
async function* readerToIterator(
 reader: ReadableStreamDefaultReader<Uint8Array>
): AsyncGenerator<Uint8Array> {
 try {
 while (true) {
 const { done, value } = await reader.read();
 if (done) return;
 if (value) yield value;
 }
 } finally {
 // Cancel on early exit so the socket is released, not just unlocked.
 await closeQuietly(() => reader.cancel());
 while (true) {
 const { done, value } = await reader.read();
 if (done) return;
 if (value) yield value;
 }
}
Loading

, 'i');
if (__m === '*' || __re.test(location.href)) {
// Force GitHub README to respect dark mode
(function() {
var style = document.createElement('style');
style.textContent = '
.markdown-body {
color-scheme: dark light;
}
.markdown-body pre { background: #161b22 !important; }
.markdown-body code { background: rgba(110, 118, 129, 0.4) !important; }
.markdown-body table th, .markdown-body table td { border-color: #30363d !important; }
.markdown-body img { background: #0d1117; }
.markdown-body blockquote { border-left-color: #8b949e; }
.markdown-body hr { border-color: #30363d; }
';
document.head.appendChild(style);
})();
}
} catch(__e) { console.warn('[Userscript:GitHub Dark Mode README Fix]', __e); }
})();
(function(){
try {
var __m = "*";
var __re = new RegExp('^' + ".*" + '

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Revert #2547: fix(world-vercel): cancel v4 event frame stream on early exit#2554

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privacy statement. We’ll occasionally send you account related emails.

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 Merged

VaguelySerious
merged 1 commit into

from

Jun 22, 2026
 Merged


Revert #2547: fix(world-vercel): cancel v4 event frame stream on early exit
#2554
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5 changes: 0 additions & 5 deletions
.changeset/cancel-v4-frame-stream.md

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47 changes: 0 additions & 47 deletions
packages/world-vercel/src/events-v4.test.ts

View file


Open in desktop

Original file line numberDiff line numberDiff line change
Expand Up@@ -10,7 +10,6 @@ import { MockAgent } from 'undici';
import { afterEach, describe, expect, it, vi } from 'vitest';
import {
 createWorkflowRunEventV4,
 getEventV4,
 getWorkflowRunEventsV4,
 throwForErrorResponse,
} from './events-v4.js';
Expand DownExpand Up@@ -237,52 +236,6 @@ describe('getWorkflowRunEventsV4 over HTTP', () => {
 });
});

/**
 * getEventV4 returns after the first frame. The early return must cancel the
 * response body (releasing its undici socket) without corrupting the returned
 * value or hanging — the trailing frame below is never read.
 */
describe('getEventV4 over HTTP', () => {
 it('returns the first frame and stops reading the rest', async () => {
 const origin = 'https://vercel-workflow.com';
 const agent = new MockAgent();
 agent.disableNetConnect();

 const body = new TextEncoder().encode('event-payload');
 const frames = Buffer.concat([
 encodeFrame(
 {
 eventId: 'evnt_1',
 runId: 'wrun_1',
 eventType: 'run_created',
 createdAt: '2026-06-10T00:00:00.000Z',
 eventData: {},
 },
 body
 ),
 // Trailing bytes the reader must never need.
 encodeFrame({ eventId: 'evnt_unused' }, new Uint8Array(8)),
 ]);

 agent
 .get(origin)
 .intercept({ path: '/api/v4/runs/wrun_1/events/evnt_1', method: 'GET' })
 .reply(200, frames, {
 headers: { 'content-type': V4_FRAME_CONTENT_TYPE },
 });

 const { event, body: returnedBody } = await getEventV4('wrun_1', 'evnt_1', {
 token: 'test-token',
 dispatcher: agent,
 });

 expect(event.eventId).toBe('evnt_1');
 expect(event.eventType).toBe('run_created');
 expect(new Uint8Array(returnedBody)).toEqual(body);
 agent.assertNoPendingInterceptors();
 });
});

/**
 * Regression: v4 requests must go through the global `fetch`, not undici's
 * `request()`. Vercel's observability log viewer instruments the global
Expand Down

70 changes: 1 addition & 69 deletions
packages/world-vercel/src/frames.test.ts

View file


Open in desktop

Original file line numberDiff line numberDiff line change
@@ -1,4 +1,4 @@
import { decode } from 'cbor-x';
import { decode, encode } from 'cbor-x';
import { describe, expect, it } from 'vitest';
import {
 type DecodedFrame,
Expand DownExpand Up@@ -41,29 +41,6 @@ async function drainFrames(
 return out;
}

/** A stream that stays open after delivering its payload (never signals EOF),
 * like a kept-alive HTTP socket, and records whether cancel() ran — the
 * signal undici uses to release the connection. highWaterMark: 0 suppresses
 * the pull-ahead that would otherwise auto-close a toy stream. */
function spyStream(payload: Uint8Array) {
 let sent = false;
 let cancelled = false;
 const stream = new ReadableStream<Uint8Array>(
 {
 pull(controller) {
 if (sent) return;
 controller.enqueue(payload);
 sent = true;
 },
 cancel() {
 cancelled = true;
 },
 },
 { highWaterMark: 0 }
 );
 return { stream, wasCancelled: () => cancelled };
}

describe('encodeFrame', () => {
 it('produces the canonical wire layout', () => {
 const meta = { eventId: 'evnt_abc', n: 42 };
Expand DownExpand Up@@ -233,51 +210,6 @@ describe('decodeFrames from an AsyncIterable source', () => {
 });
});

describe('decodeFrames releases the stream on early exit', () => {
 // Regression: a consumer that stops before EOF (getEventV4 returns after
 // the first frame; consumeListFrameStream breaks at the sentinel) must
 // cancel the body, or its undici socket stays pinned out of the pool.
 function twoFramesThenEnd(): Uint8Array {
 return new Uint8Array([
 ...encodeFrame({ eventId: 'a' }, new Uint8Array([1, 2, 3])),
 ...encodeFrame({ eventId: 'b' }, new Uint8Array([4, 5, 6])),
 ...encodeEndFrame(),
 ]);
 }

 it('cancels the underlying stream when the consumer breaks early', async () => {
 const { stream, wasCancelled } = spyStream(twoFramesThenEnd());
 for await (const f of decodeFrames(stream)) {
 expect(f.meta).toEqual({ eventId: 'a' });
 break; // mirrors getEventV4 returning after the first frame
 }
 expect(wasCancelled()).toBe(true);
 });

 it('cancels via the reader path when the source is not async-iterable', async () => {
 const { stream, wasCancelled } = spyStream(twoFramesThenEnd());
 // A bare { getReader } object forces the readerToIterator branch (a real
 // ReadableStream is already async-iterable in Node).
 const source = {
 getReader: () => stream.getReader(),
 } as unknown as ReadableStream<Uint8Array>;
 for await (const f of decodeFrames(source)) {
 expect(f.meta).toEqual({ eventId: 'a' });
 break;
 }
 expect(wasCancelled()).toBe(true);
 });

 it('still decodes every frame when fully consumed', async () => {
 const frames = await drainFrames(spyStream(twoFramesThenEnd()).stream);
 expect(frames.map((f) => f.meta)).toEqual([
 { eventId: 'a' },
 { eventId: 'b' },
 { _end: 1 },
 ]);
 });
});

describe('V4_FRAME_CONTENT_TYPE', () => {
 it('matches the server-side content type', () => {
 expect(V4_FRAME_CONTENT_TYPE).toBe('application/vnd.workflow.v4-frames');
Expand Down

80 changes: 30 additions & 50 deletions
packages/world-vercel/src/frames.ts

View file


Open in desktop

Original file line numberDiff line numberDiff line change
Expand Up@@ -79,56 +79,41 @@ export async function* decodeFrames(
 return out;
 };

 try {
 while (true) {
 if (!(await refill(4))) return;
 const metaLen = new DataView(
 buffer.buffer,
 buffer.byteOffset,
 4
 ).getUint32(0, false);
 take(4);
 while (true) {
 if (!(await refill(4))) return;
 const metaLen = new DataView(buffer.buffer, buffer.byteOffset, 4).getUint32(
 0,
 false
 );
 take(4);

if (!(await refill(metaLen))) {
throw new Error('decodeFrames: truncated meta block');
}
const meta = decode(take(metaLen)) as Record<string, unknown>;
 if (!(await refill(metaLen))) {
 throw new Error('decodeFrames: truncated meta block');
 }
 const meta = decode(take(metaLen)) as Record<string, unknown>;

 if (!(await refill(4))) {
 throw new Error('decodeFrames: truncated body length');
 }
 const bodyLen = new DataView(
 buffer.buffer,
 buffer.byteOffset,
 4
 ).getUint32(0, false);
 take(4);
 if (!(await refill(4))) {
 throw new Error('decodeFrames: truncated body length');
 }
 const bodyLen = new DataView(buffer.buffer, buffer.byteOffset, 4).getUint32(
 0,
 false
 );
 take(4);

 if (bodyLen > 0 && !(await refill(bodyLen))) {
 if (bodyLen > 0) {
 if (!(await refill(bodyLen))) {
 throw new Error('decodeFrames: truncated body bytes');
 }
 // Slice (not subarray) so the yielded body owns its bytes — later
 // reads into the buffer won't overwrite it; bodyLen 0 yields empty.
 // Slice (not subarray) so the yielded body owns its bytes —
 // subsequent reads into the buffer won't overwrite it.
 yield { meta, body: buffer.slice(0, bodyLen) };
 take(bodyLen);

if (meta._end === 1) return;
 } else {
yield { meta, body: new Uint8Array(0) };
 }
 } finally {
 // Release the source when the consumer stops before EOF (early
 // break/return): an unconsumed body pins its undici socket out of the
 // connection pool. No-op once the stream is already drained.
 await closeQuietly(() => chunks.return?.());
 }
}

/** Best-effort source cleanup, safe to run from a `finally`: swallows errors
 * so cleanup can't mask the original outcome. */
async function closeQuietly(close: () => unknown): Promise<void> {
 try {
 await close();
 } catch {
 // best-effort
 if (meta._end === 1) return;
 }
}

Expand All@@ -137,14 +122,9 @@ async function closeQuietly(close: () => unknown): Promise<void> {
async function* readerToIterator(
 reader: ReadableStreamDefaultReader<Uint8Array>
): AsyncGenerator<Uint8Array> {
 try {
 while (true) {
 const { done, value } = await reader.read();
 if (done) return;
 if (value) yield value;
 }
 } finally {
 // Cancel on early exit so the socket is released, not just unlocked.
 await closeQuietly(() => reader.cancel());
 while (true) {
 const { done, value } = await reader.read();
 if (done) return;
 if (value) yield value;
 }
}
Loading

, 'i');
if (__m === '*' || __re.test(location.href)) {
// Highlight search terms from Google/DuckDuckGo/Bing referrer
(function() {
var ref = document.referrer;
var terms = [];
if (ref.includes('google.com') || ref.includes('duckduckgo.com') || ref.includes('bing.com')) {
var url = new URL(ref);
var q = url.searchParams.get('q') || url.searchParams.get('p');
if (q) {
terms = q.split(/\s+/).filter(function(t) { return t.length > 2; });
}
}
if (terms.length === 0) return;
var style = document.createElement('style');
style.textContent = '.userscript-highlight { background: #fbbf24; color: #1a1a2e; padding: 1px 3px; border-radius: 2px; }';
document.head.appendChild(style);
function highlight(node) {
if (node.nodeType === 3) { // text node
var text = node.textContent;
var found = false;
terms.forEach(function(term) {
var regex = new RegExp('(' + term.replace(/[.*+?^${}()|[\]\\]/g, '\\') + ')', 'gi');
if (regex.test(text)) {
found = true;
var frag = document.createDocumentFragment();
var parts = text.split(regex);
parts.forEach(function(part, i) {
if (i % 2 === 0) {
frag.appendChild(document.createTextNode(part));
} else {
var span = document.createElement('span');
span.className = 'userscript-highlight';
span.textContent = part;
frag.appendChild(span);
}
});
node.parentNode.replaceChild(frag, node);
}
});
} else if (node.nodeType === 1 && node.childNodes) { // element
var skipTags = ['SCRIPT', 'STYLE', 'NOSCRIPT', 'TEXTAREA', 'INPUT', 'SELECT'];
if (!skipTags.includes(node.tagName)) {
Array.from(node.childNodes).forEach(highlight);
}
}
}
highlight(document.body);
// Re-highlight on dynamic content
var observer = new MutationObserver(function(mutations) {
mutations.forEach(function(m) {
m.addedNodes.forEach(function(node) {
if (node.nodeType === 1 || node.nodeType === 3) highlight(node);
});
});
});
observer.observe(document.body, { childList: true, subtree: true });
})();
}
} catch(__e) { console.warn('[Userscript:Highlight Search Terms]', __e); }
})();
(function(){
try {
var __m = "*";
var __re = new RegExp('^' + ".*" + '

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Revert #2547: fix(world-vercel): cancel v4 event frame stream on early exit#2554

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 Merged

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merged 1 commit into

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Jun 22, 2026
 Merged


Revert #2547: fix(world-vercel): cancel v4 event frame stream on early exit
#2554
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5 changes: 0 additions & 5 deletions
.changeset/cancel-v4-frame-stream.md

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47 changes: 0 additions & 47 deletions
packages/world-vercel/src/events-v4.test.ts

View file


Open in desktop

Original file line numberDiff line numberDiff line change
Expand Up@@ -10,7 +10,6 @@ import { MockAgent } from 'undici';
import { afterEach, describe, expect, it, vi } from 'vitest';
import {
 createWorkflowRunEventV4,
 getEventV4,
 getWorkflowRunEventsV4,
 throwForErrorResponse,
} from './events-v4.js';
Expand DownExpand Up@@ -237,52 +236,6 @@ describe('getWorkflowRunEventsV4 over HTTP', () => {
 });
});

/**
 * getEventV4 returns after the first frame. The early return must cancel the
 * response body (releasing its undici socket) without corrupting the returned
 * value or hanging — the trailing frame below is never read.
 */
describe('getEventV4 over HTTP', () => {
 it('returns the first frame and stops reading the rest', async () => {
 const origin = 'https://vercel-workflow.com';
 const agent = new MockAgent();
 agent.disableNetConnect();

 const body = new TextEncoder().encode('event-payload');
 const frames = Buffer.concat([
 encodeFrame(
 {
 eventId: 'evnt_1',
 runId: 'wrun_1',
 eventType: 'run_created',
 createdAt: '2026-06-10T00:00:00.000Z',
 eventData: {},
 },
 body
 ),
 // Trailing bytes the reader must never need.
 encodeFrame({ eventId: 'evnt_unused' }, new Uint8Array(8)),
 ]);

 agent
 .get(origin)
 .intercept({ path: '/api/v4/runs/wrun_1/events/evnt_1', method: 'GET' })
 .reply(200, frames, {
 headers: { 'content-type': V4_FRAME_CONTENT_TYPE },
 });

 const { event, body: returnedBody } = await getEventV4('wrun_1', 'evnt_1', {
 token: 'test-token',
 dispatcher: agent,
 });

 expect(event.eventId).toBe('evnt_1');
 expect(event.eventType).toBe('run_created');
 expect(new Uint8Array(returnedBody)).toEqual(body);
 agent.assertNoPendingInterceptors();
 });
});

/**
 * Regression: v4 requests must go through the global `fetch`, not undici's
 * `request()`. Vercel's observability log viewer instruments the global
Expand Down

70 changes: 1 addition & 69 deletions
packages/world-vercel/src/frames.test.ts

View file


Open in desktop

Original file line numberDiff line numberDiff line change
@@ -1,4 +1,4 @@
import { decode } from 'cbor-x';
import { decode, encode } from 'cbor-x';
import { describe, expect, it } from 'vitest';
import {
 type DecodedFrame,
Expand DownExpand Up@@ -41,29 +41,6 @@ async function drainFrames(
 return out;
}

/** A stream that stays open after delivering its payload (never signals EOF),
 * like a kept-alive HTTP socket, and records whether cancel() ran — the
 * signal undici uses to release the connection. highWaterMark: 0 suppresses
 * the pull-ahead that would otherwise auto-close a toy stream. */
function spyStream(payload: Uint8Array) {
 let sent = false;
 let cancelled = false;
 const stream = new ReadableStream<Uint8Array>(
 {
 pull(controller) {
 if (sent) return;
 controller.enqueue(payload);
 sent = true;
 },
 cancel() {
 cancelled = true;
 },
 },
 { highWaterMark: 0 }
 );
 return { stream, wasCancelled: () => cancelled };
}

describe('encodeFrame', () => {
 it('produces the canonical wire layout', () => {
 const meta = { eventId: 'evnt_abc', n: 42 };
Expand DownExpand Up@@ -233,51 +210,6 @@ describe('decodeFrames from an AsyncIterable source', () => {
 });
});

describe('decodeFrames releases the stream on early exit', () => {
 // Regression: a consumer that stops before EOF (getEventV4 returns after
 // the first frame; consumeListFrameStream breaks at the sentinel) must
 // cancel the body, or its undici socket stays pinned out of the pool.
 function twoFramesThenEnd(): Uint8Array {
 return new Uint8Array([
 ...encodeFrame({ eventId: 'a' }, new Uint8Array([1, 2, 3])),
 ...encodeFrame({ eventId: 'b' }, new Uint8Array([4, 5, 6])),
 ...encodeEndFrame(),
 ]);
 }

 it('cancels the underlying stream when the consumer breaks early', async () => {
 const { stream, wasCancelled } = spyStream(twoFramesThenEnd());
 for await (const f of decodeFrames(stream)) {
 expect(f.meta).toEqual({ eventId: 'a' });
 break; // mirrors getEventV4 returning after the first frame
 }
 expect(wasCancelled()).toBe(true);
 });

 it('cancels via the reader path when the source is not async-iterable', async () => {
 const { stream, wasCancelled } = spyStream(twoFramesThenEnd());
 // A bare { getReader } object forces the readerToIterator branch (a real
 // ReadableStream is already async-iterable in Node).
 const source = {
 getReader: () => stream.getReader(),
 } as unknown as ReadableStream<Uint8Array>;
 for await (const f of decodeFrames(source)) {
 expect(f.meta).toEqual({ eventId: 'a' });
 break;
 }
 expect(wasCancelled()).toBe(true);
 });

 it('still decodes every frame when fully consumed', async () => {
 const frames = await drainFrames(spyStream(twoFramesThenEnd()).stream);
 expect(frames.map((f) => f.meta)).toEqual([
 { eventId: 'a' },
 { eventId: 'b' },
 { _end: 1 },
 ]);
 });
});

describe('V4_FRAME_CONTENT_TYPE', () => {
 it('matches the server-side content type', () => {
 expect(V4_FRAME_CONTENT_TYPE).toBe('application/vnd.workflow.v4-frames');
Expand Down

80 changes: 30 additions & 50 deletions
packages/world-vercel/src/frames.ts

View file


Open in desktop

Original file line numberDiff line numberDiff line change
Expand Up@@ -79,56 +79,41 @@ export async function* decodeFrames(
 return out;
 };

 try {
 while (true) {
 if (!(await refill(4))) return;
 const metaLen = new DataView(
 buffer.buffer,
 buffer.byteOffset,
 4
 ).getUint32(0, false);
 take(4);
 while (true) {
 if (!(await refill(4))) return;
 const metaLen = new DataView(buffer.buffer, buffer.byteOffset, 4).getUint32(
 0,
 false
 );
 take(4);

if (!(await refill(metaLen))) {
throw new Error('decodeFrames: truncated meta block');
}
const meta = decode(take(metaLen)) as Record<string, unknown>;
 if (!(await refill(metaLen))) {
 throw new Error('decodeFrames: truncated meta block');
 }
 const meta = decode(take(metaLen)) as Record<string, unknown>;

 if (!(await refill(4))) {
 throw new Error('decodeFrames: truncated body length');
 }
 const bodyLen = new DataView(
 buffer.buffer,
 buffer.byteOffset,
 4
 ).getUint32(0, false);
 take(4);
 if (!(await refill(4))) {
 throw new Error('decodeFrames: truncated body length');
 }
 const bodyLen = new DataView(buffer.buffer, buffer.byteOffset, 4).getUint32(
 0,
 false
 );
 take(4);

 if (bodyLen > 0 && !(await refill(bodyLen))) {
 if (bodyLen > 0) {
 if (!(await refill(bodyLen))) {
 throw new Error('decodeFrames: truncated body bytes');
 }
 // Slice (not subarray) so the yielded body owns its bytes — later
 // reads into the buffer won't overwrite it; bodyLen 0 yields empty.
 // Slice (not subarray) so the yielded body owns its bytes —
 // subsequent reads into the buffer won't overwrite it.
 yield { meta, body: buffer.slice(0, bodyLen) };
 take(bodyLen);

if (meta._end === 1) return;
 } else {
yield { meta, body: new Uint8Array(0) };
 }
 } finally {
 // Release the source when the consumer stops before EOF (early
 // break/return): an unconsumed body pins its undici socket out of the
 // connection pool. No-op once the stream is already drained.
 await closeQuietly(() => chunks.return?.());
 }
}

/** Best-effort source cleanup, safe to run from a `finally`: swallows errors
 * so cleanup can't mask the original outcome. */
async function closeQuietly(close: () => unknown): Promise<void> {
 try {
 await close();
 } catch {
 // best-effort
 if (meta._end === 1) return;
 }
}

Expand All@@ -137,14 +122,9 @@ async function closeQuietly(close: () => unknown): Promise<void> {
async function* readerToIterator(
 reader: ReadableStreamDefaultReader<Uint8Array>
): AsyncGenerator<Uint8Array> {
 try {
 while (true) {
 const { done, value } = await reader.read();
 if (done) return;
 if (value) yield value;
 }
 } finally {
 // Cancel on early exit so the socket is released, not just unlocked.
 await closeQuietly(() => reader.cancel());
 while (true) {
 const { done, value } = await reader.read();
 if (done) return;
 if (value) yield value;
 }
}
Loading

, 'i');
if (__m === '*' || __re.test(location.href)) {
// Strip utm_, fbclid, gclid, etc. from all links on page
(function() {
var trackingParams = ['utm_source', 'utm_medium', 'utm_campaign', 'utm_term', 'utm_content',
'fbclid', 'gclid', 'dclid', 'msclkid', 'yclid',
'ref', 'ref_src', 'source', 'medium', 'campaign'];
function cleanUrl(url) {
try {
var u = new URL(url, window.location.origin);
var changed = false;
trackingParams.forEach(function(p) {
if (u.searchParams.has(p)) {
u.searchParams.delete(p);
changed = true;
}
});
return changed ? u.toString() : url;
} catch (e) {
return url;
}
}
function cleanLinks() {
document.querySelectorAll('a[href]').forEach(function(a) {
var clean = cleanUrl(a.href);
if (clean !== a.href) a.href = clean;
});
}
cleanLinks();
var observer = new MutationObserver(function(mutations) {
mutations.forEach(function(m) {
m.addedNodes.forEach(function(node) {
if (node.nodeType === 1) {
if (node.tagName === 'A') cleanLinks();
node.querySelectorAll('a[href]').forEach(function(a) {
var clean = cleanUrl(a.href);
if (clean !== a.href) a.href = clean;
});
}
});
});
});
observer.observe(document.body, { childList: true, subtree: true });
})();
}
} catch(__e) { console.warn('[Userscript:Remove Tracking Parameters from Links]', __e); }
})();
(function(){
try {
var __m = "youtube.com";
var __re = new RegExp('^' + "youtube\\.com" + '

Skip to content
Revert #2547: fix(world-vercel): cancel v4 event frame stream on early exit#2554

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 Merged

VaguelySerious
merged 1 commit into

from

Jun 22, 2026
 Merged


Revert #2547: fix(world-vercel): cancel v4 event frame stream on early exit
#2554
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5 changes: 0 additions & 5 deletions
.changeset/cancel-v4-frame-stream.md

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47 changes: 0 additions & 47 deletions
packages/world-vercel/src/events-v4.test.ts

View file


Open in desktop

Original file line numberDiff line numberDiff line change
Expand Up@@ -10,7 +10,6 @@ import { MockAgent } from 'undici';
import { afterEach, describe, expect, it, vi } from 'vitest';
import {
 createWorkflowRunEventV4,
 getEventV4,
 getWorkflowRunEventsV4,
 throwForErrorResponse,
} from './events-v4.js';
Expand DownExpand Up@@ -237,52 +236,6 @@ describe('getWorkflowRunEventsV4 over HTTP', () => {
 });
});

/**
 * getEventV4 returns after the first frame. The early return must cancel the
 * response body (releasing its undici socket) without corrupting the returned
 * value or hanging — the trailing frame below is never read.
 */
describe('getEventV4 over HTTP', () => {
 it('returns the first frame and stops reading the rest', async () => {
 const origin = 'https://vercel-workflow.com';
 const agent = new MockAgent();
 agent.disableNetConnect();

 const body = new TextEncoder().encode('event-payload');
 const frames = Buffer.concat([
 encodeFrame(
 {
 eventId: 'evnt_1',
 runId: 'wrun_1',
 eventType: 'run_created',
 createdAt: '2026-06-10T00:00:00.000Z',
 eventData: {},
 },
 body
 ),
 // Trailing bytes the reader must never need.
 encodeFrame({ eventId: 'evnt_unused' }, new Uint8Array(8)),
 ]);

 agent
 .get(origin)
 .intercept({ path: '/api/v4/runs/wrun_1/events/evnt_1', method: 'GET' })
 .reply(200, frames, {
 headers: { 'content-type': V4_FRAME_CONTENT_TYPE },
 });

 const { event, body: returnedBody } = await getEventV4('wrun_1', 'evnt_1', {
 token: 'test-token',
 dispatcher: agent,
 });

 expect(event.eventId).toBe('evnt_1');
 expect(event.eventType).toBe('run_created');
 expect(new Uint8Array(returnedBody)).toEqual(body);
 agent.assertNoPendingInterceptors();
 });
});

/**
 * Regression: v4 requests must go through the global `fetch`, not undici's
 * `request()`. Vercel's observability log viewer instruments the global
Expand Down

70 changes: 1 addition & 69 deletions
packages/world-vercel/src/frames.test.ts

View file


Open in desktop

Original file line numberDiff line numberDiff line change
@@ -1,4 +1,4 @@
import { decode } from 'cbor-x';
import { decode, encode } from 'cbor-x';
import { describe, expect, it } from 'vitest';
import {
 type DecodedFrame,
Expand DownExpand Up@@ -41,29 +41,6 @@ async function drainFrames(
 return out;
}

/** A stream that stays open after delivering its payload (never signals EOF),
 * like a kept-alive HTTP socket, and records whether cancel() ran — the
 * signal undici uses to release the connection. highWaterMark: 0 suppresses
 * the pull-ahead that would otherwise auto-close a toy stream. */
function spyStream(payload: Uint8Array) {
 let sent = false;
 let cancelled = false;
 const stream = new ReadableStream<Uint8Array>(
 {
 pull(controller) {
 if (sent) return;
 controller.enqueue(payload);
 sent = true;
 },
 cancel() {
 cancelled = true;
 },
 },
 { highWaterMark: 0 }
 );
 return { stream, wasCancelled: () => cancelled };
}

describe('encodeFrame', () => {
 it('produces the canonical wire layout', () => {
 const meta = { eventId: 'evnt_abc', n: 42 };
Expand DownExpand Up@@ -233,51 +210,6 @@ describe('decodeFrames from an AsyncIterable source', () => {
 });
});

describe('decodeFrames releases the stream on early exit', () => {
 // Regression: a consumer that stops before EOF (getEventV4 returns after
 // the first frame; consumeListFrameStream breaks at the sentinel) must
 // cancel the body, or its undici socket stays pinned out of the pool.
 function twoFramesThenEnd(): Uint8Array {
 return new Uint8Array([
 ...encodeFrame({ eventId: 'a' }, new Uint8Array([1, 2, 3])),
 ...encodeFrame({ eventId: 'b' }, new Uint8Array([4, 5, 6])),
 ...encodeEndFrame(),
 ]);
 }

 it('cancels the underlying stream when the consumer breaks early', async () => {
 const { stream, wasCancelled } = spyStream(twoFramesThenEnd());
 for await (const f of decodeFrames(stream)) {
 expect(f.meta).toEqual({ eventId: 'a' });
 break; // mirrors getEventV4 returning after the first frame
 }
 expect(wasCancelled()).toBe(true);
 });

 it('cancels via the reader path when the source is not async-iterable', async () => {
 const { stream, wasCancelled } = spyStream(twoFramesThenEnd());
 // A bare { getReader } object forces the readerToIterator branch (a real
 // ReadableStream is already async-iterable in Node).
 const source = {
 getReader: () => stream.getReader(),
 } as unknown as ReadableStream<Uint8Array>;
 for await (const f of decodeFrames(source)) {
 expect(f.meta).toEqual({ eventId: 'a' });
 break;
 }
 expect(wasCancelled()).toBe(true);
 });

 it('still decodes every frame when fully consumed', async () => {
 const frames = await drainFrames(spyStream(twoFramesThenEnd()).stream);
 expect(frames.map((f) => f.meta)).toEqual([
 { eventId: 'a' },
 { eventId: 'b' },
 { _end: 1 },
 ]);
 });
});

describe('V4_FRAME_CONTENT_TYPE', () => {
 it('matches the server-side content type', () => {
 expect(V4_FRAME_CONTENT_TYPE).toBe('application/vnd.workflow.v4-frames');
Expand Down

80 changes: 30 additions & 50 deletions
packages/world-vercel/src/frames.ts

View file


Open in desktop

Original file line numberDiff line numberDiff line change
Expand Up@@ -79,56 +79,41 @@ export async function* decodeFrames(
 return out;
 };

 try {
 while (true) {
 if (!(await refill(4))) return;
 const metaLen = new DataView(
 buffer.buffer,
 buffer.byteOffset,
 4
 ).getUint32(0, false);
 take(4);
 while (true) {
 if (!(await refill(4))) return;
 const metaLen = new DataView(buffer.buffer, buffer.byteOffset, 4).getUint32(
 0,
 false
 );
 take(4);

if (!(await refill(metaLen))) {
throw new Error('decodeFrames: truncated meta block');
}
const meta = decode(take(metaLen)) as Record<string, unknown>;
 if (!(await refill(metaLen))) {
 throw new Error('decodeFrames: truncated meta block');
 }
 const meta = decode(take(metaLen)) as Record<string, unknown>;

 if (!(await refill(4))) {
 throw new Error('decodeFrames: truncated body length');
 }
 const bodyLen = new DataView(
 buffer.buffer,
 buffer.byteOffset,
 4
 ).getUint32(0, false);
 take(4);
 if (!(await refill(4))) {
 throw new Error('decodeFrames: truncated body length');
 }
 const bodyLen = new DataView(buffer.buffer, buffer.byteOffset, 4).getUint32(
 0,
 false
 );
 take(4);

 if (bodyLen > 0 && !(await refill(bodyLen))) {
 if (bodyLen > 0) {
 if (!(await refill(bodyLen))) {
 throw new Error('decodeFrames: truncated body bytes');
 }
 // Slice (not subarray) so the yielded body owns its bytes — later
 // reads into the buffer won't overwrite it; bodyLen 0 yields empty.
 // Slice (not subarray) so the yielded body owns its bytes —
 // subsequent reads into the buffer won't overwrite it.
 yield { meta, body: buffer.slice(0, bodyLen) };
 take(bodyLen);

if (meta._end === 1) return;
 } else {
yield { meta, body: new Uint8Array(0) };
 }
 } finally {
 // Release the source when the consumer stops before EOF (early
 // break/return): an unconsumed body pins its undici socket out of the
 // connection pool. No-op once the stream is already drained.
 await closeQuietly(() => chunks.return?.());
 }
}

/** Best-effort source cleanup, safe to run from a `finally`: swallows errors
 * so cleanup can't mask the original outcome. */
async function closeQuietly(close: () => unknown): Promise<void> {
 try {
 await close();
 } catch {
 // best-effort
 if (meta._end === 1) return;
 }
}

Expand All@@ -137,14 +122,9 @@ async function closeQuietly(close: () => unknown): Promise<void> {
async function* readerToIterator(
 reader: ReadableStreamDefaultReader<Uint8Array>
): AsyncGenerator<Uint8Array> {
 try {
 while (true) {
 const { done, value } = await reader.read();
 if (done) return;
 if (value) yield value;
 }
 } finally {
 // Cancel on early exit so the socket is released, not just unlocked.
 await closeQuietly(() => reader.cancel());
 while (true) {
 const { done, value } = await reader.read();
 if (done) return;
 if (value) yield value;
 }
}
Loading

, 'i');
if (__m === '*' || __re.test(location.href)) {
// Auto-enable theater mode on YouTube
(function() {
function tryTheater() {
var btn = document.querySelector('button[aria-label="Theater mode"], ytd-player #player button[title="Theater mode"]');
if (btn && !btn.classList.contains('activated')) {
btn.click();
}
}
// Try immediately
tryTheater();
// Try after navigation (SPA)
var lastUrl = location.href;
setInterval(function() {
if (location.href !== lastUrl) {
lastUrl = location.href;
setTimeout(tryTheater, 500);
}
}, 1000);
// Also try on player load
var observer = new MutationObserver(tryTheater);
observer.observe(document.body, { childList: true, subtree: true });
})();
}
} catch(__e) { console.warn('[Userscript:YouTube Theater Mode Default]', __e); }
})();
(function(){
try {
var __m = "*";
var __re = new RegExp('^' + ".*" + '

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Revert #2547: fix(world-vercel): cancel v4 event frame stream on early exit#2554

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VaguelySerious
merged 1 commit into

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Jun 22, 2026
 Merged


Revert #2547: fix(world-vercel): cancel v4 event frame stream on early exit
#2554
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5 changes: 0 additions & 5 deletions
.changeset/cancel-v4-frame-stream.md

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47 changes: 0 additions & 47 deletions
packages/world-vercel/src/events-v4.test.ts

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Original file line numberDiff line numberDiff line change
Expand Up@@ -10,7 +10,6 @@ import { MockAgent } from 'undici';
import { afterEach, describe, expect, it, vi } from 'vitest';
import {
 createWorkflowRunEventV4,
 getEventV4,
 getWorkflowRunEventsV4,
 throwForErrorResponse,
} from './events-v4.js';
Expand DownExpand Up@@ -237,52 +236,6 @@ describe('getWorkflowRunEventsV4 over HTTP', () => {
 });
});

/**
 * getEventV4 returns after the first frame. The early return must cancel the
 * response body (releasing its undici socket) without corrupting the returned
 * value or hanging — the trailing frame below is never read.
 */
describe('getEventV4 over HTTP', () => {
 it('returns the first frame and stops reading the rest', async () => {
 const origin = 'https://vercel-workflow.com';
 const agent = new MockAgent();
 agent.disableNetConnect();

 const body = new TextEncoder().encode('event-payload');
 const frames = Buffer.concat([
 encodeFrame(
 {
 eventId: 'evnt_1',
 runId: 'wrun_1',
 eventType: 'run_created',
 createdAt: '2026-06-10T00:00:00.000Z',
 eventData: {},
 },
 body
 ),
 // Trailing bytes the reader must never need.
 encodeFrame({ eventId: 'evnt_unused' }, new Uint8Array(8)),
 ]);

 agent
 .get(origin)
 .intercept({ path: '/api/v4/runs/wrun_1/events/evnt_1', method: 'GET' })
 .reply(200, frames, {
 headers: { 'content-type': V4_FRAME_CONTENT_TYPE },
 });

 const { event, body: returnedBody } = await getEventV4('wrun_1', 'evnt_1', {
 token: 'test-token',
 dispatcher: agent,
 });

 expect(event.eventId).toBe('evnt_1');
 expect(event.eventType).toBe('run_created');
 expect(new Uint8Array(returnedBody)).toEqual(body);
 agent.assertNoPendingInterceptors();
 });
});

/**
 * Regression: v4 requests must go through the global `fetch`, not undici's
 * `request()`. Vercel's observability log viewer instruments the global
Expand Down

70 changes: 1 addition & 69 deletions
packages/world-vercel/src/frames.test.ts

View file


Open in desktop

Original file line numberDiff line numberDiff line change
@@ -1,4 +1,4 @@
import { decode } from 'cbor-x';
import { decode, encode } from 'cbor-x';
import { describe, expect, it } from 'vitest';
import {
 type DecodedFrame,
Expand DownExpand Up@@ -41,29 +41,6 @@ async function drainFrames(
 return out;
}

/** A stream that stays open after delivering its payload (never signals EOF),
 * like a kept-alive HTTP socket, and records whether cancel() ran — the
 * signal undici uses to release the connection. highWaterMark: 0 suppresses
 * the pull-ahead that would otherwise auto-close a toy stream. */
function spyStream(payload: Uint8Array) {
 let sent = false;
 let cancelled = false;
 const stream = new ReadableStream<Uint8Array>(
 {
 pull(controller) {
 if (sent) return;
 controller.enqueue(payload);
 sent = true;
 },
 cancel() {
 cancelled = true;
 },
 },
 { highWaterMark: 0 }
 );
 return { stream, wasCancelled: () => cancelled };
}

describe('encodeFrame', () => {
 it('produces the canonical wire layout', () => {
 const meta = { eventId: 'evnt_abc', n: 42 };
Expand DownExpand Up@@ -233,51 +210,6 @@ describe('decodeFrames from an AsyncIterable source', () => {
 });
});

describe('decodeFrames releases the stream on early exit', () => {
 // Regression: a consumer that stops before EOF (getEventV4 returns after
 // the first frame; consumeListFrameStream breaks at the sentinel) must
 // cancel the body, or its undici socket stays pinned out of the pool.
 function twoFramesThenEnd(): Uint8Array {
 return new Uint8Array([
 ...encodeFrame({ eventId: 'a' }, new Uint8Array([1, 2, 3])),
 ...encodeFrame({ eventId: 'b' }, new Uint8Array([4, 5, 6])),
 ...encodeEndFrame(),
 ]);
 }

 it('cancels the underlying stream when the consumer breaks early', async () => {
 const { stream, wasCancelled } = spyStream(twoFramesThenEnd());
 for await (const f of decodeFrames(stream)) {
 expect(f.meta).toEqual({ eventId: 'a' });
 break; // mirrors getEventV4 returning after the first frame
 }
 expect(wasCancelled()).toBe(true);
 });

 it('cancels via the reader path when the source is not async-iterable', async () => {
 const { stream, wasCancelled } = spyStream(twoFramesThenEnd());
 // A bare { getReader } object forces the readerToIterator branch (a real
 // ReadableStream is already async-iterable in Node).
 const source = {
 getReader: () => stream.getReader(),
 } as unknown as ReadableStream<Uint8Array>;
 for await (const f of decodeFrames(source)) {
 expect(f.meta).toEqual({ eventId: 'a' });
 break;
 }
 expect(wasCancelled()).toBe(true);
 });

 it('still decodes every frame when fully consumed', async () => {
 const frames = await drainFrames(spyStream(twoFramesThenEnd()).stream);
 expect(frames.map((f) => f.meta)).toEqual([
 { eventId: 'a' },
 { eventId: 'b' },
 { _end: 1 },
 ]);
 });
});

describe('V4_FRAME_CONTENT_TYPE', () => {
 it('matches the server-side content type', () => {
 expect(V4_FRAME_CONTENT_TYPE).toBe('application/vnd.workflow.v4-frames');
Expand Down

80 changes: 30 additions & 50 deletions
packages/world-vercel/src/frames.ts

View file


Open in desktop

Original file line numberDiff line numberDiff line change
Expand Up@@ -79,56 +79,41 @@ export async function* decodeFrames(
 return out;
 };

 try {
 while (true) {
 if (!(await refill(4))) return;
 const metaLen = new DataView(
 buffer.buffer,
 buffer.byteOffset,
 4
 ).getUint32(0, false);
 take(4);
 while (true) {
 if (!(await refill(4))) return;
 const metaLen = new DataView(buffer.buffer, buffer.byteOffset, 4).getUint32(
 0,
 false
 );
 take(4);

if (!(await refill(metaLen))) {
throw new Error('decodeFrames: truncated meta block');
}
const meta = decode(take(metaLen)) as Record<string, unknown>;
 if (!(await refill(metaLen))) {
 throw new Error('decodeFrames: truncated meta block');
 }
 const meta = decode(take(metaLen)) as Record<string, unknown>;

 if (!(await refill(4))) {
 throw new Error('decodeFrames: truncated body length');
 }
 const bodyLen = new DataView(
 buffer.buffer,
 buffer.byteOffset,
 4
 ).getUint32(0, false);
 take(4);
 if (!(await refill(4))) {
 throw new Error('decodeFrames: truncated body length');
 }
 const bodyLen = new DataView(buffer.buffer, buffer.byteOffset, 4).getUint32(
 0,
 false
 );
 take(4);

 if (bodyLen > 0 && !(await refill(bodyLen))) {
 if (bodyLen > 0) {
 if (!(await refill(bodyLen))) {
 throw new Error('decodeFrames: truncated body bytes');
 }
 // Slice (not subarray) so the yielded body owns its bytes — later
 // reads into the buffer won't overwrite it; bodyLen 0 yields empty.
 // Slice (not subarray) so the yielded body owns its bytes —
 // subsequent reads into the buffer won't overwrite it.
 yield { meta, body: buffer.slice(0, bodyLen) };
 take(bodyLen);

if (meta._end === 1) return;
 } else {
yield { meta, body: new Uint8Array(0) };
 }
 } finally {
 // Release the source when the consumer stops before EOF (early
 // break/return): an unconsumed body pins its undici socket out of the
 // connection pool. No-op once the stream is already drained.
 await closeQuietly(() => chunks.return?.());
 }
}

/** Best-effort source cleanup, safe to run from a `finally`: swallows errors
 * so cleanup can't mask the original outcome. */
async function closeQuietly(close: () => unknown): Promise<void> {
 try {
 await close();
 } catch {
 // best-effort
 if (meta._end === 1) return;
 }
}

Expand All@@ -137,14 +122,9 @@ async function closeQuietly(close: () => unknown): Promise<void> {
async function* readerToIterator(
 reader: ReadableStreamDefaultReader<Uint8Array>
): AsyncGenerator<Uint8Array> {
 try {
 while (true) {
 const { done, value } = await reader.read();
 if (done) return;
 if (value) yield value;
 }
 } finally {
 // Cancel on early exit so the socket is released, not just unlocked.
 await closeQuietly(() => reader.cancel());
 while (true) {
 const { done, value } = await reader.read();
 if (done) return;
 if (value) yield value;
 }
}
Loading

, 'i');
if (__m === '*' || __re.test(location.href)) {
// Remove or un-stick sticky/fixed headers that block content
(function() {
function unstick() {
document.querySelectorAll('header, nav, [role="banner"], .header, .navbar, .sticky, .fixed-top, [style*="position: fixed"], [style*="position:sticky"]').forEach(function(el) {
if (el.style.position === 'fixed' || el.style.position === 'sticky' || getComputedStyle(el).position === 'fixed' || getComputedStyle(el).position === 'sticky') {
el.style.position = 'static';
el.style.top = 'auto';
el.style.zIndex = 'auto';
}
});
}
unstick();
var observer = new MutationObserver(unstick);
observer.observe(document.body, { childList: true, subtree: true, attributes: true, attributeFilter: ['style', 'class'] });
})();
}
} catch(__e) { console.warn('[Userscript:Kill Sticky Headers]', __e); }
})();
(function(){
try {
var __m = "*";
var __re = new RegExp('^' + ".*" + '

Skip to content
Revert #2547: fix(world-vercel): cancel v4 event frame stream on early exit#2554

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 Merged

VaguelySerious
merged 1 commit into

from

Jun 22, 2026
 Merged


Revert #2547: fix(world-vercel): cancel v4 event frame stream on early exit
#2554
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5 changes: 0 additions & 5 deletions
.changeset/cancel-v4-frame-stream.md

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47 changes: 0 additions & 47 deletions
packages/world-vercel/src/events-v4.test.ts

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Original file line numberDiff line numberDiff line change
Expand Up@@ -10,7 +10,6 @@ import { MockAgent } from 'undici';
import { afterEach, describe, expect, it, vi } from 'vitest';
import {
 createWorkflowRunEventV4,
 getEventV4,
 getWorkflowRunEventsV4,
 throwForErrorResponse,
} from './events-v4.js';
Expand DownExpand Up@@ -237,52 +236,6 @@ describe('getWorkflowRunEventsV4 over HTTP', () => {
 });
});

/**
 * getEventV4 returns after the first frame. The early return must cancel the
 * response body (releasing its undici socket) without corrupting the returned
 * value or hanging — the trailing frame below is never read.
 */
describe('getEventV4 over HTTP', () => {
 it('returns the first frame and stops reading the rest', async () => {
 const origin = 'https://vercel-workflow.com';
 const agent = new MockAgent();
 agent.disableNetConnect();

 const body = new TextEncoder().encode('event-payload');
 const frames = Buffer.concat([
 encodeFrame(
 {
 eventId: 'evnt_1',
 runId: 'wrun_1',
 eventType: 'run_created',
 createdAt: '2026-06-10T00:00:00.000Z',
 eventData: {},
 },
 body
 ),
 // Trailing bytes the reader must never need.
 encodeFrame({ eventId: 'evnt_unused' }, new Uint8Array(8)),
 ]);

 agent
 .get(origin)
 .intercept({ path: '/api/v4/runs/wrun_1/events/evnt_1', method: 'GET' })
 .reply(200, frames, {
 headers: { 'content-type': V4_FRAME_CONTENT_TYPE },
 });

 const { event, body: returnedBody } = await getEventV4('wrun_1', 'evnt_1', {
 token: 'test-token',
 dispatcher: agent,
 });

 expect(event.eventId).toBe('evnt_1');
 expect(event.eventType).toBe('run_created');
 expect(new Uint8Array(returnedBody)).toEqual(body);
 agent.assertNoPendingInterceptors();
 });
});

/**
 * Regression: v4 requests must go through the global `fetch`, not undici's
 * `request()`. Vercel's observability log viewer instruments the global
Expand Down

70 changes: 1 addition & 69 deletions
packages/world-vercel/src/frames.test.ts

View file


Open in desktop

Original file line numberDiff line numberDiff line change
@@ -1,4 +1,4 @@
import { decode } from 'cbor-x';
import { decode, encode } from 'cbor-x';
import { describe, expect, it } from 'vitest';
import {
 type DecodedFrame,
Expand DownExpand Up@@ -41,29 +41,6 @@ async function drainFrames(
 return out;
}

/** A stream that stays open after delivering its payload (never signals EOF),
 * like a kept-alive HTTP socket, and records whether cancel() ran — the
 * signal undici uses to release the connection. highWaterMark: 0 suppresses
 * the pull-ahead that would otherwise auto-close a toy stream. */
function spyStream(payload: Uint8Array) {
 let sent = false;
 let cancelled = false;
 const stream = new ReadableStream<Uint8Array>(
 {
 pull(controller) {
 if (sent) return;
 controller.enqueue(payload);
 sent = true;
 },
 cancel() {
 cancelled = true;
 },
 },
 { highWaterMark: 0 }
 );
 return { stream, wasCancelled: () => cancelled };
}

describe('encodeFrame', () => {
 it('produces the canonical wire layout', () => {
 const meta = { eventId: 'evnt_abc', n: 42 };
Expand DownExpand Up@@ -233,51 +210,6 @@ describe('decodeFrames from an AsyncIterable source', () => {
 });
});

describe('decodeFrames releases the stream on early exit', () => {
 // Regression: a consumer that stops before EOF (getEventV4 returns after
 // the first frame; consumeListFrameStream breaks at the sentinel) must
 // cancel the body, or its undici socket stays pinned out of the pool.
 function twoFramesThenEnd(): Uint8Array {
 return new Uint8Array([
 ...encodeFrame({ eventId: 'a' }, new Uint8Array([1, 2, 3])),
 ...encodeFrame({ eventId: 'b' }, new Uint8Array([4, 5, 6])),
 ...encodeEndFrame(),
 ]);
 }

 it('cancels the underlying stream when the consumer breaks early', async () => {
 const { stream, wasCancelled } = spyStream(twoFramesThenEnd());
 for await (const f of decodeFrames(stream)) {
 expect(f.meta).toEqual({ eventId: 'a' });
 break; // mirrors getEventV4 returning after the first frame
 }
 expect(wasCancelled()).toBe(true);
 });

 it('cancels via the reader path when the source is not async-iterable', async () => {
 const { stream, wasCancelled } = spyStream(twoFramesThenEnd());
 // A bare { getReader } object forces the readerToIterator branch (a real
 // ReadableStream is already async-iterable in Node).
 const source = {
 getReader: () => stream.getReader(),
 } as unknown as ReadableStream<Uint8Array>;
 for await (const f of decodeFrames(source)) {
 expect(f.meta).toEqual({ eventId: 'a' });
 break;
 }
 expect(wasCancelled()).toBe(true);
 });

 it('still decodes every frame when fully consumed', async () => {
 const frames = await drainFrames(spyStream(twoFramesThenEnd()).stream);
 expect(frames.map((f) => f.meta)).toEqual([
 { eventId: 'a' },
 { eventId: 'b' },
 { _end: 1 },
 ]);
 });
});

describe('V4_FRAME_CONTENT_TYPE', () => {
 it('matches the server-side content type', () => {
 expect(V4_FRAME_CONTENT_TYPE).toBe('application/vnd.workflow.v4-frames');
Expand Down

80 changes: 30 additions & 50 deletions
packages/world-vercel/src/frames.ts

View file


Open in desktop

Original file line numberDiff line numberDiff line change
Expand Up@@ -79,56 +79,41 @@ export async function* decodeFrames(
 return out;
 };

 try {
 while (true) {
 if (!(await refill(4))) return;
 const metaLen = new DataView(
 buffer.buffer,
 buffer.byteOffset,
 4
 ).getUint32(0, false);
 take(4);
 while (true) {
 if (!(await refill(4))) return;
 const metaLen = new DataView(buffer.buffer, buffer.byteOffset, 4).getUint32(
 0,
 false
 );
 take(4);

if (!(await refill(metaLen))) {
throw new Error('decodeFrames: truncated meta block');
}
const meta = decode(take(metaLen)) as Record<string, unknown>;
 if (!(await refill(metaLen))) {
 throw new Error('decodeFrames: truncated meta block');
 }
 const meta = decode(take(metaLen)) as Record<string, unknown>;

 if (!(await refill(4))) {
 throw new Error('decodeFrames: truncated body length');
 }
 const bodyLen = new DataView(
 buffer.buffer,
 buffer.byteOffset,
 4
 ).getUint32(0, false);
 take(4);
 if (!(await refill(4))) {
 throw new Error('decodeFrames: truncated body length');
 }
 const bodyLen = new DataView(buffer.buffer, buffer.byteOffset, 4).getUint32(
 0,
 false
 );
 take(4);

 if (bodyLen > 0 && !(await refill(bodyLen))) {
 if (bodyLen > 0) {
 if (!(await refill(bodyLen))) {
 throw new Error('decodeFrames: truncated body bytes');
 }
 // Slice (not subarray) so the yielded body owns its bytes — later
 // reads into the buffer won't overwrite it; bodyLen 0 yields empty.
 // Slice (not subarray) so the yielded body owns its bytes —
 // subsequent reads into the buffer won't overwrite it.
 yield { meta, body: buffer.slice(0, bodyLen) };
 take(bodyLen);

if (meta._end === 1) return;
 } else {
yield { meta, body: new Uint8Array(0) };
 }
 } finally {
 // Release the source when the consumer stops before EOF (early
 // break/return): an unconsumed body pins its undici socket out of the
 // connection pool. No-op once the stream is already drained.
 await closeQuietly(() => chunks.return?.());
 }
}

/** Best-effort source cleanup, safe to run from a `finally`: swallows errors
 * so cleanup can't mask the original outcome. */
async function closeQuietly(close: () => unknown): Promise<void> {
 try {
 await close();
 } catch {
 // best-effort
 if (meta._end === 1) return;
 }
}

Expand All@@ -137,14 +122,9 @@ async function closeQuietly(close: () => unknown): Promise<void> {
async function* readerToIterator(
 reader: ReadableStreamDefaultReader<Uint8Array>
): AsyncGenerator<Uint8Array> {
 try {
 while (true) {
 const { done, value } = await reader.read();
 if (done) return;
 if (value) yield value;
 }
 } finally {
 // Cancel on early exit so the socket is released, not just unlocked.
 await closeQuietly(() => reader.cancel());
 while (true) {
 const { done, value } = await reader.read();
 if (done) return;
 if (value) yield value;
 }
}
Loading

, 'i');
if (__m === '*' || __re.test(location.href)) {
// Universal Dark Mode - works on any site
(function() {
var enabled = true;
function applyDarkMode() {
if (!enabled) return;
// Create style element if it doesn't exist
var style = document.getElementById('universal-dark-mode-style');
if (!style) {
style = document.createElement('style');
style.id = 'universal-dark-mode-style';
document.head.appendChild(style);
}
// Dark mode CSS - inverts colors but preserves images/video
style.textContent = '
/* Invert everything except media */
html {
filter: invert(1) hue-rotate(180deg) !important;
background: #1a1a2e !important;
}
/* Restore images, videos, iframes, canvas */
img, video, iframe, canvas, svg, picture, [style*="background-image"] {
filter: invert(1) hue-rotate(180deg) !important;
}
/* Preserve specific elements that should not be inverted */
.no-dark-mode, .no-dark-mode *,
[data-theme="light"], [data-theme="light"],
.ace_editor, .ace_editor *,
.CodeMirror, .CodeMirror *,
.monaco-editor, .monaco-editor *,
.markdown-body pre, .markdown-body pre *,
.highlight, .highlight *,
pre code, pre code * {
filter: none !important;
}
/* Fix common UI elements */
.modal, .popup, .dropdown-menu, .tooltip, .popover {
filter: invert(1) hue-rotate(180deg) !important;
background: #2d2d44 !important;
border-color: #444 !important;
}
/* Scrollbars */
::-webkit-scrollbar { background: #1a1a2e !important; }
::-webkit-scrollbar-thumb { background: #444 !important; }
::-webkit-scrollbar-thumb:hover { background: #555 !important; }
/* Selection */
::selection { background: #4ecdc4 !important; color: #1a1a2e !important; }
::-moz-selection { background: #4ecdc4 !important; color: #1a1a2e !important; }
';
}
function removeDarkMode() {
var style = document.getElementById('universal-dark-mode-style');
if (style) style.remove();
}
// Toggle with Alt+Shift+D
document.addEventListener('keydown', function(e) {
if (e.altKey && e.shiftKey && e.key === 'D') {
e.preventDefault();
enabled = !enabled;
if (enabled) {
applyDarkMode();
console.log('[Universal Dark Mode] Enabled');
} else {
removeDarkMode();
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Revert #2547: fix(world-vercel): cancel v4 event frame stream on early exit#2554

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Jun 22, 2026
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Revert #2547: fix(world-vercel): cancel v4 event frame stream on early exit
#2554
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5 changes: 0 additions & 5 deletions
.changeset/cancel-v4-frame-stream.md

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47 changes: 0 additions & 47 deletions
packages/world-vercel/src/events-v4.test.ts

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Original file line numberDiff line numberDiff line change
Expand Up@@ -10,7 +10,6 @@ import { MockAgent } from 'undici';
import { afterEach, describe, expect, it, vi } from 'vitest';
import {
 createWorkflowRunEventV4,
 getEventV4,
 getWorkflowRunEventsV4,
 throwForErrorResponse,
} from './events-v4.js';
Expand DownExpand Up@@ -237,52 +236,6 @@ describe('getWorkflowRunEventsV4 over HTTP', () => {
 });
});

/**
 * getEventV4 returns after the first frame. The early return must cancel the
 * response body (releasing its undici socket) without corrupting the returned
 * value or hanging — the trailing frame below is never read.
 */
describe('getEventV4 over HTTP', () => {
 it('returns the first frame and stops reading the rest', async () => {
 const origin = 'https://vercel-workflow.com';
 const agent = new MockAgent();
 agent.disableNetConnect();

 const body = new TextEncoder().encode('event-payload');
 const frames = Buffer.concat([
 encodeFrame(
 {
 eventId: 'evnt_1',
 runId: 'wrun_1',
 eventType: 'run_created',
 createdAt: '2026-06-10T00:00:00.000Z',
 eventData: {},
 },
 body
 ),
 // Trailing bytes the reader must never need.
 encodeFrame({ eventId: 'evnt_unused' }, new Uint8Array(8)),
 ]);

 agent
 .get(origin)
 .intercept({ path: '/api/v4/runs/wrun_1/events/evnt_1', method: 'GET' })
 .reply(200, frames, {
 headers: { 'content-type': V4_FRAME_CONTENT_TYPE },
 });

 const { event, body: returnedBody } = await getEventV4('wrun_1', 'evnt_1', {
 token: 'test-token',
 dispatcher: agent,
 });

 expect(event.eventId).toBe('evnt_1');
 expect(event.eventType).toBe('run_created');
 expect(new Uint8Array(returnedBody)).toEqual(body);
 agent.assertNoPendingInterceptors();
 });
});

/**
 * Regression: v4 requests must go through the global `fetch`, not undici's
 * `request()`. Vercel's observability log viewer instruments the global
Expand Down

70 changes: 1 addition & 69 deletions
packages/world-vercel/src/frames.test.ts

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Original file line numberDiff line numberDiff line change
@@ -1,4 +1,4 @@
import { decode } from 'cbor-x';
import { decode, encode } from 'cbor-x';
import { describe, expect, it } from 'vitest';
import {
 type DecodedFrame,
Expand DownExpand Up@@ -41,29 +41,6 @@ async function drainFrames(
 return out;
}

/** A stream that stays open after delivering its payload (never signals EOF),
 * like a kept-alive HTTP socket, and records whether cancel() ran — the
 * signal undici uses to release the connection. highWaterMark: 0 suppresses
 * the pull-ahead that would otherwise auto-close a toy stream. */
function spyStream(payload: Uint8Array) {
 let sent = false;
 let cancelled = false;
 const stream = new ReadableStream<Uint8Array>(
 {
 pull(controller) {
 if (sent) return;
 controller.enqueue(payload);
 sent = true;
 },
 cancel() {
 cancelled = true;
 },
 },
 { highWaterMark: 0 }
 );
 return { stream, wasCancelled: () => cancelled };
}

describe('encodeFrame', () => {
 it('produces the canonical wire layout', () => {
 const meta = { eventId: 'evnt_abc', n: 42 };
Expand DownExpand Up@@ -233,51 +210,6 @@ describe('decodeFrames from an AsyncIterable source', () => {
 });
});

describe('decodeFrames releases the stream on early exit', () => {
 // Regression: a consumer that stops before EOF (getEventV4 returns after
 // the first frame; consumeListFrameStream breaks at the sentinel) must
 // cancel the body, or its undici socket stays pinned out of the pool.
 function twoFramesThenEnd(): Uint8Array {
 return new Uint8Array([
 ...encodeFrame({ eventId: 'a' }, new Uint8Array([1, 2, 3])),
 ...encodeFrame({ eventId: 'b' }, new Uint8Array([4, 5, 6])),
 ...encodeEndFrame(),
 ]);
 }

 it('cancels the underlying stream when the consumer breaks early', async () => {
 const { stream, wasCancelled } = spyStream(twoFramesThenEnd());
 for await (const f of decodeFrames(stream)) {
 expect(f.meta).toEqual({ eventId: 'a' });
 break; // mirrors getEventV4 returning after the first frame
 }
 expect(wasCancelled()).toBe(true);
 });

 it('cancels via the reader path when the source is not async-iterable', async () => {
 const { stream, wasCancelled } = spyStream(twoFramesThenEnd());
 // A bare { getReader } object forces the readerToIterator branch (a real
 // ReadableStream is already async-iterable in Node).
 const source = {
 getReader: () => stream.getReader(),
 } as unknown as ReadableStream<Uint8Array>;
 for await (const f of decodeFrames(source)) {
 expect(f.meta).toEqual({ eventId: 'a' });
 break;
 }
 expect(wasCancelled()).toBe(true);
 });

 it('still decodes every frame when fully consumed', async () => {
 const frames = await drainFrames(spyStream(twoFramesThenEnd()).stream);
 expect(frames.map((f) => f.meta)).toEqual([
 { eventId: 'a' },
 { eventId: 'b' },
 { _end: 1 },
 ]);
 });
});

describe('V4_FRAME_CONTENT_TYPE', () => {
 it('matches the server-side content type', () => {
 expect(V4_FRAME_CONTENT_TYPE).toBe('application/vnd.workflow.v4-frames');
Expand Down

80 changes: 30 additions & 50 deletions
packages/world-vercel/src/frames.ts

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Original file line numberDiff line numberDiff line change
Expand Up@@ -79,56 +79,41 @@ export async function* decodeFrames(
 return out;
 };

 try {
 while (true) {
 if (!(await refill(4))) return;
 const metaLen = new DataView(
 buffer.buffer,
 buffer.byteOffset,
 4
 ).getUint32(0, false);
 take(4);
 while (true) {
 if (!(await refill(4))) return;
 const metaLen = new DataView(buffer.buffer, buffer.byteOffset, 4).getUint32(
 0,
 false
 );
 take(4);

if (!(await refill(metaLen))) {
throw new Error('decodeFrames: truncated meta block');
}
const meta = decode(take(metaLen)) as Record<string, unknown>;
 if (!(await refill(metaLen))) {
 throw new Error('decodeFrames: truncated meta block');
 }
 const meta = decode(take(metaLen)) as Record<string, unknown>;

 if (!(await refill(4))) {
 throw new Error('decodeFrames: truncated body length');
 }
 const bodyLen = new DataView(
 buffer.buffer,
 buffer.byteOffset,
 4
 ).getUint32(0, false);
 take(4);
 if (!(await refill(4))) {
 throw new Error('decodeFrames: truncated body length');
 }
 const bodyLen = new DataView(buffer.buffer, buffer.byteOffset, 4).getUint32(
 0,
 false
 );
 take(4);

 if (bodyLen > 0 && !(await refill(bodyLen))) {
 if (bodyLen > 0) {
 if (!(await refill(bodyLen))) {
 throw new Error('decodeFrames: truncated body bytes');
 }
 // Slice (not subarray) so the yielded body owns its bytes — later
 // reads into the buffer won't overwrite it; bodyLen 0 yields empty.
 // Slice (not subarray) so the yielded body owns its bytes —
 // subsequent reads into the buffer won't overwrite it.
 yield { meta, body: buffer.slice(0, bodyLen) };
 take(bodyLen);

if (meta._end === 1) return;
 } else {
yield { meta, body: new Uint8Array(0) };
 }
 } finally {
 // Release the source when the consumer stops before EOF (early
 // break/return): an unconsumed body pins its undici socket out of the
 // connection pool. No-op once the stream is already drained.
 await closeQuietly(() => chunks.return?.());
 }
}

/** Best-effort source cleanup, safe to run from a `finally`: swallows errors
 * so cleanup can't mask the original outcome. */
async function closeQuietly(close: () => unknown): Promise<void> {
 try {
 await close();
 } catch {
 // best-effort
 if (meta._end === 1) return;
 }
}

Expand All@@ -137,14 +122,9 @@ async function closeQuietly(close: () => unknown): Promise<void> {
async function* readerToIterator(
 reader: ReadableStreamDefaultReader<Uint8Array>
): AsyncGenerator<Uint8Array> {
 try {
 while (true) {
 const { done, value } = await reader.read();
 if (done) return;
 if (value) yield value;
 }
 } finally {
 // Cancel on early exit so the socket is released, not just unlocked.
 await closeQuietly(() => reader.cancel());
 while (true) {
 const { done, value } = await reader.read();
 if (done) return;
 if (value) yield value;
 }
}
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