[core] Fix webhook 404s on Nitro apps running Node 24 by VaguelySerious · Pull Request #4575 · vercel/workflow

VaguelySerious · 2026-10-01T20:03:53Z

Webhooks on Nitro-based apps (Express, Fastify, and other nitro presets) return 404 on Node 24. Every resumeWebhook call fails while serializing the incoming request:

Error during resumeWebhook Error: Failed to serialize step return value
Caused by: TypeError: Cannot read private member #headersList from an object whose class did not declare it
    at headersToEntries (serialization/hardened.ts)

This is what turned the express/fastify Vercel e2e lanes red on main (webhookWorkflow, parallelStepsThenWebhookWorkflow). Those lanes went red when the workbench projects' runtime moved from nodejs22.x to nodejs24.x. No SDK commit caused it.

Cause

srvx (Nitro's server layer) gives handlers a Headers look-alike. It inherits from Headers.prototype and forwards every member, symbol-keyed ones included, to a native Headers it creates lazily. headersToEntries iterates with the native iterator captured at boot:

Node 22: undici reads header state through a symbol-keyed prototype accessor, which srvx forwards, so this works.
Node 24: undici keeps that state in #headersList private fields. A forwarding wrapper can't provide those, so the iterator throws.

Fix

If the native iterator throws a TypeError, iterate through the object's own iterator instead, and record that as guest code ({ kind: 'method', detail: 'Headers[Symbol.iterator]' }), the same way other non-intrinsic execution in this module is recorded. Genuine Headers instances, from the host or the VM, still take the side-effect-free path and record nothing.

Testing

New test in hardened.test.ts: a forwarding look-alike shaped like srvx's NodeRequestHeaders round-trips and records the fallback. It fails on main with the #headersList TypeError on Node 20, 22 and 24, and passes on Node 22 and 24 with the fix.
Checked by hand on Node 24: real srvx 0.12.8 NodeRequest headers go through the built devalueCodec and round-trip.
The express/fastify Vercel Prod lanes in this PR's CI exercise the end-to-end path on Node 24.

🤖 Generated with Claude Code

srvx (Nitro) hands out request headers that inherit from Headers.prototype but forward to a wrapped native instance. Node 24's undici keeps header state in private fields, so the boot-captured Headers iterator rejects them, and resumeWebhook failed with a SerializationError (404) for every webhook on Nitro apps. Fall back to the object's own iterator and record it as guest code. Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

vercel · 2026-10-01T20:03:56Z

The latest updates on your projects. Learn more about Vercel for GitHub.

Project	Deployment	Actions	Updated
example-nextjs-workflow-turbopack	Ready	Preview, v0	Oct 1, 2026 8:09pm UTC
example-nextjs-workflow-webpack	Ready	Preview, v0	Oct 1, 2026 8:09pm UTC
example-workflow	Ready	Preview, v0	Oct 1, 2026 8:09pm UTC
workbench-astro-workflow	Ready	Preview, v0	Oct 1, 2026 8:09pm UTC
workbench-express-workflow	Ready	Preview, v0	Oct 1, 2026 8:09pm UTC
workbench-fastify-workflow	Ready	Preview, v0	Oct 1, 2026 8:09pm UTC
workbench-hono-workflow	Ready	Preview, v0	Oct 1, 2026 8:09pm UTC
workbench-nestjs-workflow	Ready	Preview, v0	Oct 1, 2026 8:09pm UTC
workbench-nitro-workflow	Ready	Preview, v0	Oct 1, 2026 8:09pm UTC
workbench-nuxt-workflow	Ready	Preview, v0	Oct 1, 2026 8:09pm UTC
workbench-python-workflow	Ready	Preview, v0	Oct 1, 2026 8:09pm UTC
workbench-sveltekit-workflow	Ready	Preview, v0	Oct 1, 2026 8:09pm UTC
workbench-tanstack-start-workflow	Ready	Preview, v0	Oct 1, 2026 8:09pm UTC
workbench-vite-workflow	Ready	Preview, v0	Oct 1, 2026 8:09pm UTC
workflow-docs	Ready	Preview, v0	Oct 1, 2026 8:09pm UTC
workflow-swc-playground	Ready	Preview, v0	Oct 1, 2026 8:09pm UTC
workflow-tarballs	Ready	Preview, v0	Oct 1, 2026 8:09pm UTC
workflow-web	Ready	Preview, v0	Oct 1, 2026 8:09pm UTC

changeset-bot · 2026-10-01T20:03:58Z

🦋 Changeset detected

Latest commit: 33476aa

The changes in this PR will be included in the next version bump.

This PR includes changesets to release 17 packages

Name	Type
@workflow/core	Patch
@workflow/builders	Patch
@workflow/cli	Patch
@workflow/next	Patch
@workflow/nitro	Patch
@workflow/vitest	Patch
@workflow/web-shared	Patch
@workflow/web	Patch
workflow	Patch
@workflow/world-testing	Patch
@workflow/astro	Patch
@workflow/nest	Patch
@workflow/rollup	Patch
@workflow/sveltekit	Patch
@workflow/vite	Patch
@workflow/nuxt	Patch
@workflow/world-vercel	Patch

Not sure what this means? Click here to learn what changesets are.

Click here if you're a maintainer who wants to add another changeset to this PR

github-actions · 2026-10-01T20:04:33Z

📊 Workflow Benchmarks

commit 33476aa · Thu, 01 Oct 2026 20:30:58 GMT · run logs

Backend: vercel · app: nextjs-turbopack

Metric	Scenario	Best (ms)	P75 (ms)	P90 (ms)	P99 (ms)	Samples
TTFS	step	2232 (+30%) 🔻	2378 🔴 (+25%) 🔻	2420 🔴 (+24%) 🔻	2489 🔴 (+18%) 🔻	30
TTFS	stream	2225 (+68%) 🔻	2301 🔴 (+30%) 🔻	2326 🔴 (+29%) 🔻	2371 🔴 (+27%) 🔻	30
TTFS	hook + stream	2458 (+24%) 🔻	2608 🔴 (+20%) 🔻	2647 🔴 (+14%)	2728 🔴 (+7.7%)	30
Fan-out TTFS	Promise.all(100 steps)	553 (+13%)	757 (+14%)	2591 (+52%) 🔻	2600 (+27%) 🔻	10
Fan-out TTLS	Promise.all(100 steps)	1511 (-10%)	3024 (+5.2%)	4941 (+5.3%)	10154 (+39%) 🔻	10
STSO	1020 steps (inline)	148 (-1.3%)	184 (-22%) 💚	205 (-30%) 💚	337 (-50%) 💚	1019
WO	1020 steps	183864 (-21%) 💚	183864 (-21%) 💚	183864 (-21%) 💚	183864 (-21%) 💚	1
CRTT	first chunk (pooled)	70 (-5.4%)	114 (±0%)	195 (+42%) 🔻	4203 (+2527%) 🔻	28

Streams

Scenario	CRTT 1st	p75	p90	p99	CDV max	iters
paced control (100/s, 60B)	92.5 (-14%)	172 (+4%)	705 (+209%)	4174 (+761%)	149 (-14%)	10
size sweep (100/s, 160B-12KB)	106 (+11%)	215 (+24%)	624 (+134%)	968 (-44%)	209 (+33%)	10
replay gateway-gpt-5.4-nano-2000t (1x)	90 (-18%)	155 (+1%)	193 (-1%)	450 (+36%)	331 (+56%)	3
replay eve-gpt-5.6-sol-2000t (1x)	90 (-24%)	160 (-14%)	194 (-21%)	410 (-7%)	319 (+16%)	2
replay eve-gpt-5.6-sol-2000t (2x)	110 (±0%)	204 (-2%)	286 (+3%)	461 (-3%)	336 (+18%)	3

📈 STSO distribution vs main (inline / queue-hop histograms)

1020 steps (inline)

Cumulative STSO time: main 232433ms → this run 183494ms (Δ -48939ms, -21%)

  100-150 ms  ┃                         main   0  this   5    +5
  150-200 ms  ████████████░░░░░░░░░░░┃  main 447  this 894  +447
  200-250 ms  █┃████████                main 381  this  84  -297
  250-300 ms  ┃██                       main  98  this  19   -79
  300-350 ms  ┃                         main  36  this   8   -28
  350-400 ms  ┃                         main  15  this   4   -11
  400-450 ms  ┃                         main  10  this   2    -8
  450-500 ms  ┃                         main  12  this   2   -10
  500-550 ms  ┃                         main   5  this   1    -4
  550-600 ms  ┃                         main   3  this   0    -3
  600-650 ms  ┃                         main   1  this   0    -1
  650-700 ms  ┃                         main   4  this   0    -4
  700-750 ms  ┃                         main   1  this   0    -1
  750-800 ms  ┃                         main   1  this   0    -1
  800-850 ms  ┃                         main   2  this   0    -2
  850-900 ms  ┃                         main   1  this   0    -1
  900-950 ms  ┃                         main   1  this   0    -1
1200-1250 ms  ┃                         main   1  this   0    -1

📈 CRTT drill-down vs main (RTT distributions & profiles)

variant  RTT 1ms→5s+              avg         p50          p90           p99     n
control  ······▃█▂▁▁▁·  416.5 (+207%)   123 (-1%)  705 (+209%)  4174 (+761%)  3000
sweep    ······▂█▂▁···    188.6 (+2%)   136 (+1%)  624 (+134%)    968 (-44%)  3000
gw 1x    ·····▁▃█▁▁···    134.3 (-1%)   129 (+1%)    193 (-1%)    450 (+36%)  5295
eve 1x   ·····▁▃█▂▁···   134.2 (-12%)  115 (-14%)   194 (-21%)     410 (-7%)  5186
eve 2x   ······▂█▃▁···    161.4 (-6%)   151 (-5%)    286 (+3%)     461 (-3%)  7779

RTT over stream progress (avg per tenth of stream, bars scaled min→max):

control  █▇▆▅▄▄▃▂▁▁  286–567ms
sweep    ▂▂█▇▄▂▁▂▄▄  155–250ms
gw 1x    █▄▃▅▄▃▄▁▃▅  116–158ms
eve 1x   ▃▁▃▃▃█▄▆▃▁  118–163ms
eve 2x   ▇▁▅▂▆▃▆█▃▄  138–187ms

RTT by chunk size (avg per log size bin, ~160B → ~12KB serialized, bars scaled min→max):

sweep  ▁▅█▇▇▅▄  186–190ms

Delivery jitter over stream progress (avg positive CDV per tenth of stream, bars scaled min→max):

control  ▂▂▁▁▄▄▆▃▂█  36–68ms
sweep    ▃▂█▆▄▁▂▃▄▃  54–85ms
gw 1x    █▅▄▄▅▁▆▁▃▅  34–47ms
eve 1x   ▂▁▂▃▂█▃▃▃▃  23–37ms
eve 2x   ▇▆▅▃▇▄█▁▃▇  20–35ms

ℹ️ Metric definitions & methodology

_{Streams: first-chunk RTT (the stream-open path, before any buffering/backpressure), CRTT percentiles, and worst delivery stall (CDV max). Cells are medians across iterations; per-run values in the artifacts. No 🔴/🟢 marks until targets attach.}

_{The collapsed STSO distribution section above buckets every step gap, split inline (same warm process — pure framework overhead) vs queue-hop (fresh process — dispatch, reinit, replay). █ = main, ┃ = this run, ░ = fill.}

_{The collapsed CRTT drill-down: per-variant RTT histograms (fixed log bins, · = empty) and mean RTT/positive-CDV profile lines over stream progress and chunk size. Histograms, avgs, and profiles merge exactly across runs; p50–p99 are percentile-of-percentiles. Per-index rows live in the artifacts.}

_{Best/P75/P90/P99 deltas compare against the most recent benchmark run on main at the time of this run. 🔻 flags a delta worse than +15%, 💚 one better than −15%.}

_{Metrics — TTFS: time to first step body (in-deployment start() → first step body) · Fan-out TTFS: fan-out time to first step (in-deployment start() → first of the parallel step bodies to complete) · Fan-out TTLS: fan-out time to last step (in-deployment start() → last of the parallel step bodies to complete, i.e. when the Promise.all resolves) · STSO: step-to-step overhead (gap between consecutive step bodies) · WO: workflow overhead (whole-run time outside step bodies, in-deployment anchored) · CRTT: chunk round-trip time (per-chunk write → read latency, one clock domain: deployment → stream backend → same deployment) · CDV: chunk delay variation / delivery jitter (inter-arrival gap minus inter-write gap per seq-adjacent pair; skew-free; the row is each run's MAX positive value, so one stall moves it)}

_{Scenarios — step: one trivial no-op step, no stream; no hooks, so the run stays in turbo mode (in-process fast path) · stream: one streaming step; no hooks, so the run stays in turbo mode (in-process fast path) · hook + stream: registers a hook before one step, which exits turbo mode (dispatch path) · 1020 steps: 1020 trivial sequential steps; STSO is measured between consecutive steps in the given step ranges, and WO is the whole-run overhead outside step bodies · Promise.all(100 steps): 100 trivial no-op steps started together in a single Promise.all; Fan-out TTFS is the first of them to complete and Fan-out TTLS the last, both from the in-deployment clientStart, so their gap is the spread the runtime adds across the fan-out · paced control (100/s, 60B): the control: 300 tiny (~60B) deltas metronome-paced at 100/s — zero workload structure, so it reads the transport floor and flush cadence, and disambiguates transport-wide vs workload-specific when a replay row moves · size sweep (100/s, 160B-12KB): same pacing as the control with deltas padded in rotation across seven log-spaced sizes (~160B–12KB) — rotation decouples size from stream position, so it isolates whether chunk size causes latency · replay gateway-gpt-5.4-nano-2000t (1x): raw provider SSE cadence captured at the AI gateway boundary (gpt-5.4-nano, the most popular gateway model; per-token deltas p50 208B = the modal production chunk size), replayed exactly as measured — the typical customer's workload; its CDV is the typical customer's real delivery jitter · replay eve-gpt-5.6-sol-2000t (1x): a captured eve turn (gpt-5.6-sol, the most-used demanding eve model; ~2000 output tokens = production p50 turn length) replayed exactly as measured — eve's envelope protocol re-ships the cumulative message so sizes ramp 142B→13KB; the demanding outlier tenant's reality · replay eve-gpt-5.6-sol-2000t (2x): the same eve capture at 2x — the headroom/stress row; real fast-tier models emit the same chunk sizes at proportionally higher rate, so time compression is a faithful speed model · first chunk (pooled): every run's seq-0 RTT pooled across all stream scenarios — the first chunk precedes any workload differentiation, so pooling samples one shared stream-open path with exact percentiles}

_{Replay cadences (semantic sha256) — eve-gpt-5.6-sol-2000t eaf22f5946e7c61f3c65c7006d550df180cfabd4e706254a09f22aec0cfb420d · gateway-gpt-5.4-nano-2000t 6f24ac518b6b83ff1d0e85a5fe78230db192716d66a7fc6b2fe022752001d041}

_{🔴 marks a percentile over its target (within target is left unmarked). Targets (p75/p90/p99, ms) — TTFS 200/300/600}

_{All timestamps are deployment-side; runs are triggered in-deployment, so the CI runner and api.vercel.com sit outside every measured window. TTFS = start() → first step body (includes dispatch + any cold start); Fan-out TTFS/TTLS = first/last step completion of one Promise.all from the same anchor (the gap is the runtime’s fan-out spread); STSO/WO between step bodies; CRTT inside the workflow (excludes the api.vercel.com read path).}

_{Cold starts stay in the numbers (real bursty-workload latency, inflates P75+); Best is the warm floor.}

github-actions · 2026-10-01T20:04:35Z

🧪 E2E Test Results

✅ All tests passed

⚠️ Flaky E2E Tests (passed on retry)

These tests failed at least once and passed on a retry. A recurring entry here is a real race worth investigating.

'hookGetConflictWithPriorStepWorkflow' - hook.getConflict() does not block step execution (nextjs-webpack · local-dev / local / node / stable) — flaked in 2 jobs
a run can take over its own earlier hook (nextjs-webpack · local-dev / local / quickjs / stable)
hookGetConflictWorkflow - awaiting hook.getConflict() registers hook without payload (nextjs-webpack · local-dev / local / node / stable)

🛠 Infra Events (absorbed by the harness)

Platform anomalies the e2e harness detected and worked around (e.g. a run the queue never picked up, replaced by a fresh run). Clustered timestamps indicate a backend blip; a steady drip indicates a platform issue worth escalating.

run-pickup-stall · runs app-generated source against a registered step (tanstack-start) · at 20:09:57Z · abandoned wrun_01M3WHCJPB4NW5K476KW7D10HE
cold-start-warmup · suite warmup (tanstack-start) · at 20:10:05Z · abandoned wrun_01M3WHCJQ5B50J0YXVKGENRKYW
run-pickup-stall · hookCleanupTestWorkflow - hook token reuse after workflow completion (nextjs-webpack) · at 20:16:44Z · abandoned wrun_01M3WHRZCJ0CXHN6XCE2JCPV0S
run-pickup-stall · hookGetConflictWorkflow - awaiting hook.getConflict() registers hook without payload (nextjs-webpack) · at 20:16:52Z · abandoned wrun_01M3WHS74N1C1NKEX8WGF8J9J3
run-pickup-stall · 'hookGetConflictWithPriorStepWorkflow' - hook.getConflict() does not block step execution (nextjs-webpack) · at 20:16:52Z · abandoned wrun_01M3WHS7B5S81NEE90ZY8P7R9D

E2E Test Summary

Summary

	Passed	Skipped	Total
✅ ▲ Vercel Production	3904	875	4779
✅ 💻 Local Development	4582	551	5133
✅ 📦 Local Production	4582	551	5133
✅ 🐘 Local Postgres	4582	551	5133
✅ 🪟 Windows	342	12	354
✅ 🌐 Cross-language Conformance	68	84	152
✅ dynamic-runs	0	0	0
✅ vercel-http-transport	879	183	1062
✅ vercel-multi-region	27	0	27
✅ vercel-ws-transport	595	113	708
Total	19561	2920	22481

Details by Category

✅ ▲ Vercel Production

App	Passed	Skipped
✅ astro-node	142	35
✅ astro-quickjs	142	35
✅ example-node	142	35
✅ example-quickjs	142	35
✅ express-node	142	35
✅ express-quickjs	142	35
✅ fastify-node	142	35
✅ fastify-quickjs	142	35
✅ hono-node	142	35
✅ hono-quickjs	142	35
✅ nest-node	142	35
✅ nest-quickjs	142	35
✅ nextjs-turbopack-node	169	8
✅ nextjs-turbopack-quickjs	169	8
✅ nextjs-webpack-node	169	8
✅ nextjs-webpack-quickjs	169	8
✅ nitro-node	142	35
✅ nitro-quickjs	142	35
✅ nuxt-node	142	35
✅ nuxt-quickjs	142	35
✅ python-node	66	111
✅ sveltekit-node	161	16
✅ sveltekit-quickjs	161	16
✅ tanstack-start-node	142	35
✅ tanstack-start-quickjs	142	35
✅ vite-node	142	35
✅ vite-quickjs	142	35

✅ 💻 Local Development

App	Passed	Skipped
✅ astro-stable-node	148	29
✅ astro-stable-quickjs	148	29
✅ express-stable-node	148	29
✅ express-stable-quickjs	148	29
✅ fastify-stable-node	148	29
✅ fastify-stable-quickjs	148	29
✅ hono-stable-node	148	29
✅ hono-stable-quickjs	148	29
✅ nest-stable-node	148	29
✅ nest-stable-quickjs	148	29
✅ nextjs-turbopack-canary-node	176	1
✅ nextjs-turbopack-canary-quickjs	176	1
✅ nextjs-turbopack-quickjs-snapshot	176	1
✅ nextjs-turbopack-stable-node	176	1
✅ nextjs-turbopack-stable-quickjs	176	1
✅ nextjs-webpack-canary-node	176	1
✅ nextjs-webpack-canary-quickjs	176	1
✅ nextjs-webpack-stable-node	176	1
✅ nextjs-webpack-stable-quickjs	176	1
✅ nitro-stable-node	148	29
✅ nitro-stable-quickjs	148	29
✅ nuxt-stable-node	148	29
✅ nuxt-stable-quickjs	148	29
✅ sveltekit-stable-node	167	10
✅ sveltekit-stable-quickjs	167	10
✅ tanstack-start-node	148	29
✅ tanstack-start-quickjs	148	29
✅ vite-stable-node	148	29
✅ vite-stable-quickjs	148	29

✅ 📦 Local Production

App	Passed	Skipped
✅ astro-stable-node	148	29
✅ astro-stable-quickjs	148	29
✅ express-stable-node	148	29
✅ express-stable-quickjs	148	29
✅ fastify-stable-node	148	29
✅ fastify-stable-quickjs	148	29
✅ hono-stable-node	148	29
✅ hono-stable-quickjs	148	29
✅ nest-stable-node	148	29
✅ nest-stable-quickjs	148	29
✅ nextjs-turbopack-canary-node	176	1
✅ nextjs-turbopack-canary-quickjs	176	1
✅ nextjs-turbopack-quickjs-snapshot	176	1
✅ nextjs-turbopack-stable-node	176	1
✅ nextjs-turbopack-stable-quickjs	176	1
✅ nextjs-webpack-canary-node	176	1
✅ nextjs-webpack-canary-quickjs	176	1
✅ nextjs-webpack-stable-node	176	1
✅ nextjs-webpack-stable-quickjs	176	1
✅ nitro-stable-node	148	29
✅ nitro-stable-quickjs	148	29
✅ nuxt-stable-node	148	29
✅ nuxt-stable-quickjs	148	29
✅ sveltekit-stable-node	167	10
✅ sveltekit-stable-quickjs	167	10
✅ tanstack-start-node	148	29
✅ tanstack-start-quickjs	148	29
✅ vite-stable-node	148	29
✅ vite-stable-quickjs	148	29

✅ 🐘 Local Postgres

App	Passed	Skipped
✅ astro-stable-node	148	29
✅ astro-stable-quickjs	148	29
✅ express-stable-node	148	29
✅ express-stable-quickjs	148	29
✅ fastify-stable-node	148	29
✅ fastify-stable-quickjs	148	29
✅ hono-stable-node	148	29
✅ hono-stable-quickjs	148	29
✅ nest-stable-node	148	29
✅ nest-stable-quickjs	148	29
✅ nextjs-turbopack-canary-node	176	1
✅ nextjs-turbopack-canary-quickjs	176	1
✅ nextjs-turbopack-quickjs-snapshot	176	1
✅ nextjs-turbopack-stable-node	176	1
✅ nextjs-turbopack-stable-quickjs	176	1
✅ nextjs-webpack-canary-node	176	1
✅ nextjs-webpack-canary-quickjs	176	1
✅ nextjs-webpack-stable-node	176	1
✅ nextjs-webpack-stable-quickjs	176	1
✅ nitro-stable-node	148	29
✅ nitro-stable-quickjs	148	29
✅ nuxt-stable-node	148	29
✅ nuxt-stable-quickjs	148	29
✅ sveltekit-stable-node	167	10
✅ sveltekit-stable-quickjs	167	10
✅ tanstack-start-node	148	29
✅ tanstack-start-quickjs	148	29
✅ vite-stable-node	148	29
✅ vite-stable-quickjs	148	29

✅ 🪟 Windows

App	Passed	Failed	Skipped
✅ nextjs-turbopack-node	171	0	6
✅ nextjs-turbopack-quickjs	171	0	6

✅ 🌐 Cross-language Conformance

App	Passed	Failed	Skipped
✅ python	68	0	84

✅ dynamic-runs

App	Passed	Failed	Skipped
✅ astro-vercel	0	0	0
✅ example-vercel	0	0	0
✅ express-vercel	0	0	0
✅ fastify-vercel	0	0	0
✅ hono-vercel	0	0	0
✅ nest-vercel	0	0	0
✅ nextjs-turbopack-vercel	0	0	0
✅ nextjs-webpack-vercel	0	0	0
✅ nitro-vercel	0	0	0
✅ nuxt-vercel	0	0	0
✅ sveltekit-vercel	0	0	0
✅ tanstack-start-vercel	0	0	0
✅ vite-vercel	0	0	0

✅ vercel-http-transport

App	Passed	Skipped
✅ example	142	35
✅ express	142	35
✅ hono	142	35
✅ nextjs-turbopack	169	8
✅ nitro	142	35
✅ vite	142	35

✅ vercel-multi-region

App	Passed	Failed	Skipped
✅ nextjs-turbopack	27	0	0

✅ vercel-ws-transport

App	Passed	Skipped
✅ example	142	35
✅ express	142	35
✅ nextjs-turbopack	169	8
✅ vite	142	35

📋 View full workflow run

github-actions · 2026-10-01T20:08:03Z

Sim World

Simulated world deterministic testing for races. Traces

🟠 world-sim scenario book — 1 fail of 42 total

fence=per-spec

scenario	outcome	events	virt	replay
✅ `smoke-no-steps`	completed	3	0ms	ok
✅ `smoke-one-step`	completed	6	0ms	ok
✅ `hook-at-step-started`	completed	12	0ms	ok
✅ `hook-at-step-completed`	completed	12	0ms	ok
✅ `hook-at-hook-created`	completed	12	0ms	ok
✅ `deadline-hook-wins`	completed	7	1.0h	ok
✅ `deadline-expires`	completed	7	1.0h	ok
✅ `step-vs-timer-early-settlement`	completed	8	1.0h	ok
✅ `long-sleep`	completed	11	30.0d	ok
✅ `hook-never-arrives`	stalled	3	0ms	skipped
✅ `step-retries-twice`	completed	10	2.0s	ok
✅ `parallel-steps`	completed	9	0ms	ok
✅ `hook-on-execution-state`	completed	12	0ms	ok
✅ `peek-hook-before-branch`	completed	12	0ms	ok
✅ `peek-hook-after-branch`	completed	12	0ms	ok
✅ `peek-hook-at-registration`	completed	12	0ms	ok
✅ `race-hook-before-probe`	completed	12	0ms	ok
✅ `race-hook-after-probe`	completed	12	0ms	ok
✅ `race-duplicate-delivery`	completed	13	0ms	ok
✅ `attr-hook-before-step`	completed	11	0ms	ok
✅ `attr-hook-after-step`	completed	11	0ms	ok
✅ `attr-from-step-body`	completed	13	0ms	ok
✅ `fork-hook-after-timeout`	completed	14	1.0m	ok
✅ `fork-hook-before-timeout`	completed	14	1.0m	ok
✅ `count-hook-after-timeout`	completed	17	1.0m	ok
✅ `count-hook-before-timeout`	completed	20	1.0m	ok
✅ `stale-read-step-count-fork`	completed	20	1.0m	ok
✅ `stale-read-equal-step-counts`	completed	14	1.0m	ok
✅ `step-vs-step-fork`	completed	12	0ms	ok
✅ `step-vs-step-fork-fenced`	completed	12	0ms	ok
✅ `fence-catches-benign-direction`	completed	12	5ms	ok
✅ `in-flight-before-decision`	completed	17	1.0m	ok
❌ `in-flight-before-decision-counted`	completed	17	1.0m	ok
✅ `in-flight-after-decision`	completed	19	2.0m	ok
✅ `stale-read-step-count-fork-fenced`	completed	20	1.0m	ok
✅ `fork-hook-wins`	completed	13	1.0m	ok
✅ `fork-timeout-wins`	completed	13	1.0m	ok
✅ `unclaimed-payload-under-fork`	completed	17	1.0m	ok
✅ `claimed-payload-under-fork`	completed	17	1.0m	ok
✅ `writers-independent-step-bodies`	completed	12	0ms	ok
✅ `writers-scripted-tempo`	completed	12	0ms	ok
✅ `cancel-mid-step`	cancelled	7	0ms	skipped

Full trace: world-sim.txt

github-actions · 2026-10-01T20:09:18Z

Framework	Flow route	Step reg.	Framework output
hono	267.2 KiB (±0)	97.3 KiB (±0)	2.00 MiB (+229 B)
nextjs-turbopack	274.6 KiB (±0)	426 B (±0)	985.6 KiB (+33 B)

About these numbers

Sizes are gzip; parentheses show the change against main.
Flow route and Step reg. gate this job, on raw bytes rather than the gzip shown, at max(2%, 50.0 KiB). Framework output is informational.

33476aa · run

karthikscale3

No blockers found. The focused hardened-serialization suite passes locally on Node 22 and Node 24. The current Vitest Plugin Tests (node) failure is in the unrelated hook-token-reuse test.

github-actions · 2026-10-01T20:18:50Z

No backport to stable for 3b09dd7 (AI decision).

This is a genuine bug fix, but it targets packages/core/src/serialization/hardened.ts, which does not exist on stable (verified: packages/core/src/serialization/ is absent there and no headersToEntries/headersIterator exists anywhere in the branch). stable serializes Headers via plain Array.from(value) in packages/core/src/serialization.ts:1285, which uses the object's own iterator and therefore never hits the Node 24 #headersList TypeError, so the maintenance line is not affected by this defect. There is nothing to apply and no bug to fix on stable.

To override, re-run the Backport to stable workflow manually via workflow_dispatch and paste this commit SHA into the ref input:

3b09dd7da5ea4e5de852d59c33db8db10a3d314b

VaguelySerious requested a review from a team as a code owner October 1, 2026 20:03

vercel Bot deployed to Preview – workflow-docs October 1, 2026 20:06 View deployment

TooTallNate approved these changes Oct 1, 2026

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karthikscale3 approved these changes Oct 1, 2026

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VaguelySerious merged commit 3b09dd7 into main Oct 1, 2026
182 of 184 checks passed

VaguelySerious deleted the peter/headers-node24-brand-check branch October 1, 2026 20:17

github-actions Bot mentioned this pull request Oct 1, 2026

Version Packages #4526

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[core] Fix webhook 404s on Nitro apps running Node 24 - #4575

[core] Fix webhook 404s on Nitro apps running Node 24#4575
VaguelySerious merged 1 commit into
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VaguelySerious commented Oct 1, 2026

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