fix(core): sharpen dynamic workflow validation and its messages by alangenfeld · Pull Request #4534 · vercel/workflow

alangenfeld · 2026-09-30T19:54:29Z

Summary & Motivation

exportName is capped at 64 characters, rejected at the call site rather than as a queue-name failure downstream.
"use step" is detected as a directive prologue on the parsed AST, so a string literal that merely reads use step no longer rejects a valid source.
A parse failure now ends with a hint to declare the function async, since a non-async workflow using await fails as a bare "Unexpected token".
A workflow declaration that is duplicated, a generator, or non-async says which.
The Vercel execution-context budget error names step IDs and exportName, not only aliases — step IDs, built from the step's file path and function name, usually dominate the budget.

Test Plan

Unit tests added.

changeset-bot · 2026-09-30T19:54:34Z

🦋 Changeset detected

Latest commit: 1a425aa

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/world-vercel	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

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

vercel · 2026-09-30T19:54:37Z

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 3:58pm UTC
example-nextjs-workflow-webpack	Ready	Preview, v0	Oct 1, 2026 3:58pm UTC
example-workflow	Ready	Preview, v0	Oct 1, 2026 3:58pm UTC
workbench-astro-workflow	Ready	Preview, v0	Oct 1, 2026 3:58pm UTC
workbench-express-workflow	Ready	Preview, v0	Oct 1, 2026 3:58pm UTC
workbench-fastify-workflow	Ready	Preview, v0	Oct 1, 2026 3:58pm UTC
workbench-hono-workflow	Ready	Preview, v0	Oct 1, 2026 3:58pm UTC
workbench-nestjs-workflow	Ready	Preview, v0	Oct 1, 2026 3:58pm UTC
workbench-nitro-workflow	Ready	Preview, v0	Oct 1, 2026 3:58pm UTC
workbench-nuxt-workflow	Ready	Preview, v0	Oct 1, 2026 3:58pm UTC
workbench-python-workflow	Ready	Preview, v0	Oct 1, 2026 3:58pm UTC
workbench-sveltekit-workflow	Ready	Preview, v0	Oct 1, 2026 3:58pm UTC
workbench-tanstack-start-workflow	Ready	Preview, v0	Oct 1, 2026 3:58pm UTC
workbench-vite-workflow	Ready	Preview, v0	Oct 1, 2026 3:58pm UTC
workflow-docs	Ready	Preview, v0	Oct 1, 2026 3:58pm UTC
workflow-swc-playground	Ready	Preview, v0	Oct 1, 2026 3:58pm UTC
workflow-tarballs	Ready	Preview, v0	Oct 1, 2026 3:58pm UTC
workflow-web	Ready	Preview, v0	Oct 1, 2026 3:58pm UTC

github-actions · 2026-09-30T19:59:16Z

📊 Workflow Benchmarks

commit 1a425aa · Thu, 01 Oct 2026 16:22:58 GMT · run logs

Backend: vercel · app: nextjs-turbopack

Metric	Scenario	Best (ms)	P75 (ms)	P90 (ms)	P99 (ms)	Samples
TTFS	step	411 (-44%) 💚	2511 🔴 (+130%) 🔻	2629 🔴 (+136%) 🔻	2983 🔴 (+148%) 🔻	30
TTFS	stream	428 (+95%) 🔻	2552 🔴 (+143%) 🔻	2983 🔴 (+172%) 🔻	3109 🔴 (+118%) 🔻	30
TTFS	hook + stream	676 (-23%) 💚	2890 🔴 (+118%) 🔻	2910 🔴 (+107%) 🔻	2967 🔴 (+90%) 🔻	30
Fan-out TTFS	Promise.all(100 steps)	638 (-26%) 💚	863 (-50%) 💚	931 (-48%) 💚	2461 (+31%) 🔻	10
Fan-out TTLS	Promise.all(100 steps)	2103 (-8.3%)	6006 (+65%) 🔻	6306 (+67%) 🔻	6385 (-12%)	10
STSO	1020 steps (inline)	155 (+55%) 🔻	216 (+66%) 🔻	242 (+57%) 🔻	366 (+80%) 🔻	1019
WO	1020 steps	207720 (+58%) 🔻	207720 (+58%) 🔻	207720 (+58%) 🔻	207720 (+58%) 🔻	1
CRTT	first chunk (pooled)	81 (+13%)	115 (-19%) 💚	137 (-35%) 💚	186 (-48%) 💚	28

Streams

Scenario	CRTT 1st	p75	p90	p99	CDV max	iters
paced control (100/s, 60B)	102 (+3%)	166 (-14%)	211 (-30%)	387 (-21%)	132 (-41%)	10
size sweep (100/s, 160B-12KB)	92 (-11%)	163 (-28%)	219 (-38%)	407 (-36%)	148 (-30%)	10
replay gateway-gpt-5.4-nano-2000t (1x)	112 (-18%)	145 (-24%)	172 (-47%)	253 (-56%)	210 (-52%)	3
replay eve-gpt-5.6-sol-2000t (1x)	161 (+54%)	153 (-22%)	186 (-39%)	324 (-41%)	325 (-28%)	2
replay eve-gpt-5.6-sol-2000t (2x)	109 (-23%)	189 (-42%)	229 (-53%)	370 (-61%)	213 (-55%)	3

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

1020 steps (inline)

Cumulative STSO time: main 131526ms → this run 207167ms (Δ +75641ms, +58%)

100-150 ms  ┃███████████████████████  main 899  this   0  -899
150-200 ms  ███░░░░░░░░░░░░┃          main 108  this 610  +502
200-250 ms  █░░░░░░░┃                 main   8  this 324  +316
250-300 ms  ┃                         main   2  this  52   +50
300-350 ms  ┃                         main   0  this  19   +19
350-400 ms  ┃                         main   1  this   9    +8
400-450 ms  ┃                         main   1  this   5    +4

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

variant  RTT 1ms→5s+             avg         p50         p90         p99     n
control  ······▂█▁····  138.3 (-12%)   133 (-4%)  211 (-30%)  387 (-21%)  3000
sweep    ······▂█▁····  138.8 (-21%)  127 (-18%)  219 (-38%)  407 (-36%)  3000
gw 1x    ·····▁▃█▁····  125.7 (-21%)  121 (-11%)  172 (-47%)  253 (-56%)  5295
eve 1x   ·····▁▃█▁▁···  131.4 (-19%)  121 (-10%)  186 (-39%)  324 (-41%)  5186
eve 2x   ······▂█▂····  155.4 (-33%)  148 (-31%)  229 (-53%)  370 (-61%)  7779

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

control  █▄▅▃▁▂▅▅▃▂  128–154ms
sweep    ▆▄▇██▄▂▃▁█  123–150ms
gw 1x    ▇▆▅█▅▅▇▁▅▃  117–132ms
eve 1x   ▂▁▁▂▂▄█▄▃▁  121–159ms
eve 2x   ▂▁▃▄▂▇▆█▅▆  132–182ms

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

sweep  ▁▇█▇▂▅▂  137–140ms

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

control  ▂▂▄▁▃▁▂█▅▃  38–53ms
sweep    ▁▇███▅▇▄▃█  50–62ms
gw 1x    ▅▅▅▄▁▃█▃▃▄  35–44ms
eve 1x   ▃▄▁▃▇▅█▆▂▆  22–30ms
eve 2x   ▅▄▄▃▆▄▃▁▃█  19–33ms

📜 Previous results (2)

`62cb38f`

Wed, 30 Sep 2026 21:29:58 GMT · run logs

vercel / nextjs-turbopack

Metric	Scenario	Best (ms)	P75 (ms)	P90 (ms)	P99 (ms)	Samples
TTFS	step	404 (-1.9%)	2468 🔴 (+25%) 🔻	2539 🔴 (+9.6%)	2624 🔴 (+6.7%)	30
TTFS	stream	424 (+15%)	2475 🔴 (+25%) 🔻	2930 🔴 (+41%) 🔻	3075 🔴 (+34%) 🔻	30
TTFS	hook + stream	2661 (+259%) 🔻	3304 🔴 (+45%) 🔻	3332 🔴 (+44%) 🔻	3365 🔴 (+44%) 🔻	30
Fan-out TTFS	Promise.all(100 steps)	564 (+6.0%)	830 (-1.1%)	850 (-5.7%)	3429 (+41%) 🔻	10
Fan-out TTLS	Promise.all(100 steps)	1765 (-1.5%)	5112 (+52%) 🔻	5226 (+12%)	7113 (-12%)	10
STSO	1020 steps (inline)	148 (±0%)	201 (-8.6%)	228 (-11%)	357 (-23%) 💚	1019
WO	1020 steps	198027 (-8.0%)	198027 (-8.0%)	198027 (-8.0%)	198027 (-8.0%)	1
CRTT	first chunk (pooled)	76 (+12%)	133 (+21%) 🔻	183 (+36%) 🔻	209 (-30%) 💚	28

Streams

Scenario	CRTT 1st	p75	p90	p99	CDV max	iters
paced control (100/s, 60B)	96.5 (+1%)	170 (-10%)	242 (-17%)	338 (-30%)	146 (-27%)	10
size sweep (100/s, 160B-12KB)	116 (+26%)	176 (-13%)	214 (-76%)	359 (-70%)	128 (-33%)	10
replay gateway-gpt-5.4-nano-2000t (1x)	133 (+3%)	165 (-11%)	224 (-13%)	523 (-46%)	373 (-18%)	3
replay eve-gpt-5.6-sol-2000t (1x)	120 (+9%)	170 (-86%)	228 (-96%)	437 (-95%)	358 (-94%)	2
replay eve-gpt-5.6-sol-2000t (2x)	133 (+28%)	208 (-22%)	260 (-40%)	435 (-66%)	231 (-46%)	3

`1c46b0d`

Wed, 30 Sep 2026 20:35:51 GMT · run logs

vercel / nextjs-turbopack

Metric	Scenario	Best (ms)	P75 (ms)	P90 (ms)	P99 (ms)	Samples
TTFS	step	2054 (+4.7%)	2427 🔴 (+11%)	2489 🔴 (-8.1%)	2664 🔴 (-17%) 💚	30
TTFS	stream	2114 (+25%) 🔻	2427 🔴 (+20%) 🔻	2458 🔴 (+19%) 🔻	2937 🔴 (+32%) 🔻	30
TTFS	hook + stream	2616 (+38%) 🔻	3228 🔴 (+33%) 🔻	3288 🔴 (+32%) 🔻	7439 🔴 (+162%) 🔻	30
Fan-out TTFS	Promise.all(100 steps)	568 (-29%) 💚	2911 (+170%) 🔻	3183 (+30%) 🔻	4172 (+53%) 🔻	10
Fan-out TTLS	Promise.all(100 steps)	2081 (-30%) 💚	5841 (+57%) 🔻	7052 (+72%) 🔻	9224 (+51%) 🔻	10
STSO	1020 steps (inline)	158 (-5.4%)	203 (-13%)	231 (-17%) 💚	361 (-35%) 💚	1019
WO	1020 steps	200790 (-14%)	200790 (-14%)	200790 (-14%)	200790 (-14%)	1
CRTT	first chunk (pooled)	57 (-35%) 💚	107 (-33%) 💚	182 (-2.7%)	477 (+81%) 🔻	28

Streams

Scenario	CRTT 1st	p75	p90	p99	CDV max	iters
paced control (100/s, 60B)	97 (-27%)	165 (-36%)	385 (-3%)	725 (-3%)	166 (-11%)	10
size sweep (100/s, 160B-12KB)	98 (-12%)	172 (-18%)	217 (-18%)	417 (+17%)	143 (-7%)	10
replay gateway-gpt-5.4-nano-2000t (1x)	96 (-24%)	152 (-20%)	194 (-28%)	1033 (-19%)	287 (-60%)	3
replay eve-gpt-5.6-sol-2000t (1x)	108 (-34%)	149 (-33%)	179 (-48%)	237 (-81%)	194 (-69%)	2
replay eve-gpt-5.6-sol-2000t (2x)	132 (-19%)	3225 (+1272%)	4254 (+1225%)	5100 (+603%)	889 (+116%)	3

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 · 2026-09-30T19:59:35Z

🧪 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 / canary)
health check (CLI) - workflow health command reports healthy endpoints (nitro · 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 15:58:48Z · abandoned wrun_01M3W30PTF672075P3PA2TNTBN
cold-start-warmup · suite warmup (tanstack-start) · at 15:58:56Z · abandoned wrun_01M3W30PV2T68DXZBR9Q0YZ0M8
run-pickup-stall · Calculator.calculate - static workflow method using static step methods from another class (nest) · at 16:00:46Z · abandoned wrun_01M3W34A5QQGEA49D89VAKAFSQ
run-pickup-stall · hookCleanupTestWorkflow - hook token reuse after workflow completion (nextjs-webpack) · at 16:08:37Z · abandoned wrun_01M3W3JNJ0JC8KR09ES6SCZ70J

E2E Test Summary

Summary

	Passed	Skipped	Total
✅ ▲ Vercel Production	3904	875	4779
✅ 💻 Local Development	4406	550	4956
✅ 📦 Local Production	4406	550	4956
✅ 🐘 Local Postgres	4406	550	4956
✅ 🪟 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	19033	2917	21950

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-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-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-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 · 2026-09-30T20:01:11Z

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 · 2026-09-30T20:04:13Z

Framework	Flow route	Step reg.	Framework output
hono	265.9 KiB (±0)	97.3 KiB (±0)	1.99 MiB (+822 B)
nextjs-turbopack	273.3 KiB (±0)	426 B (±0)	982.1 KiB (+359 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.

1a425aa · run

Signed-off-by: Alex Langenfeld <alex.langenfeld@vercel.com>

github-actions · 2026-10-01T16:20:47Z

No backport to stable for 0147fa5 (AI decision).

The entire dynamic-workflow feature this commit refines does not exist on stable: packages/core/src/runtime/dynamic-workflow.ts, packages/world-vercel/src/execution-context.ts, and docs/content/docs/v5/advanced/dynamic-workflows.mdx are all absent from origin/stable (verified with git ls-tree). There is nothing on the maintenance line for these validation and error-message changes to fix, and the new 64-character exportName cap would be added validation for an API stable users cannot call.

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

0147fa58417d6fbbed25428388309a4b684c80eb

## Summary & Motivation Fills gaps the 5.0.0 dogfood surfaced on the dynamic workflows concept page: a table of the per-gate refusals and which of them are fatal, how a Vercel project gets dynamic-source storage, what the 2,048-byte execution-context budget actually buys, that the workflow ID hashes raw source bytes, and that "trusted" means reviewed application code rather than anything a model did not write. Stacked on #4541, which adds the cookbook recipe this page now links to. ## Test Plan Docs only. Links, anchors, quoted error messages, and the fatal/retryable behavior were checked by hand against the runtime source on main. #4534 (open) edits this page's `exportName` rule. This PR leaves that line alone, quotes only the stable prefix of the execution-context error that #4534 extends, and does not document #4534's validation messages. ## Docs Preview | Page | Link | | --- | --- | | Dynamic workflows | [/docs/advanced/dynamic-workflows](https://workflow-docs-rakhde7hj.vercel.sh/docs/advanced/dynamic-workflows) | | Errors for each gate | [#errors-for-each-gate](https://workflow-docs-rakhde7hj.vercel.sh/docs/advanced/dynamic-workflows#errors-for-each-gate) | | Enabling storage on Vercel | [#enabling-storage-on-vercel](https://workflow-docs-rakhde7hj.vercel.sh/docs/advanced/dynamic-workflows#enabling-storage-on-vercel) | --------- Signed-off-by: Alex Langenfeld <alex.langenfeld@vercel.com>

vercel Bot deployed to Preview – workflow-docs September 30, 2026 19:57 View deployment

vercel Bot deployed to Preview – workflow-docs September 30, 2026 20:13 View deployment

vercel Bot deployed to Preview – workflow-docs September 30, 2026 20:56 View deployment

vercel Bot deployed to Preview – workflow-docs September 30, 2026 21:05 View deployment

alangenfeld marked this pull request as ready for review September 30, 2026 21:05

alangenfeld requested a review from a team as a code owner September 30, 2026 21:05

alangenfeld mentioned this pull request Oct 1, 2026

[docs] Fill gaps in the dynamic workflows concept page #4550

Merged

VaguelySerious approved these changes Oct 1, 2026

View reviewed changes

fix(core): sharpen dynamic workflow validation and its messages

1a425aa

Signed-off-by: Alex Langenfeld <alex.langenfeld@vercel.com>

alangenfeld force-pushed the alangenfeld/dynamic-start-validation branch from 62cb38f to 1a425aa Compare October 1, 2026 15:53

vercel Bot deployed to Preview – workflow-docs October 1, 2026 15:55 View deployment

alangenfeld merged commit 0147fa5 into main Oct 1, 2026
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alangenfeld deleted the alangenfeld/dynamic-start-validation branch October 1, 2026 16:19

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

Version Packages #4526

Merged

pranaygp mentioned this pull request Oct 2, 2026

[docs] Document Serializable, fatal dynamic start() refusals, and snapshot storage #4588

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fix(core): sharpen dynamic workflow validation and its messages - #4534

fix(core): sharpen dynamic workflow validation and its messages#4534
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Summary & Motivation

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🦋 Changeset detected

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📊 Workflow Benchmarks

62cb38f

1c46b0d

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🧪 E2E Test Results

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Sim World

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