[world-vercel] Name the failing fields of an invalid v4 createEvent response by alangenfeld · Pull Request #5072 · vercel/workflow

alangenfeld · 2026-10-26T18:29:26Z

Summary & Motivation

An invalid v4 createEvent response used to fail with only v4 createEvent: invalid response body. The error now also names the event type and where the response broke its schema, without including any of the response's values.

Each failing field is listed as its path and Zod issue code, e.g. (step_completed: event.eventType custom). A root-level failure shows as <root>.
At most five issues are listed, followed by +N more if there are others, because a union's issues can multiply.

Setup failures are logged with only the error's message. When the server answered a run_started without its run, that message was all the logs showed, so the bug couldn't be traced from them.

Test Plan

The existing schema test now checks for the more detailed message.

…esponse Setup logs only the error's message, so 'invalid response body' alone left a contract violation undiagnosable. The message now names the event type and up to five failing paths and issue codes, without values. Signed-off-by: Alex Langenfeld <alex.langenfeld@vercel.com>

vercel · 2026-10-26T18:29:30Z

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

Project	Deployment	Actions	Updated
example-nextjs-workflow-turbopack	Ready	Preview, v0	Oct 26, 2026 6:32pm UTC
example-nextjs-workflow-webpack	Ready	Preview, v0	Oct 26, 2026 6:32pm UTC
example-workflow	Ready	Preview, v0	Oct 26, 2026 6:32pm UTC
workbench-astro-workflow	Ready	Preview, v0	Oct 26, 2026 6:32pm UTC
workbench-express-workflow	Ready	Preview, v0	Oct 26, 2026 6:32pm UTC
workbench-fastify-workflow	Ready	Preview, v0	Oct 26, 2026 6:32pm UTC
workbench-hono-workflow	Ready	Preview, v0	Oct 26, 2026 6:32pm UTC
workbench-nestjs-workflow	Ready	Preview, v0	Oct 26, 2026 6:32pm UTC
workbench-nitro-workflow	Ready	Preview, v0	Oct 26, 2026 6:32pm UTC
workbench-nuxt-workflow	Ready	Preview, v0	Oct 26, 2026 6:32pm UTC
workbench-python-workflow	Ready	Preview, v0	Oct 26, 2026 6:32pm UTC
workbench-sveltekit-workflow	Ready	Preview, v0	Oct 26, 2026 6:32pm UTC
workbench-tanstack-start-workflow	Ready	Preview, v0	Oct 26, 2026 6:32pm UTC
workbench-vite-workflow	Ready	Preview, v0	Oct 26, 2026 6:32pm UTC
workflow-docs	Ready	Preview, v0	Oct 26, 2026 6:32pm UTC
workflow-swc-playground	Ready	Preview, v0	Oct 26, 2026 6:32pm UTC
workflow-tarballs	Ready	Preview, v0	Oct 26, 2026 6:32pm UTC
workflow-web	Ready	Preview, v0	Oct 26, 2026 6:32pm UTC

changeset-bot · 2026-10-26T18:29:33Z

🦋 Changeset detected

Latest commit: 4da0446

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

This PR includes changesets to release 17 packages

Name	Type
@workflow/world-vercel	Patch
@workflow/cli	Patch
@workflow/core	Patch
@workflow/web	Patch
workflow	Patch
@workflow/world-testing	Patch
@workflow/builders	Patch
@workflow/next	Patch
@workflow/nitro	Patch
@workflow/vitest	Patch
@workflow/web-shared	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

github-actions · 2026-10-26T18:30:35Z

📊 Workflow Benchmarks

commit 4da0446 · Mon, 26 Oct 2026 18:48:49 GMT · run logs

Backend: vercel · app: nextjs-turbopack

Metric	Scenario	Best (ms)	P75 (ms)	P90 (ms)	P99 (ms)	Samples
TTFS	step	339 (-18%) 💚	1948 🔴 (+22%) 🔻	1978 🔴 (+22%) 🔻	2053 🔴 (+23%) 🔻	30
TTFS	stream	1849 (+35%) 🔻	1929 🔴 (+22%) 🔻	1967 🔴 (+20%) 🔻	2112 🔴 (+16%) 🔻	30
TTFS	hook + stream	2132 (+29%) 🔻	2229 🔴 (+28%) 🔻	2489 🔴 (+41%) 🔻	2732 🔴 (+34%) 🔻	30
Fan-out TTFS	Promise.all(100 steps)	564 (+3.9%)	800 (-4.9%)	2299 (+149%) 🔻	2354 (+40%) 🔻	10
Fan-out TTLS	Promise.all(100 steps)	3504 (-1.1%)	4208 (-2.7%)	5097 (+16%) 🔻	5206 (-17%) 💚	10
STSO	1020 steps (inline)	71 (+13%)	96 (-3.0%)	114 (-5.8%)	144 (-58%) 💚	1019
WO	1020 steps	95582 (-7.4%)	95582 (-7.4%)	95582 (-7.4%)	95582 (-7.4%)	1

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

1020 steps (inline)

Cumulative STSO time: main 102649ms → this run 95300ms (Δ -7349ms, -7%)

 50-100 ms  ███████████████████████┃  main 765  this 815   +50
100-150 ms  █████┃                    main 210  this 194   -16
150-200 ms  ┃                         main  19  this   2   -17
200-250 ms  ┃                         main   6  this   5    -1
250-300 ms  ┃                         main   6  this   1    -5
300-350 ms  ┃                         main   4  this   0    -4
350-400 ms  ┃                         main   5  this   2    -3
400-450 ms  ┃                         main   1  this   0    -1
450-500 ms  ┃                         main   1  this   0    -1
600-650 ms  ┃                         main   1  this   0    -1
700-750 ms  ┃                         main   1  this   0    -1

ℹ️ Metric definitions & methodology

_{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.}

_{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)}

_{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}

_{🔴 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. Streaming delivery performance is measured in durabench.}

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

github-actions · 2026-10-26T18:31:26Z

🧪 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.

parallelStepsThenWebhookWorkflow - no hook_conflict from same-tick replay race (nextjs-turbopack · vercel-prod / vercel / node / production)

E2E Test Summary

Summary

	Passed	Skipped	Total
✅ ▲ Vercel Production	3982	878	4860
✅ 💻 Local Development	4669	551	5220
✅ 📦 Local Production	4669	551	5220
✅ 🐘 Local Postgres	4669	551	5220
✅ 🪟 Windows	348	12	360
✅ 🌐 Cross-language Conformance	68	87	155
✅ dynamic-runs	0	0	0
✅ vercel-http-transport	897	183	1080
✅ vercel-multi-region	27	0	27
✅ vercel-ws-transport	607	113	720
Total	19936	2926	22862

Details by Category

✅ ▲ Vercel Production

App	Passed	Skipped
✅ astro-node	145	35
✅ astro-quickjs	145	35
✅ example-node	145	35
✅ example-quickjs	145	35
✅ express-node	145	35
✅ express-quickjs	145	35
✅ fastify-node	145	35
✅ fastify-quickjs	145	35
✅ hono-node	145	35
✅ hono-quickjs	145	35
✅ nest-node	145	35
✅ nest-quickjs	145	35
✅ nextjs-turbopack-node	172	8
✅ nextjs-turbopack-quickjs	172	8
✅ nextjs-webpack-node	172	8
✅ nextjs-webpack-quickjs	172	8
✅ nitro-node	145	35
✅ nitro-quickjs	145	35
✅ nuxt-node	145	35
✅ nuxt-quickjs	145	35
✅ python-node	66	114
✅ sveltekit-node	164	16
✅ sveltekit-quickjs	164	16
✅ tanstack-start-node	145	35
✅ tanstack-start-quickjs	145	35
✅ vite-node	145	35
✅ vite-quickjs	145	35

✅ 💻 Local Development

App	Passed	Skipped
✅ astro-stable-node	151	29
✅ astro-stable-quickjs	151	29
✅ express-stable-node	151	29
✅ express-stable-quickjs	151	29
✅ fastify-stable-node	151	29
✅ fastify-stable-quickjs	151	29
✅ hono-stable-node	151	29
✅ hono-stable-quickjs	151	29
✅ nest-stable-node	151	29
✅ nest-stable-quickjs	151	29
✅ nextjs-turbopack-canary-node	179	1
✅ nextjs-turbopack-canary-quickjs	179	1
✅ nextjs-turbopack-quickjs-snapshot	179	1
✅ nextjs-turbopack-stable-node	179	1
✅ nextjs-turbopack-stable-quickjs	179	1
✅ nextjs-webpack-canary-node	179	1
✅ nextjs-webpack-canary-quickjs	179	1
✅ nextjs-webpack-stable-node	179	1
✅ nextjs-webpack-stable-quickjs	179	1
✅ nitro-stable-node	151	29
✅ nitro-stable-quickjs	151	29
✅ nuxt-stable-node	151	29
✅ nuxt-stable-quickjs	151	29
✅ sveltekit-stable-node	170	10
✅ sveltekit-stable-quickjs	170	10
✅ tanstack-start-node	151	29
✅ tanstack-start-quickjs	151	29
✅ vite-stable-node	151	29
✅ vite-stable-quickjs	151	29

✅ 📦 Local Production

App	Passed	Skipped
✅ astro-stable-node	151	29
✅ astro-stable-quickjs	151	29
✅ express-stable-node	151	29
✅ express-stable-quickjs	151	29
✅ fastify-stable-node	151	29
✅ fastify-stable-quickjs	151	29
✅ hono-stable-node	151	29
✅ hono-stable-quickjs	151	29
✅ nest-stable-node	151	29
✅ nest-stable-quickjs	151	29
✅ nextjs-turbopack-canary-node	179	1
✅ nextjs-turbopack-canary-quickjs	179	1
✅ nextjs-turbopack-quickjs-snapshot	179	1
✅ nextjs-turbopack-stable-node	179	1
✅ nextjs-turbopack-stable-quickjs	179	1
✅ nextjs-webpack-canary-node	179	1
✅ nextjs-webpack-canary-quickjs	179	1
✅ nextjs-webpack-stable-node	179	1
✅ nextjs-webpack-stable-quickjs	179	1
✅ nitro-stable-node	151	29
✅ nitro-stable-quickjs	151	29
✅ nuxt-stable-node	151	29
✅ nuxt-stable-quickjs	151	29
✅ sveltekit-stable-node	170	10
✅ sveltekit-stable-quickjs	170	10
✅ tanstack-start-node	151	29
✅ tanstack-start-quickjs	151	29
✅ vite-stable-node	151	29
✅ vite-stable-quickjs	151	29

✅ 🐘 Local Postgres

App	Passed	Skipped
✅ astro-stable-node	151	29
✅ astro-stable-quickjs	151	29
✅ express-stable-node	151	29
✅ express-stable-quickjs	151	29
✅ fastify-stable-node	151	29
✅ fastify-stable-quickjs	151	29
✅ hono-stable-node	151	29
✅ hono-stable-quickjs	151	29
✅ nest-stable-node	151	29
✅ nest-stable-quickjs	151	29
✅ nextjs-turbopack-canary-node	179	1
✅ nextjs-turbopack-canary-quickjs	179	1
✅ nextjs-turbopack-quickjs-snapshot	179	1
✅ nextjs-turbopack-stable-node	179	1
✅ nextjs-turbopack-stable-quickjs	179	1
✅ nextjs-webpack-canary-node	179	1
✅ nextjs-webpack-canary-quickjs	179	1
✅ nextjs-webpack-stable-node	179	1
✅ nextjs-webpack-stable-quickjs	179	1
✅ nitro-stable-node	151	29
✅ nitro-stable-quickjs	151	29
✅ nuxt-stable-node	151	29
✅ nuxt-stable-quickjs	151	29
✅ sveltekit-stable-node	170	10
✅ sveltekit-stable-quickjs	170	10
✅ tanstack-start-node	151	29
✅ tanstack-start-quickjs	151	29
✅ vite-stable-node	151	29
✅ vite-stable-quickjs	151	29

✅ 🪟 Windows

App	Passed	Failed	Skipped
✅ nextjs-turbopack-node	174	0	6
✅ nextjs-turbopack-quickjs	174	0	6

✅ 🌐 Cross-language Conformance

App	Passed	Failed	Skipped
✅ python	68	0	87

✅ 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	145	35
✅ express	145	35
✅ hono	145	35
✅ nextjs-turbopack	172	8
✅ nitro	145	35
✅ vite	145	35

✅ vercel-multi-region

App	Passed	Failed	Skipped
✅ nextjs-turbopack	27	0	0

✅ vercel-ws-transport

App	Passed	Skipped
✅ example	145	35
✅ express	145	35
✅ nextjs-turbopack	172	8
✅ vite	145	35

📋 View full workflow run

github-actions · 2026-10-26T18:33:57Z

Sim World

Simulated world deterministic testing for races. Traces

🟢 world-sim scenario book — 0 fail of 44 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	11	0ms	ok
✅ `hook-at-step-completed`	completed	11	0ms	ok
✅ `hook-at-hook-created`	completed	11	0ms	ok
✅ `claim-hook-at-registration`	completed	11	0ms	ok
✅ `claim-hook-at-step-started`	completed	11	0ms	ok
✅ `deadline-hook-wins`	completed	6	1.0h	ok
✅ `deadline-expires`	completed	6	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	11	0ms	ok
✅ `peek-hook-before-branch`	completed	11	0ms	ok
✅ `peek-hook-after-branch`	completed	11	0ms	ok
✅ `peek-hook-at-registration`	completed	11	0ms	ok
✅ `race-hook-before-probe`	completed	11	0ms	ok
✅ `race-hook-after-probe`	completed	11	0ms	ok
✅ `race-duplicate-delivery`	completed	12	0ms	ok
✅ `attr-hook-before-step`	completed	10	0ms	ok
✅ `attr-hook-after-step`	completed	10	0ms	ok
✅ `attr-from-step-body`	completed	12	0ms	ok
✅ `fork-hook-after-timeout`	completed	13	1.0m	ok
✅ `fork-hook-before-timeout`	completed	13	1.0m	ok
✅ `count-hook-after-timeout`	completed	16	1.0m	ok
✅ `count-hook-before-timeout`	completed	19	1.0m	ok
✅ `stale-read-step-count-fork`	completed	19	1.0m	ok
✅ `stale-read-equal-step-counts`	completed	13	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	16	1.0m	ok
✅ `in-flight-before-decision-counted`	completed	16	1.0m	ok
✅ `in-flight-after-decision`	completed	18	2.0m	ok
✅ `stale-read-step-count-fork-fenced`	completed	19	1.0m	ok
✅ `fork-hook-wins`	completed	12	1.0m	ok
✅ `fork-timeout-wins`	completed	12	1.0m	ok
✅ `unclaimed-payload-under-fork`	completed	16	1.0m	ok
✅ `claimed-payload-under-fork`	completed	16	1.0m	ok
✅ `writers-independent-step-bodies`	completed	12	0ms	ok
✅ `writers-scripted-tempo`	completed	11	0ms	ok
✅ `cancel-mid-step`	cancelled	7	0ms	skipped

Full trace: world-sim.txt

github-actions · 2026-10-26T18:47:48Z

Framework	Flow route	Step reg.	Framework output
hono	267.6 KiB (±0)	95.6 KiB (±0)	2.00 MiB (+228 B)
nextjs-turbopack	275.0 KiB (±0)	426 B (±0)	975.4 KiB (+97 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.

4da0446 · run

github-actions · 2026-10-26T19:15:36Z

No backport to stable for 612c5f4 (AI decision).

This is a diagnostics enhancement, not a fix: it enriches an existing error message with Zod issue paths without changing any faulty behavior. It also builds on main-only code — decodeCreateEventResponse, the v4 createEvent: invalid response body error, and packages/world-vercel/src/events-v4-response-schema.test.ts are all absent from stable's packages/world-vercel/src/events-v4.ts, so there is nothing on the maintenance line for it to improve.

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

612c5f4d558e61ea8c55dd269f2511b7bca69636

vercel Bot deployed to Preview – workflow-docs October 26, 2026 18:31

View deployment

alangenfeld mentioned this pull request Oct 26, 2026

Admit start({ hook }) candidates on the single-orchestrator engine #5008

Closed

alangenfeld marked this pull request as ready for review October 26, 2026 18:49

alangenfeld requested a review from a team as a code owner October 26, 2026 18:49

VaguelySerious approved these changes Oct 26, 2026

View reviewed changes

alangenfeld merged commit 612c5f4 into main Oct 26, 2026
187 of 188 checks passed

alangenfeld deleted the alangenfeld/v4-response-issue-paths branch October 26, 2026 19:14

github-actions Bot mentioned this pull request Oct 26, 2026

Version Packages #4961

Merged

This was referenced Oct 27, 2026

[docs] Catch up docs with recently shipped SDK changes #5094

Open

[docs] Document abort packet framing, World queue/stream contract, and resilient-start public key #5102

Open

Navigation Menu

Repository navigation

[world-vercel] Name the failing fields of an invalid v4 createEvent response - #5072

[world-vercel] Name the failing fields of an invalid v4 createEvent response#5072
alangenfeld merged 1 commit into
mainfrom
alangenfeld/v4-response-issue-paths

alangenfeld commented Oct 26, 2026

Uh oh!

vercel Bot commented Oct 26, 2026 •

edited

Loading

Uh oh!

changeset-bot Bot commented Oct 26, 2026

Uh oh!

github-actions Bot commented Oct 26, 2026 •

edited

Loading

Uh oh!

github-actions Bot commented Oct 26, 2026 •

edited

Loading

Uh oh!

github-actions Bot commented Oct 26, 2026

Uh oh!

github-actions Bot commented Oct 26, 2026

Uh oh!

Uh oh!

github-actions Bot commented Oct 26, 2026

Uh oh!

This branch was successfully deployed

Reviewers

Uh oh!

Assignees

Labels

Projects

Milestone

Development

Uh oh!

2 participants

Conversation

alangenfeld commented Oct 26, 2026

Summary & Motivation

Test Plan

Uh oh!

vercel Bot commented Oct 26, 2026 • edited Loading Uh oh! There was an error while loading. Please reload this page.

Uh oh!

Uh oh!

changeset-bot Bot commented Oct 26, 2026

🦋 Changeset detected

Uh oh!

github-actions Bot commented Oct 26, 2026 • edited Loading Uh oh! There was an error while loading. Please reload this page.

Uh oh!

📊 Workflow Benchmarks

Uh oh!

github-actions Bot commented Oct 26, 2026 • edited Loading Uh oh! There was an error while loading. Please reload this page.

Uh oh!

🧪 E2E Test Results

⚠️ Flaky E2E Tests (passed on retry)

E2E Test Summary

Uh oh!

github-actions Bot commented Oct 26, 2026

Sim World

Uh oh!

github-actions Bot commented Oct 26, 2026

Uh oh!

Uh oh!

github-actions Bot commented Oct 26, 2026

Uh oh!

This branch was successfully deployed

Reviewers

Uh oh!

Assignees

Labels

Projects

Milestone

Development

Uh oh!

2 participants

vercel Bot commented Oct 26, 2026 •

edited

Loading

github-actions Bot commented Oct 26, 2026 •

edited

Loading

github-actions Bot commented Oct 26, 2026 •

edited

Loading