fix(web-shared): describe map-like iterables via entries()

[mitul-s]

Why

Hydrated Headers and URLSearchParams keep their pairs in internal slots. Object.entries returns nothing, so the inspector drew them as empty objects.

The first version of this PR walked Symbol.iterator and treated every 2-element yield as a field. That matched old react-inspector behavior. It also turned a list of coordinate pairs into fake keys.

Scope

describeContainer now follows the same re-iterable pattern as Map and Set. A value with entries() renders as {} pair rows from that iterator. Any other iterable renders as [] unlabeled list rows from Symbol.iterator.

DataRender and ClassInstanceNode no longer memoize describeContainer. Tests use renderToStaticMarkup instead of jsdom. jsdom is removed from @workflow/web-shared.

Out of scope. serializeForClipboard still runs JSON.stringify on Headers and copies {}. hasDisplayContent still uses Object.keys.

Tradeoffs

Live re-iteration instead of a collapseRefs snapshot. Headers and URLSearchParams are re-iterable, which is the production case. One-shot generators are no longer snapshotted across rerenders.

Blast radius

Observability UI only, @workflow/web-sharedDataInspector. Step input and output views that hydrate Request, Headers, or URLSearchParams now show the real pairs. Custom iterables without entries() render as lists, not keyed objects.

Verification

In packages/web-shared:

pnpm exec vitest run test/data-inspector.test.ts test/collapse-refs.test.ts test/copyable-data-block.test.ts

37 tests passed.

The new tests against the previous describeContainer failed in 3 cases. TestIterable rendered 0: labels. CoordinatePairs rendered 1:2. MapLike ignored entries() and showed the default iterator.

The full @workflow/web-shared suite was 218 passed. test/zstd-decoder.test.ts failed on zlib.zstdCompressSync, which this change does not touch.

PR Checklist - Required to merge

• 📦 Added a patch changeset for @workflow/web-shared
• 🔒 Commits include DCO sign-off
• 📝 Ping @vercel/workflow in a comment once the PR is ready

Slack Thread

[changeset-bot]

🦋 Changeset detected

Latest commit: 13fc38c

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

This PR includes changesets to release 16 packages

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

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

Project	Deployment	Actions	Updated (UTC)
example-nextjs-workflow-turbopack	Ready	Preview, v0	Aug 26, 2026 7:43pm
example-nextjs-workflow-webpack	Ready	Preview, v0	Aug 26, 2026 7:43pm
example-workflow	Ready	Preview, v0	Aug 26, 2026 7:43pm
workbench-astro-workflow	Ready	Preview, v0	Aug 26, 2026 7:43pm
workbench-express-workflow	Ready	Preview, v0	Aug 26, 2026 7:43pm
workbench-fastify-workflow	Ready	Preview, v0	Aug 26, 2026 7:43pm
workbench-hono-workflow	Ready	Preview, v0	Aug 26, 2026 7:43pm
workbench-nestjs-workflow	Ready	Preview, v0	Aug 26, 2026 7:43pm
workbench-nitro-workflow	Ready	Preview, v0	Aug 26, 2026 7:43pm
workbench-nuxt-workflow	Ready	Preview, v0	Aug 26, 2026 7:43pm
workbench-python-workflow	Ready	Preview, v0	Aug 26, 2026 7:43pm
workbench-sveltekit-workflow	Ready	Preview, v0	Aug 26, 2026 7:43pm
workbench-tanstack-start-workflow	Ready	Preview, v0	Aug 26, 2026 7:43pm
workbench-vite-workflow	Ready	Preview, v0	Aug 26, 2026 7:43pm
workflow-docs	Ready	Preview, v0	Aug 26, 2026 7:43pm
workflow-swc-playground	Ready	Preview, v0	Aug 26, 2026 7:43pm
workflow-tarballs	Ready	Preview, v0	Aug 26, 2026 7:43pm
workflow-web	Ready	Preview, v0	Aug 26, 2026 7:43pm

[TooTallNate]

More generally, we should be able to expand any value that implements Symbol.iterator, rather than special casing Headers and URLSearchParams

[github-actions]

🧪 E2E Test Results

❌ Some tests failed

❌ Failed E2E Tests

▲ Vercel Production (8 failed)

python-node (8 failed):

• promiseAllWorkflow | wrun_41M0ZKVKE60GRTE4KH2QZ7DTC4 | 🔍 observability
• sleepingWorkflow | wrun_41M0ZKW7BW0GXPGM0GVD1EAEKR | 🔍 observability
• parallelSleepWorkflow | wrun_41M0ZKW7EY0GHGEV96Q39D7PMA | 🔍 observability
• nullByteWorkflow | wrun_41M0ZKWDR00GY8QCX6JSTGSJAQ | 🔍 observability
• cancelRun - cancelling a running workflow | wrun_41M0ZM0KJG0GTHJCCJF5M9M6E2 | 🔍 observability
• cancelRun via CLI - cancelling a running workflow | wrun_41M0ZM0MG50GMVCWAJFATE272J | 🔍 observability
• sleepInLoopWorkflow - sleep inside loop with steps actually delays each iteration | wrun_41M0ZM0S270GSASPMDRG9C4HW2 | 🔍 observability
• resilient start: addTenWorkflow completes when run_created returns 500 | wrun_41M0ZM19S70GWKV1MVG6V7GW7S | 🔍 observability

🌐 Cross-language Conformance (9 failed)

python (9 failed):

• deploymentId: 'latest' is a no-op in non-Vercel worlds | wrun_01M0ZM4X0N34FZTTVJCZ7E2G9G
• promiseAllWorkflow | wrun_41M0ZKVKE60GRTE4KH2QZ7DTC4
• sleepingWorkflow | wrun_41M0ZKW7BW0GXPGM0GVD1EAEKR
• parallelSleepWorkflow | wrun_41M0ZKW7EY0GHGEV96Q39D7PMA
• nullByteWorkflow | wrun_41M0ZKWDR00GY8QCX6JSTGSJAQ
• cancelRun - cancelling a running workflow | wrun_41M0ZM0KJG0GTHJCCJF5M9M6E2
• cancelRun via CLI - cancelling a running workflow | wrun_41M0ZM0MG50GMVCWAJFATE272J
• sleepInLoopWorkflow - sleep inside loop with steps actually delays each iteration | wrun_41M0ZM0S270GSASPMDRG9C4HW2
• resilient start: addTenWorkflow completes when run_created returns 500 | wrun_41M0ZM19S70GWKV1MVG6V7GW7S

⚠️ 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.

• cancelRun via CLI - cancelling a running workflow (express)
• hook created by a sfo1 run resolves by token and resumes the run (nextjs-turbopack)
• hookWorkflow (tanstack-start)
• promiseAllWorkflow (express)
• promiseRaceStressTestWorkflow (vite)
• promiseRaceWorkflow (hono)
• promiseRaceWorkflow (sveltekit)

🛠 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.

34 infra events

• cold-start-warmup · suite warmup (python) · at 18:05:09Z · abandoned wrun_41M0ZKTYBS0GPDS9W8WHKT22HR · (+7 more)
• run-pickup-stall · promiseAllWorkflow (python) · at 18:05:25Z · abandoned wrun_41M0ZKYM2M0GYCWSNESMWEGYZW
• run-pickup-stall · nullByteWorkflow (python) · at 18:05:25Z · abandoned wrun_41M0ZKYM2X0GJ5QJENP5KAR8DK
• run-pickup-stall · sleepingWorkflow (python) · at 18:05:25Z · abandoned wrun_41M0ZKYM2S0GGQ93SXWWAXH1PE
• run-pickup-stall · parallelSleepWorkflow (python) · at 18:05:25Z · abandoned wrun_41M0ZKYM2S0GGQ93SXWWAXH1PF
• run-pickup-stall · cancelRun - cancelling a running workflow (python) · at 18:05:26Z · abandoned wrun_41M0ZKYMFQ0GNQK9XTZZS00G68
• run-pickup-stall · cancelRun - cancelling a running workflow (python) · at 18:05:58Z · abandoned wrun_41M0ZKZMDG0GKJCTA3BYYGXFDX
• cold-start-warmup · suite warmup (tanstack-start) · at 18:06:22Z · abandoned wrun_01M0ZM010XFRBR7N3GCYFHT0KD
• run-pickup-stall · sleepingWorkflow (python) · at 18:06:26Z · abandoned wrun_41M0ZM0FRD0GJ6BN11NRKBMJ9N
• run-pickup-stall · promiseAllWorkflow (python) · at 18:06:26Z · abandoned wrun_41M0ZM0FQG0GRFWWW9CP6NEVRF
• run-pickup-stall · nullByteWorkflow (python) · at 18:06:26Z · abandoned wrun_41M0ZM0FSY0GXM6P4BV6D1NTVQ
• run-pickup-stall · parallelSleepWorkflow (python) · at 18:06:26Z · abandoned wrun_41M0ZM0FJX0GR49QWPXV7A356M
• run-pickup-stall · cancelRun via CLI - cancelling a running workflow (python) · at 18:07:16Z · abandoned wrun_41M0ZM0M5E0GX9F0KQ6Q082MS1
• cold-start-warmup · suite warmup (python) · at 18:07:19Z · abandoned wrun_01M0ZKYYKD0KPD3MBEX0E432BE · (+7 more)
• run-pickup-stall · deploymentId: 'latest' is a no-op in non-Vercel worlds (python) · at 18:07:34Z · abandoned wrun_01M0ZM2KQNF8AWHK32575V2461
• run-pickup-stall · promiseAllWorkflow (python) · at 18:07:34Z · abandoned wrun_01M0ZM2KQPQPQWKSRGPTBXH847
• run-pickup-stall · parallelSleepWorkflow (python) · at 18:07:34Z · abandoned wrun_01M0ZM2KQY592H6FWWEF0NRP1S
• run-pickup-stall · sleepingWorkflow (python) · at 18:07:34Z · abandoned wrun_01M0ZM2KQWET1C8DARN3W95P1R
• run-pickup-stall · nullByteWorkflow (python) · at 18:07:34Z · abandoned wrun_01M0ZM2KR13RD8ECG6Q0BCWN67
• run-pickup-stall · instanceMethodStepWorkflow - instance methods with "use step" directive (nuxt) · at 18:08:09Z · abandoned wrun_01M0ZM3NZ7D3G82TGVPJ8YWN5T
• run-pickup-stall · deploymentId: 'latest' is a no-op in non-Vercel worlds (python) · at 18:08:34Z · abandoned wrun_01M0ZM4EB8QN7E7Y2GE2DME665
• run-pickup-stall · promiseAllWorkflow (python) · at 18:08:34Z · abandoned wrun_01M0ZM4EBDCPVVDS39BS95RA70
• run-pickup-stall · sleepingWorkflow (python) · at 18:08:34Z · abandoned wrun_01M0ZM4EBH838SW4S33HVVHJ86
• run-pickup-stall · parallelSleepWorkflow (python) · at 18:08:34Z · abandoned wrun_01M0ZM4EBQG3D97DYY2VTKVPYK
• run-pickup-stall · nullByteWorkflow (python) · at 18:08:34Z · abandoned wrun_01M0ZM4EBV1GDM3GJBCXC3EA81
• run-pickup-stall · sleepInLoopWorkflow - sleep inside loop with steps actually delays each iteration (python) · at 18:08:58Z · abandoned wrun_41M0ZM37FF0GHKTCT7733J4VH5
• run-pickup-stall · cancelRun - cancelling a running workflow (python) · at 18:09:34Z · abandoned wrun_01M0ZM68YTAQ3XS41G6YFCKT43
• run-pickup-stall · cancelRun via CLI - cancelling a running workflow (python) · at 18:09:34Z · abandoned wrun_01M0ZM68Z493DW9VT63EVBWHV7
• run-pickup-stall · sleepInLoopWorkflow - sleep inside loop with steps actually delays each iteration (python) · at 18:09:34Z · abandoned wrun_01M0ZM68Z77GYDRKXMEJ9H7AR0
• run-pickup-stall · cancelRun via CLI - cancelling a running workflow (python) · at 18:09:38Z · abandoned wrun_41M0ZM3C210GMFQNJV10YHJTFC
• run-pickup-stall · cancelRun - cancelling a running workflow (python) · at 18:10:04Z · abandoned wrun_01M0ZM76A942EQRE76CRQS2GBD
• run-pickup-stall · cancelRun via CLI - cancelling a running workflow (python) · at 18:10:04Z · abandoned wrun_01M0ZM76AB9XFB6P68M9GWJJBJ
• run-pickup-stall · sleepInLoopWorkflow - sleep inside loop with steps actually delays each iteration (python) · at 18:10:34Z · abandoned wrun_01M0ZM83JA93Q68M99DXENAZED
• run-pickup-stall · hookWithSleepWorkflow - hook payloads delivered correctly with concurrent sleep (nextjs-webpack) · at 18:11:29Z · abandoned wrun_01M0ZM9RYGF6CTNHDK8KQB4CVK

E2E Test Summary

Summary

	Passed	Failed	Skipped	Total
❌ ▲ Vercel Production	3570	8	742	4320
✅ 💻 Local Development	3922	0	558	4480
✅ 📦 Local Production	3922	0	558	4480
✅ 🐘 Local Postgres	3922	0	558	4480
✅ 🪟 Windows	320	0	0	320
❌ 🌐 Cross-language Conformance	0	9	132	141
✅ vercel-http-transport	817	0	143	960
✅ vercel-multi-region	27	0	0	27
✅ vercel-ws-transport	553	0	87	640
Total	17053	17	2778	19848

Details by Category

❌ ▲ Vercel Production

App	Passed	Failed	Skipped
✅ astro-node	132	0	28
✅ astro-quickjs	132	0	28
✅ example-node	132	0	28
✅ example-quickjs	132	0	28
✅ express-node	132	0	28
✅ express-quickjs	132	0	28
✅ fastify-node	132	0	28
✅ fastify-quickjs	132	0	28
✅ hono-node	132	0	28
✅ hono-quickjs	132	0	28
✅ nest-node	132	0	28
✅ nest-quickjs	132	0	28
✅ nextjs-turbopack-node	157	0	3
✅ nextjs-turbopack-quickjs	157	0	3
✅ nextjs-webpack-node	157	0	3
✅ nextjs-webpack-quickjs	157	0	3
✅ nitro-node	132	0	28
✅ nitro-quickjs	132	0	28
✅ nuxt-node	132	0	28
✅ nuxt-quickjs	132	0	28
❌ python-node	0	8	152
✅ sveltekit-node	151	0	9
✅ sveltekit-quickjs	151	0	9
✅ tanstack-start-node	132	0	28
✅ tanstack-start-quickjs	132	0	28
✅ vite-node	132	0	28
✅ vite-quickjs	132	0	28

✅ 💻 Local Development

App	Passed	Failed	Skipped
✅ astro-stable-node	134	0	26
✅ astro-stable-quickjs	134	0	26
✅ express-stable-node	134	0	26
✅ express-stable-quickjs	134	0	26
✅ fastify-stable-node	134	0	26
✅ fastify-stable-quickjs	134	0	26
✅ hono-stable-node	134	0	26
✅ hono-stable-quickjs	134	0	26
✅ nest-stable-node	134	0	26
✅ nest-stable-quickjs	134	0	26
✅ nextjs-turbopack-canary-node	141	0	19
✅ nextjs-turbopack-canary-quickjs	141	0	19
✅ nextjs-turbopack-stable-node	160	0	0
✅ nextjs-turbopack-stable-quickjs	160	0	0
✅ nextjs-webpack-canary-node	141	0	19
✅ nextjs-webpack-canary-quickjs	141	0	19
✅ nextjs-webpack-stable-node	160	0	0
✅ nextjs-webpack-stable-quickjs	160	0	0
✅ nitro-stable-node	134	0	26
✅ nitro-stable-quickjs	134	0	26
✅ nuxt-stable-node	134	0	26
✅ nuxt-stable-quickjs	134	0	26
✅ sveltekit-stable-node	153	0	7
✅ sveltekit-stable-quickjs	153	0	7
✅ tanstack-start-node	134	0	26
✅ tanstack-start-quickjs	134	0	26
✅ vite-stable-node	134	0	26
✅ vite-stable-quickjs	134	0	26

✅ 📦 Local Production

App	Passed	Failed	Skipped
✅ astro-stable-node	134	0	26
✅ astro-stable-quickjs	134	0	26
✅ express-stable-node	134	0	26
✅ express-stable-quickjs	134	0	26
✅ fastify-stable-node	134	0	26
✅ fastify-stable-quickjs	134	0	26
✅ hono-stable-node	134	0	26
✅ hono-stable-quickjs	134	0	26
✅ nest-stable-node	134	0	26
✅ nest-stable-quickjs	134	0	26
✅ nextjs-turbopack-canary-node	141	0	19
✅ nextjs-turbopack-canary-quickjs	141	0	19
✅ nextjs-turbopack-stable-node	160	0	0
✅ nextjs-turbopack-stable-quickjs	160	0	0
✅ nextjs-webpack-canary-node	141	0	19
✅ nextjs-webpack-canary-quickjs	141	0	19
✅ nextjs-webpack-stable-node	160	0	0
✅ nextjs-webpack-stable-quickjs	160	0	0
✅ nitro-stable-node	134	0	26
✅ nitro-stable-quickjs	134	0	26
✅ nuxt-stable-node	134	0	26
✅ nuxt-stable-quickjs	134	0	26
✅ sveltekit-stable-node	153	0	7
✅ sveltekit-stable-quickjs	153	0	7
✅ tanstack-start-node	134	0	26
✅ tanstack-start-quickjs	134	0	26
✅ vite-stable-node	134	0	26
✅ vite-stable-quickjs	134	0	26

✅ 🐘 Local Postgres

App	Passed	Failed	Skipped
✅ astro-stable-node	134	0	26
✅ astro-stable-quickjs	134	0	26
✅ express-stable-node	134	0	26
✅ express-stable-quickjs	134	0	26
✅ fastify-stable-node	134	0	26
✅ fastify-stable-quickjs	134	0	26
✅ hono-stable-node	134	0	26
✅ hono-stable-quickjs	134	0	26
✅ nest-stable-node	134	0	26
✅ nest-stable-quickjs	134	0	26
✅ nextjs-turbopack-canary-node	141	0	19
✅ nextjs-turbopack-canary-quickjs	141	0	19
✅ nextjs-turbopack-stable-node	160	0	0
✅ nextjs-turbopack-stable-quickjs	160	0	0
✅ nextjs-webpack-canary-node	141	0	19
✅ nextjs-webpack-canary-quickjs	141	0	19
✅ nextjs-webpack-stable-node	160	0	0
✅ nextjs-webpack-stable-quickjs	160	0	0
✅ nitro-stable-node	134	0	26
✅ nitro-stable-quickjs	134	0	26
✅ nuxt-stable-node	134	0	26
✅ nuxt-stable-quickjs	134	0	26
✅ sveltekit-stable-node	153	0	7
✅ sveltekit-stable-quickjs	153	0	7
✅ tanstack-start-node	134	0	26
✅ tanstack-start-quickjs	134	0	26
✅ vite-stable-node	134	0	26
✅ vite-stable-quickjs	134	0	26

✅ 🪟 Windows

App	Passed	Failed	Skipped
✅ nextjs-turbopack-node	160	0	0
✅ nextjs-turbopack-quickjs	160	0	0

❌ 🌐 Cross-language Conformance

App	Passed	Failed	Skipped
❌ python	0	9	132

✅ vercel-http-transport

App	Passed	Failed	Skipped
✅ example	132	0	28
✅ express	132	0	28
✅ hono	132	0	28
✅ nextjs-turbopack	157	0	3
✅ nitro	132	0	28
✅ vite	132	0	28

✅ vercel-multi-region

App	Passed	Failed	Skipped
✅ nextjs-turbopack	27	0	0

✅ vercel-ws-transport

App	Passed	Failed	Skipped
✅ example	132	0	28
✅ express	132	0	28
✅ nextjs-turbopack	157	0	3
✅ vite	132	0	28

---

📋 View full workflow run

[github-actions]

📊 Workflow Benchmarks

❌ The benchmark run for 6b3ece8 failed. See the run logs for details.

commit 19c0720 · Wed, 26 Aug 2026 17:27:47 GMT · run logs

Backend: vercel · app: nextjs-turbopack

Metric	Scenario	Best (ms)	P75 (ms)	P90 (ms)	P99 (ms)	Samples
TTFS	step	204 (+13%)	1253 🔴 (+18%) 🔻	1409 🔴 (+32%) 🔻	1500 🔴 (+13%)	30
TTFS	stream	176 (-15%)	1293 🔴 (+18%) 🔻	1389 🔴 (+13%)	1435 🔴 (-6.8%)	30
TTFS	hook + stream	1318 (+58%) 🔻	1733 🔴 (+24%) 🔻	1826 🔴 (+23%) 🔻	1898 🔴 (+17%) 🔻	30
Fan-out TTFS	Promise.all(100 steps)	546 (-29%) 💚	1921 (+10%)	2263 (+27%) 🔻	2440 (+25%) 🔻	10
Fan-out TTLS	Promise.all(100 steps)	2014 (+4.7%)	3550 (-2.0%)	3789 (+2.7%)	8013 (+95%) 🔻	10
STSO	1020 steps (inline)	118 (-7.8%)	152 (-15%) 💚	178 (-14%)	762 (+144%) 🔻	1019
WO	1020 steps	167911 (-3.1%)	167911 (-3.1%)	167911 (-3.1%)	167911 (-3.1%)	1
CRTT	first chunk (pooled)	91 (-9.0%)	135 (-16%) 💚	206 (-21%) 💚	286 (-16%) 💚	28

Streams

Scenario	CRTT 1st	p75	p90	p99	CDV max	iters
paced control (100/s, 60B)	118 (-18%)	183 (-39%)	242 (-69%)	479 (-59%)	153 (-29%)	10
size sweep (100/s, 160B-12KB)	119 (-15%)	187 (-14%)	325 (-7%)	594 (+9%)	165 (-20%)	10
replay gateway-gpt-5.4-nano-2000t (1x)	250 (+116%)	143 (-25%)	196 (-89%)	387 (-89%)	192 (-43%)	3
replay eve-gpt-5.6-sol-2000t (1x)	147 (+19%)	140 (-17%)	188 (-19%)	380 (-34%)	353 (-42%)	2
replay eve-gpt-5.6-sol-2000t (2x)	123 (-45%)	209 (-38%)	292 (-51%)	511 (-44%)	302 (-31%)	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.}

_{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-2000teaf22f5946e7c61f3c65c7006d550df180cfabd4e706254a09f22aec0cfb420d · gateway-gpt-5.4-nano-2000t6f24ac518b6b83ff1d0e85a5fe78230db192716d66a7fc6b2fe022752001d041}

_{🔴 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]

Sim World

Simulated world deterministic testing for races. Traces

🟠 world-sim scenario book — 1 fail of 41 total

fence=per-spec

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

Full trace: world-sim.txt

[github-actions]

Framework	Flow route	Step reg.	Framework output
hono	200.9 KiB (±0)	40.3 KiB (±0)	1.76 MiB (±0)
nextjs-turbopack	206.3 KiB (±0)	439 B (±0)	763.1 KiB (±0)

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.

6b3ece8 · run

[github-actions]

No backport to stable for 695a1b7 (AI decision).

This fixes describeContainer in the custom data-inspector tree renderer, which exists only on main: origin/stable:packages/web-shared/src/components/ui/data-inspector.tsx is a 417-line component still built on react-inspector with no describeContainer, ExpandableContainer, or collapseRefs. The defect (hydrated Headers/URLSearchParams drawn as empty objects) and the code being changed are both properties of the main-only renderer, so there is nothing on stable for this patch to fix. It also adds new rendering behavior for arbitrary iterables, which is additive capability rather than a maintenance fix.

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

695a1b76d0e14b1093f93757232efa5c2818d0da

[mitul-s]

Why

Hydrated Headers and URLSearchParams keep their pairs in internal slots. Object.entries returns nothing, so the inspector drew them as empty objects.

The first version of this PR walked Symbol.iterator and treated every 2-element yield as a field. That matched old react-inspector behavior. It also turned a list of coordinate pairs into fake keys.

Scope

describeContainer now follows the same re-iterable pattern as Map and Set. A value with entries() renders as {} pair rows from that iterator. Any other iterable renders as [] unlabeled list rows from Symbol.iterator.

DataRender and ClassInstanceNode no longer memoize describeContainer. Tests use renderToStaticMarkup instead of jsdom. jsdom is removed from @workflow/web-shared.

Out of scope. serializeForClipboard still runs JSON.stringify on Headers and copies {}. hasDisplayContent still uses Object.keys.

Tradeoffs

Live re-iteration instead of a collapseRefs snapshot. Headers and URLSearchParams are re-iterable, which is the production case. One-shot generators are no longer snapshotted across rerenders.

Blast radius

Observability UI only, @workflow/web-sharedDataInspector. Step input and output views that hydrate Request, Headers, or URLSearchParams now show the real pairs. Custom iterables without entries() render as lists, not keyed objects.

Verification

In packages/web-shared:

pnpm exec vitest run test/data-inspector.test.ts test/collapse-refs.test.ts test/copyable-data-block.test.ts

37 tests passed.

The new tests against the previous describeContainer failed in 3 cases. TestIterable rendered 0: labels. CoordinatePairs rendered 1:2. MapLike ignored entries() and showed the default iterator.

The full @workflow/web-shared suite was 218 passed. test/zstd-decoder.test.ts failed on zlib.zstdCompressSync, which this change does not touch.

PR Checklist - Required to merge

• 📦 Added a patch changeset for @workflow/web-shared
• 🔒 Commits include DCO sign-off
• 📝 Ping @vercel/workflow in a comment once the PR is ready

Slack Thread

[changeset-bot]

🦋 Changeset detected

Latest commit: 13fc38c

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

This PR includes changesets to release 16 packages

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

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

Project	Deployment	Actions	Updated (UTC)
example-nextjs-workflow-turbopack	Ready	Preview, v0	Aug 26, 2026 7:43pm
example-nextjs-workflow-webpack	Ready	Preview, v0	Aug 26, 2026 7:43pm
example-workflow	Ready	Preview, v0	Aug 26, 2026 7:43pm
workbench-astro-workflow	Ready	Preview, v0	Aug 26, 2026 7:43pm
workbench-express-workflow	Ready	Preview, v0	Aug 26, 2026 7:43pm
workbench-fastify-workflow	Ready	Preview, v0	Aug 26, 2026 7:43pm
workbench-hono-workflow	Ready	Preview, v0	Aug 26, 2026 7:43pm
workbench-nestjs-workflow	Ready	Preview, v0	Aug 26, 2026 7:43pm
workbench-nitro-workflow	Ready	Preview, v0	Aug 26, 2026 7:43pm
workbench-nuxt-workflow	Ready	Preview, v0	Aug 26, 2026 7:43pm
workbench-python-workflow	Ready	Preview, v0	Aug 26, 2026 7:43pm
workbench-sveltekit-workflow	Ready	Preview, v0	Aug 26, 2026 7:43pm
workbench-tanstack-start-workflow	Ready	Preview, v0	Aug 26, 2026 7:43pm
workbench-vite-workflow	Ready	Preview, v0	Aug 26, 2026 7:43pm
workflow-docs	Ready	Preview, v0	Aug 26, 2026 7:43pm
workflow-swc-playground	Ready	Preview, v0	Aug 26, 2026 7:43pm
workflow-tarballs	Ready	Preview, v0	Aug 26, 2026 7:43pm
workflow-web	Ready	Preview, v0	Aug 26, 2026 7:43pm

[TooTallNate]

More generally, we should be able to expand any value that implements Symbol.iterator, rather than special casing Headers and URLSearchParams

[github-actions]

🧪 E2E Test Results

❌ Some tests failed

❌ Failed E2E Tests

▲ Vercel Production (8 failed)

python-node (8 failed):

• promiseAllWorkflow | wrun_41M0ZKVKE60GRTE4KH2QZ7DTC4 | 🔍 observability
• sleepingWorkflow | wrun_41M0ZKW7BW0GXPGM0GVD1EAEKR | 🔍 observability
• parallelSleepWorkflow | wrun_41M0ZKW7EY0GHGEV96Q39D7PMA | 🔍 observability
• nullByteWorkflow | wrun_41M0ZKWDR00GY8QCX6JSTGSJAQ | 🔍 observability
• cancelRun - cancelling a running workflow | wrun_41M0ZM0KJG0GTHJCCJF5M9M6E2 | 🔍 observability
• cancelRun via CLI - cancelling a running workflow | wrun_41M0ZM0MG50GMVCWAJFATE272J | 🔍 observability
• sleepInLoopWorkflow - sleep inside loop with steps actually delays each iteration | wrun_41M0ZM0S270GSASPMDRG9C4HW2 | 🔍 observability
• resilient start: addTenWorkflow completes when run_created returns 500 | wrun_41M0ZM19S70GWKV1MVG6V7GW7S | 🔍 observability

🌐 Cross-language Conformance (9 failed)

python (9 failed):

• deploymentId: 'latest' is a no-op in non-Vercel worlds | wrun_01M0ZM4X0N34FZTTVJCZ7E2G9G
• promiseAllWorkflow | wrun_41M0ZKVKE60GRTE4KH2QZ7DTC4
• sleepingWorkflow | wrun_41M0ZKW7BW0GXPGM0GVD1EAEKR
• parallelSleepWorkflow | wrun_41M0ZKW7EY0GHGEV96Q39D7PMA
• nullByteWorkflow | wrun_41M0ZKWDR00GY8QCX6JSTGSJAQ
• cancelRun - cancelling a running workflow | wrun_41M0ZM0KJG0GTHJCCJF5M9M6E2
• cancelRun via CLI - cancelling a running workflow | wrun_41M0ZM0MG50GMVCWAJFATE272J
• sleepInLoopWorkflow - sleep inside loop with steps actually delays each iteration | wrun_41M0ZM0S270GSASPMDRG9C4HW2
• resilient start: addTenWorkflow completes when run_created returns 500 | wrun_41M0ZM19S70GWKV1MVG6V7GW7S

⚠️ 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.

• cancelRun via CLI - cancelling a running workflow (express)
• hook created by a sfo1 run resolves by token and resumes the run (nextjs-turbopack)
• hookWorkflow (tanstack-start)
• promiseAllWorkflow (express)
• promiseRaceStressTestWorkflow (vite)
• promiseRaceWorkflow (hono)
• promiseRaceWorkflow (sveltekit)

🛠 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.

34 infra events

• cold-start-warmup · suite warmup (python) · at 18:05:09Z · abandoned wrun_41M0ZKTYBS0GPDS9W8WHKT22HR · (+7 more)
• run-pickup-stall · promiseAllWorkflow (python) · at 18:05:25Z · abandoned wrun_41M0ZKYM2M0GYCWSNESMWEGYZW
• run-pickup-stall · nullByteWorkflow (python) · at 18:05:25Z · abandoned wrun_41M0ZKYM2X0GJ5QJENP5KAR8DK
• run-pickup-stall · sleepingWorkflow (python) · at 18:05:25Z · abandoned wrun_41M0ZKYM2S0GGQ93SXWWAXH1PE
• run-pickup-stall · parallelSleepWorkflow (python) · at 18:05:25Z · abandoned wrun_41M0ZKYM2S0GGQ93SXWWAXH1PF
• run-pickup-stall · cancelRun - cancelling a running workflow (python) · at 18:05:26Z · abandoned wrun_41M0ZKYMFQ0GNQK9XTZZS00G68
• run-pickup-stall · cancelRun - cancelling a running workflow (python) · at 18:05:58Z · abandoned wrun_41M0ZKZMDG0GKJCTA3BYYGXFDX
• cold-start-warmup · suite warmup (tanstack-start) · at 18:06:22Z · abandoned wrun_01M0ZM010XFRBR7N3GCYFHT0KD
• run-pickup-stall · sleepingWorkflow (python) · at 18:06:26Z · abandoned wrun_41M0ZM0FRD0GJ6BN11NRKBMJ9N
• run-pickup-stall · promiseAllWorkflow (python) · at 18:06:26Z · abandoned wrun_41M0ZM0FQG0GRFWWW9CP6NEVRF
• run-pickup-stall · nullByteWorkflow (python) · at 18:06:26Z · abandoned wrun_41M0ZM0FSY0GXM6P4BV6D1NTVQ
• run-pickup-stall · parallelSleepWorkflow (python) · at 18:06:26Z · abandoned wrun_41M0ZM0FJX0GR49QWPXV7A356M
• run-pickup-stall · cancelRun via CLI - cancelling a running workflow (python) · at 18:07:16Z · abandoned wrun_41M0ZM0M5E0GX9F0KQ6Q082MS1
• cold-start-warmup · suite warmup (python) · at 18:07:19Z · abandoned wrun_01M0ZKYYKD0KPD3MBEX0E432BE · (+7 more)
• run-pickup-stall · deploymentId: 'latest' is a no-op in non-Vercel worlds (python) · at 18:07:34Z · abandoned wrun_01M0ZM2KQNF8AWHK32575V2461
• run-pickup-stall · promiseAllWorkflow (python) · at 18:07:34Z · abandoned wrun_01M0ZM2KQPQPQWKSRGPTBXH847
• run-pickup-stall · parallelSleepWorkflow (python) · at 18:07:34Z · abandoned wrun_01M0ZM2KQY592H6FWWEF0NRP1S
• run-pickup-stall · sleepingWorkflow (python) · at 18:07:34Z · abandoned wrun_01M0ZM2KQWET1C8DARN3W95P1R
• run-pickup-stall · nullByteWorkflow (python) · at 18:07:34Z · abandoned wrun_01M0ZM2KR13RD8ECG6Q0BCWN67
• run-pickup-stall · instanceMethodStepWorkflow - instance methods with "use step" directive (nuxt) · at 18:08:09Z · abandoned wrun_01M0ZM3NZ7D3G82TGVPJ8YWN5T
• run-pickup-stall · deploymentId: 'latest' is a no-op in non-Vercel worlds (python) · at 18:08:34Z · abandoned wrun_01M0ZM4EB8QN7E7Y2GE2DME665
• run-pickup-stall · promiseAllWorkflow (python) · at 18:08:34Z · abandoned wrun_01M0ZM4EBDCPVVDS39BS95RA70
• run-pickup-stall · sleepingWorkflow (python) · at 18:08:34Z · abandoned wrun_01M0ZM4EBH838SW4S33HVVHJ86
• run-pickup-stall · parallelSleepWorkflow (python) · at 18:08:34Z · abandoned wrun_01M0ZM4EBQG3D97DYY2VTKVPYK
• run-pickup-stall · nullByteWorkflow (python) · at 18:08:34Z · abandoned wrun_01M0ZM4EBV1GDM3GJBCXC3EA81
• run-pickup-stall · sleepInLoopWorkflow - sleep inside loop with steps actually delays each iteration (python) · at 18:08:58Z · abandoned wrun_41M0ZM37FF0GHKTCT7733J4VH5
• run-pickup-stall · cancelRun - cancelling a running workflow (python) · at 18:09:34Z · abandoned wrun_01M0ZM68YTAQ3XS41G6YFCKT43
• run-pickup-stall · cancelRun via CLI - cancelling a running workflow (python) · at 18:09:34Z · abandoned wrun_01M0ZM68Z493DW9VT63EVBWHV7
• run-pickup-stall · sleepInLoopWorkflow - sleep inside loop with steps actually delays each iteration (python) · at 18:09:34Z · abandoned wrun_01M0ZM68Z77GYDRKXMEJ9H7AR0
• run-pickup-stall · cancelRun via CLI - cancelling a running workflow (python) · at 18:09:38Z · abandoned wrun_41M0ZM3C210GMFQNJV10YHJTFC
• run-pickup-stall · cancelRun - cancelling a running workflow (python) · at 18:10:04Z · abandoned wrun_01M0ZM76A942EQRE76CRQS2GBD
• run-pickup-stall · cancelRun via CLI - cancelling a running workflow (python) · at 18:10:04Z · abandoned wrun_01M0ZM76AB9XFB6P68M9GWJJBJ
• run-pickup-stall · sleepInLoopWorkflow - sleep inside loop with steps actually delays each iteration (python) · at 18:10:34Z · abandoned wrun_01M0ZM83JA93Q68M99DXENAZED
• run-pickup-stall · hookWithSleepWorkflow - hook payloads delivered correctly with concurrent sleep (nextjs-webpack) · at 18:11:29Z · abandoned wrun_01M0ZM9RYGF6CTNHDK8KQB4CVK

E2E Test Summary

Summary

	Passed	Failed	Skipped	Total
❌ ▲ Vercel Production	3570	8	742	4320
✅ 💻 Local Development	3922	0	558	4480
✅ 📦 Local Production	3922	0	558	4480
✅ 🐘 Local Postgres	3922	0	558	4480
✅ 🪟 Windows	320	0	0	320
❌ 🌐 Cross-language Conformance	0	9	132	141
✅ vercel-http-transport	817	0	143	960
✅ vercel-multi-region	27	0	0	27
✅ vercel-ws-transport	553	0	87	640
Total	17053	17	2778	19848

Details by Category

❌ ▲ Vercel Production

App	Passed	Failed	Skipped
✅ astro-node	132	0	28
✅ astro-quickjs	132	0	28
✅ example-node	132	0	28
✅ example-quickjs	132	0	28
✅ express-node	132	0	28
✅ express-quickjs	132	0	28
✅ fastify-node	132	0	28
✅ fastify-quickjs	132	0	28
✅ hono-node	132	0	28
✅ hono-quickjs	132	0	28
✅ nest-node	132	0	28
✅ nest-quickjs	132	0	28
✅ nextjs-turbopack-node	157	0	3
✅ nextjs-turbopack-quickjs	157	0	3
✅ nextjs-webpack-node	157	0	3
✅ nextjs-webpack-quickjs	157	0	3
✅ nitro-node	132	0	28
✅ nitro-quickjs	132	0	28
✅ nuxt-node	132	0	28
✅ nuxt-quickjs	132	0	28
❌ python-node	0	8	152
✅ sveltekit-node	151	0	9
✅ sveltekit-quickjs	151	0	9
✅ tanstack-start-node	132	0	28
✅ tanstack-start-quickjs	132	0	28
✅ vite-node	132	0	28
✅ vite-quickjs	132	0	28

✅ 💻 Local Development

App	Passed	Failed	Skipped
✅ astro-stable-node	134	0	26
✅ astro-stable-quickjs	134	0	26
✅ express-stable-node	134	0	26
✅ express-stable-quickjs	134	0	26
✅ fastify-stable-node	134	0	26
✅ fastify-stable-quickjs	134	0	26
✅ hono-stable-node	134	0	26
✅ hono-stable-quickjs	134	0	26
✅ nest-stable-node	134	0	26
✅ nest-stable-quickjs	134	0	26
✅ nextjs-turbopack-canary-node	141	0	19
✅ nextjs-turbopack-canary-quickjs	141	0	19
✅ nextjs-turbopack-stable-node	160	0	0
✅ nextjs-turbopack-stable-quickjs	160	0	0
✅ nextjs-webpack-canary-node	141	0	19
✅ nextjs-webpack-canary-quickjs	141	0	19
✅ nextjs-webpack-stable-node	160	0	0
✅ nextjs-webpack-stable-quickjs	160	0	0
✅ nitro-stable-node	134	0	26
✅ nitro-stable-quickjs	134	0	26
✅ nuxt-stable-node	134	0	26
✅ nuxt-stable-quickjs	134	0	26
✅ sveltekit-stable-node	153	0	7
✅ sveltekit-stable-quickjs	153	0	7
✅ tanstack-start-node	134	0	26
✅ tanstack-start-quickjs	134	0	26
✅ vite-stable-node	134	0	26
✅ vite-stable-quickjs	134	0	26

✅ 📦 Local Production

App	Passed	Failed	Skipped
✅ astro-stable-node	134	0	26
✅ astro-stable-quickjs	134	0	26
✅ express-stable-node	134	0	26
✅ express-stable-quickjs	134	0	26
✅ fastify-stable-node	134	0	26
✅ fastify-stable-quickjs	134	0	26
✅ hono-stable-node	134	0	26
✅ hono-stable-quickjs	134	0	26
✅ nest-stable-node	134	0	26
✅ nest-stable-quickjs	134	0	26
✅ nextjs-turbopack-canary-node	141	0	19
✅ nextjs-turbopack-canary-quickjs	141	0	19
✅ nextjs-turbopack-stable-node	160	0	0
✅ nextjs-turbopack-stable-quickjs	160	0	0
✅ nextjs-webpack-canary-node	141	0	19
✅ nextjs-webpack-canary-quickjs	141	0	19
✅ nextjs-webpack-stable-node	160	0	0
✅ nextjs-webpack-stable-quickjs	160	0	0
✅ nitro-stable-node	134	0	26
✅ nitro-stable-quickjs	134	0	26
✅ nuxt-stable-node	134	0	26
✅ nuxt-stable-quickjs	134	0	26
✅ sveltekit-stable-node	153	0	7
✅ sveltekit-stable-quickjs	153	0	7
✅ tanstack-start-node	134	0	26
✅ tanstack-start-quickjs	134	0	26
✅ vite-stable-node	134	0	26
✅ vite-stable-quickjs	134	0	26

✅ 🐘 Local Postgres

App	Passed	Failed	Skipped
✅ astro-stable-node	134	0	26
✅ astro-stable-quickjs	134	0	26
✅ express-stable-node	134	0	26
✅ express-stable-quickjs	134	0	26
✅ fastify-stable-node	134	0	26
✅ fastify-stable-quickjs	134	0	26
✅ hono-stable-node	134	0	26
✅ hono-stable-quickjs	134	0	26
✅ nest-stable-node	134	0	26
✅ nest-stable-quickjs	134	0	26
✅ nextjs-turbopack-canary-node	141	0	19
✅ nextjs-turbopack-canary-quickjs	141	0	19
✅ nextjs-turbopack-stable-node	160	0	0
✅ nextjs-turbopack-stable-quickjs	160	0	0
✅ nextjs-webpack-canary-node	141	0	19
✅ nextjs-webpack-canary-quickjs	141	0	19
✅ nextjs-webpack-stable-node	160	0	0
✅ nextjs-webpack-stable-quickjs	160	0	0
✅ nitro-stable-node	134	0	26
✅ nitro-stable-quickjs	134	0	26
✅ nuxt-stable-node	134	0	26
✅ nuxt-stable-quickjs	134	0	26
✅ sveltekit-stable-node	153	0	7
✅ sveltekit-stable-quickjs	153	0	7
✅ tanstack-start-node	134	0	26
✅ tanstack-start-quickjs	134	0	26
✅ vite-stable-node	134	0	26
✅ vite-stable-quickjs	134	0	26

✅ 🪟 Windows

App	Passed	Failed	Skipped
✅ nextjs-turbopack-node	160	0	0
✅ nextjs-turbopack-quickjs	160	0	0

❌ 🌐 Cross-language Conformance

App	Passed	Failed	Skipped
❌ python	0	9	132

✅ vercel-http-transport

App	Passed	Failed	Skipped
✅ example	132	0	28
✅ express	132	0	28
✅ hono	132	0	28
✅ nextjs-turbopack	157	0	3
✅ nitro	132	0	28
✅ vite	132	0	28

✅ vercel-multi-region

App	Passed	Failed	Skipped
✅ nextjs-turbopack	27	0	0

✅ vercel-ws-transport

App	Passed	Failed	Skipped
✅ example	132	0	28
✅ express	132	0	28
✅ nextjs-turbopack	157	0	3
✅ vite	132	0	28

---

📋 View full workflow run

[github-actions]

📊 Workflow Benchmarks

❌ The benchmark run for 6b3ece8 failed. See the run logs for details.

commit 19c0720 · Wed, 26 Aug 2026 17:27:47 GMT · run logs

Backend: vercel · app: nextjs-turbopack

Metric	Scenario	Best (ms)	P75 (ms)	P90 (ms)	P99 (ms)	Samples
TTFS	step	204 (+13%)	1253 🔴 (+18%) 🔻	1409 🔴 (+32%) 🔻	1500 🔴 (+13%)	30
TTFS	stream	176 (-15%)	1293 🔴 (+18%) 🔻	1389 🔴 (+13%)	1435 🔴 (-6.8%)	30
TTFS	hook + stream	1318 (+58%) 🔻	1733 🔴 (+24%) 🔻	1826 🔴 (+23%) 🔻	1898 🔴 (+17%) 🔻	30
Fan-out TTFS	Promise.all(100 steps)	546 (-29%) 💚	1921 (+10%)	2263 (+27%) 🔻	2440 (+25%) 🔻	10
Fan-out TTLS	Promise.all(100 steps)	2014 (+4.7%)	3550 (-2.0%)	3789 (+2.7%)	8013 (+95%) 🔻	10
STSO	1020 steps (inline)	118 (-7.8%)	152 (-15%) 💚	178 (-14%)	762 (+144%) 🔻	1019
WO	1020 steps	167911 (-3.1%)	167911 (-3.1%)	167911 (-3.1%)	167911 (-3.1%)	1
CRTT	first chunk (pooled)	91 (-9.0%)	135 (-16%) 💚	206 (-21%) 💚	286 (-16%) 💚	28

Streams

Scenario	CRTT 1st	p75	p90	p99	CDV max	iters
paced control (100/s, 60B)	118 (-18%)	183 (-39%)	242 (-69%)	479 (-59%)	153 (-29%)	10
size sweep (100/s, 160B-12KB)	119 (-15%)	187 (-14%)	325 (-7%)	594 (+9%)	165 (-20%)	10
replay gateway-gpt-5.4-nano-2000t (1x)	250 (+116%)	143 (-25%)	196 (-89%)	387 (-89%)	192 (-43%)	3
replay eve-gpt-5.6-sol-2000t (1x)	147 (+19%)	140 (-17%)	188 (-19%)	380 (-34%)	353 (-42%)	2
replay eve-gpt-5.6-sol-2000t (2x)	123 (-45%)	209 (-38%)	292 (-51%)	511 (-44%)	302 (-31%)	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.}

_{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-2000teaf22f5946e7c61f3c65c7006d550df180cfabd4e706254a09f22aec0cfb420d · gateway-gpt-5.4-nano-2000t6f24ac518b6b83ff1d0e85a5fe78230db192716d66a7fc6b2fe022752001d041}

_{🔴 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]

Sim World

Simulated world deterministic testing for races. Traces

🟠 world-sim scenario book — 1 fail of 41 total

fence=per-spec

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

Full trace: world-sim.txt

[github-actions]

Framework	Flow route	Step reg.	Framework output
hono	200.9 KiB (±0)	40.3 KiB (±0)	1.76 MiB (±0)
nextjs-turbopack	206.3 KiB (±0)	439 B (±0)	763.1 KiB (±0)

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.

6b3ece8 · run

[github-actions]

No backport to stable for 695a1b7 (AI decision).

This fixes describeContainer in the custom data-inspector tree renderer, which exists only on main: origin/stable:packages/web-shared/src/components/ui/data-inspector.tsx is a 417-line component still built on react-inspector with no describeContainer, ExpandableContainer, or collapseRefs. The defect (hydrated Headers/URLSearchParams drawn as empty objects) and the code being changed are both properties of the main-only renderer, so there is nothing on stable for this patch to fix. It also adds new rendering behavior for arbitrary iterables, which is additive capability rather than a maintenance fix.

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

695a1b76d0e14b1093f93757232efa5c2818d0da

[mitul-s]

Why

Hydrated Headers and URLSearchParams keep their pairs in internal slots. Object.entries returns nothing, so the inspector drew them as empty objects.

The first version of this PR walked Symbol.iterator and treated every 2-element yield as a field. That matched old react-inspector behavior. It also turned a list of coordinate pairs into fake keys.

Scope

describeContainer now follows the same re-iterable pattern as Map and Set. A value with entries() renders as {} pair rows from that iterator. Any other iterable renders as [] unlabeled list rows from Symbol.iterator.

DataRender and ClassInstanceNode no longer memoize describeContainer. Tests use renderToStaticMarkup instead of jsdom. jsdom is removed from @workflow/web-shared.

Out of scope. serializeForClipboard still runs JSON.stringify on Headers and copies {}. hasDisplayContent still uses Object.keys.

Tradeoffs

Live re-iteration instead of a collapseRefs snapshot. Headers and URLSearchParams are re-iterable, which is the production case. One-shot generators are no longer snapshotted across rerenders.

Blast radius

Observability UI only, @workflow/web-sharedDataInspector. Step input and output views that hydrate Request, Headers, or URLSearchParams now show the real pairs. Custom iterables without entries() render as lists, not keyed objects.

Verification

In packages/web-shared:

pnpm exec vitest run test/data-inspector.test.ts test/collapse-refs.test.ts test/copyable-data-block.test.ts

37 tests passed.

The new tests against the previous describeContainer failed in 3 cases. TestIterable rendered 0: labels. CoordinatePairs rendered 1:2. MapLike ignored entries() and showed the default iterator.

The full @workflow/web-shared suite was 218 passed. test/zstd-decoder.test.ts failed on zlib.zstdCompressSync, which this change does not touch.

PR Checklist - Required to merge

• 📦 Added a patch changeset for @workflow/web-shared
• 🔒 Commits include DCO sign-off
• 📝 Ping @vercel/workflow in a comment once the PR is ready

Slack Thread

[changeset-bot]

🦋 Changeset detected

Latest commit: 13fc38c

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

This PR includes changesets to release 16 packages

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

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

Project	Deployment	Actions	Updated (UTC)
example-nextjs-workflow-turbopack	Ready	Preview, v0	Aug 26, 2026 7:43pm
example-nextjs-workflow-webpack	Ready	Preview, v0	Aug 26, 2026 7:43pm
example-workflow	Ready	Preview, v0	Aug 26, 2026 7:43pm
workbench-astro-workflow	Ready	Preview, v0	Aug 26, 2026 7:43pm
workbench-express-workflow	Ready	Preview, v0	Aug 26, 2026 7:43pm
workbench-fastify-workflow	Ready	Preview, v0	Aug 26, 2026 7:43pm
workbench-hono-workflow	Ready	Preview, v0	Aug 26, 2026 7:43pm
workbench-nestjs-workflow	Ready	Preview, v0	Aug 26, 2026 7:43pm
workbench-nitro-workflow	Ready	Preview, v0	Aug 26, 2026 7:43pm
workbench-nuxt-workflow	Ready	Preview, v0	Aug 26, 2026 7:43pm
workbench-python-workflow	Ready	Preview, v0	Aug 26, 2026 7:43pm
workbench-sveltekit-workflow	Ready	Preview, v0	Aug 26, 2026 7:43pm
workbench-tanstack-start-workflow	Ready	Preview, v0	Aug 26, 2026 7:43pm
workbench-vite-workflow	Ready	Preview, v0	Aug 26, 2026 7:43pm
workflow-docs	Ready	Preview, v0	Aug 26, 2026 7:43pm
workflow-swc-playground	Ready	Preview, v0	Aug 26, 2026 7:43pm
workflow-tarballs	Ready	Preview, v0	Aug 26, 2026 7:43pm
workflow-web	Ready	Preview, v0	Aug 26, 2026 7:43pm

[TooTallNate]

More generally, we should be able to expand any value that implements Symbol.iterator, rather than special casing Headers and URLSearchParams

[github-actions]

🧪 E2E Test Results

❌ Some tests failed

❌ Failed E2E Tests

▲ Vercel Production (8 failed)

python-node (8 failed):

• promiseAllWorkflow | wrun_41M0ZKVKE60GRTE4KH2QZ7DTC4 | 🔍 observability
• sleepingWorkflow | wrun_41M0ZKW7BW0GXPGM0GVD1EAEKR | 🔍 observability
• parallelSleepWorkflow | wrun_41M0ZKW7EY0GHGEV96Q39D7PMA | 🔍 observability
• nullByteWorkflow | wrun_41M0ZKWDR00GY8QCX6JSTGSJAQ | 🔍 observability
• cancelRun - cancelling a running workflow | wrun_41M0ZM0KJG0GTHJCCJF5M9M6E2 | 🔍 observability
• cancelRun via CLI - cancelling a running workflow | wrun_41M0ZM0MG50GMVCWAJFATE272J | 🔍 observability
• sleepInLoopWorkflow - sleep inside loop with steps actually delays each iteration | wrun_41M0ZM0S270GSASPMDRG9C4HW2 | 🔍 observability
• resilient start: addTenWorkflow completes when run_created returns 500 | wrun_41M0ZM19S70GWKV1MVG6V7GW7S | 🔍 observability

🌐 Cross-language Conformance (9 failed)

python (9 failed):

• deploymentId: 'latest' is a no-op in non-Vercel worlds | wrun_01M0ZM4X0N34FZTTVJCZ7E2G9G
• promiseAllWorkflow | wrun_41M0ZKVKE60GRTE4KH2QZ7DTC4
• sleepingWorkflow | wrun_41M0ZKW7BW0GXPGM0GVD1EAEKR
• parallelSleepWorkflow | wrun_41M0ZKW7EY0GHGEV96Q39D7PMA
• nullByteWorkflow | wrun_41M0ZKWDR00GY8QCX6JSTGSJAQ
• cancelRun - cancelling a running workflow | wrun_41M0ZM0KJG0GTHJCCJF5M9M6E2
• cancelRun via CLI - cancelling a running workflow | wrun_41M0ZM0MG50GMVCWAJFATE272J
• sleepInLoopWorkflow - sleep inside loop with steps actually delays each iteration | wrun_41M0ZM0S270GSASPMDRG9C4HW2
• resilient start: addTenWorkflow completes when run_created returns 500 | wrun_41M0ZM19S70GWKV1MVG6V7GW7S

⚠️ 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.

• cancelRun via CLI - cancelling a running workflow (express)
• hook created by a sfo1 run resolves by token and resumes the run (nextjs-turbopack)
• hookWorkflow (tanstack-start)
• promiseAllWorkflow (express)
• promiseRaceStressTestWorkflow (vite)
• promiseRaceWorkflow (hono)
• promiseRaceWorkflow (sveltekit)

🛠 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.

34 infra events

• cold-start-warmup · suite warmup (python) · at 18:05:09Z · abandoned wrun_41M0ZKTYBS0GPDS9W8WHKT22HR · (+7 more)
• run-pickup-stall · promiseAllWorkflow (python) · at 18:05:25Z · abandoned wrun_41M0ZKYM2M0GYCWSNESMWEGYZW
• run-pickup-stall · nullByteWorkflow (python) · at 18:05:25Z · abandoned wrun_41M0ZKYM2X0GJ5QJENP5KAR8DK
• run-pickup-stall · sleepingWorkflow (python) · at 18:05:25Z · abandoned wrun_41M0ZKYM2S0GGQ93SXWWAXH1PE
• run-pickup-stall · parallelSleepWorkflow (python) · at 18:05:25Z · abandoned wrun_41M0ZKYM2S0GGQ93SXWWAXH1PF
• run-pickup-stall · cancelRun - cancelling a running workflow (python) · at 18:05:26Z · abandoned wrun_41M0ZKYMFQ0GNQK9XTZZS00G68
• run-pickup-stall · cancelRun - cancelling a running workflow (python) · at 18:05:58Z · abandoned wrun_41M0ZKZMDG0GKJCTA3BYYGXFDX
• cold-start-warmup · suite warmup (tanstack-start) · at 18:06:22Z · abandoned wrun_01M0ZM010XFRBR7N3GCYFHT0KD
• run-pickup-stall · sleepingWorkflow (python) · at 18:06:26Z · abandoned wrun_41M0ZM0FRD0GJ6BN11NRKBMJ9N
• run-pickup-stall · promiseAllWorkflow (python) · at 18:06:26Z · abandoned wrun_41M0ZM0FQG0GRFWWW9CP6NEVRF
• run-pickup-stall · nullByteWorkflow (python) · at 18:06:26Z · abandoned wrun_41M0ZM0FSY0GXM6P4BV6D1NTVQ
• run-pickup-stall · parallelSleepWorkflow (python) · at 18:06:26Z · abandoned wrun_41M0ZM0FJX0GR49QWPXV7A356M
• run-pickup-stall · cancelRun via CLI - cancelling a running workflow (python) · at 18:07:16Z · abandoned wrun_41M0ZM0M5E0GX9F0KQ6Q082MS1
• cold-start-warmup · suite warmup (python) · at 18:07:19Z · abandoned wrun_01M0ZKYYKD0KPD3MBEX0E432BE · (+7 more)
• run-pickup-stall · deploymentId: 'latest' is a no-op in non-Vercel worlds (python) · at 18:07:34Z · abandoned wrun_01M0ZM2KQNF8AWHK32575V2461
• run-pickup-stall · promiseAllWorkflow (python) · at 18:07:34Z · abandoned wrun_01M0ZM2KQPQPQWKSRGPTBXH847
• run-pickup-stall · parallelSleepWorkflow (python) · at 18:07:34Z · abandoned wrun_01M0ZM2KQY592H6FWWEF0NRP1S
• run-pickup-stall · sleepingWorkflow (python) · at 18:07:34Z · abandoned wrun_01M0ZM2KQWET1C8DARN3W95P1R
• run-pickup-stall · nullByteWorkflow (python) · at 18:07:34Z · abandoned wrun_01M0ZM2KR13RD8ECG6Q0BCWN67
• run-pickup-stall · instanceMethodStepWorkflow - instance methods with "use step" directive (nuxt) · at 18:08:09Z · abandoned wrun_01M0ZM3NZ7D3G82TGVPJ8YWN5T
• run-pickup-stall · deploymentId: 'latest' is a no-op in non-Vercel worlds (python) · at 18:08:34Z · abandoned wrun_01M0ZM4EB8QN7E7Y2GE2DME665
• run-pickup-stall · promiseAllWorkflow (python) · at 18:08:34Z · abandoned wrun_01M0ZM4EBDCPVVDS39BS95RA70
• run-pickup-stall · sleepingWorkflow (python) · at 18:08:34Z · abandoned wrun_01M0ZM4EBH838SW4S33HVVHJ86
• run-pickup-stall · parallelSleepWorkflow (python) · at 18:08:34Z · abandoned wrun_01M0ZM4EBQG3D97DYY2VTKVPYK
• run-pickup-stall · nullByteWorkflow (python) · at 18:08:34Z · abandoned wrun_01M0ZM4EBV1GDM3GJBCXC3EA81
• run-pickup-stall · sleepInLoopWorkflow - sleep inside loop with steps actually delays each iteration (python) · at 18:08:58Z · abandoned wrun_41M0ZM37FF0GHKTCT7733J4VH5
• run-pickup-stall · cancelRun - cancelling a running workflow (python) · at 18:09:34Z · abandoned wrun_01M0ZM68YTAQ3XS41G6YFCKT43
• run-pickup-stall · cancelRun via CLI - cancelling a running workflow (python) · at 18:09:34Z · abandoned wrun_01M0ZM68Z493DW9VT63EVBWHV7
• run-pickup-stall · sleepInLoopWorkflow - sleep inside loop with steps actually delays each iteration (python) · at 18:09:34Z · abandoned wrun_01M0ZM68Z77GYDRKXMEJ9H7AR0
• run-pickup-stall · cancelRun via CLI - cancelling a running workflow (python) · at 18:09:38Z · abandoned wrun_41M0ZM3C210GMFQNJV10YHJTFC
• run-pickup-stall · cancelRun - cancelling a running workflow (python) · at 18:10:04Z · abandoned wrun_01M0ZM76A942EQRE76CRQS2GBD
• run-pickup-stall · cancelRun via CLI - cancelling a running workflow (python) · at 18:10:04Z · abandoned wrun_01M0ZM76AB9XFB6P68M9GWJJBJ
• run-pickup-stall · sleepInLoopWorkflow - sleep inside loop with steps actually delays each iteration (python) · at 18:10:34Z · abandoned wrun_01M0ZM83JA93Q68M99DXENAZED
• run-pickup-stall · hookWithSleepWorkflow - hook payloads delivered correctly with concurrent sleep (nextjs-webpack) · at 18:11:29Z · abandoned wrun_01M0ZM9RYGF6CTNHDK8KQB4CVK

E2E Test Summary

Summary

	Passed	Failed	Skipped	Total
❌ ▲ Vercel Production	3570	8	742	4320
✅ 💻 Local Development	3922	0	558	4480
✅ 📦 Local Production	3922	0	558	4480
✅ 🐘 Local Postgres	3922	0	558	4480
✅ 🪟 Windows	320	0	0	320
❌ 🌐 Cross-language Conformance	0	9	132	141
✅ vercel-http-transport	817	0	143	960
✅ vercel-multi-region	27	0	0	27
✅ vercel-ws-transport	553	0	87	640
Total	17053	17	2778	19848

Details by Category

❌ ▲ Vercel Production

App	Passed	Failed	Skipped
✅ astro-node	132	0	28
✅ astro-quickjs	132	0	28
✅ example-node	132	0	28
✅ example-quickjs	132	0	28
✅ express-node	132	0	28
✅ express-quickjs	132	0	28
✅ fastify-node	132	0	28
✅ fastify-quickjs	132	0	28
✅ hono-node	132	0	28
✅ hono-quickjs	132	0	28
✅ nest-node	132	0	28
✅ nest-quickjs	132	0	28
✅ nextjs-turbopack-node	157	0	3
✅ nextjs-turbopack-quickjs	157	0	3
✅ nextjs-webpack-node	157	0	3
✅ nextjs-webpack-quickjs	157	0	3
✅ nitro-node	132	0	28
✅ nitro-quickjs	132	0	28
✅ nuxt-node	132	0	28
✅ nuxt-quickjs	132	0	28
❌ python-node	0	8	152
✅ sveltekit-node	151	0	9
✅ sveltekit-quickjs	151	0	9
✅ tanstack-start-node	132	0	28
✅ tanstack-start-quickjs	132	0	28
✅ vite-node	132	0	28
✅ vite-quickjs	132	0	28

✅ 💻 Local Development

App	Passed	Failed	Skipped
✅ astro-stable-node	134	0	26
✅ astro-stable-quickjs	134	0	26
✅ express-stable-node	134	0	26
✅ express-stable-quickjs	134	0	26
✅ fastify-stable-node	134	0	26
✅ fastify-stable-quickjs	134	0	26
✅ hono-stable-node	134	0	26
✅ hono-stable-quickjs	134	0	26
✅ nest-stable-node	134	0	26
✅ nest-stable-quickjs	134	0	26
✅ nextjs-turbopack-canary-node	141	0	19
✅ nextjs-turbopack-canary-quickjs	141	0	19
✅ nextjs-turbopack-stable-node	160	0	0
✅ nextjs-turbopack-stable-quickjs	160	0	0
✅ nextjs-webpack-canary-node	141	0	19
✅ nextjs-webpack-canary-quickjs	141	0	19
✅ nextjs-webpack-stable-node	160	0	0
✅ nextjs-webpack-stable-quickjs	160	0	0
✅ nitro-stable-node	134	0	26
✅ nitro-stable-quickjs	134	0	26
✅ nuxt-stable-node	134	0	26
✅ nuxt-stable-quickjs	134	0	26
✅ sveltekit-stable-node	153	0	7
✅ sveltekit-stable-quickjs	153	0	7
✅ tanstack-start-node	134	0	26
✅ tanstack-start-quickjs	134	0	26
✅ vite-stable-node	134	0	26
✅ vite-stable-quickjs	134	0	26

✅ 📦 Local Production

App	Passed	Failed	Skipped
✅ astro-stable-node	134	0	26
✅ astro-stable-quickjs	134	0	26
✅ express-stable-node	134	0	26
✅ express-stable-quickjs	134	0	26
✅ fastify-stable-node	134	0	26
✅ fastify-stable-quickjs	134	0	26
✅ hono-stable-node	134	0	26
✅ hono-stable-quickjs	134	0	26
✅ nest-stable-node	134	0	26
✅ nest-stable-quickjs	134	0	26
✅ nextjs-turbopack-canary-node	141	0	19
✅ nextjs-turbopack-canary-quickjs	141	0	19
✅ nextjs-turbopack-stable-node	160	0	0
✅ nextjs-turbopack-stable-quickjs	160	0	0
✅ nextjs-webpack-canary-node	141	0	19
✅ nextjs-webpack-canary-quickjs	141	0	19
✅ nextjs-webpack-stable-node	160	0	0
✅ nextjs-webpack-stable-quickjs	160	0	0
✅ nitro-stable-node	134	0	26
✅ nitro-stable-quickjs	134	0	26
✅ nuxt-stable-node	134	0	26
✅ nuxt-stable-quickjs	134	0	26
✅ sveltekit-stable-node	153	0	7
✅ sveltekit-stable-quickjs	153	0	7
✅ tanstack-start-node	134	0	26
✅ tanstack-start-quickjs	134	0	26
✅ vite-stable-node	134	0	26
✅ vite-stable-quickjs	134	0	26

✅ 🐘 Local Postgres

App	Passed	Failed	Skipped
✅ astro-stable-node	134	0	26
✅ astro-stable-quickjs	134	0	26
✅ express-stable-node	134	0	26
✅ express-stable-quickjs	134	0	26
✅ fastify-stable-node	134	0	26
✅ fastify-stable-quickjs	134	0	26
✅ hono-stable-node	134	0	26
✅ hono-stable-quickjs	134	0	26
✅ nest-stable-node	134	0	26
✅ nest-stable-quickjs	134	0	26
✅ nextjs-turbopack-canary-node	141	0	19
✅ nextjs-turbopack-canary-quickjs	141	0	19
✅ nextjs-turbopack-stable-node	160	0	0
✅ nextjs-turbopack-stable-quickjs	160	0	0
✅ nextjs-webpack-canary-node	141	0	19
✅ nextjs-webpack-canary-quickjs	141	0	19
✅ nextjs-webpack-stable-node	160	0	0
✅ nextjs-webpack-stable-quickjs	160	0	0
✅ nitro-stable-node	134	0	26
✅ nitro-stable-quickjs	134	0	26
✅ nuxt-stable-node	134	0	26
✅ nuxt-stable-quickjs	134	0	26
✅ sveltekit-stable-node	153	0	7
✅ sveltekit-stable-quickjs	153	0	7
✅ tanstack-start-node	134	0	26
✅ tanstack-start-quickjs	134	0	26
✅ vite-stable-node	134	0	26
✅ vite-stable-quickjs	134	0	26

✅ 🪟 Windows

App	Passed	Failed	Skipped
✅ nextjs-turbopack-node	160	0	0
✅ nextjs-turbopack-quickjs	160	0	0

❌ 🌐 Cross-language Conformance

App	Passed	Failed	Skipped
❌ python	0	9	132

✅ vercel-http-transport

App	Passed	Failed	Skipped
✅ example	132	0	28
✅ express	132	0	28
✅ hono	132	0	28
✅ nextjs-turbopack	157	0	3
✅ nitro	132	0	28
✅ vite	132	0	28

✅ vercel-multi-region

App	Passed	Failed	Skipped
✅ nextjs-turbopack	27	0	0

✅ vercel-ws-transport

App	Passed	Failed	Skipped
✅ example	132	0	28
✅ express	132	0	28
✅ nextjs-turbopack	157	0	3
✅ vite	132	0	28

---

📋 View full workflow run

[github-actions]

📊 Workflow Benchmarks

❌ The benchmark run for 6b3ece8 failed. See the run logs for details.

commit 19c0720 · Wed, 26 Aug 2026 17:27:47 GMT · run logs

Backend: vercel · app: nextjs-turbopack

Metric	Scenario	Best (ms)	P75 (ms)	P90 (ms)	P99 (ms)	Samples
TTFS	step	204 (+13%)	1253 🔴 (+18%) 🔻	1409 🔴 (+32%) 🔻	1500 🔴 (+13%)	30
TTFS	stream	176 (-15%)	1293 🔴 (+18%) 🔻	1389 🔴 (+13%)	1435 🔴 (-6.8%)	30
TTFS	hook + stream	1318 (+58%) 🔻	1733 🔴 (+24%) 🔻	1826 🔴 (+23%) 🔻	1898 🔴 (+17%) 🔻	30
Fan-out TTFS	Promise.all(100 steps)	546 (-29%) 💚	1921 (+10%)	2263 (+27%) 🔻	2440 (+25%) 🔻	10
Fan-out TTLS	Promise.all(100 steps)	2014 (+4.7%)	3550 (-2.0%)	3789 (+2.7%)	8013 (+95%) 🔻	10
STSO	1020 steps (inline)	118 (-7.8%)	152 (-15%) 💚	178 (-14%)	762 (+144%) 🔻	1019
WO	1020 steps	167911 (-3.1%)	167911 (-3.1%)	167911 (-3.1%)	167911 (-3.1%)	1
CRTT	first chunk (pooled)	91 (-9.0%)	135 (-16%) 💚	206 (-21%) 💚	286 (-16%) 💚	28

Streams

Scenario	CRTT 1st	p75	p90	p99	CDV max	iters
paced control (100/s, 60B)	118 (-18%)	183 (-39%)	242 (-69%)	479 (-59%)	153 (-29%)	10
size sweep (100/s, 160B-12KB)	119 (-15%)	187 (-14%)	325 (-7%)	594 (+9%)	165 (-20%)	10
replay gateway-gpt-5.4-nano-2000t (1x)	250 (+116%)	143 (-25%)	196 (-89%)	387 (-89%)	192 (-43%)	3
replay eve-gpt-5.6-sol-2000t (1x)	147 (+19%)	140 (-17%)	188 (-19%)	380 (-34%)	353 (-42%)	2
replay eve-gpt-5.6-sol-2000t (2x)	123 (-45%)	209 (-38%)	292 (-51%)	511 (-44%)	302 (-31%)	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.}

_{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-2000teaf22f5946e7c61f3c65c7006d550df180cfabd4e706254a09f22aec0cfb420d · gateway-gpt-5.4-nano-2000t6f24ac518b6b83ff1d0e85a5fe78230db192716d66a7fc6b2fe022752001d041}

_{🔴 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]

Sim World

Simulated world deterministic testing for races. Traces

🟠 world-sim scenario book — 1 fail of 41 total

fence=per-spec

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

Full trace: world-sim.txt

[github-actions]

Framework	Flow route	Step reg.	Framework output
hono	200.9 KiB (±0)	40.3 KiB (±0)	1.76 MiB (±0)
nextjs-turbopack	206.3 KiB (±0)	439 B (±0)	763.1 KiB (±0)

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.

6b3ece8 · run

[github-actions]

No backport to stable for 695a1b7 (AI decision).

This fixes describeContainer in the custom data-inspector tree renderer, which exists only on main: origin/stable:packages/web-shared/src/components/ui/data-inspector.tsx is a 417-line component still built on react-inspector with no describeContainer, ExpandableContainer, or collapseRefs. The defect (hydrated Headers/URLSearchParams drawn as empty objects) and the code being changed are both properties of the main-only renderer, so there is nothing on stable for this patch to fix. It also adds new rendering behavior for arbitrary iterables, which is additive capability rather than a maintenance fix.

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

695a1b76d0e14b1093f93757232efa5c2818d0da

[mitul-s]

Why

Hydrated Headers and URLSearchParams keep their pairs in internal slots. Object.entries returns nothing, so the inspector drew them as empty objects.

The first version of this PR walked Symbol.iterator and treated every 2-element yield as a field. That matched old react-inspector behavior. It also turned a list of coordinate pairs into fake keys.

Scope

describeContainer now follows the same re-iterable pattern as Map and Set. A value with entries() renders as {} pair rows from that iterator. Any other iterable renders as [] unlabeled list rows from Symbol.iterator.

DataRender and ClassInstanceNode no longer memoize describeContainer. Tests use renderToStaticMarkup instead of jsdom. jsdom is removed from @workflow/web-shared.

Out of scope. serializeForClipboard still runs JSON.stringify on Headers and copies {}. hasDisplayContent still uses Object.keys.

Tradeoffs

Live re-iteration instead of a collapseRefs snapshot. Headers and URLSearchParams are re-iterable, which is the production case. One-shot generators are no longer snapshotted across rerenders.

Blast radius

Observability UI only, @workflow/web-sharedDataInspector. Step input and output views that hydrate Request, Headers, or URLSearchParams now show the real pairs. Custom iterables without entries() render as lists, not keyed objects.

Verification

In packages/web-shared:

pnpm exec vitest run test/data-inspector.test.ts test/collapse-refs.test.ts test/copyable-data-block.test.ts

37 tests passed.

The new tests against the previous describeContainer failed in 3 cases. TestIterable rendered 0: labels. CoordinatePairs rendered 1:2. MapLike ignored entries() and showed the default iterator.

The full @workflow/web-shared suite was 218 passed. test/zstd-decoder.test.ts failed on zlib.zstdCompressSync, which this change does not touch.

PR Checklist - Required to merge

• 📦 Added a patch changeset for @workflow/web-shared
• 🔒 Commits include DCO sign-off
• 📝 Ping @vercel/workflow in a comment once the PR is ready

Slack Thread

[changeset-bot]

🦋 Changeset detected

Latest commit: 13fc38c

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

This PR includes changesets to release 16 packages

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

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

Project	Deployment	Actions	Updated (UTC)
example-nextjs-workflow-turbopack	Ready	Preview, v0	Aug 26, 2026 7:43pm
example-nextjs-workflow-webpack	Ready	Preview, v0	Aug 26, 2026 7:43pm
example-workflow	Ready	Preview, v0	Aug 26, 2026 7:43pm
workbench-astro-workflow	Ready	Preview, v0	Aug 26, 2026 7:43pm
workbench-express-workflow	Ready	Preview, v0	Aug 26, 2026 7:43pm
workbench-fastify-workflow	Ready	Preview, v0	Aug 26, 2026 7:43pm
workbench-hono-workflow	Ready	Preview, v0	Aug 26, 2026 7:43pm
workbench-nestjs-workflow	Ready	Preview, v0	Aug 26, 2026 7:43pm
workbench-nitro-workflow	Ready	Preview, v0	Aug 26, 2026 7:43pm
workbench-nuxt-workflow	Ready	Preview, v0	Aug 26, 2026 7:43pm
workbench-python-workflow	Ready	Preview, v0	Aug 26, 2026 7:43pm
workbench-sveltekit-workflow	Ready	Preview, v0	Aug 26, 2026 7:43pm
workbench-tanstack-start-workflow	Ready	Preview, v0	Aug 26, 2026 7:43pm
workbench-vite-workflow	Ready	Preview, v0	Aug 26, 2026 7:43pm
workflow-docs	Ready	Preview, v0	Aug 26, 2026 7:43pm
workflow-swc-playground	Ready	Preview, v0	Aug 26, 2026 7:43pm
workflow-tarballs	Ready	Preview, v0	Aug 26, 2026 7:43pm
workflow-web	Ready	Preview, v0	Aug 26, 2026 7:43pm

[TooTallNate]

More generally, we should be able to expand any value that implements Symbol.iterator, rather than special casing Headers and URLSearchParams

[github-actions]

🧪 E2E Test Results

❌ Some tests failed

❌ Failed E2E Tests

▲ Vercel Production (8 failed)

python-node (8 failed):

• promiseAllWorkflow | wrun_41M0ZKVKE60GRTE4KH2QZ7DTC4 | 🔍 observability
• sleepingWorkflow | wrun_41M0ZKW7BW0GXPGM0GVD1EAEKR | 🔍 observability
• parallelSleepWorkflow | wrun_41M0ZKW7EY0GHGEV96Q39D7PMA | 🔍 observability
• nullByteWorkflow | wrun_41M0ZKWDR00GY8QCX6JSTGSJAQ | 🔍 observability
• cancelRun - cancelling a running workflow | wrun_41M0ZM0KJG0GTHJCCJF5M9M6E2 | 🔍 observability
• cancelRun via CLI - cancelling a running workflow | wrun_41M0ZM0MG50GMVCWAJFATE272J | 🔍 observability
• sleepInLoopWorkflow - sleep inside loop with steps actually delays each iteration | wrun_41M0ZM0S270GSASPMDRG9C4HW2 | 🔍 observability
• resilient start: addTenWorkflow completes when run_created returns 500 | wrun_41M0ZM19S70GWKV1MVG6V7GW7S | 🔍 observability

🌐 Cross-language Conformance (9 failed)

python (9 failed):

• deploymentId: 'latest' is a no-op in non-Vercel worlds | wrun_01M0ZM4X0N34FZTTVJCZ7E2G9G
• promiseAllWorkflow | wrun_41M0ZKVKE60GRTE4KH2QZ7DTC4
• sleepingWorkflow | wrun_41M0ZKW7BW0GXPGM0GVD1EAEKR
• parallelSleepWorkflow | wrun_41M0ZKW7EY0GHGEV96Q39D7PMA
• nullByteWorkflow | wrun_41M0ZKWDR00GY8QCX6JSTGSJAQ
• cancelRun - cancelling a running workflow | wrun_41M0ZM0KJG0GTHJCCJF5M9M6E2
• cancelRun via CLI - cancelling a running workflow | wrun_41M0ZM0MG50GMVCWAJFATE272J
• sleepInLoopWorkflow - sleep inside loop with steps actually delays each iteration | wrun_41M0ZM0S270GSASPMDRG9C4HW2
• resilient start: addTenWorkflow completes when run_created returns 500 | wrun_41M0ZM19S70GWKV1MVG6V7GW7S

⚠️ 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.

• cancelRun via CLI - cancelling a running workflow (express)
• hook created by a sfo1 run resolves by token and resumes the run (nextjs-turbopack)
• hookWorkflow (tanstack-start)
• promiseAllWorkflow (express)
• promiseRaceStressTestWorkflow (vite)
• promiseRaceWorkflow (hono)
• promiseRaceWorkflow (sveltekit)

🛠 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.

34 infra events

• cold-start-warmup · suite warmup (python) · at 18:05:09Z · abandoned wrun_41M0ZKTYBS0GPDS9W8WHKT22HR · (+7 more)
• run-pickup-stall · promiseAllWorkflow (python) · at 18:05:25Z · abandoned wrun_41M0ZKYM2M0GYCWSNESMWEGYZW
• run-pickup-stall · nullByteWorkflow (python) · at 18:05:25Z · abandoned wrun_41M0ZKYM2X0GJ5QJENP5KAR8DK
• run-pickup-stall · sleepingWorkflow (python) · at 18:05:25Z · abandoned wrun_41M0ZKYM2S0GGQ93SXWWAXH1PE
• run-pickup-stall · parallelSleepWorkflow (python) · at 18:05:25Z · abandoned wrun_41M0ZKYM2S0GGQ93SXWWAXH1PF
• run-pickup-stall · cancelRun - cancelling a running workflow (python) · at 18:05:26Z · abandoned wrun_41M0ZKYMFQ0GNQK9XTZZS00G68
• run-pickup-stall · cancelRun - cancelling a running workflow (python) · at 18:05:58Z · abandoned wrun_41M0ZKZMDG0GKJCTA3BYYGXFDX
• cold-start-warmup · suite warmup (tanstack-start) · at 18:06:22Z · abandoned wrun_01M0ZM010XFRBR7N3GCYFHT0KD
• run-pickup-stall · sleepingWorkflow (python) · at 18:06:26Z · abandoned wrun_41M0ZM0FRD0GJ6BN11NRKBMJ9N
• run-pickup-stall · promiseAllWorkflow (python) · at 18:06:26Z · abandoned wrun_41M0ZM0FQG0GRFWWW9CP6NEVRF
• run-pickup-stall · nullByteWorkflow (python) · at 18:06:26Z · abandoned wrun_41M0ZM0FSY0GXM6P4BV6D1NTVQ
• run-pickup-stall · parallelSleepWorkflow (python) · at 18:06:26Z · abandoned wrun_41M0ZM0FJX0GR49QWPXV7A356M
• run-pickup-stall · cancelRun via CLI - cancelling a running workflow (python) · at 18:07:16Z · abandoned wrun_41M0ZM0M5E0GX9F0KQ6Q082MS1
• cold-start-warmup · suite warmup (python) · at 18:07:19Z · abandoned wrun_01M0ZKYYKD0KPD3MBEX0E432BE · (+7 more)
• run-pickup-stall · deploymentId: 'latest' is a no-op in non-Vercel worlds (python) · at 18:07:34Z · abandoned wrun_01M0ZM2KQNF8AWHK32575V2461
• run-pickup-stall · promiseAllWorkflow (python) · at 18:07:34Z · abandoned wrun_01M0ZM2KQPQPQWKSRGPTBXH847
• run-pickup-stall · parallelSleepWorkflow (python) · at 18:07:34Z · abandoned wrun_01M0ZM2KQY592H6FWWEF0NRP1S
• run-pickup-stall · sleepingWorkflow (python) · at 18:07:34Z · abandoned wrun_01M0ZM2KQWET1C8DARN3W95P1R
• run-pickup-stall · nullByteWorkflow (python) · at 18:07:34Z · abandoned wrun_01M0ZM2KR13RD8ECG6Q0BCWN67
• run-pickup-stall · instanceMethodStepWorkflow - instance methods with "use step" directive (nuxt) · at 18:08:09Z · abandoned wrun_01M0ZM3NZ7D3G82TGVPJ8YWN5T
• run-pickup-stall · deploymentId: 'latest' is a no-op in non-Vercel worlds (python) · at 18:08:34Z · abandoned wrun_01M0ZM4EB8QN7E7Y2GE2DME665
• run-pickup-stall · promiseAllWorkflow (python) · at 18:08:34Z · abandoned wrun_01M0ZM4EBDCPVVDS39BS95RA70
• run-pickup-stall · sleepingWorkflow (python) · at 18:08:34Z · abandoned wrun_01M0ZM4EBH838SW4S33HVVHJ86
• run-pickup-stall · parallelSleepWorkflow (python) · at 18:08:34Z · abandoned wrun_01M0ZM4EBQG3D97DYY2VTKVPYK
• run-pickup-stall · nullByteWorkflow (python) · at 18:08:34Z · abandoned wrun_01M0ZM4EBV1GDM3GJBCXC3EA81
• run-pickup-stall · sleepInLoopWorkflow - sleep inside loop with steps actually delays each iteration (python) · at 18:08:58Z · abandoned wrun_41M0ZM37FF0GHKTCT7733J4VH5
• run-pickup-stall · cancelRun - cancelling a running workflow (python) · at 18:09:34Z · abandoned wrun_01M0ZM68YTAQ3XS41G6YFCKT43
• run-pickup-stall · cancelRun via CLI - cancelling a running workflow (python) · at 18:09:34Z · abandoned wrun_01M0ZM68Z493DW9VT63EVBWHV7
• run-pickup-stall · sleepInLoopWorkflow - sleep inside loop with steps actually delays each iteration (python) · at 18:09:34Z · abandoned wrun_01M0ZM68Z77GYDRKXMEJ9H7AR0
• run-pickup-stall · cancelRun via CLI - cancelling a running workflow (python) · at 18:09:38Z · abandoned wrun_41M0ZM3C210GMFQNJV10YHJTFC
• run-pickup-stall · cancelRun - cancelling a running workflow (python) · at 18:10:04Z · abandoned wrun_01M0ZM76A942EQRE76CRQS2GBD
• run-pickup-stall · cancelRun via CLI - cancelling a running workflow (python) · at 18:10:04Z · abandoned wrun_01M0ZM76AB9XFB6P68M9GWJJBJ
• run-pickup-stall · sleepInLoopWorkflow - sleep inside loop with steps actually delays each iteration (python) · at 18:10:34Z · abandoned wrun_01M0ZM83JA93Q68M99DXENAZED
• run-pickup-stall · hookWithSleepWorkflow - hook payloads delivered correctly with concurrent sleep (nextjs-webpack) · at 18:11:29Z · abandoned wrun_01M0ZM9RYGF6CTNHDK8KQB4CVK

E2E Test Summary

Summary

	Passed	Failed	Skipped	Total
❌ ▲ Vercel Production	3570	8	742	4320
✅ 💻 Local Development	3922	0	558	4480
✅ 📦 Local Production	3922	0	558	4480
✅ 🐘 Local Postgres	3922	0	558	4480
✅ 🪟 Windows	320	0	0	320
❌ 🌐 Cross-language Conformance	0	9	132	141
✅ vercel-http-transport	817	0	143	960
✅ vercel-multi-region	27	0	0	27
✅ vercel-ws-transport	553	0	87	640
Total	17053	17	2778	19848

Details by Category

❌ ▲ Vercel Production

App	Passed	Failed	Skipped
✅ astro-node	132	0	28
✅ astro-quickjs	132	0	28
✅ example-node	132	0	28
✅ example-quickjs	132	0	28
✅ express-node	132	0	28
✅ express-quickjs	132	0	28
✅ fastify-node	132	0	28
✅ fastify-quickjs	132	0	28
✅ hono-node	132	0	28
✅ hono-quickjs	132	0	28
✅ nest-node	132	0	28
✅ nest-quickjs	132	0	28
✅ nextjs-turbopack-node	157	0	3
✅ nextjs-turbopack-quickjs	157	0	3
✅ nextjs-webpack-node	157	0	3
✅ nextjs-webpack-quickjs	157	0	3
✅ nitro-node	132	0	28
✅ nitro-quickjs	132	0	28
✅ nuxt-node	132	0	28
✅ nuxt-quickjs	132	0	28
❌ python-node	0	8	152
✅ sveltekit-node	151	0	9
✅ sveltekit-quickjs	151	0	9
✅ tanstack-start-node	132	0	28
✅ tanstack-start-quickjs	132	0	28
✅ vite-node	132	0	28
✅ vite-quickjs	132	0	28

✅ 💻 Local Development

App	Passed	Failed	Skipped
✅ astro-stable-node	134	0	26
✅ astro-stable-quickjs	134	0	26
✅ express-stable-node	134	0	26
✅ express-stable-quickjs	134	0	26
✅ fastify-stable-node	134	0	26
✅ fastify-stable-quickjs	134	0	26
✅ hono-stable-node	134	0	26
✅ hono-stable-quickjs	134	0	26
✅ nest-stable-node	134	0	26
✅ nest-stable-quickjs	134	0	26
✅ nextjs-turbopack-canary-node	141	0	19
✅ nextjs-turbopack-canary-quickjs	141	0	19
✅ nextjs-turbopack-stable-node	160	0	0
✅ nextjs-turbopack-stable-quickjs	160	0	0
✅ nextjs-webpack-canary-node	141	0	19
✅ nextjs-webpack-canary-quickjs	141	0	19
✅ nextjs-webpack-stable-node	160	0	0
✅ nextjs-webpack-stable-quickjs	160	0	0
✅ nitro-stable-node	134	0	26
✅ nitro-stable-quickjs	134	0	26
✅ nuxt-stable-node	134	0	26
✅ nuxt-stable-quickjs	134	0	26
✅ sveltekit-stable-node	153	0	7
✅ sveltekit-stable-quickjs	153	0	7
✅ tanstack-start-node	134	0	26
✅ tanstack-start-quickjs	134	0	26
✅ vite-stable-node	134	0	26
✅ vite-stable-quickjs	134	0	26

✅ 📦 Local Production

App	Passed	Failed	Skipped
✅ astro-stable-node	134	0	26
✅ astro-stable-quickjs	134	0	26
✅ express-stable-node	134	0	26
✅ express-stable-quickjs	134	0	26
✅ fastify-stable-node	134	0	26
✅ fastify-stable-quickjs	134	0	26
✅ hono-stable-node	134	0	26
✅ hono-stable-quickjs	134	0	26
✅ nest-stable-node	134	0	26
✅ nest-stable-quickjs	134	0	26
✅ nextjs-turbopack-canary-node	141	0	19
✅ nextjs-turbopack-canary-quickjs	141	0	19
✅ nextjs-turbopack-stable-node	160	0	0
✅ nextjs-turbopack-stable-quickjs	160	0	0
✅ nextjs-webpack-canary-node	141	0	19
✅ nextjs-webpack-canary-quickjs	141	0	19
✅ nextjs-webpack-stable-node	160	0	0
✅ nextjs-webpack-stable-quickjs	160	0	0
✅ nitro-stable-node	134	0	26
✅ nitro-stable-quickjs	134	0	26
✅ nuxt-stable-node	134	0	26
✅ nuxt-stable-quickjs	134	0	26
✅ sveltekit-stable-node	153	0	7
✅ sveltekit-stable-quickjs	153	0	7
✅ tanstack-start-node	134	0	26
✅ tanstack-start-quickjs	134	0	26
✅ vite-stable-node	134	0	26
✅ vite-stable-quickjs	134	0	26

✅ 🐘 Local Postgres

App	Passed	Failed	Skipped
✅ astro-stable-node	134	0	26
✅ astro-stable-quickjs	134	0	26
✅ express-stable-node	134	0	26
✅ express-stable-quickjs	134	0	26
✅ fastify-stable-node	134	0	26
✅ fastify-stable-quickjs	134	0	26
✅ hono-stable-node	134	0	26
✅ hono-stable-quickjs	134	0	26
✅ nest-stable-node	134	0	26
✅ nest-stable-quickjs	134	0	26
✅ nextjs-turbopack-canary-node	141	0	19
✅ nextjs-turbopack-canary-quickjs	141	0	19
✅ nextjs-turbopack-stable-node	160	0	0
✅ nextjs-turbopack-stable-quickjs	160	0	0
✅ nextjs-webpack-canary-node	141	0	19
✅ nextjs-webpack-canary-quickjs	141	0	19
✅ nextjs-webpack-stable-node	160	0	0
✅ nextjs-webpack-stable-quickjs	160	0	0
✅ nitro-stable-node	134	0	26
✅ nitro-stable-quickjs	134	0	26
✅ nuxt-stable-node	134	0	26
✅ nuxt-stable-quickjs	134	0	26
✅ sveltekit-stable-node	153	0	7
✅ sveltekit-stable-quickjs	153	0	7
✅ tanstack-start-node	134	0	26
✅ tanstack-start-quickjs	134	0	26
✅ vite-stable-node	134	0	26
✅ vite-stable-quickjs	134	0	26

✅ 🪟 Windows

App	Passed	Failed	Skipped
✅ nextjs-turbopack-node	160	0	0
✅ nextjs-turbopack-quickjs	160	0	0

❌ 🌐 Cross-language Conformance

App	Passed	Failed	Skipped
❌ python	0	9	132

✅ vercel-http-transport

App	Passed	Failed	Skipped
✅ example	132	0	28
✅ express	132	0	28
✅ hono	132	0	28
✅ nextjs-turbopack	157	0	3
✅ nitro	132	0	28
✅ vite	132	0	28

✅ vercel-multi-region

App	Passed	Failed	Skipped
✅ nextjs-turbopack	27	0	0

✅ vercel-ws-transport

App	Passed	Failed	Skipped
✅ example	132	0	28
✅ express	132	0	28
✅ nextjs-turbopack	157	0	3
✅ vite	132	0	28

---

📋 View full workflow run

[github-actions]

📊 Workflow Benchmarks

❌ The benchmark run for 6b3ece8 failed. See the run logs for details.

commit 19c0720 · Wed, 26 Aug 2026 17:27:47 GMT · run logs

Backend: vercel · app: nextjs-turbopack

Metric	Scenario	Best (ms)	P75 (ms)	P90 (ms)	P99 (ms)	Samples
TTFS	step	204 (+13%)	1253 🔴 (+18%) 🔻	1409 🔴 (+32%) 🔻	1500 🔴 (+13%)	30
TTFS	stream	176 (-15%)	1293 🔴 (+18%) 🔻	1389 🔴 (+13%)	1435 🔴 (-6.8%)	30
TTFS	hook + stream	1318 (+58%) 🔻	1733 🔴 (+24%) 🔻	1826 🔴 (+23%) 🔻	1898 🔴 (+17%) 🔻	30
Fan-out TTFS	Promise.all(100 steps)	546 (-29%) 💚	1921 (+10%)	2263 (+27%) 🔻	2440 (+25%) 🔻	10
Fan-out TTLS	Promise.all(100 steps)	2014 (+4.7%)	3550 (-2.0%)	3789 (+2.7%)	8013 (+95%) 🔻	10
STSO	1020 steps (inline)	118 (-7.8%)	152 (-15%) 💚	178 (-14%)	762 (+144%) 🔻	1019
WO	1020 steps	167911 (-3.1%)	167911 (-3.1%)	167911 (-3.1%)	167911 (-3.1%)	1
CRTT	first chunk (pooled)	91 (-9.0%)	135 (-16%) 💚	206 (-21%) 💚	286 (-16%) 💚	28

Streams

Scenario	CRTT 1st	p75	p90	p99	CDV max	iters
paced control (100/s, 60B)	118 (-18%)	183 (-39%)	242 (-69%)	479 (-59%)	153 (-29%)	10
size sweep (100/s, 160B-12KB)	119 (-15%)	187 (-14%)	325 (-7%)	594 (+9%)	165 (-20%)	10
replay gateway-gpt-5.4-nano-2000t (1x)	250 (+116%)	143 (-25%)	196 (-89%)	387 (-89%)	192 (-43%)	3
replay eve-gpt-5.6-sol-2000t (1x)	147 (+19%)	140 (-17%)	188 (-19%)	380 (-34%)	353 (-42%)	2
replay eve-gpt-5.6-sol-2000t (2x)	123 (-45%)	209 (-38%)	292 (-51%)	511 (-44%)	302 (-31%)	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.}

_{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-2000teaf22f5946e7c61f3c65c7006d550df180cfabd4e706254a09f22aec0cfb420d · gateway-gpt-5.4-nano-2000t6f24ac518b6b83ff1d0e85a5fe78230db192716d66a7fc6b2fe022752001d041}

_{🔴 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]

Sim World

Simulated world deterministic testing for races. Traces

🟠 world-sim scenario book — 1 fail of 41 total

fence=per-spec

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

Full trace: world-sim.txt

[github-actions]

Framework	Flow route	Step reg.	Framework output
hono	200.9 KiB (±0)	40.3 KiB (±0)	1.76 MiB (±0)
nextjs-turbopack	206.3 KiB (±0)	439 B (±0)	763.1 KiB (±0)

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.

6b3ece8 · run

[github-actions]

No backport to stable for 695a1b7 (AI decision).

This fixes describeContainer in the custom data-inspector tree renderer, which exists only on main: origin/stable:packages/web-shared/src/components/ui/data-inspector.tsx is a 417-line component still built on react-inspector with no describeContainer, ExpandableContainer, or collapseRefs. The defect (hydrated Headers/URLSearchParams drawn as empty objects) and the code being changed are both properties of the main-only renderer, so there is nothing on stable for this patch to fix. It also adds new rendering behavior for arbitrary iterables, which is additive capability rather than a maintenance fix.

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

695a1b76d0e14b1093f93757232efa5c2818d0da

[mitul-s]

Why

Hydrated Headers and URLSearchParams keep their pairs in internal slots. Object.entries returns nothing, so the inspector drew them as empty objects.

The first version of this PR walked Symbol.iterator and treated every 2-element yield as a field. That matched old react-inspector behavior. It also turned a list of coordinate pairs into fake keys.

Scope

describeContainer now follows the same re-iterable pattern as Map and Set. A value with entries() renders as {} pair rows from that iterator. Any other iterable renders as [] unlabeled list rows from Symbol.iterator.

DataRender and ClassInstanceNode no longer memoize describeContainer. Tests use renderToStaticMarkup instead of jsdom. jsdom is removed from @workflow/web-shared.

Out of scope. serializeForClipboard still runs JSON.stringify on Headers and copies {}. hasDisplayContent still uses Object.keys.

Tradeoffs

Live re-iteration instead of a collapseRefs snapshot. Headers and URLSearchParams are re-iterable, which is the production case. One-shot generators are no longer snapshotted across rerenders.

Blast radius

Observability UI only, @workflow/web-sharedDataInspector. Step input and output views that hydrate Request, Headers, or URLSearchParams now show the real pairs. Custom iterables without entries() render as lists, not keyed objects.

Verification

In packages/web-shared:

pnpm exec vitest run test/data-inspector.test.ts test/collapse-refs.test.ts test/copyable-data-block.test.ts

37 tests passed.

The new tests against the previous describeContainer failed in 3 cases. TestIterable rendered 0: labels. CoordinatePairs rendered 1:2. MapLike ignored entries() and showed the default iterator.

The full @workflow/web-shared suite was 218 passed. test/zstd-decoder.test.ts failed on zlib.zstdCompressSync, which this change does not touch.

PR Checklist - Required to merge

• 📦 Added a patch changeset for @workflow/web-shared
• 🔒 Commits include DCO sign-off
• 📝 Ping @vercel/workflow in a comment once the PR is ready

Slack Thread

[changeset-bot]

🦋 Changeset detected

Latest commit: 13fc38c

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

This PR includes changesets to release 16 packages

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

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

Project	Deployment	Actions	Updated (UTC)
example-nextjs-workflow-turbopack	Ready	Preview, v0	Aug 26, 2026 7:43pm
example-nextjs-workflow-webpack	Ready	Preview, v0	Aug 26, 2026 7:43pm
example-workflow	Ready	Preview, v0	Aug 26, 2026 7:43pm
workbench-astro-workflow	Ready	Preview, v0	Aug 26, 2026 7:43pm
workbench-express-workflow	Ready	Preview, v0	Aug 26, 2026 7:43pm
workbench-fastify-workflow	Ready	Preview, v0	Aug 26, 2026 7:43pm
workbench-hono-workflow	Ready	Preview, v0	Aug 26, 2026 7:43pm
workbench-nestjs-workflow	Ready	Preview, v0	Aug 26, 2026 7:43pm
workbench-nitro-workflow	Ready	Preview, v0	Aug 26, 2026 7:43pm
workbench-nuxt-workflow	Ready	Preview, v0	Aug 26, 2026 7:43pm
workbench-python-workflow	Ready	Preview, v0	Aug 26, 2026 7:43pm
workbench-sveltekit-workflow	Ready	Preview, v0	Aug 26, 2026 7:43pm
workbench-tanstack-start-workflow	Ready	Preview, v0	Aug 26, 2026 7:43pm
workbench-vite-workflow	Ready	Preview, v0	Aug 26, 2026 7:43pm
workflow-docs	Ready	Preview, v0	Aug 26, 2026 7:43pm
workflow-swc-playground	Ready	Preview, v0	Aug 26, 2026 7:43pm
workflow-tarballs	Ready	Preview, v0	Aug 26, 2026 7:43pm
workflow-web	Ready	Preview, v0	Aug 26, 2026 7:43pm

[TooTallNate]

More generally, we should be able to expand any value that implements Symbol.iterator, rather than special casing Headers and URLSearchParams

[github-actions]

🧪 E2E Test Results

❌ Some tests failed

❌ Failed E2E Tests

▲ Vercel Production (8 failed)

python-node (8 failed):

• promiseAllWorkflow | wrun_41M0ZKVKE60GRTE4KH2QZ7DTC4 | 🔍 observability
• sleepingWorkflow | wrun_41M0ZKW7BW0GXPGM0GVD1EAEKR | 🔍 observability
• parallelSleepWorkflow | wrun_41M0ZKW7EY0GHGEV96Q39D7PMA | 🔍 observability
• nullByteWorkflow | wrun_41M0ZKWDR00GY8QCX6JSTGSJAQ | 🔍 observability
• cancelRun - cancelling a running workflow | wrun_41M0ZM0KJG0GTHJCCJF5M9M6E2 | 🔍 observability
• cancelRun via CLI - cancelling a running workflow | wrun_41M0ZM0MG50GMVCWAJFATE272J | 🔍 observability
• sleepInLoopWorkflow - sleep inside loop with steps actually delays each iteration | wrun_41M0ZM0S270GSASPMDRG9C4HW2 | 🔍 observability
• resilient start: addTenWorkflow completes when run_created returns 500 | wrun_41M0ZM19S70GWKV1MVG6V7GW7S | 🔍 observability

🌐 Cross-language Conformance (9 failed)

python (9 failed):

• deploymentId: 'latest' is a no-op in non-Vercel worlds | wrun_01M0ZM4X0N34FZTTVJCZ7E2G9G
• promiseAllWorkflow | wrun_41M0ZKVKE60GRTE4KH2QZ7DTC4
• sleepingWorkflow | wrun_41M0ZKW7BW0GXPGM0GVD1EAEKR
• parallelSleepWorkflow | wrun_41M0ZKW7EY0GHGEV96Q39D7PMA
• nullByteWorkflow | wrun_41M0ZKWDR00GY8QCX6JSTGSJAQ
• cancelRun - cancelling a running workflow | wrun_41M0ZM0KJG0GTHJCCJF5M9M6E2
• cancelRun via CLI - cancelling a running workflow | wrun_41M0ZM0MG50GMVCWAJFATE272J
• sleepInLoopWorkflow - sleep inside loop with steps actually delays each iteration | wrun_41M0ZM0S270GSASPMDRG9C4HW2
• resilient start: addTenWorkflow completes when run_created returns 500 | wrun_41M0ZM19S70GWKV1MVG6V7GW7S

⚠️ 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.

• cancelRun via CLI - cancelling a running workflow (express)
• hook created by a sfo1 run resolves by token and resumes the run (nextjs-turbopack)
• hookWorkflow (tanstack-start)
• promiseAllWorkflow (express)
• promiseRaceStressTestWorkflow (vite)
• promiseRaceWorkflow (hono)
• promiseRaceWorkflow (sveltekit)

🛠 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.

34 infra events

• cold-start-warmup · suite warmup (python) · at 18:05:09Z · abandoned wrun_41M0ZKTYBS0GPDS9W8WHKT22HR · (+7 more)
• run-pickup-stall · promiseAllWorkflow (python) · at 18:05:25Z · abandoned wrun_41M0ZKYM2M0GYCWSNESMWEGYZW
• run-pickup-stall · nullByteWorkflow (python) · at 18:05:25Z · abandoned wrun_41M0ZKYM2X0GJ5QJENP5KAR8DK
• run-pickup-stall · sleepingWorkflow (python) · at 18:05:25Z · abandoned wrun_41M0ZKYM2S0GGQ93SXWWAXH1PE
• run-pickup-stall · parallelSleepWorkflow (python) · at 18:05:25Z · abandoned wrun_41M0ZKYM2S0GGQ93SXWWAXH1PF
• run-pickup-stall · cancelRun - cancelling a running workflow (python) · at 18:05:26Z · abandoned wrun_41M0ZKYMFQ0GNQK9XTZZS00G68
• run-pickup-stall · cancelRun - cancelling a running workflow (python) · at 18:05:58Z · abandoned wrun_41M0ZKZMDG0GKJCTA3BYYGXFDX
• cold-start-warmup · suite warmup (tanstack-start) · at 18:06:22Z · abandoned wrun_01M0ZM010XFRBR7N3GCYFHT0KD
• run-pickup-stall · sleepingWorkflow (python) · at 18:06:26Z · abandoned wrun_41M0ZM0FRD0GJ6BN11NRKBMJ9N
• run-pickup-stall · promiseAllWorkflow (python) · at 18:06:26Z · abandoned wrun_41M0ZM0FQG0GRFWWW9CP6NEVRF
• run-pickup-stall · nullByteWorkflow (python) · at 18:06:26Z · abandoned wrun_41M0ZM0FSY0GXM6P4BV6D1NTVQ
• run-pickup-stall · parallelSleepWorkflow (python) · at 18:06:26Z · abandoned wrun_41M0ZM0FJX0GR49QWPXV7A356M
• run-pickup-stall · cancelRun via CLI - cancelling a running workflow (python) · at 18:07:16Z · abandoned wrun_41M0ZM0M5E0GX9F0KQ6Q082MS1
• cold-start-warmup · suite warmup (python) · at 18:07:19Z · abandoned wrun_01M0ZKYYKD0KPD3MBEX0E432BE · (+7 more)
• run-pickup-stall · deploymentId: 'latest' is a no-op in non-Vercel worlds (python) · at 18:07:34Z · abandoned wrun_01M0ZM2KQNF8AWHK32575V2461
• run-pickup-stall · promiseAllWorkflow (python) · at 18:07:34Z · abandoned wrun_01M0ZM2KQPQPQWKSRGPTBXH847
• run-pickup-stall · parallelSleepWorkflow (python) · at 18:07:34Z · abandoned wrun_01M0ZM2KQY592H6FWWEF0NRP1S
• run-pickup-stall · sleepingWorkflow (python) · at 18:07:34Z · abandoned wrun_01M0ZM2KQWET1C8DARN3W95P1R
• run-pickup-stall · nullByteWorkflow (python) · at 18:07:34Z · abandoned wrun_01M0ZM2KR13RD8ECG6Q0BCWN67
• run-pickup-stall · instanceMethodStepWorkflow - instance methods with "use step" directive (nuxt) · at 18:08:09Z · abandoned wrun_01M0ZM3NZ7D3G82TGVPJ8YWN5T
• run-pickup-stall · deploymentId: 'latest' is a no-op in non-Vercel worlds (python) · at 18:08:34Z · abandoned wrun_01M0ZM4EB8QN7E7Y2GE2DME665
• run-pickup-stall · promiseAllWorkflow (python) · at 18:08:34Z · abandoned wrun_01M0ZM4EBDCPVVDS39BS95RA70
• run-pickup-stall · sleepingWorkflow (python) · at 18:08:34Z · abandoned wrun_01M0ZM4EBH838SW4S33HVVHJ86
• run-pickup-stall · parallelSleepWorkflow (python) · at 18:08:34Z · abandoned wrun_01M0ZM4EBQG3D97DYY2VTKVPYK
• run-pickup-stall · nullByteWorkflow (python) · at 18:08:34Z · abandoned wrun_01M0ZM4EBV1GDM3GJBCXC3EA81
• run-pickup-stall · sleepInLoopWorkflow - sleep inside loop with steps actually delays each iteration (python) · at 18:08:58Z · abandoned wrun_41M0ZM37FF0GHKTCT7733J4VH5
• run-pickup-stall · cancelRun - cancelling a running workflow (python) · at 18:09:34Z · abandoned wrun_01M0ZM68YTAQ3XS41G6YFCKT43
• run-pickup-stall · cancelRun via CLI - cancelling a running workflow (python) · at 18:09:34Z · abandoned wrun_01M0ZM68Z493DW9VT63EVBWHV7
• run-pickup-stall · sleepInLoopWorkflow - sleep inside loop with steps actually delays each iteration (python) · at 18:09:34Z · abandoned wrun_01M0ZM68Z77GYDRKXMEJ9H7AR0
• run-pickup-stall · cancelRun via CLI - cancelling a running workflow (python) · at 18:09:38Z · abandoned wrun_41M0ZM3C210GMFQNJV10YHJTFC
• run-pickup-stall · cancelRun - cancelling a running workflow (python) · at 18:10:04Z · abandoned wrun_01M0ZM76A942EQRE76CRQS2GBD
• run-pickup-stall · cancelRun via CLI - cancelling a running workflow (python) · at 18:10:04Z · abandoned wrun_01M0ZM76AB9XFB6P68M9GWJJBJ
• run-pickup-stall · sleepInLoopWorkflow - sleep inside loop with steps actually delays each iteration (python) · at 18:10:34Z · abandoned wrun_01M0ZM83JA93Q68M99DXENAZED
• run-pickup-stall · hookWithSleepWorkflow - hook payloads delivered correctly with concurrent sleep (nextjs-webpack) · at 18:11:29Z · abandoned wrun_01M0ZM9RYGF6CTNHDK8KQB4CVK

E2E Test Summary

Summary

	Passed	Failed	Skipped	Total
❌ ▲ Vercel Production	3570	8	742	4320
✅ 💻 Local Development	3922	0	558	4480
✅ 📦 Local Production	3922	0	558	4480
✅ 🐘 Local Postgres	3922	0	558	4480
✅ 🪟 Windows	320	0	0	320
❌ 🌐 Cross-language Conformance	0	9	132	141
✅ vercel-http-transport	817	0	143	960
✅ vercel-multi-region	27	0	0	27
✅ vercel-ws-transport	553	0	87	640
Total	17053	17	2778	19848

Details by Category

❌ ▲ Vercel Production

App	Passed	Failed	Skipped
✅ astro-node	132	0	28
✅ astro-quickjs	132	0	28
✅ example-node	132	0	28
✅ example-quickjs	132	0	28
✅ express-node	132	0	28
✅ express-quickjs	132	0	28
✅ fastify-node	132	0	28
✅ fastify-quickjs	132	0	28
✅ hono-node	132	0	28
✅ hono-quickjs	132	0	28
✅ nest-node	132	0	28
✅ nest-quickjs	132	0	28
✅ nextjs-turbopack-node	157	0	3
✅ nextjs-turbopack-quickjs	157	0	3
✅ nextjs-webpack-node	157	0	3
✅ nextjs-webpack-quickjs	157	0	3
✅ nitro-node	132	0	28
✅ nitro-quickjs	132	0	28
✅ nuxt-node	132	0	28
✅ nuxt-quickjs	132	0	28
❌ python-node	0	8	152
✅ sveltekit-node	151	0	9
✅ sveltekit-quickjs	151	0	9
✅ tanstack-start-node	132	0	28
✅ tanstack-start-quickjs	132	0	28
✅ vite-node	132	0	28
✅ vite-quickjs	132	0	28

✅ 💻 Local Development

App	Passed	Failed	Skipped
✅ astro-stable-node	134	0	26
✅ astro-stable-quickjs	134	0	26
✅ express-stable-node	134	0	26
✅ express-stable-quickjs	134	0	26
✅ fastify-stable-node	134	0	26
✅ fastify-stable-quickjs	134	0	26
✅ hono-stable-node	134	0	26
✅ hono-stable-quickjs	134	0	26
✅ nest-stable-node	134	0	26
✅ nest-stable-quickjs	134	0	26
✅ nextjs-turbopack-canary-node	141	0	19
✅ nextjs-turbopack-canary-quickjs	141	0	19
✅ nextjs-turbopack-stable-node	160	0	0
✅ nextjs-turbopack-stable-quickjs	160	0	0
✅ nextjs-webpack-canary-node	141	0	19
✅ nextjs-webpack-canary-quickjs	141	0	19
✅ nextjs-webpack-stable-node	160	0	0
✅ nextjs-webpack-stable-quickjs	160	0	0
✅ nitro-stable-node	134	0	26
✅ nitro-stable-quickjs	134	0	26
✅ nuxt-stable-node	134	0	26
✅ nuxt-stable-quickjs	134	0	26
✅ sveltekit-stable-node	153	0	7
✅ sveltekit-stable-quickjs	153	0	7
✅ tanstack-start-node	134	0	26
✅ tanstack-start-quickjs	134	0	26
✅ vite-stable-node	134	0	26
✅ vite-stable-quickjs	134	0	26

✅ 📦 Local Production

App	Passed	Failed	Skipped
✅ astro-stable-node	134	0	26
✅ astro-stable-quickjs	134	0	26
✅ express-stable-node	134	0	26
✅ express-stable-quickjs	134	0	26
✅ fastify-stable-node	134	0	26
✅ fastify-stable-quickjs	134	0	26
✅ hono-stable-node	134	0	26
✅ hono-stable-quickjs	134	0	26
✅ nest-stable-node	134	0	26
✅ nest-stable-quickjs	134	0	26
✅ nextjs-turbopack-canary-node	141	0	19
✅ nextjs-turbopack-canary-quickjs	141	0	19
✅ nextjs-turbopack-stable-node	160	0	0
✅ nextjs-turbopack-stable-quickjs	160	0	0
✅ nextjs-webpack-canary-node	141	0	19
✅ nextjs-webpack-canary-quickjs	141	0	19
✅ nextjs-webpack-stable-node	160	0	0
✅ nextjs-webpack-stable-quickjs	160	0	0
✅ nitro-stable-node	134	0	26
✅ nitro-stable-quickjs	134	0	26
✅ nuxt-stable-node	134	0	26
✅ nuxt-stable-quickjs	134	0	26
✅ sveltekit-stable-node	153	0	7
✅ sveltekit-stable-quickjs	153	0	7
✅ tanstack-start-node	134	0	26
✅ tanstack-start-quickjs	134	0	26
✅ vite-stable-node	134	0	26
✅ vite-stable-quickjs	134	0	26

✅ 🐘 Local Postgres

App	Passed	Failed	Skipped
✅ astro-stable-node	134	0	26
✅ astro-stable-quickjs	134	0	26
✅ express-stable-node	134	0	26
✅ express-stable-quickjs	134	0	26
✅ fastify-stable-node	134	0	26
✅ fastify-stable-quickjs	134	0	26
✅ hono-stable-node	134	0	26
✅ hono-stable-quickjs	134	0	26
✅ nest-stable-node	134	0	26
✅ nest-stable-quickjs	134	0	26
✅ nextjs-turbopack-canary-node	141	0	19
✅ nextjs-turbopack-canary-quickjs	141	0	19
✅ nextjs-turbopack-stable-node	160	0	0
✅ nextjs-turbopack-stable-quickjs	160	0	0
✅ nextjs-webpack-canary-node	141	0	19
✅ nextjs-webpack-canary-quickjs	141	0	19
✅ nextjs-webpack-stable-node	160	0	0
✅ nextjs-webpack-stable-quickjs	160	0	0
✅ nitro-stable-node	134	0	26
✅ nitro-stable-quickjs	134	0	26
✅ nuxt-stable-node	134	0	26
✅ nuxt-stable-quickjs	134	0	26
✅ sveltekit-stable-node	153	0	7
✅ sveltekit-stable-quickjs	153	0	7
✅ tanstack-start-node	134	0	26
✅ tanstack-start-quickjs	134	0	26
✅ vite-stable-node	134	0	26
✅ vite-stable-quickjs	134	0	26

✅ 🪟 Windows

App	Passed	Failed	Skipped
✅ nextjs-turbopack-node	160	0	0
✅ nextjs-turbopack-quickjs	160	0	0

❌ 🌐 Cross-language Conformance

App	Passed	Failed	Skipped
❌ python	0	9	132

✅ vercel-http-transport

App	Passed	Failed	Skipped
✅ example	132	0	28
✅ express	132	0	28
✅ hono	132	0	28
✅ nextjs-turbopack	157	0	3
✅ nitro	132	0	28
✅ vite	132	0	28

✅ vercel-multi-region

App	Passed	Failed	Skipped
✅ nextjs-turbopack	27	0	0

✅ vercel-ws-transport

App	Passed	Failed	Skipped
✅ example	132	0	28
✅ express	132	0	28
✅ nextjs-turbopack	157	0	3
✅ vite	132	0	28

---

📋 View full workflow run

[github-actions]

📊 Workflow Benchmarks

❌ The benchmark run for 6b3ece8 failed. See the run logs for details.

commit 19c0720 · Wed, 26 Aug 2026 17:27:47 GMT · run logs

Backend: vercel · app: nextjs-turbopack

Metric	Scenario	Best (ms)	P75 (ms)	P90 (ms)	P99 (ms)	Samples
TTFS	step	204 (+13%)	1253 🔴 (+18%) 🔻	1409 🔴 (+32%) 🔻	1500 🔴 (+13%)	30
TTFS	stream	176 (-15%)	1293 🔴 (+18%) 🔻	1389 🔴 (+13%)	1435 🔴 (-6.8%)	30
TTFS	hook + stream	1318 (+58%) 🔻	1733 🔴 (+24%) 🔻	1826 🔴 (+23%) 🔻	1898 🔴 (+17%) 🔻	30
Fan-out TTFS	Promise.all(100 steps)	546 (-29%) 💚	1921 (+10%)	2263 (+27%) 🔻	2440 (+25%) 🔻	10
Fan-out TTLS	Promise.all(100 steps)	2014 (+4.7%)	3550 (-2.0%)	3789 (+2.7%)	8013 (+95%) 🔻	10
STSO	1020 steps (inline)	118 (-7.8%)	152 (-15%) 💚	178 (-14%)	762 (+144%) 🔻	1019
WO	1020 steps	167911 (-3.1%)	167911 (-3.1%)	167911 (-3.1%)	167911 (-3.1%)	1
CRTT	first chunk (pooled)	91 (-9.0%)	135 (-16%) 💚	206 (-21%) 💚	286 (-16%) 💚	28

Streams

Scenario	CRTT 1st	p75	p90	p99	CDV max	iters
paced control (100/s, 60B)	118 (-18%)	183 (-39%)	242 (-69%)	479 (-59%)	153 (-29%)	10
size sweep (100/s, 160B-12KB)	119 (-15%)	187 (-14%)	325 (-7%)	594 (+9%)	165 (-20%)	10
replay gateway-gpt-5.4-nano-2000t (1x)	250 (+116%)	143 (-25%)	196 (-89%)	387 (-89%)	192 (-43%)	3
replay eve-gpt-5.6-sol-2000t (1x)	147 (+19%)	140 (-17%)	188 (-19%)	380 (-34%)	353 (-42%)	2
replay eve-gpt-5.6-sol-2000t (2x)	123 (-45%)	209 (-38%)	292 (-51%)	511 (-44%)	302 (-31%)	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.}

_{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-2000teaf22f5946e7c61f3c65c7006d550df180cfabd4e706254a09f22aec0cfb420d · gateway-gpt-5.4-nano-2000t6f24ac518b6b83ff1d0e85a5fe78230db192716d66a7fc6b2fe022752001d041}

_{🔴 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]

Sim World

Simulated world deterministic testing for races. Traces

🟠 world-sim scenario book — 1 fail of 41 total

fence=per-spec

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

Full trace: world-sim.txt

[github-actions]

Framework	Flow route	Step reg.	Framework output
hono	200.9 KiB (±0)	40.3 KiB (±0)	1.76 MiB (±0)
nextjs-turbopack	206.3 KiB (±0)	439 B (±0)	763.1 KiB (±0)

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.

6b3ece8 · run

[github-actions]

No backport to stable for 695a1b7 (AI decision).

This fixes describeContainer in the custom data-inspector tree renderer, which exists only on main: origin/stable:packages/web-shared/src/components/ui/data-inspector.tsx is a 417-line component still built on react-inspector with no describeContainer, ExpandableContainer, or collapseRefs. The defect (hydrated Headers/URLSearchParams drawn as empty objects) and the code being changed are both properties of the main-only renderer, so there is nothing on stable for this patch to fix. It also adds new rendering behavior for arbitrary iterables, which is additive capability rather than a maintenance fix.

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

695a1b76d0e14b1093f93757232efa5c2818d0da

[mitul-s]

Why

Hydrated Headers and URLSearchParams keep their pairs in internal slots. Object.entries returns nothing, so the inspector drew them as empty objects.

The first version of this PR walked Symbol.iterator and treated every 2-element yield as a field. That matched old react-inspector behavior. It also turned a list of coordinate pairs into fake keys.

Scope

describeContainer now follows the same re-iterable pattern as Map and Set. A value with entries() renders as {} pair rows from that iterator. Any other iterable renders as [] unlabeled list rows from Symbol.iterator.

DataRender and ClassInstanceNode no longer memoize describeContainer. Tests use renderToStaticMarkup instead of jsdom. jsdom is removed from @workflow/web-shared.

Out of scope. serializeForClipboard still runs JSON.stringify on Headers and copies {}. hasDisplayContent still uses Object.keys.

Tradeoffs

Live re-iteration instead of a collapseRefs snapshot. Headers and URLSearchParams are re-iterable, which is the production case. One-shot generators are no longer snapshotted across rerenders.

Blast radius

Observability UI only, @workflow/web-sharedDataInspector. Step input and output views that hydrate Request, Headers, or URLSearchParams now show the real pairs. Custom iterables without entries() render as lists, not keyed objects.

Verification

In packages/web-shared:

pnpm exec vitest run test/data-inspector.test.ts test/collapse-refs.test.ts test/copyable-data-block.test.ts

37 tests passed.

The new tests against the previous describeContainer failed in 3 cases. TestIterable rendered 0: labels. CoordinatePairs rendered 1:2. MapLike ignored entries() and showed the default iterator.

The full @workflow/web-shared suite was 218 passed. test/zstd-decoder.test.ts failed on zlib.zstdCompressSync, which this change does not touch.

PR Checklist - Required to merge

• 📦 Added a patch changeset for @workflow/web-shared
• 🔒 Commits include DCO sign-off
• 📝 Ping @vercel/workflow in a comment once the PR is ready

Slack Thread

[changeset-bot]

🦋 Changeset detected

Latest commit: 13fc38c

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

This PR includes changesets to release 16 packages

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

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

Project	Deployment	Actions	Updated (UTC)
example-nextjs-workflow-turbopack	Ready	Preview, v0	Aug 26, 2026 7:43pm
example-nextjs-workflow-webpack	Ready	Preview, v0	Aug 26, 2026 7:43pm
example-workflow	Ready	Preview, v0	Aug 26, 2026 7:43pm
workbench-astro-workflow	Ready	Preview, v0	Aug 26, 2026 7:43pm
workbench-express-workflow	Ready	Preview, v0	Aug 26, 2026 7:43pm
workbench-fastify-workflow	Ready	Preview, v0	Aug 26, 2026 7:43pm
workbench-hono-workflow	Ready	Preview, v0	Aug 26, 2026 7:43pm
workbench-nestjs-workflow	Ready	Preview, v0	Aug 26, 2026 7:43pm
workbench-nitro-workflow	Ready	Preview, v0	Aug 26, 2026 7:43pm
workbench-nuxt-workflow	Ready	Preview, v0	Aug 26, 2026 7:43pm
workbench-python-workflow	Ready	Preview, v0	Aug 26, 2026 7:43pm
workbench-sveltekit-workflow	Ready	Preview, v0	Aug 26, 2026 7:43pm
workbench-tanstack-start-workflow	Ready	Preview, v0	Aug 26, 2026 7:43pm
workbench-vite-workflow	Ready	Preview, v0	Aug 26, 2026 7:43pm
workflow-docs	Ready	Preview, v0	Aug 26, 2026 7:43pm
workflow-swc-playground	Ready	Preview, v0	Aug 26, 2026 7:43pm
workflow-tarballs	Ready	Preview, v0	Aug 26, 2026 7:43pm
workflow-web	Ready	Preview, v0	Aug 26, 2026 7:43pm

[TooTallNate]

More generally, we should be able to expand any value that implements Symbol.iterator, rather than special casing Headers and URLSearchParams

[github-actions]

🧪 E2E Test Results

❌ Some tests failed

❌ Failed E2E Tests

▲ Vercel Production (8 failed)

python-node (8 failed):

• promiseAllWorkflow | wrun_41M0ZKVKE60GRTE4KH2QZ7DTC4 | 🔍 observability
• sleepingWorkflow | wrun_41M0ZKW7BW0GXPGM0GVD1EAEKR | 🔍 observability
• parallelSleepWorkflow | wrun_41M0ZKW7EY0GHGEV96Q39D7PMA | 🔍 observability
• nullByteWorkflow | wrun_41M0ZKWDR00GY8QCX6JSTGSJAQ | 🔍 observability
• cancelRun - cancelling a running workflow | wrun_41M0ZM0KJG0GTHJCCJF5M9M6E2 | 🔍 observability
• cancelRun via CLI - cancelling a running workflow | wrun_41M0ZM0MG50GMVCWAJFATE272J | 🔍 observability
• sleepInLoopWorkflow - sleep inside loop with steps actually delays each iteration | wrun_41M0ZM0S270GSASPMDRG9C4HW2 | 🔍 observability
• resilient start: addTenWorkflow completes when run_created returns 500 | wrun_41M0ZM19S70GWKV1MVG6V7GW7S | 🔍 observability

🌐 Cross-language Conformance (9 failed)

python (9 failed):

• deploymentId: 'latest' is a no-op in non-Vercel worlds | wrun_01M0ZM4X0N34FZTTVJCZ7E2G9G
• promiseAllWorkflow | wrun_41M0ZKVKE60GRTE4KH2QZ7DTC4
• sleepingWorkflow | wrun_41M0ZKW7BW0GXPGM0GVD1EAEKR
• parallelSleepWorkflow | wrun_41M0ZKW7EY0GHGEV96Q39D7PMA
• nullByteWorkflow | wrun_41M0ZKWDR00GY8QCX6JSTGSJAQ
• cancelRun - cancelling a running workflow | wrun_41M0ZM0KJG0GTHJCCJF5M9M6E2
• cancelRun via CLI - cancelling a running workflow | wrun_41M0ZM0MG50GMVCWAJFATE272J
• sleepInLoopWorkflow - sleep inside loop with steps actually delays each iteration | wrun_41M0ZM0S270GSASPMDRG9C4HW2
• resilient start: addTenWorkflow completes when run_created returns 500 | wrun_41M0ZM19S70GWKV1MVG6V7GW7S

⚠️ 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.

• cancelRun via CLI - cancelling a running workflow (express)
• hook created by a sfo1 run resolves by token and resumes the run (nextjs-turbopack)
• hookWorkflow (tanstack-start)
• promiseAllWorkflow (express)
• promiseRaceStressTestWorkflow (vite)
• promiseRaceWorkflow (hono)
• promiseRaceWorkflow (sveltekit)

🛠 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.

34 infra events

• cold-start-warmup · suite warmup (python) · at 18:05:09Z · abandoned wrun_41M0ZKTYBS0GPDS9W8WHKT22HR · (+7 more)
• run-pickup-stall · promiseAllWorkflow (python) · at 18:05:25Z · abandoned wrun_41M0ZKYM2M0GYCWSNESMWEGYZW
• run-pickup-stall · nullByteWorkflow (python) · at 18:05:25Z · abandoned wrun_41M0ZKYM2X0GJ5QJENP5KAR8DK
• run-pickup-stall · sleepingWorkflow (python) · at 18:05:25Z · abandoned wrun_41M0ZKYM2S0GGQ93SXWWAXH1PE
• run-pickup-stall · parallelSleepWorkflow (python) · at 18:05:25Z · abandoned wrun_41M0ZKYM2S0GGQ93SXWWAXH1PF
• run-pickup-stall · cancelRun - cancelling a running workflow (python) · at 18:05:26Z · abandoned wrun_41M0ZKYMFQ0GNQK9XTZZS00G68
• run-pickup-stall · cancelRun - cancelling a running workflow (python) · at 18:05:58Z · abandoned wrun_41M0ZKZMDG0GKJCTA3BYYGXFDX
• cold-start-warmup · suite warmup (tanstack-start) · at 18:06:22Z · abandoned wrun_01M0ZM010XFRBR7N3GCYFHT0KD
• run-pickup-stall · sleepingWorkflow (python) · at 18:06:26Z · abandoned wrun_41M0ZM0FRD0GJ6BN11NRKBMJ9N
• run-pickup-stall · promiseAllWorkflow (python) · at 18:06:26Z · abandoned wrun_41M0ZM0FQG0GRFWWW9CP6NEVRF
• run-pickup-stall · nullByteWorkflow (python) · at 18:06:26Z · abandoned wrun_41M0ZM0FSY0GXM6P4BV6D1NTVQ
• run-pickup-stall · parallelSleepWorkflow (python) · at 18:06:26Z · abandoned wrun_41M0ZM0FJX0GR49QWPXV7A356M
• run-pickup-stall · cancelRun via CLI - cancelling a running workflow (python) · at 18:07:16Z · abandoned wrun_41M0ZM0M5E0GX9F0KQ6Q082MS1
• cold-start-warmup · suite warmup (python) · at 18:07:19Z · abandoned wrun_01M0ZKYYKD0KPD3MBEX0E432BE · (+7 more)
• run-pickup-stall · deploymentId: 'latest' is a no-op in non-Vercel worlds (python) · at 18:07:34Z · abandoned wrun_01M0ZM2KQNF8AWHK32575V2461
• run-pickup-stall · promiseAllWorkflow (python) · at 18:07:34Z · abandoned wrun_01M0ZM2KQPQPQWKSRGPTBXH847
• run-pickup-stall · parallelSleepWorkflow (python) · at 18:07:34Z · abandoned wrun_01M0ZM2KQY592H6FWWEF0NRP1S
• run-pickup-stall · sleepingWorkflow (python) · at 18:07:34Z · abandoned wrun_01M0ZM2KQWET1C8DARN3W95P1R
• run-pickup-stall · nullByteWorkflow (python) · at 18:07:34Z · abandoned wrun_01M0ZM2KR13RD8ECG6Q0BCWN67
• run-pickup-stall · instanceMethodStepWorkflow - instance methods with "use step" directive (nuxt) · at 18:08:09Z · abandoned wrun_01M0ZM3NZ7D3G82TGVPJ8YWN5T
• run-pickup-stall · deploymentId: 'latest' is a no-op in non-Vercel worlds (python) · at 18:08:34Z · abandoned wrun_01M0ZM4EB8QN7E7Y2GE2DME665
• run-pickup-stall · promiseAllWorkflow (python) · at 18:08:34Z · abandoned wrun_01M0ZM4EBDCPVVDS39BS95RA70
• run-pickup-stall · sleepingWorkflow (python) · at 18:08:34Z · abandoned wrun_01M0ZM4EBH838SW4S33HVVHJ86
• run-pickup-stall · parallelSleepWorkflow (python) · at 18:08:34Z · abandoned wrun_01M0ZM4EBQG3D97DYY2VTKVPYK
• run-pickup-stall · nullByteWorkflow (python) · at 18:08:34Z · abandoned wrun_01M0ZM4EBV1GDM3GJBCXC3EA81
• run-pickup-stall · sleepInLoopWorkflow - sleep inside loop with steps actually delays each iteration (python) · at 18:08:58Z · abandoned wrun_41M0ZM37FF0GHKTCT7733J4VH5
• run-pickup-stall · cancelRun - cancelling a running workflow (python) · at 18:09:34Z · abandoned wrun_01M0ZM68YTAQ3XS41G6YFCKT43
• run-pickup-stall · cancelRun via CLI - cancelling a running workflow (python) · at 18:09:34Z · abandoned wrun_01M0ZM68Z493DW9VT63EVBWHV7
• run-pickup-stall · sleepInLoopWorkflow - sleep inside loop with steps actually delays each iteration (python) · at 18:09:34Z · abandoned wrun_01M0ZM68Z77GYDRKXMEJ9H7AR0
• run-pickup-stall · cancelRun via CLI - cancelling a running workflow (python) · at 18:09:38Z · abandoned wrun_41M0ZM3C210GMFQNJV10YHJTFC
• run-pickup-stall · cancelRun - cancelling a running workflow (python) · at 18:10:04Z · abandoned wrun_01M0ZM76A942EQRE76CRQS2GBD
• run-pickup-stall · cancelRun via CLI - cancelling a running workflow (python) · at 18:10:04Z · abandoned wrun_01M0ZM76AB9XFB6P68M9GWJJBJ
• run-pickup-stall · sleepInLoopWorkflow - sleep inside loop with steps actually delays each iteration (python) · at 18:10:34Z · abandoned wrun_01M0ZM83JA93Q68M99DXENAZED
• run-pickup-stall · hookWithSleepWorkflow - hook payloads delivered correctly with concurrent sleep (nextjs-webpack) · at 18:11:29Z · abandoned wrun_01M0ZM9RYGF6CTNHDK8KQB4CVK

E2E Test Summary

Summary

	Passed	Failed	Skipped	Total
❌ ▲ Vercel Production	3570	8	742	4320
✅ 💻 Local Development	3922	0	558	4480
✅ 📦 Local Production	3922	0	558	4480
✅ 🐘 Local Postgres	3922	0	558	4480
✅ 🪟 Windows	320	0	0	320
❌ 🌐 Cross-language Conformance	0	9	132	141
✅ vercel-http-transport	817	0	143	960
✅ vercel-multi-region	27	0	0	27
✅ vercel-ws-transport	553	0	87	640
Total	17053	17	2778	19848

Details by Category

❌ ▲ Vercel Production

App	Passed	Failed	Skipped
✅ astro-node	132	0	28
✅ astro-quickjs	132	0	28
✅ example-node	132	0	28
✅ example-quickjs	132	0	28
✅ express-node	132	0	28
✅ express-quickjs	132	0	28
✅ fastify-node	132	0	28
✅ fastify-quickjs	132	0	28
✅ hono-node	132	0	28
✅ hono-quickjs	132	0	28
✅ nest-node	132	0	28
✅ nest-quickjs	132	0	28
✅ nextjs-turbopack-node	157	0	3
✅ nextjs-turbopack-quickjs	157	0	3
✅ nextjs-webpack-node	157	0	3
✅ nextjs-webpack-quickjs	157	0	3
✅ nitro-node	132	0	28
✅ nitro-quickjs	132	0	28
✅ nuxt-node	132	0	28
✅ nuxt-quickjs	132	0	28
❌ python-node	0	8	152
✅ sveltekit-node	151	0	9
✅ sveltekit-quickjs	151	0	9
✅ tanstack-start-node	132	0	28
✅ tanstack-start-quickjs	132	0	28
✅ vite-node	132	0	28
✅ vite-quickjs	132	0	28

✅ 💻 Local Development

App	Passed	Failed	Skipped
✅ astro-stable-node	134	0	26
✅ astro-stable-quickjs	134	0	26
✅ express-stable-node	134	0	26
✅ express-stable-quickjs	134	0	26
✅ fastify-stable-node	134	0	26
✅ fastify-stable-quickjs	134	0	26
✅ hono-stable-node	134	0	26
✅ hono-stable-quickjs	134	0	26
✅ nest-stable-node	134	0	26
✅ nest-stable-quickjs	134	0	26
✅ nextjs-turbopack-canary-node	141	0	19
✅ nextjs-turbopack-canary-quickjs	141	0	19
✅ nextjs-turbopack-stable-node	160	0	0
✅ nextjs-turbopack-stable-quickjs	160	0	0
✅ nextjs-webpack-canary-node	141	0	19
✅ nextjs-webpack-canary-quickjs	141	0	19
✅ nextjs-webpack-stable-node	160	0	0
✅ nextjs-webpack-stable-quickjs	160	0	0
✅ nitro-stable-node	134	0	26
✅ nitro-stable-quickjs	134	0	26
✅ nuxt-stable-node	134	0	26
✅ nuxt-stable-quickjs	134	0	26
✅ sveltekit-stable-node	153	0	7
✅ sveltekit-stable-quickjs	153	0	7
✅ tanstack-start-node	134	0	26
✅ tanstack-start-quickjs	134	0	26
✅ vite-stable-node	134	0	26
✅ vite-stable-quickjs	134	0	26

✅ 📦 Local Production

App	Passed	Failed	Skipped
✅ astro-stable-node	134	0	26
✅ astro-stable-quickjs	134	0	26
✅ express-stable-node	134	0	26
✅ express-stable-quickjs	134	0	26
✅ fastify-stable-node	134	0	26
✅ fastify-stable-quickjs	134	0	26
✅ hono-stable-node	134	0	26
✅ hono-stable-quickjs	134	0	26
✅ nest-stable-node	134	0	26
✅ nest-stable-quickjs	134	0	26
✅ nextjs-turbopack-canary-node	141	0	19
✅ nextjs-turbopack-canary-quickjs	141	0	19
✅ nextjs-turbopack-stable-node	160	0	0
✅ nextjs-turbopack-stable-quickjs	160	0	0
✅ nextjs-webpack-canary-node	141	0	19
✅ nextjs-webpack-canary-quickjs	141	0	19
✅ nextjs-webpack-stable-node	160	0	0
✅ nextjs-webpack-stable-quickjs	160	0	0
✅ nitro-stable-node	134	0	26
✅ nitro-stable-quickjs	134	0	26
✅ nuxt-stable-node	134	0	26
✅ nuxt-stable-quickjs	134	0	26
✅ sveltekit-stable-node	153	0	7
✅ sveltekit-stable-quickjs	153	0	7
✅ tanstack-start-node	134	0	26
✅ tanstack-start-quickjs	134	0	26
✅ vite-stable-node	134	0	26
✅ vite-stable-quickjs	134	0	26

✅ 🐘 Local Postgres

App	Passed	Failed	Skipped
✅ astro-stable-node	134	0	26
✅ astro-stable-quickjs	134	0	26
✅ express-stable-node	134	0	26
✅ express-stable-quickjs	134	0	26
✅ fastify-stable-node	134	0	26
✅ fastify-stable-quickjs	134	0	26
✅ hono-stable-node	134	0	26
✅ hono-stable-quickjs	134	0	26
✅ nest-stable-node	134	0	26
✅ nest-stable-quickjs	134	0	26
✅ nextjs-turbopack-canary-node	141	0	19
✅ nextjs-turbopack-canary-quickjs	141	0	19
✅ nextjs-turbopack-stable-node	160	0	0
✅ nextjs-turbopack-stable-quickjs	160	0	0
✅ nextjs-webpack-canary-node	141	0	19
✅ nextjs-webpack-canary-quickjs	141	0	19
✅ nextjs-webpack-stable-node	160	0	0
✅ nextjs-webpack-stable-quickjs	160	0	0
✅ nitro-stable-node	134	0	26
✅ nitro-stable-quickjs	134	0	26
✅ nuxt-stable-node	134	0	26
✅ nuxt-stable-quickjs	134	0	26
✅ sveltekit-stable-node	153	0	7
✅ sveltekit-stable-quickjs	153	0	7
✅ tanstack-start-node	134	0	26
✅ tanstack-start-quickjs	134	0	26
✅ vite-stable-node	134	0	26
✅ vite-stable-quickjs	134	0	26

✅ 🪟 Windows

App	Passed	Failed	Skipped
✅ nextjs-turbopack-node	160	0	0
✅ nextjs-turbopack-quickjs	160	0	0

❌ 🌐 Cross-language Conformance

App	Passed	Failed	Skipped
❌ python	0	9	132

✅ vercel-http-transport

App	Passed	Failed	Skipped
✅ example	132	0	28
✅ express	132	0	28
✅ hono	132	0	28
✅ nextjs-turbopack	157	0	3
✅ nitro	132	0	28
✅ vite	132	0	28

✅ vercel-multi-region

App	Passed	Failed	Skipped
✅ nextjs-turbopack	27	0	0

✅ vercel-ws-transport

App	Passed	Failed	Skipped
✅ example	132	0	28
✅ express	132	0	28
✅ nextjs-turbopack	157	0	3
✅ vite	132	0	28

---

📋 View full workflow run

[github-actions]

📊 Workflow Benchmarks

❌ The benchmark run for 6b3ece8 failed. See the run logs for details.

commit 19c0720 · Wed, 26 Aug 2026 17:27:47 GMT · run logs

Backend: vercel · app: nextjs-turbopack

Metric	Scenario	Best (ms)	P75 (ms)	P90 (ms)	P99 (ms)	Samples
TTFS	step	204 (+13%)	1253 🔴 (+18%) 🔻	1409 🔴 (+32%) 🔻	1500 🔴 (+13%)	30
TTFS	stream	176 (-15%)	1293 🔴 (+18%) 🔻	1389 🔴 (+13%)	1435 🔴 (-6.8%)	30
TTFS	hook + stream	1318 (+58%) 🔻	1733 🔴 (+24%) 🔻	1826 🔴 (+23%) 🔻	1898 🔴 (+17%) 🔻	30
Fan-out TTFS	Promise.all(100 steps)	546 (-29%) 💚	1921 (+10%)	2263 (+27%) 🔻	2440 (+25%) 🔻	10
Fan-out TTLS	Promise.all(100 steps)	2014 (+4.7%)	3550 (-2.0%)	3789 (+2.7%)	8013 (+95%) 🔻	10
STSO	1020 steps (inline)	118 (-7.8%)	152 (-15%) 💚	178 (-14%)	762 (+144%) 🔻	1019
WO	1020 steps	167911 (-3.1%)	167911 (-3.1%)	167911 (-3.1%)	167911 (-3.1%)	1
CRTT	first chunk (pooled)	91 (-9.0%)	135 (-16%) 💚	206 (-21%) 💚	286 (-16%) 💚	28

Streams

Scenario	CRTT 1st	p75	p90	p99	CDV max	iters
paced control (100/s, 60B)	118 (-18%)	183 (-39%)	242 (-69%)	479 (-59%)	153 (-29%)	10
size sweep (100/s, 160B-12KB)	119 (-15%)	187 (-14%)	325 (-7%)	594 (+9%)	165 (-20%)	10
replay gateway-gpt-5.4-nano-2000t (1x)	250 (+116%)	143 (-25%)	196 (-89%)	387 (-89%)	192 (-43%)	3
replay eve-gpt-5.6-sol-2000t (1x)	147 (+19%)	140 (-17%)	188 (-19%)	380 (-34%)	353 (-42%)	2
replay eve-gpt-5.6-sol-2000t (2x)	123 (-45%)	209 (-38%)	292 (-51%)	511 (-44%)	302 (-31%)	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.}

_{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-2000teaf22f5946e7c61f3c65c7006d550df180cfabd4e706254a09f22aec0cfb420d · gateway-gpt-5.4-nano-2000t6f24ac518b6b83ff1d0e85a5fe78230db192716d66a7fc6b2fe022752001d041}

_{🔴 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]

Sim World

Simulated world deterministic testing for races. Traces

🟠 world-sim scenario book — 1 fail of 41 total

fence=per-spec

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

Full trace: world-sim.txt

[github-actions]

Framework	Flow route	Step reg.	Framework output
hono	200.9 KiB (±0)	40.3 KiB (±0)	1.76 MiB (±0)
nextjs-turbopack	206.3 KiB (±0)	439 B (±0)	763.1 KiB (±0)

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.

6b3ece8 · run

[github-actions]

No backport to stable for 695a1b7 (AI decision).

This fixes describeContainer in the custom data-inspector tree renderer, which exists only on main: origin/stable:packages/web-shared/src/components/ui/data-inspector.tsx is a 417-line component still built on react-inspector with no describeContainer, ExpandableContainer, or collapseRefs. The defect (hydrated Headers/URLSearchParams drawn as empty objects) and the code being changed are both properties of the main-only renderer, so there is nothing on stable for this patch to fix. It also adds new rendering behavior for arbitrary iterables, which is additive capability rather than a maintenance fix.

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

695a1b76d0e14b1093f93757232efa5c2818d0da

[mitul-s]

Why

Hydrated Headers and URLSearchParams keep their pairs in internal slots. Object.entries returns nothing, so the inspector drew them as empty objects.

The first version of this PR walked Symbol.iterator and treated every 2-element yield as a field. That matched old react-inspector behavior. It also turned a list of coordinate pairs into fake keys.

Scope

describeContainer now follows the same re-iterable pattern as Map and Set. A value with entries() renders as {} pair rows from that iterator. Any other iterable renders as [] unlabeled list rows from Symbol.iterator.

DataRender and ClassInstanceNode no longer memoize describeContainer. Tests use renderToStaticMarkup instead of jsdom. jsdom is removed from @workflow/web-shared.

Out of scope. serializeForClipboard still runs JSON.stringify on Headers and copies {}. hasDisplayContent still uses Object.keys.

Tradeoffs

Live re-iteration instead of a collapseRefs snapshot. Headers and URLSearchParams are re-iterable, which is the production case. One-shot generators are no longer snapshotted across rerenders.

Blast radius

Observability UI only, @workflow/web-sharedDataInspector. Step input and output views that hydrate Request, Headers, or URLSearchParams now show the real pairs. Custom iterables without entries() render as lists, not keyed objects.

Verification

In packages/web-shared:

pnpm exec vitest run test/data-inspector.test.ts test/collapse-refs.test.ts test/copyable-data-block.test.ts

37 tests passed.

The new tests against the previous describeContainer failed in 3 cases. TestIterable rendered 0: labels. CoordinatePairs rendered 1:2. MapLike ignored entries() and showed the default iterator.

The full @workflow/web-shared suite was 218 passed. test/zstd-decoder.test.ts failed on zlib.zstdCompressSync, which this change does not touch.

PR Checklist - Required to merge

• 📦 Added a patch changeset for @workflow/web-shared
• 🔒 Commits include DCO sign-off
• 📝 Ping @vercel/workflow in a comment once the PR is ready

Slack Thread

[changeset-bot]

🦋 Changeset detected

Latest commit: 13fc38c

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

This PR includes changesets to release 16 packages

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

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

Project	Deployment	Actions	Updated (UTC)
example-nextjs-workflow-turbopack	Ready	Preview, v0	Aug 26, 2026 7:43pm
example-nextjs-workflow-webpack	Ready	Preview, v0	Aug 26, 2026 7:43pm
example-workflow	Ready	Preview, v0	Aug 26, 2026 7:43pm
workbench-astro-workflow	Ready	Preview, v0	Aug 26, 2026 7:43pm
workbench-express-workflow	Ready	Preview, v0	Aug 26, 2026 7:43pm
workbench-fastify-workflow	Ready	Preview, v0	Aug 26, 2026 7:43pm
workbench-hono-workflow	Ready	Preview, v0	Aug 26, 2026 7:43pm
workbench-nestjs-workflow	Ready	Preview, v0	Aug 26, 2026 7:43pm
workbench-nitro-workflow	Ready	Preview, v0	Aug 26, 2026 7:43pm
workbench-nuxt-workflow	Ready	Preview, v0	Aug 26, 2026 7:43pm
workbench-python-workflow	Ready	Preview, v0	Aug 26, 2026 7:43pm
workbench-sveltekit-workflow	Ready	Preview, v0	Aug 26, 2026 7:43pm
workbench-tanstack-start-workflow	Ready	Preview, v0	Aug 26, 2026 7:43pm
workbench-vite-workflow	Ready	Preview, v0	Aug 26, 2026 7:43pm
workflow-docs	Ready	Preview, v0	Aug 26, 2026 7:43pm
workflow-swc-playground	Ready	Preview, v0	Aug 26, 2026 7:43pm
workflow-tarballs	Ready	Preview, v0	Aug 26, 2026 7:43pm
workflow-web	Ready	Preview, v0	Aug 26, 2026 7:43pm

[TooTallNate]

More generally, we should be able to expand any value that implements Symbol.iterator, rather than special casing Headers and URLSearchParams

[github-actions]

🧪 E2E Test Results

❌ Some tests failed

❌ Failed E2E Tests

▲ Vercel Production (8 failed)

python-node (8 failed):

• promiseAllWorkflow | wrun_41M0ZKVKE60GRTE4KH2QZ7DTC4 | 🔍 observability
• sleepingWorkflow | wrun_41M0ZKW7BW0GXPGM0GVD1EAEKR | 🔍 observability
• parallelSleepWorkflow | wrun_41M0ZKW7EY0GHGEV96Q39D7PMA | 🔍 observability
• nullByteWorkflow | wrun_41M0ZKWDR00GY8QCX6JSTGSJAQ | 🔍 observability
• cancelRun - cancelling a running workflow | wrun_41M0ZM0KJG0GTHJCCJF5M9M6E2 | 🔍 observability
• cancelRun via CLI - cancelling a running workflow | wrun_41M0ZM0MG50GMVCWAJFATE272J | 🔍 observability
• sleepInLoopWorkflow - sleep inside loop with steps actually delays each iteration | wrun_41M0ZM0S270GSASPMDRG9C4HW2 | 🔍 observability
• resilient start: addTenWorkflow completes when run_created returns 500 | wrun_41M0ZM19S70GWKV1MVG6V7GW7S | 🔍 observability

🌐 Cross-language Conformance (9 failed)

python (9 failed):

• deploymentId: 'latest' is a no-op in non-Vercel worlds | wrun_01M0ZM4X0N34FZTTVJCZ7E2G9G
• promiseAllWorkflow | wrun_41M0ZKVKE60GRTE4KH2QZ7DTC4
• sleepingWorkflow | wrun_41M0ZKW7BW0GXPGM0GVD1EAEKR
• parallelSleepWorkflow | wrun_41M0ZKW7EY0GHGEV96Q39D7PMA
• nullByteWorkflow | wrun_41M0ZKWDR00GY8QCX6JSTGSJAQ
• cancelRun - cancelling a running workflow | wrun_41M0ZM0KJG0GTHJCCJF5M9M6E2
• cancelRun via CLI - cancelling a running workflow | wrun_41M0ZM0MG50GMVCWAJFATE272J
• sleepInLoopWorkflow - sleep inside loop with steps actually delays each iteration | wrun_41M0ZM0S270GSASPMDRG9C4HW2
• resilient start: addTenWorkflow completes when run_created returns 500 | wrun_41M0ZM19S70GWKV1MVG6V7GW7S

⚠️ 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.

• cancelRun via CLI - cancelling a running workflow (express)
• hook created by a sfo1 run resolves by token and resumes the run (nextjs-turbopack)
• hookWorkflow (tanstack-start)
• promiseAllWorkflow (express)
• promiseRaceStressTestWorkflow (vite)
• promiseRaceWorkflow (hono)
• promiseRaceWorkflow (sveltekit)

🛠 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.

34 infra events

• cold-start-warmup · suite warmup (python) · at 18:05:09Z · abandoned wrun_41M0ZKTYBS0GPDS9W8WHKT22HR · (+7 more)
• run-pickup-stall · promiseAllWorkflow (python) · at 18:05:25Z · abandoned wrun_41M0ZKYM2M0GYCWSNESMWEGYZW
• run-pickup-stall · nullByteWorkflow (python) · at 18:05:25Z · abandoned wrun_41M0ZKYM2X0GJ5QJENP5KAR8DK
• run-pickup-stall · sleepingWorkflow (python) · at 18:05:25Z · abandoned wrun_41M0ZKYM2S0GGQ93SXWWAXH1PE
• run-pickup-stall · parallelSleepWorkflow (python) · at 18:05:25Z · abandoned wrun_41M0ZKYM2S0GGQ93SXWWAXH1PF
• run-pickup-stall · cancelRun - cancelling a running workflow (python) · at 18:05:26Z · abandoned wrun_41M0ZKYMFQ0GNQK9XTZZS00G68
• run-pickup-stall · cancelRun - cancelling a running workflow (python) · at 18:05:58Z · abandoned wrun_41M0ZKZMDG0GKJCTA3BYYGXFDX
• cold-start-warmup · suite warmup (tanstack-start) · at 18:06:22Z · abandoned wrun_01M0ZM010XFRBR7N3GCYFHT0KD
• run-pickup-stall · sleepingWorkflow (python) · at 18:06:26Z · abandoned wrun_41M0ZM0FRD0GJ6BN11NRKBMJ9N
• run-pickup-stall · promiseAllWorkflow (python) · at 18:06:26Z · abandoned wrun_41M0ZM0FQG0GRFWWW9CP6NEVRF
• run-pickup-stall · nullByteWorkflow (python) · at 18:06:26Z · abandoned wrun_41M0ZM0FSY0GXM6P4BV6D1NTVQ
• run-pickup-stall · parallelSleepWorkflow (python) · at 18:06:26Z · abandoned wrun_41M0ZM0FJX0GR49QWPXV7A356M
• run-pickup-stall · cancelRun via CLI - cancelling a running workflow (python) · at 18:07:16Z · abandoned wrun_41M0ZM0M5E0GX9F0KQ6Q082MS1
• cold-start-warmup · suite warmup (python) · at 18:07:19Z · abandoned wrun_01M0ZKYYKD0KPD3MBEX0E432BE · (+7 more)
• run-pickup-stall · deploymentId: 'latest' is a no-op in non-Vercel worlds (python) · at 18:07:34Z · abandoned wrun_01M0ZM2KQNF8AWHK32575V2461
• run-pickup-stall · promiseAllWorkflow (python) · at 18:07:34Z · abandoned wrun_01M0ZM2KQPQPQWKSRGPTBXH847
• run-pickup-stall · parallelSleepWorkflow (python) · at 18:07:34Z · abandoned wrun_01M0ZM2KQY592H6FWWEF0NRP1S
• run-pickup-stall · sleepingWorkflow (python) · at 18:07:34Z · abandoned wrun_01M0ZM2KQWET1C8DARN3W95P1R
• run-pickup-stall · nullByteWorkflow (python) · at 18:07:34Z · abandoned wrun_01M0ZM2KR13RD8ECG6Q0BCWN67
• run-pickup-stall · instanceMethodStepWorkflow - instance methods with "use step" directive (nuxt) · at 18:08:09Z · abandoned wrun_01M0ZM3NZ7D3G82TGVPJ8YWN5T
• run-pickup-stall · deploymentId: 'latest' is a no-op in non-Vercel worlds (python) · at 18:08:34Z · abandoned wrun_01M0ZM4EB8QN7E7Y2GE2DME665
• run-pickup-stall · promiseAllWorkflow (python) · at 18:08:34Z · abandoned wrun_01M0ZM4EBDCPVVDS39BS95RA70
• run-pickup-stall · sleepingWorkflow (python) · at 18:08:34Z · abandoned wrun_01M0ZM4EBH838SW4S33HVVHJ86
• run-pickup-stall · parallelSleepWorkflow (python) · at 18:08:34Z · abandoned wrun_01M0ZM4EBQG3D97DYY2VTKVPYK
• run-pickup-stall · nullByteWorkflow (python) · at 18:08:34Z · abandoned wrun_01M0ZM4EBV1GDM3GJBCXC3EA81
• run-pickup-stall · sleepInLoopWorkflow - sleep inside loop with steps actually delays each iteration (python) · at 18:08:58Z · abandoned wrun_41M0ZM37FF0GHKTCT7733J4VH5
• run-pickup-stall · cancelRun - cancelling a running workflow (python) · at 18:09:34Z · abandoned wrun_01M0ZM68YTAQ3XS41G6YFCKT43
• run-pickup-stall · cancelRun via CLI - cancelling a running workflow (python) · at 18:09:34Z · abandoned wrun_01M0ZM68Z493DW9VT63EVBWHV7
• run-pickup-stall · sleepInLoopWorkflow - sleep inside loop with steps actually delays each iteration (python) · at 18:09:34Z · abandoned wrun_01M0ZM68Z77GYDRKXMEJ9H7AR0
• run-pickup-stall · cancelRun via CLI - cancelling a running workflow (python) · at 18:09:38Z · abandoned wrun_41M0ZM3C210GMFQNJV10YHJTFC
• run-pickup-stall · cancelRun - cancelling a running workflow (python) · at 18:10:04Z · abandoned wrun_01M0ZM76A942EQRE76CRQS2GBD
• run-pickup-stall · cancelRun via CLI - cancelling a running workflow (python) · at 18:10:04Z · abandoned wrun_01M0ZM76AB9XFB6P68M9GWJJBJ
• run-pickup-stall · sleepInLoopWorkflow - sleep inside loop with steps actually delays each iteration (python) · at 18:10:34Z · abandoned wrun_01M0ZM83JA93Q68M99DXENAZED
• run-pickup-stall · hookWithSleepWorkflow - hook payloads delivered correctly with concurrent sleep (nextjs-webpack) · at 18:11:29Z · abandoned wrun_01M0ZM9RYGF6CTNHDK8KQB4CVK

E2E Test Summary

Summary

	Passed	Failed	Skipped	Total
❌ ▲ Vercel Production	3570	8	742	4320
✅ 💻 Local Development	3922	0	558	4480
✅ 📦 Local Production	3922	0	558	4480
✅ 🐘 Local Postgres	3922	0	558	4480
✅ 🪟 Windows	320	0	0	320
❌ 🌐 Cross-language Conformance	0	9	132	141
✅ vercel-http-transport	817	0	143	960
✅ vercel-multi-region	27	0	0	27
✅ vercel-ws-transport	553	0	87	640
Total	17053	17	2778	19848

Details by Category

❌ ▲ Vercel Production

App	Passed	Failed	Skipped
✅ astro-node	132	0	28
✅ astro-quickjs	132	0	28
✅ example-node	132	0	28
✅ example-quickjs	132	0	28
✅ express-node	132	0	28
✅ express-quickjs	132	0	28
✅ fastify-node	132	0	28
✅ fastify-quickjs	132	0	28
✅ hono-node	132	0	28
✅ hono-quickjs	132	0	28
✅ nest-node	132	0	28
✅ nest-quickjs	132	0	28
✅ nextjs-turbopack-node	157	0	3
✅ nextjs-turbopack-quickjs	157	0	3
✅ nextjs-webpack-node	157	0	3
✅ nextjs-webpack-quickjs	157	0	3
✅ nitro-node	132	0	28
✅ nitro-quickjs	132	0	28
✅ nuxt-node	132	0	28
✅ nuxt-quickjs	132	0	28
❌ python-node	0	8	152
✅ sveltekit-node	151	0	9
✅ sveltekit-quickjs	151	0	9
✅ tanstack-start-node	132	0	28
✅ tanstack-start-quickjs	132	0	28
✅ vite-node	132	0	28
✅ vite-quickjs	132	0	28

✅ 💻 Local Development

App	Passed	Failed	Skipped
✅ astro-stable-node	134	0	26
✅ astro-stable-quickjs	134	0	26
✅ express-stable-node	134	0	26
✅ express-stable-quickjs	134	0	26
✅ fastify-stable-node	134	0	26
✅ fastify-stable-quickjs	134	0	26
✅ hono-stable-node	134	0	26
✅ hono-stable-quickjs	134	0	26
✅ nest-stable-node	134	0	26
✅ nest-stable-quickjs	134	0	26
✅ nextjs-turbopack-canary-node	141	0	19
✅ nextjs-turbopack-canary-quickjs	141	0	19
✅ nextjs-turbopack-stable-node	160	0	0
✅ nextjs-turbopack-stable-quickjs	160	0	0
✅ nextjs-webpack-canary-node	141	0	19
✅ nextjs-webpack-canary-quickjs	141	0	19
✅ nextjs-webpack-stable-node	160	0	0
✅ nextjs-webpack-stable-quickjs	160	0	0
✅ nitro-stable-node	134	0	26
✅ nitro-stable-quickjs	134	0	26
✅ nuxt-stable-node	134	0	26
✅ nuxt-stable-quickjs	134	0	26
✅ sveltekit-stable-node	153	0	7
✅ sveltekit-stable-quickjs	153	0	7
✅ tanstack-start-node	134	0	26
✅ tanstack-start-quickjs	134	0	26
✅ vite-stable-node	134	0	26
✅ vite-stable-quickjs	134	0	26

✅ 📦 Local Production

App	Passed	Failed	Skipped
✅ astro-stable-node	134	0	26
✅ astro-stable-quickjs	134	0	26
✅ express-stable-node	134	0	26
✅ express-stable-quickjs	134	0	26
✅ fastify-stable-node	134	0	26
✅ fastify-stable-quickjs	134	0	26
✅ hono-stable-node	134	0	26
✅ hono-stable-quickjs	134	0	26
✅ nest-stable-node	134	0	26
✅ nest-stable-quickjs	134	0	26
✅ nextjs-turbopack-canary-node	141	0	19
✅ nextjs-turbopack-canary-quickjs	141	0	19
✅ nextjs-turbopack-stable-node	160	0	0
✅ nextjs-turbopack-stable-quickjs	160	0	0
✅ nextjs-webpack-canary-node	141	0	19
✅ nextjs-webpack-canary-quickjs	141	0	19
✅ nextjs-webpack-stable-node	160	0	0
✅ nextjs-webpack-stable-quickjs	160	0	0
✅ nitro-stable-node	134	0	26
✅ nitro-stable-quickjs	134	0	26
✅ nuxt-stable-node	134	0	26
✅ nuxt-stable-quickjs	134	0	26
✅ sveltekit-stable-node	153	0	7
✅ sveltekit-stable-quickjs	153	0	7
✅ tanstack-start-node	134	0	26
✅ tanstack-start-quickjs	134	0	26
✅ vite-stable-node	134	0	26
✅ vite-stable-quickjs	134	0	26

✅ 🐘 Local Postgres

App	Passed	Failed	Skipped
✅ astro-stable-node	134	0	26
✅ astro-stable-quickjs	134	0	26
✅ express-stable-node	134	0	26
✅ express-stable-quickjs	134	0	26
✅ fastify-stable-node	134	0	26
✅ fastify-stable-quickjs	134	0	26
✅ hono-stable-node	134	0	26
✅ hono-stable-quickjs	134	0	26
✅ nest-stable-node	134	0	26
✅ nest-stable-quickjs	134	0	26
✅ nextjs-turbopack-canary-node	141	0	19
✅ nextjs-turbopack-canary-quickjs	141	0	19
✅ nextjs-turbopack-stable-node	160	0	0
✅ nextjs-turbopack-stable-quickjs	160	0	0
✅ nextjs-webpack-canary-node	141	0	19
✅ nextjs-webpack-canary-quickjs	141	0	19
✅ nextjs-webpack-stable-node	160	0	0
✅ nextjs-webpack-stable-quickjs	160	0	0
✅ nitro-stable-node	134	0	26
✅ nitro-stable-quickjs	134	0	26
✅ nuxt-stable-node	134	0	26
✅ nuxt-stable-quickjs	134	0	26
✅ sveltekit-stable-node	153	0	7
✅ sveltekit-stable-quickjs	153	0	7
✅ tanstack-start-node	134	0	26
✅ tanstack-start-quickjs	134	0	26
✅ vite-stable-node	134	0	26
✅ vite-stable-quickjs	134	0	26

✅ 🪟 Windows

App	Passed	Failed	Skipped
✅ nextjs-turbopack-node	160	0	0
✅ nextjs-turbopack-quickjs	160	0	0

❌ 🌐 Cross-language Conformance

App	Passed	Failed	Skipped
❌ python	0	9	132

✅ vercel-http-transport

App	Passed	Failed	Skipped
✅ example	132	0	28
✅ express	132	0	28
✅ hono	132	0	28
✅ nextjs-turbopack	157	0	3
✅ nitro	132	0	28
✅ vite	132	0	28

✅ vercel-multi-region

App	Passed	Failed	Skipped
✅ nextjs-turbopack	27	0	0

✅ vercel-ws-transport

App	Passed	Failed	Skipped
✅ example	132	0	28
✅ express	132	0	28
✅ nextjs-turbopack	157	0	3
✅ vite	132	0	28

---

📋 View full workflow run

[github-actions]

📊 Workflow Benchmarks

❌ The benchmark run for 6b3ece8 failed. See the run logs for details.

commit 19c0720 · Wed, 26 Aug 2026 17:27:47 GMT · run logs

Backend: vercel · app: nextjs-turbopack

Metric	Scenario	Best (ms)	P75 (ms)	P90 (ms)	P99 (ms)	Samples
TTFS	step	204 (+13%)	1253 🔴 (+18%) 🔻	1409 🔴 (+32%) 🔻	1500 🔴 (+13%)	30
TTFS	stream	176 (-15%)	1293 🔴 (+18%) 🔻	1389 🔴 (+13%)	1435 🔴 (-6.8%)	30
TTFS	hook + stream	1318 (+58%) 🔻	1733 🔴 (+24%) 🔻	1826 🔴 (+23%) 🔻	1898 🔴 (+17%) 🔻	30
Fan-out TTFS	Promise.all(100 steps)	546 (-29%) 💚	1921 (+10%)	2263 (+27%) 🔻	2440 (+25%) 🔻	10
Fan-out TTLS	Promise.all(100 steps)	2014 (+4.7%)	3550 (-2.0%)	3789 (+2.7%)	8013 (+95%) 🔻	10
STSO	1020 steps (inline)	118 (-7.8%)	152 (-15%) 💚	178 (-14%)	762 (+144%) 🔻	1019
WO	1020 steps	167911 (-3.1%)	167911 (-3.1%)	167911 (-3.1%)	167911 (-3.1%)	1
CRTT	first chunk (pooled)	91 (-9.0%)	135 (-16%) 💚	206 (-21%) 💚	286 (-16%) 💚	28

Streams

Scenario	CRTT 1st	p75	p90	p99	CDV max	iters
paced control (100/s, 60B)	118 (-18%)	183 (-39%)	242 (-69%)	479 (-59%)	153 (-29%)	10
size sweep (100/s, 160B-12KB)	119 (-15%)	187 (-14%)	325 (-7%)	594 (+9%)	165 (-20%)	10
replay gateway-gpt-5.4-nano-2000t (1x)	250 (+116%)	143 (-25%)	196 (-89%)	387 (-89%)	192 (-43%)	3
replay eve-gpt-5.6-sol-2000t (1x)	147 (+19%)	140 (-17%)	188 (-19%)	380 (-34%)	353 (-42%)	2
replay eve-gpt-5.6-sol-2000t (2x)	123 (-45%)	209 (-38%)	292 (-51%)	511 (-44%)	302 (-31%)	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.}

_{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-2000teaf22f5946e7c61f3c65c7006d550df180cfabd4e706254a09f22aec0cfb420d · gateway-gpt-5.4-nano-2000t6f24ac518b6b83ff1d0e85a5fe78230db192716d66a7fc6b2fe022752001d041}

_{🔴 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]

Sim World

Simulated world deterministic testing for races. Traces

🟠 world-sim scenario book — 1 fail of 41 total

fence=per-spec

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

Full trace: world-sim.txt

[github-actions]

Framework	Flow route	Step reg.	Framework output
hono	200.9 KiB (±0)	40.3 KiB (±0)	1.76 MiB (±0)
nextjs-turbopack	206.3 KiB (±0)	439 B (±0)	763.1 KiB (±0)

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.

6b3ece8 · run

[github-actions]

No backport to stable for 695a1b7 (AI decision).

This fixes describeContainer in the custom data-inspector tree renderer, which exists only on main: origin/stable:packages/web-shared/src/components/ui/data-inspector.tsx is a 417-line component still built on react-inspector with no describeContainer, ExpandableContainer, or collapseRefs. The defect (hydrated Headers/URLSearchParams drawn as empty objects) and the code being changed are both properties of the main-only renderer, so there is nothing on stable for this patch to fix. It also adds new rendering behavior for arbitrary iterables, which is additive capability rather than a maintenance fix.

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

695a1b76d0e14b1093f93757232efa5c2818d0da

[mitul-s]

Why

Hydrated Headers and URLSearchParams keep their pairs in internal slots. Object.entries returns nothing, so the inspector drew them as empty objects.

The first version of this PR walked Symbol.iterator and treated every 2-element yield as a field. That matched old react-inspector behavior. It also turned a list of coordinate pairs into fake keys.

Scope

describeContainer now follows the same re-iterable pattern as Map and Set. A value with entries() renders as {} pair rows from that iterator. Any other iterable renders as [] unlabeled list rows from Symbol.iterator.

DataRender and ClassInstanceNode no longer memoize describeContainer. Tests use renderToStaticMarkup instead of jsdom. jsdom is removed from @workflow/web-shared.

Out of scope. serializeForClipboard still runs JSON.stringify on Headers and copies {}. hasDisplayContent still uses Object.keys.

Tradeoffs

Live re-iteration instead of a collapseRefs snapshot. Headers and URLSearchParams are re-iterable, which is the production case. One-shot generators are no longer snapshotted across rerenders.

Blast radius

Observability UI only, @workflow/web-sharedDataInspector. Step input and output views that hydrate Request, Headers, or URLSearchParams now show the real pairs. Custom iterables without entries() render as lists, not keyed objects.

Verification

In packages/web-shared:

pnpm exec vitest run test/data-inspector.test.ts test/collapse-refs.test.ts test/copyable-data-block.test.ts

37 tests passed.

The new tests against the previous describeContainer failed in 3 cases. TestIterable rendered 0: labels. CoordinatePairs rendered 1:2. MapLike ignored entries() and showed the default iterator.

The full @workflow/web-shared suite was 218 passed. test/zstd-decoder.test.ts failed on zlib.zstdCompressSync, which this change does not touch.

PR Checklist - Required to merge

• 📦 Added a patch changeset for @workflow/web-shared
• 🔒 Commits include DCO sign-off
• 📝 Ping @vercel/workflow in a comment once the PR is ready

Slack Thread

[changeset-bot]

🦋 Changeset detected

Latest commit: 13fc38c

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

This PR includes changesets to release 16 packages

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

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

Project	Deployment	Actions	Updated (UTC)
example-nextjs-workflow-turbopack	Ready	Preview, v0	Aug 26, 2026 7:43pm
example-nextjs-workflow-webpack	Ready	Preview, v0	Aug 26, 2026 7:43pm
example-workflow	Ready	Preview, v0	Aug 26, 2026 7:43pm
workbench-astro-workflow	Ready	Preview, v0	Aug 26, 2026 7:43pm
workbench-express-workflow	Ready	Preview, v0	Aug 26, 2026 7:43pm
workbench-fastify-workflow	Ready	Preview, v0	Aug 26, 2026 7:43pm
workbench-hono-workflow	Ready	Preview, v0	Aug 26, 2026 7:43pm
workbench-nestjs-workflow	Ready	Preview, v0	Aug 26, 2026 7:43pm
workbench-nitro-workflow	Ready	Preview, v0	Aug 26, 2026 7:43pm
workbench-nuxt-workflow	Ready	Preview, v0	Aug 26, 2026 7:43pm
workbench-python-workflow	Ready	Preview, v0	Aug 26, 2026 7:43pm
workbench-sveltekit-workflow	Ready	Preview, v0	Aug 26, 2026 7:43pm
workbench-tanstack-start-workflow	Ready	Preview, v0	Aug 26, 2026 7:43pm
workbench-vite-workflow	Ready	Preview, v0	Aug 26, 2026 7:43pm
workflow-docs	Ready	Preview, v0	Aug 26, 2026 7:43pm
workflow-swc-playground	Ready	Preview, v0	Aug 26, 2026 7:43pm
workflow-tarballs	Ready	Preview, v0	Aug 26, 2026 7:43pm
workflow-web	Ready	Preview, v0	Aug 26, 2026 7:43pm

[TooTallNate]

More generally, we should be able to expand any value that implements Symbol.iterator, rather than special casing Headers and URLSearchParams

[github-actions]

🧪 E2E Test Results

❌ Some tests failed

❌ Failed E2E Tests

▲ Vercel Production (8 failed)

python-node (8 failed):

• promiseAllWorkflow | wrun_41M0ZKVKE60GRTE4KH2QZ7DTC4 | 🔍 observability
• sleepingWorkflow | wrun_41M0ZKW7BW0GXPGM0GVD1EAEKR | 🔍 observability
• parallelSleepWorkflow | wrun_41M0ZKW7EY0GHGEV96Q39D7PMA | 🔍 observability
• nullByteWorkflow | wrun_41M0ZKWDR00GY8QCX6JSTGSJAQ | 🔍 observability
• cancelRun - cancelling a running workflow | wrun_41M0ZM0KJG0GTHJCCJF5M9M6E2 | 🔍 observability
• cancelRun via CLI - cancelling a running workflow | wrun_41M0ZM0MG50GMVCWAJFATE272J | 🔍 observability
• sleepInLoopWorkflow - sleep inside loop with steps actually delays each iteration | wrun_41M0ZM0S270GSASPMDRG9C4HW2 | 🔍 observability
• resilient start: addTenWorkflow completes when run_created returns 500 | wrun_41M0ZM19S70GWKV1MVG6V7GW7S | 🔍 observability

🌐 Cross-language Conformance (9 failed)

python (9 failed):

• deploymentId: 'latest' is a no-op in non-Vercel worlds | wrun_01M0ZM4X0N34FZTTVJCZ7E2G9G
• promiseAllWorkflow | wrun_41M0ZKVKE60GRTE4KH2QZ7DTC4
• sleepingWorkflow | wrun_41M0ZKW7BW0GXPGM0GVD1EAEKR
• parallelSleepWorkflow | wrun_41M0ZKW7EY0GHGEV96Q39D7PMA
• nullByteWorkflow | wrun_41M0ZKWDR00GY8QCX6JSTGSJAQ
• cancelRun - cancelling a running workflow | wrun_41M0ZM0KJG0GTHJCCJF5M9M6E2
• cancelRun via CLI - cancelling a running workflow | wrun_41M0ZM0MG50GMVCWAJFATE272J
• sleepInLoopWorkflow - sleep inside loop with steps actually delays each iteration | wrun_41M0ZM0S270GSASPMDRG9C4HW2
• resilient start: addTenWorkflow completes when run_created returns 500 | wrun_41M0ZM19S70GWKV1MVG6V7GW7S

⚠️ 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.

• cancelRun via CLI - cancelling a running workflow (express)
• hook created by a sfo1 run resolves by token and resumes the run (nextjs-turbopack)
• hookWorkflow (tanstack-start)
• promiseAllWorkflow (express)
• promiseRaceStressTestWorkflow (vite)
• promiseRaceWorkflow (hono)
• promiseRaceWorkflow (sveltekit)

🛠 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.

34 infra events

• cold-start-warmup · suite warmup (python) · at 18:05:09Z · abandoned wrun_41M0ZKTYBS0GPDS9W8WHKT22HR · (+7 more)
• run-pickup-stall · promiseAllWorkflow (python) · at 18:05:25Z · abandoned wrun_41M0ZKYM2M0GYCWSNESMWEGYZW
• run-pickup-stall · nullByteWorkflow (python) · at 18:05:25Z · abandoned wrun_41M0ZKYM2X0GJ5QJENP5KAR8DK
• run-pickup-stall · sleepingWorkflow (python) · at 18:05:25Z · abandoned wrun_41M0ZKYM2S0GGQ93SXWWAXH1PE
• run-pickup-stall · parallelSleepWorkflow (python) · at 18:05:25Z · abandoned wrun_41M0ZKYM2S0GGQ93SXWWAXH1PF
• run-pickup-stall · cancelRun - cancelling a running workflow (python) · at 18:05:26Z · abandoned wrun_41M0ZKYMFQ0GNQK9XTZZS00G68
• run-pickup-stall · cancelRun - cancelling a running workflow (python) · at 18:05:58Z · abandoned wrun_41M0ZKZMDG0GKJCTA3BYYGXFDX
• cold-start-warmup · suite warmup (tanstack-start) · at 18:06:22Z · abandoned wrun_01M0ZM010XFRBR7N3GCYFHT0KD
• run-pickup-stall · sleepingWorkflow (python) · at 18:06:26Z · abandoned wrun_41M0ZM0FRD0GJ6BN11NRKBMJ9N
• run-pickup-stall · promiseAllWorkflow (python) · at 18:06:26Z · abandoned wrun_41M0ZM0FQG0GRFWWW9CP6NEVRF
• run-pickup-stall · nullByteWorkflow (python) · at 18:06:26Z · abandoned wrun_41M0ZM0FSY0GXM6P4BV6D1NTVQ
• run-pickup-stall · parallelSleepWorkflow (python) · at 18:06:26Z · abandoned wrun_41M0ZM0FJX0GR49QWPXV7A356M
• run-pickup-stall · cancelRun via CLI - cancelling a running workflow (python) · at 18:07:16Z · abandoned wrun_41M0ZM0M5E0GX9F0KQ6Q082MS1
• cold-start-warmup · suite warmup (python) · at 18:07:19Z · abandoned wrun_01M0ZKYYKD0KPD3MBEX0E432BE · (+7 more)
• run-pickup-stall · deploymentId: 'latest' is a no-op in non-Vercel worlds (python) · at 18:07:34Z · abandoned wrun_01M0ZM2KQNF8AWHK32575V2461
• run-pickup-stall · promiseAllWorkflow (python) · at 18:07:34Z · abandoned wrun_01M0ZM2KQPQPQWKSRGPTBXH847
• run-pickup-stall · parallelSleepWorkflow (python) · at 18:07:34Z · abandoned wrun_01M0ZM2KQY592H6FWWEF0NRP1S
• run-pickup-stall · sleepingWorkflow (python) · at 18:07:34Z · abandoned wrun_01M0ZM2KQWET1C8DARN3W95P1R
• run-pickup-stall · nullByteWorkflow (python) · at 18:07:34Z · abandoned wrun_01M0ZM2KR13RD8ECG6Q0BCWN67
• run-pickup-stall · instanceMethodStepWorkflow - instance methods with "use step" directive (nuxt) · at 18:08:09Z · abandoned wrun_01M0ZM3NZ7D3G82TGVPJ8YWN5T
• run-pickup-stall · deploymentId: 'latest' is a no-op in non-Vercel worlds (python) · at 18:08:34Z · abandoned wrun_01M0ZM4EB8QN7E7Y2GE2DME665
• run-pickup-stall · promiseAllWorkflow (python) · at 18:08:34Z · abandoned wrun_01M0ZM4EBDCPVVDS39BS95RA70
• run-pickup-stall · sleepingWorkflow (python) · at 18:08:34Z · abandoned wrun_01M0ZM4EBH838SW4S33HVVHJ86
• run-pickup-stall · parallelSleepWorkflow (python) · at 18:08:34Z · abandoned wrun_01M0ZM4EBQG3D97DYY2VTKVPYK
• run-pickup-stall · nullByteWorkflow (python) · at 18:08:34Z · abandoned wrun_01M0ZM4EBV1GDM3GJBCXC3EA81
• run-pickup-stall · sleepInLoopWorkflow - sleep inside loop with steps actually delays each iteration (python) · at 18:08:58Z · abandoned wrun_41M0ZM37FF0GHKTCT7733J4VH5
• run-pickup-stall · cancelRun - cancelling a running workflow (python) · at 18:09:34Z · abandoned wrun_01M0ZM68YTAQ3XS41G6YFCKT43
• run-pickup-stall · cancelRun via CLI - cancelling a running workflow (python) · at 18:09:34Z · abandoned wrun_01M0ZM68Z493DW9VT63EVBWHV7
• run-pickup-stall · sleepInLoopWorkflow - sleep inside loop with steps actually delays each iteration (python) · at 18:09:34Z · abandoned wrun_01M0ZM68Z77GYDRKXMEJ9H7AR0
• run-pickup-stall · cancelRun via CLI - cancelling a running workflow (python) · at 18:09:38Z · abandoned wrun_41M0ZM3C210GMFQNJV10YHJTFC
• run-pickup-stall · cancelRun - cancelling a running workflow (python) · at 18:10:04Z · abandoned wrun_01M0ZM76A942EQRE76CRQS2GBD
• run-pickup-stall · cancelRun via CLI - cancelling a running workflow (python) · at 18:10:04Z · abandoned wrun_01M0ZM76AB9XFB6P68M9GWJJBJ
• run-pickup-stall · sleepInLoopWorkflow - sleep inside loop with steps actually delays each iteration (python) · at 18:10:34Z · abandoned wrun_01M0ZM83JA93Q68M99DXENAZED
• run-pickup-stall · hookWithSleepWorkflow - hook payloads delivered correctly with concurrent sleep (nextjs-webpack) · at 18:11:29Z · abandoned wrun_01M0ZM9RYGF6CTNHDK8KQB4CVK

E2E Test Summary

Summary

	Passed	Failed	Skipped	Total
❌ ▲ Vercel Production	3570	8	742	4320
✅ 💻 Local Development	3922	0	558	4480
✅ 📦 Local Production	3922	0	558	4480
✅ 🐘 Local Postgres	3922	0	558	4480
✅ 🪟 Windows	320	0	0	320
❌ 🌐 Cross-language Conformance	0	9	132	141
✅ vercel-http-transport	817	0	143	960
✅ vercel-multi-region	27	0	0	27
✅ vercel-ws-transport	553	0	87	640
Total	17053	17	2778	19848

Details by Category

❌ ▲ Vercel Production

App	Passed	Failed	Skipped
✅ astro-node	132	0	28
✅ astro-quickjs	132	0	28
✅ example-node	132	0	28
✅ example-quickjs	132	0	28
✅ express-node	132	0	28
✅ express-quickjs	132	0	28
✅ fastify-node	132	0	28
✅ fastify-quickjs	132	0	28
✅ hono-node	132	0	28
✅ hono-quickjs	132	0	28
✅ nest-node	132	0	28
✅ nest-quickjs	132	0	28
✅ nextjs-turbopack-node	157	0	3
✅ nextjs-turbopack-quickjs	157	0	3
✅ nextjs-webpack-node	157	0	3
✅ nextjs-webpack-quickjs	157	0	3
✅ nitro-node	132	0	28
✅ nitro-quickjs	132	0	28
✅ nuxt-node	132	0	28
✅ nuxt-quickjs	132	0	28
❌ python-node	0	8	152
✅ sveltekit-node	151	0	9
✅ sveltekit-quickjs	151	0	9
✅ tanstack-start-node	132	0	28
✅ tanstack-start-quickjs	132	0	28
✅ vite-node	132	0	28
✅ vite-quickjs	132	0	28

✅ 💻 Local Development

App	Passed	Failed	Skipped
✅ astro-stable-node	134	0	26
✅ astro-stable-quickjs	134	0	26
✅ express-stable-node	134	0	26
✅ express-stable-quickjs	134	0	26
✅ fastify-stable-node	134	0	26
✅ fastify-stable-quickjs	134	0	26
✅ hono-stable-node	134	0	26
✅ hono-stable-quickjs	134	0	26
✅ nest-stable-node	134	0	26
✅ nest-stable-quickjs	134	0	26
✅ nextjs-turbopack-canary-node	141	0	19
✅ nextjs-turbopack-canary-quickjs	141	0	19
✅ nextjs-turbopack-stable-node	160	0	0
✅ nextjs-turbopack-stable-quickjs	160	0	0
✅ nextjs-webpack-canary-node	141	0	19
✅ nextjs-webpack-canary-quickjs	141	0	19
✅ nextjs-webpack-stable-node	160	0	0
✅ nextjs-webpack-stable-quickjs	160	0	0
✅ nitro-stable-node	134	0	26
✅ nitro-stable-quickjs	134	0	26
✅ nuxt-stable-node	134	0	26
✅ nuxt-stable-quickjs	134	0	26
✅ sveltekit-stable-node	153	0	7
✅ sveltekit-stable-quickjs	153	0	7
✅ tanstack-start-node	134	0	26
✅ tanstack-start-quickjs	134	0	26
✅ vite-stable-node	134	0	26
✅ vite-stable-quickjs	134	0	26

✅ 📦 Local Production

App	Passed	Failed	Skipped
✅ astro-stable-node	134	0	26
✅ astro-stable-quickjs	134	0	26
✅ express-stable-node	134	0	26
✅ express-stable-quickjs	134	0	26
✅ fastify-stable-node	134	0	26
✅ fastify-stable-quickjs	134	0	26
✅ hono-stable-node	134	0	26
✅ hono-stable-quickjs	134	0	26
✅ nest-stable-node	134	0	26
✅ nest-stable-quickjs	134	0	26
✅ nextjs-turbopack-canary-node	141	0	19
✅ nextjs-turbopack-canary-quickjs	141	0	19
✅ nextjs-turbopack-stable-node	160	0	0
✅ nextjs-turbopack-stable-quickjs	160	0	0
✅ nextjs-webpack-canary-node	141	0	19
✅ nextjs-webpack-canary-quickjs	141	0	19
✅ nextjs-webpack-stable-node	160	0	0
✅ nextjs-webpack-stable-quickjs	160	0	0
✅ nitro-stable-node	134	0	26
✅ nitro-stable-quickjs	134	0	26
✅ nuxt-stable-node	134	0	26
✅ nuxt-stable-quickjs	134	0	26
✅ sveltekit-stable-node	153	0	7
✅ sveltekit-stable-quickjs	153	0	7
✅ tanstack-start-node	134	0	26
✅ tanstack-start-quickjs	134	0	26
✅ vite-stable-node	134	0	26
✅ vite-stable-quickjs	134	0	26

✅ 🐘 Local Postgres

App	Passed	Failed	Skipped
✅ astro-stable-node	134	0	26
✅ astro-stable-quickjs	134	0	26
✅ express-stable-node	134	0	26
✅ express-stable-quickjs	134	0	26
✅ fastify-stable-node	134	0	26
✅ fastify-stable-quickjs	134	0	26
✅ hono-stable-node	134	0	26
✅ hono-stable-quickjs	134	0	26
✅ nest-stable-node	134	0	26
✅ nest-stable-quickjs	134	0	26
✅ nextjs-turbopack-canary-node	141	0	19
✅ nextjs-turbopack-canary-quickjs	141	0	19
✅ nextjs-turbopack-stable-node	160	0	0
✅ nextjs-turbopack-stable-quickjs	160	0	0
✅ nextjs-webpack-canary-node	141	0	19
✅ nextjs-webpack-canary-quickjs	141	0	19
✅ nextjs-webpack-stable-node	160	0	0
✅ nextjs-webpack-stable-quickjs	160	0	0
✅ nitro-stable-node	134	0	26
✅ nitro-stable-quickjs	134	0	26
✅ nuxt-stable-node	134	0	26
✅ nuxt-stable-quickjs	134	0	26
✅ sveltekit-stable-node	153	0	7
✅ sveltekit-stable-quickjs	153	0	7
✅ tanstack-start-node	134	0	26
✅ tanstack-start-quickjs	134	0	26
✅ vite-stable-node	134	0	26
✅ vite-stable-quickjs	134	0	26

✅ 🪟 Windows

App	Passed	Failed	Skipped
✅ nextjs-turbopack-node	160	0	0
✅ nextjs-turbopack-quickjs	160	0	0

❌ 🌐 Cross-language Conformance

App	Passed	Failed	Skipped
❌ python	0	9	132

✅ vercel-http-transport

App	Passed	Failed	Skipped
✅ example	132	0	28
✅ express	132	0	28
✅ hono	132	0	28
✅ nextjs-turbopack	157	0	3
✅ nitro	132	0	28
✅ vite	132	0	28

✅ vercel-multi-region

App	Passed	Failed	Skipped
✅ nextjs-turbopack	27	0	0

✅ vercel-ws-transport

App	Passed	Failed	Skipped
✅ example	132	0	28
✅ express	132	0	28
✅ nextjs-turbopack	157	0	3
✅ vite	132	0	28

---

📋 View full workflow run

[github-actions]

📊 Workflow Benchmarks

❌ The benchmark run for 6b3ece8 failed. See the run logs for details.

commit 19c0720 · Wed, 26 Aug 2026 17:27:47 GMT · run logs

Backend: vercel · app: nextjs-turbopack

Metric	Scenario	Best (ms)	P75 (ms)	P90 (ms)	P99 (ms)	Samples
TTFS	step	204 (+13%)	1253 🔴 (+18%) 🔻	1409 🔴 (+32%) 🔻	1500 🔴 (+13%)	30
TTFS	stream	176 (-15%)	1293 🔴 (+18%) 🔻	1389 🔴 (+13%)	1435 🔴 (-6.8%)	30
TTFS	hook + stream	1318 (+58%) 🔻	1733 🔴 (+24%) 🔻	1826 🔴 (+23%) 🔻	1898 🔴 (+17%) 🔻	30
Fan-out TTFS	Promise.all(100 steps)	546 (-29%) 💚	1921 (+10%)	2263 (+27%) 🔻	2440 (+25%) 🔻	10
Fan-out TTLS	Promise.all(100 steps)	2014 (+4.7%)	3550 (-2.0%)	3789 (+2.7%)	8013 (+95%) 🔻	10
STSO	1020 steps (inline)	118 (-7.8%)	152 (-15%) 💚	178 (-14%)	762 (+144%) 🔻	1019
WO	1020 steps	167911 (-3.1%)	167911 (-3.1%)	167911 (-3.1%)	167911 (-3.1%)	1
CRTT	first chunk (pooled)	91 (-9.0%)	135 (-16%) 💚	206 (-21%) 💚	286 (-16%) 💚	28

Streams

Scenario	CRTT 1st	p75	p90	p99	CDV max	iters
paced control (100/s, 60B)	118 (-18%)	183 (-39%)	242 (-69%)	479 (-59%)	153 (-29%)	10
size sweep (100/s, 160B-12KB)	119 (-15%)	187 (-14%)	325 (-7%)	594 (+9%)	165 (-20%)	10
replay gateway-gpt-5.4-nano-2000t (1x)	250 (+116%)	143 (-25%)	196 (-89%)	387 (-89%)	192 (-43%)	3
replay eve-gpt-5.6-sol-2000t (1x)	147 (+19%)	140 (-17%)	188 (-19%)	380 (-34%)	353 (-42%)	2
replay eve-gpt-5.6-sol-2000t (2x)	123 (-45%)	209 (-38%)	292 (-51%)	511 (-44%)	302 (-31%)	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.}

_{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-2000teaf22f5946e7c61f3c65c7006d550df180cfabd4e706254a09f22aec0cfb420d · gateway-gpt-5.4-nano-2000t6f24ac518b6b83ff1d0e85a5fe78230db192716d66a7fc6b2fe022752001d041}

_{🔴 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]

Sim World

Simulated world deterministic testing for races. Traces

🟠 world-sim scenario book — 1 fail of 41 total

fence=per-spec

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

Full trace: world-sim.txt

[github-actions]

Framework	Flow route	Step reg.	Framework output
hono	200.9 KiB (±0)	40.3 KiB (±0)	1.76 MiB (±0)
nextjs-turbopack	206.3 KiB (±0)	439 B (±0)	763.1 KiB (±0)

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.

6b3ece8 · run

[github-actions]

No backport to stable for 695a1b7 (AI decision).

This fixes describeContainer in the custom data-inspector tree renderer, which exists only on main: origin/stable:packages/web-shared/src/components/ui/data-inspector.tsx is a 417-line component still built on react-inspector with no describeContainer, ExpandableContainer, or collapseRefs. The defect (hydrated Headers/URLSearchParams drawn as empty objects) and the code being changed are both properties of the main-only renderer, so there is nothing on stable for this patch to fix. It also adds new rendering behavior for arbitrary iterables, which is additive capability rather than a maintenance fix.

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

695a1b76d0e14b1093f93757232efa5c2818d0da