[core] Decode replay payloads synchronously by NathanColosimo · Pull Request #3547 · vercel/workflow

NathanColosimo · 2026-08-14T03:54:31Z

Summary

retain raw AES key material beside module-imported non-extractable CryptoKeys
use Node createDecipheriv for the common symmetric replay-decrypt path
preserve Web Crypto for portable runtimes, older Node discovery, and sealed-envelope work
keep zstd replay decompression synchronous while retaining the async gzip facade for existing callers
avoid Promise creation when decrypt and decompress both complete synchronously

Compatibility note

The portable module discovers node:crypto through process.getBuiltinModule, which exists on Node 22.3 and newer. Node 18/20 therefore retain the Web Crypto fallback in this version. Splitting this layer makes that compatibility decision reviewable independently from streaming orchestration.

Local latency check on Node 22.18

At 64 KiB, synchronous AES-GCM measured about 12.2 µs per decrypt versus 27.3 µs for sequential Web Crypto. A batch of 16 Web Crypto jobs reached about 12.4 µs/op wall throughput by overlapping work; that is throughput rather than single-event latency.

Stack

[world-vercel] Resume partial replay streams after validated events #3546 — replay stream recovery
[core] Decode replay payloads synchronously #3547 — synchronous replay decode
[core] Prepare replay payloads as event frames arrive #3548 — streamed replay preparation
[core] Trace fresh workflow replay phases #3523 — replay phase tracing
[core] Prune schema modules from workflow bundles #3550 — prune sandbox dependency graph
[workflow] Load per-source replay bundles #3551 — per-source lazy VM bundles

Validation

focused crypto and serialization suite
414 tests passed

changeset-bot · 2026-08-14T03:54:36Z

🦋 Changeset detected

Latest commit: d626964

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

This PR includes changesets to release 17 packages

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

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

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

vercel · 2026-08-14T03:54:48Z

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

Project	Deployment	Actions	Updated (UTC)
example-nextjs-workflow-turbopack	Ready	Preview	Aug 14, 2026 9:28pm
example-nextjs-workflow-webpack	Ready	Preview	Aug 14, 2026 9:28pm
example-workflow	Ready	Preview	Aug 14, 2026 9:28pm
workbench-astro-workflow	Ready	Preview	Aug 14, 2026 9:28pm
workbench-express-workflow	Ready	Preview	Aug 14, 2026 9:28pm
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workbench-python-workflow	Error		Aug 14, 2026 9:28pm
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workflow-tarballs	Ready	Preview	Aug 14, 2026 9:28pm
workflow-web	Ready	Preview	Aug 14, 2026 9:28pm

github-actions · 2026-08-14T03:54:50Z

🧪 E2E Test Results

❌ Some tests failed

❌ Failed E2E Tests

▲ Vercel Production (1 failed)

nuxt-quickjs (1 failed):

webhookWorkflow | wrun_41M012SXM60GXSE5ES1TV5W79D | 🔍 observability

E2E Test Summary

Summary

	Passed	Failed	Skipped	Total
❌ ▲ Vercel Production	3465	1	590	4056
✅ 💻 Local Development	3810	0	558	4368
✅ 📦 Local Production	3810	0	558	4368
✅ 🐘 Local Postgres	3810	0	558	4368
✅ 🪟 Windows	312	0	0	312
✅ vercel-multi-region	27	0	0	27
Total	15234	1	2264	17499

Details by Category

❌ ▲ Vercel Production

App	Passed	Failed	Skipped
✅ astro-node	128	0	28
✅ astro-quickjs	128	0	28
✅ example-node	128	0	28
✅ example-quickjs	128	0	28
✅ express-node	128	0	28
✅ express-quickjs	128	0	28
✅ fastify-node	128	0	28
✅ fastify-quickjs	128	0	28
✅ hono-node	128	0	28
✅ hono-quickjs	128	0	28
✅ nest-node	128	0	28
✅ nest-quickjs	128	0	28
✅ nextjs-turbopack-node	153	0	3
✅ nextjs-turbopack-quickjs	153	0	3
✅ nextjs-webpack-node	153	0	3
✅ nextjs-webpack-quickjs	153	0	3
✅ nitro-node	128	0	28
✅ nitro-quickjs	128	0	28
✅ nuxt-node	128	0	28
❌ nuxt-quickjs	127	1	28
✅ sveltekit-node	147	0	9
✅ sveltekit-quickjs	147	0	9
✅ tanstack-start-node	128	0	28
✅ tanstack-start-quickjs	128	0	28
✅ vite-node	128	0	28
✅ vite-quickjs	128	0	28

✅ 💻 Local Development

App	Passed	Skipped
✅ astro-stable-node	130	26
✅ astro-stable-quickjs	130	26
✅ express-stable-node	130	26
✅ express-stable-quickjs	130	26
✅ fastify-stable-node	130	26
✅ fastify-stable-quickjs	130	26
✅ hono-stable-node	130	26
✅ hono-stable-quickjs	130	26
✅ nest-stable-node	130	26
✅ nest-stable-quickjs	130	26
✅ nextjs-turbopack-canary-node	137	19
✅ nextjs-turbopack-canary-quickjs	137	19
✅ nextjs-turbopack-stable-node	156	0
✅ nextjs-turbopack-stable-quickjs	156	0
✅ nextjs-webpack-canary-node	137	19
✅ nextjs-webpack-canary-quickjs	137	19
✅ nextjs-webpack-stable-node	156	0
✅ nextjs-webpack-stable-quickjs	156	0
✅ nitro-stable-node	130	26
✅ nitro-stable-quickjs	130	26
✅ nuxt-stable-node	130	26
✅ nuxt-stable-quickjs	130	26
✅ sveltekit-stable-node	149	7
✅ sveltekit-stable-quickjs	149	7
✅ tanstack-start-node	130	26
✅ tanstack-start-quickjs	130	26
✅ vite-stable-node	130	26
✅ vite-stable-quickjs	130	26

✅ 📦 Local Production

App	Passed	Skipped
✅ astro-stable-node	130	26
✅ astro-stable-quickjs	130	26
✅ express-stable-node	130	26
✅ express-stable-quickjs	130	26
✅ fastify-stable-node	130	26
✅ fastify-stable-quickjs	130	26
✅ hono-stable-node	130	26
✅ hono-stable-quickjs	130	26
✅ nest-stable-node	130	26
✅ nest-stable-quickjs	130	26
✅ nextjs-turbopack-canary-node	137	19
✅ nextjs-turbopack-canary-quickjs	137	19
✅ nextjs-turbopack-stable-node	156	0
✅ nextjs-turbopack-stable-quickjs	156	0
✅ nextjs-webpack-canary-node	137	19
✅ nextjs-webpack-canary-quickjs	137	19
✅ nextjs-webpack-stable-node	156	0
✅ nextjs-webpack-stable-quickjs	156	0
✅ nitro-stable-node	130	26
✅ nitro-stable-quickjs	130	26
✅ nuxt-stable-node	130	26
✅ nuxt-stable-quickjs	130	26
✅ sveltekit-stable-node	149	7
✅ sveltekit-stable-quickjs	149	7
✅ tanstack-start-node	130	26
✅ tanstack-start-quickjs	130	26
✅ vite-stable-node	130	26
✅ vite-stable-quickjs	130	26

✅ 🐘 Local Postgres

App	Passed	Skipped
✅ astro-stable-node	130	26
✅ astro-stable-quickjs	130	26
✅ express-stable-node	130	26
✅ express-stable-quickjs	130	26
✅ fastify-stable-node	130	26
✅ fastify-stable-quickjs	130	26
✅ hono-stable-node	130	26
✅ hono-stable-quickjs	130	26
✅ nest-stable-node	130	26
✅ nest-stable-quickjs	130	26
✅ nextjs-turbopack-canary-node	137	19
✅ nextjs-turbopack-canary-quickjs	137	19
✅ nextjs-turbopack-stable-node	156	0
✅ nextjs-turbopack-stable-quickjs	156	0
✅ nextjs-webpack-canary-node	137	19
✅ nextjs-webpack-canary-quickjs	137	19
✅ nextjs-webpack-stable-node	156	0
✅ nextjs-webpack-stable-quickjs	156	0
✅ nitro-stable-node	130	26
✅ nitro-stable-quickjs	130	26
✅ nuxt-stable-node	130	26
✅ nuxt-stable-quickjs	130	26
✅ sveltekit-stable-node	149	7
✅ sveltekit-stable-quickjs	149	7
✅ tanstack-start-node	130	26
✅ tanstack-start-quickjs	130	26
✅ vite-stable-node	130	26
✅ vite-stable-quickjs	130	26

✅ 🪟 Windows

App	Passed	Failed	Skipped
✅ nextjs-turbopack-node	156	0	0
✅ nextjs-turbopack-quickjs	156	0	0

✅ vercel-multi-region

App	Passed	Failed	Skipped
✅ nextjs-turbopack	27	0	0

📋 View full workflow run

github-actions · 2026-08-14T03:57:14Z

Sim World

Simulated world deterministic testing for races. Traces

🟠 Mint-ordered log — 3 fail of 41 total

log=mint-ordered · 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`	failed	9	1.0m	MISMATCH	1
❌ `in-flight-before-decision-counted`	failed	9	1.0m	MISMATCH	1
❌ `in-flight-after-decision`	failed	9	1.0m	MISMATCH	1
✅ `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-mint.txt

🟢 Append-only log — 0 fail of 41 total

log=append-only · fence=per-spec

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

Full trace: world-sim-append-only.txt

github-actions · 2026-08-14T03:57:22Z

📊 Workflow Benchmarks

commit d626964 · Fri, 14 Aug 2026 21:49:41 GMT · run logs

Backend: vercel · app: nextjs-turbopack

Metric	Scenario	Best (ms)	P75 (ms)	P90 (ms)	P99 (ms)	Samples
TTFS	step	291 (-58%) 💚	1360 🔴 (+22%) 🔻	1378 🔴 (+20%) 🔻	1428 🔴 (-7.1%)	30
TTFS	stream	204 (-80%) 💚	1356 🔴 (+20%) 🔻	1375 🔴 (+20%) 🔻	1535 🔴 (+25%) 🔻	30
TTFS	hook + stream	1579 (+28%) 🔻	1681 🔴 (+23%) 🔻	1714 🔴 (+23%) 🔻	1744 🔴 (-6.8%)	30
Fan-out TTFS	Promise.all(100 steps)	8927 (-3.7%)	9416 (-8.9%)	9936 (-4.2%)	14652 (+34%) 🔻	10
Fan-out TTLS	Promise.all(100 steps)	17930 (-1.3%)	22236 (+8.3%)	24688 (+14%)	24822 (±0%)	10
STSO	1020 steps (inline)	120 (-22%) 💚	394 (-20%) 💚	430 (-21%) 💚	556 (-26%) 💚	1018
STSO	1020 steps (queue-hop)	2176 (-29%) 💚	2176 (-29%) 💚	2176 (-29%) 💚	2176 (-29%) 💚	1
WO	1020 steps	354090 (-22%) 💚	354090 (-22%) 💚	354090 (-22%) 💚	354090 (-22%) 💚	1
SL	stream latency	82	104 🔴	113 🔴	155 🔴	30
SO	stream overhead (text)	104	161	198	429	30
SO	stream overhead (structured)	100	151	250	3628 🔴	30

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

1020 steps (inline)

Cumulative STSO time: main 448487ms → this run 351691ms (Δ -96796ms, -22%)

  100-150 ms  ┃                         main   0  this  11   +11
  150-200 ms  ██┃                       main  25  this  38   +13
  200-250 ms  █░░░░░┃                   main  15  this  88   +73
  250-300 ms  ████░░░░░░░░░░┃           main  46  this 189  +143
  300-350 ms  ████████████░░░░░░░┃      main 152  this 250   +98
  350-400 ms  ███████░░░░░░░░░┃         main  82  this 209  +127
  400-450 ms  ██████████████┃           main 171  this 182   +11
  450-500 ms  ██┃█████████████████████  main 300  this  38  -262
  500-550 ms  ┃██████████               main 137  this   2  -135
  550-600 ms  ┃██                       main  40  this   1   -39
  600-650 ms  ┃█                        main  23  this   2   -21
  650-700 ms  ┃                         main   4  this   3    -1
  700-750 ms  ┃                         main  12  this   0   -12
  750-800 ms  ┃                         main   6  this   0    -6
  800-850 ms  ┃                         main   1  this   0    -1
  900-950 ms  ┃                         main   1  this   1    +0
 950-1000 ms  ┃                         main   1  this   1    +0
1000-1050 ms  ┃                         main   0  this   1    +1
1050-1100 ms  ┃                         main   1  this   0    -1
3600-3650 ms  ┃                         main   1  this   0    -1
4500-4550 ms  ┃                         main   0  this   1    +1
5500-5550 ms  ┃                         main   0  this   1    +1

1020 steps (queue-hop)

Cumulative STSO time: main 3070ms → this run 2176ms (Δ -894ms, -29%)

2000-2500 ms  ░░░░░░░░░░░░░░░░░░░░░░░┃  main 0  this 1  +1
3000-3500 ms  ┃███████████████████████  main 1  this 0  -1

📜 Previous results (2)

`5b5b8cf`

Fri, 14 Aug 2026 20:27:31 GMT · run logs

vercel / nextjs-turbopack

Metric	Scenario	Best (ms)	P75 (ms)	P90 (ms)	P99 (ms)	Samples
TTFS	step	258 (+17%) 🔻	1351 🔴 (+21%) 🔻	1480 🔴 (+25%) 🔻	1663 🔴 (+38%) 🔻	30
TTFS	stream	279 (+17%) 🔻	1349 🔴 (+21%) 🔻	1356 🔴 (+19%) 🔻	1529 🔴 (+23%) 🔻	30
TTFS	hook + stream	1546 (+212%) 🔻	1629 🔴 (+23%) 🔻	1661 🔴 (+20%) 🔻	1917 🔴 (+37%) 🔻	30
Fan-out TTFS	Promise.all(100 steps)	9087 (±0%)	13281 (+32%) 🔻	16042 (+57%) 🔻	16563 (+60%) 🔻	10
Fan-out TTLS	Promise.all(100 steps)	18220 (+3.2%)	28589 (+53%) 🔻	31944 (+70%) 🔻	35491 (+78%) 🔻	10
STSO	1020 steps (inline)	117 (-17%) 💚	393 (+86%) 🔻	429 (+80%) 🔻	507 (+40%) 🔻	1018
STSO	1020 steps (queue-hop)	2149	2149	2149	2149	1
WO	1020 steps	343088 (+69%) 🔻	343088 (+69%) 🔻	343088 (+69%) 🔻	343088 (+69%) 🔻	1
SL	stream latency	82 (-15%)	112 🔴 (-30%) 💚	129 🔴 (-32%) 💚	181 🔴 (-51%) 💚	30
SO	stream overhead (text)	102 (-32%) 💚	212 (-15%)	366 (-43%) 💚	588 (-67%) 💚	30
SO	stream overhead (structured)	101 (-34%) 💚	170 (-45%) 💚	287 (-23%) 💚	889 (+30%) 🔻	30

`1e92acf`

Fri, 14 Aug 2026 04:18:27 GMT · run logs

vercel / nextjs-turbopack

Metric	Scenario	Best (ms)	P75 (ms)	P90 (ms)	P99 (ms)	Samples
TTFS	step	1169 (+207%) 🔻	1296 🔴 (+16%) 🔻	1331 🔴 (+17%) 🔻	1774 🔴 (+16%) 🔻	30
TTFS	stream	1153 (+15%)	1222 🔴 (+16%) 🔻	1256 🔴 (+17%) 🔻	1400 🔴 (+26%) 🔻	30
TTFS	hook + stream	1430 (+12%)	1532 🔴 (+11%)	1594 🔴 (+12%)	1926 🔴 (+19%) 🔻	30
Fan-out TTFS	Promise.all(100 steps)	8855 (-0.7%)	9094 (-8.6%)	9200 (-8.7%)	9712 (-28%) 💚	10
Fan-out TTLS	Promise.all(100 steps)	17330 (-1.9%)	17736 (-6.0%)	17812 (-6.3%)	19802 (-16%) 💚	10
STSO	1020 steps (inline)	119 (-3.3%)	163 (-15%)	180 (-21%) 💚	294 (-49%) 💚	1019
WO	1020 steps	162311 (-17%) 💚	162311 (-17%) 💚	162311 (-17%) 💚	162311 (-17%) 💚	1
SL	stream latency	85 (+7.6%)	110 🔴 (±0%)	134 🔴 (+3.9%)	305 🔴 (-11%)	30
SO	stream overhead (text)	99 (-11%)	191 (+6.1%)	212 (+2.9%)	608 (+0.7%)	30
SO	stream overhead (structured)	95 (-1.0%)	167 (+7.1%)	254 (+52%) 🔻	638 (+251%) 🔻	30

ℹ️ Metric definitions & methodology

_{The collapsed STSO distribution section above buckets every step gap of the sequential-steps run (not a sampled window), split by whether the step ending the gap ran inline — in the same warm process as the step before it, so the gap is pure framework overhead — or after a queue-hop — the first step of a fresh process, which pays queue dispatch, client reinit and event-log replay. Bars overlay the two runs: █ is main, ┃ marks where this run lands, ░ bridges the gap when this run has more samples in a bucket.}

_{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, deployment clocks) · 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) · SL: stream latency (in-deployment write → read propagation, readAt - writtenAt) · SO: stream overhead (end-to-end write+consume time beyond the modelled generation window)}

_{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 · stream latency: parallel reader/writer steps on a dedicated stream; SL is the in-deployment write->read propagation (readAt - writtenAt) · stream overhead (text): writer streams 300 variable-length text token deltas paced at 100/s for 3s (a haiku-size LLM's token throughput) while a parallel reader drains the whole stream; SO is the end-to-end write+consume time beyond the 3s generation window (overhead/backpressure) · stream overhead (structured): same workload as stream overhead (text), but each delta is an AI-SDK-style structured object ({ type: 'text-delta', id, text }) instead of a raw string, so the SO gap vs the text scenario is the added serialization cost}

_{🔴 marks a percentile over its target (within target is left unmarked). Targets (p75/p90/p99, ms) — TTFS 200/300/600 · SL 50/60/125 · SO 250/500/1000}

_{All metrics are measured from deployment-side timestamps only. Runs are triggered by an in-deployment route that stamps the anchor (clientStart) right before start(), so the CI runner’s request and its path through api.vercel.com sit outside every measured window. TTFS = in-deployment start() → first step body (turbo uses the in-process fast path, non-turbo the dispatch path), and includes the VQS dispatch hop plus any /flow cold start. Fan-out TTFS/TTLS are the first and last step completions of a single Promise.all over trivial steps, from the same anchor, so the gap between the two rows is the spread the runtime adds across the fan-out. STSO/WO are measured between step bodies on the deployment. SL is measured inside the workflow (parallel reader/writer steps), so it no longer includes the api.vercel.com read path.}

_{Cold starts are kept in the numbers on purpose — they are part of real bursty-workload latency. The workbench deployment cold-starts the /flow invocation for a large fraction of runs, inflating P75+; the Best column shows the fastest (warm-start) sample for comparison.}

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NathanColosimo changed the title ~~Decode replay payloads synchronously~~ [core] Decode replay payloads synchronously Aug 14, 2026

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[world-vercel] Resume partial replay streams after validated events #3546

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[core] Prepare replay payloads as event frames arrive #3548

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[core] Trace fresh workflow replay phases #3523

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NathanColosimo added 3 commits August 14, 2026 12:23

Decode replay payloads synchronously

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[core] Simplify synchronous replay decoding

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[core] Simplify synchronous replay payload APIs

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[core] Deepen payload codec boundaries

a1c3799

[core] Consolidate payload codecs

af7fc94

[core] Avoid native codec result copies

d6b90b2

[core] Reuse loaded encryption helpers

474b1f2

[core] Fix legacy replay payload tagging

df0175c

[core] Consolidate replay decryption

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[core] Decode replay payloads synchronously - #3547

[core] Decode replay payloads synchronously#3547
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Local latency check on Node 22.18

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