[core] Prepare replay payloads as event frames arrive by NathanColosimo · Pull Request #3548 · vercel/workflow

NathanColosimo · 2026-08-14T03:54:35Z

Summary

resolve the run key as soon as a deployment-bearing replay event arrives
buffer decoded event references until that one key resolution completes, then decrypt and decompress them in one pass without per-payload key promises
prepare subsequent payloads synchronously from the validated-frame callback, with natural response backpressure
keep one invocation-scoped cache of prepared payloads across fresh VMs and use a full event-array scan as a simple correctness safety net
reuse immutable primitive values for successful results, errors, hooks, and aborts while rehydrating object graphs per VM
let ordered consumers await only the genuinely asynchronous payload formats they touch

Performance signal

The latest benchmark and previous behavior run were recorded on the original cumulative branch before this review split. Across those runs, inline STSO improved 4–20% at p75, 10–24% at p90, and 39–51% at p99; total 1020-step workflow overhead improved 7–23%.

Cold TTFS regressed in both runs, including the turbo control that does not preload or prepare replay events, so that signal is dominated by deployment cold-start variability. The benchmarked branch also contained the small tracing layer in #3523.

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

core typecheck passed
full core suite: 2,112 tests passed, with 3 expected failures
focused replay cache, key helper, delivery-ordering, hook, and abort suites: 198 tests passed

changeset-bot · 2026-08-14T03:54:39Z

🦋 Changeset detected

Latest commit: a641ca3

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

This PR includes changesets to release 16 packages

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

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 · 2026-08-14T03:54:53Z

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

Project	Deployment	Actions	Updated (UTC)
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github-actions · 2026-08-14T03:54:53Z

🧪 E2E Test Results

✅ All tests passed

🛠 Infra Events (absorbed by the harness)

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

run-pickup-stall · addTenWorkflow (tanstack-start) · at 06:18:15Z · abandoned wrun_01M0213WSTYP3QNGN5HB5W9TPX
run-pickup-stall · abortFetchInFlightWorkflow: aborting cancels an in-flight fetch (nextjs-webpack) · at 06:31:30Z · abandoned wrun_01M021W5577RNMMRPKSAPQNVRH

E2E Test Summary

Summary

	Passed	Skipped	Total
✅ ▲ Vercel Production	3474	738	4212
✅ 💻 Local Development	3810	558	4368
✅ 📦 Local Production	3810	558	4368
✅ 🐘 Local Postgres	3810	558	4368
✅ 🪟 Windows	312	0	312
✅ 🌐 Cross-language Conformance	9	128	137
✅ vercel-multi-region	27	0	27
Total	15252	2540	17792

Details by Category

✅ ▲ Vercel Production

App	Passed	Skipped
✅ astro-node	128	28
✅ astro-quickjs	128	28
✅ example-node	128	28
✅ example-quickjs	128	28
✅ express-node	128	28
✅ express-quickjs	128	28
✅ fastify-node	128	28
✅ fastify-quickjs	128	28
✅ hono-node	128	28
✅ hono-quickjs	128	28
✅ nest-node	128	28
✅ nest-quickjs	128	28
✅ nextjs-turbopack-node	153	3
✅ nextjs-turbopack-quickjs	153	3
✅ nextjs-webpack-node	153	3
✅ nextjs-webpack-quickjs	153	3
✅ nitro-node	128	28
✅ nitro-quickjs	128	28
✅ nuxt-node	128	28
✅ nuxt-quickjs	128	28
✅ python-node	8	148
✅ sveltekit-node	147	9
✅ sveltekit-quickjs	147	9
✅ tanstack-start-node	128	28
✅ tanstack-start-quickjs	128	28
✅ vite-node	128	28
✅ vite-quickjs	128	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

✅ 🌐 Cross-language Conformance

App	Passed	Failed	Skipped
✅ python	9	0	128

✅ 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 · 2026-08-14T03:57:23Z

📊 Workflow Benchmarks

commit a641ca3 · Sat, 15 Aug 2026 06:38:01 GMT · run logs

Backend: vercel · app: nextjs-turbopack

Metric	Scenario	Best (ms)	P75 (ms)	P90 (ms)	P99 (ms)	Samples
TTFS	step	216 (-69%) 💚	1391 🔴 (+38%) 🔻	1532 🔴 (+51%) 🔻	1758 🔴 (+17%) 🔻	30
TTFS	stream	227 (-76%) 💚	1373 🔴 (+39%) 🔻	1400 🔴 (+39%) 🔻	1504 🔴 (+43%) 🔻	30
TTFS	hook + stream	372 (-69%) 💚	1648 🔴 (+28%) 🔻	1682 🔴 (+26%) 🔻	1812 🔴 (+13%)	30
Fan-out TTFS	Promise.all(100 steps)	1399	3148	3447	3650	10
Fan-out TTLS	Promise.all(100 steps)	10538	12493	12941	14062	10
STSO	1020 steps (inline)	137	464	504	645	1018
STSO	1020 steps (queue-hop)	2097	2097	2097	2097	1
WO	1020 steps	422035 (+9.3%)	422035 (+9.3%)	422035 (+9.3%)	422035 (+9.3%)	1
CRTT	first chunk (pooled)	91	145	243	372	28

Streams

Scenario	wr c/s	rd c/s	wr KiB/s	rd KiB/s	CRTT 1st	p75	p90	p99	CDV max	iters
paced control (100/s, 60B)	100	98.3	5	4.9	119	186	237	1089	212	10
size sweep (100/s, 160B-12KB)	100	98.1	334	327	122	232	365	1017	213	10
replay gateway-gpt-5.4-nano-2000t (1x)	89.2	89.1	16.2	16.2	100	149	210	533	824	3
replay eve-gpt-5.6-sol-2000t (1x)	54.7	54.8	355	356	121	142	194	410	520	2
replay eve-gpt-5.6-sol-2000t (2x)	109	109	710	708	164	192	286	760	544	3

📈 STSO distribution (inline / queue-hop histograms)

1020 steps (inline)

Cumulative STSO time: 419510ms over 1018 samples

_{No main baseline with raw samples yet — showing this run's distribution on its own; the diff appears once a run on main has recorded them.}

  100-150 ms  █                         steps   4
  150-200 ms  █                         steps  11
  200-250 ms  ███                       steps  30
  250-300 ms  ████                      steps  46
  300-350 ms  █████████████             steps 148
  350-400 ms  ██████████████            steps 157
  400-450 ms  ████████████████████████  steps 279
  450-500 ms  ████████████████████      steps 229
  500-550 ms  ███████                   steps  80
  550-600 ms  ██                        steps  19
  600-650 ms  █                         steps   5
  650-700 ms  █                         steps   5
  700-750 ms  █                         steps   1
  750-800 ms  █                         steps   2
  850-900 ms  █                         steps   1
1150-1200 ms  █                         steps   1

1020 steps (queue-hop)

Cumulative STSO time: 2097ms over 1 samples

_{No main baseline with raw samples yet — showing this run's distribution on its own; the diff appears once a run on main has recorded them.}

2000-2200 ms  ████████████████████████  steps 1

📈 CRTT drill-down (RTT distributions & profiles)

_{No main baseline yet — percentages appear once a run on main has recorded CRTT.}

variant  RTT 1ms→5s+      avg  p50  p90   p99     n
control  ······▂█▂▁▁··  161.7  137  237  1089  3000
sweep    ······▂█▃▁▁··  176.2  139  365  1017  3000
gw 1x    ·····▁▄█▂▁···  136.2  117  210   533  5295
eve 1x   ·····▁▅█▂▁···  125.6  113  194   410  5186
eve 2x   ·····▁▂█▃▁···  168.4  144  286   760  7779

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

control  ▂▁▅▃█▆▃▃█▆  136–190ms
sweep    ▅▃▁▅▃█▅▄▄▅  140–217ms
gw 1x    ▁█▄▄▁▁▁▁▂▄  115–198ms
eve 1x   █▃▂▃▆▃▅▄▃▁  105–156ms
eve 2x   ▁▂▄▂▁▂▃█▃▂  125–293ms

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

sweep  ▂▅▆█▅▂▁  173–181ms

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

control  ▂▁▆▂▆▄▃▄█▆  38–80ms
sweep    ▄▃▃█▁▅▁▂▅█  49–90ms
gw 1x    ▁█▃▂▁▂▃▂▂▃  36–66ms
eve 1x   █▃▁▃▆▃▇▄▃▁  25–38ms
eve 2x   ▂▃█▂▃▁▃▅▃▆  28–42ms

ℹ️ Metric definitions & methodology

_{Streams: writer/reader sustained rates (steady window, 10% trimmed each side), first-chunk RTT (the stream-open path, before any buffering/backpressure), CRTT percentiles, and worst delivery stall (CDV max). Cells are medians across iterations; per-run values in the artifacts. No 🔴/🟢 marks until targets attach.}

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

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

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

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

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

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

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

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

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

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NathanColosimo changed the title ~~Prepare replay payloads during event streaming~~ [core] Prepare replay payloads as event frames arrive Aug 14, 2026

This was referenced Aug 14, 2026

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

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[core] Trace fresh workflow replay phases #3523

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[core] Decode replay payloads synchronously #3547

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NathanColosimo added 9 commits August 14, 2026 23:09

Prepare replay payloads during event streaming

b127e30

[core] Centralize replay event hydration

6f3f179

[core] Simplify replay payload caching

259f241

[core] Name replay preparation states explicitly

4147aba

[core] Key replay payloads by event

c4e25f1

[core] Collapse replay cache state machinery

40ee01b

[core] Pass replay event loading options directly

847c3c3

Simplify streamed replay payload preparation

52920db

Sort replay runtime imports

a641ca3

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

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