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[world-vercel] Fail the run on a lost event payload instead of retrying forever - #3742

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alangenfeld merged 5 commits into
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peter/v4-terminal-payload-missing
Aug 27, 2026
Merged

alangenfeld merged 5 commits into
mainfrom
peter/v4-terminal-payload-missing

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@VaguelySerious

@VaguelySerious VaguelySerious commented Aug 22, 2026 •

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Summary & Motivation

The backend now closes a frame stream with a terminal {_error: 1, code} frame instead of a truncated body, which previously read as a dropped socket. payload-missing becomes a CorruptedEventLogError so the run fails with CORRUPTED_EVENT_LOG; any unrecognized code becomes a terminal WorkflowWorldError, so a future code can't turn into a redelivery loop.

Test Plan

Tests added for both codes in the v4 events reader and for the retry/terminal classification in core; typecheck clean.

Docs Preview

Page Preview
Errors and retries https://workflow-docs-git-peter-v4-terminal-payload-missing.vercel.sh/docs/foundations/errors-and-retries#error-codes
Corrupted event log https://workflow-docs-git-peter-v4-terminal-payload-missing.vercel.sh/docs/errors/corrupted-event-log

…trying

A frame stream that dies mid-body reaches us as a truncated response, which
is exactly what a dropped socket looks like. So an event whose stored payload
is permanently gone was indistinguishable from a transient blip, and the
runtime kept redelivering a replay that could never succeed: one run re-read
a single missing payload 12,932 times in 26 minutes, and the backend query
behind each attempt throttled its table.

The World now sends a terminal `{_error: 1, code}` frame for failures that a
retry cannot fix. Handle it:

- `payload-missing` raises `CorruptedEventLogError`, so the run fails with
  `CORRUPTED_EVENT_LOG` rather than looping. The log does reference a payload
  nothing can produce.
- An unknown code raises a `WorkflowWorldError` with no retryable code and no
  status, which is also terminal. A future code stays safe without needing a
  client release first.

Co-Authored-By: Claude Opus 5 (1M context) <noreply@anthropic.com>
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changeset-bot Bot commented Aug 22, 2026 •

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🦋 Changeset detected

Latest commit: 9bdc6be

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

This PR includes changesets to release 17 packages
Name Type
@workflow/world-vercel Patch
@workflow/cli Patch
@workflow/core Patch
@workflow/web Patch
workflow Patch
@workflow/world-testing Patch
@workflow/builders Patch
@workflow/next Patch
@workflow/nitro Patch
@workflow/vitest Patch
@workflow/web-shared Patch
@workflow/astro Patch
@workflow/nest Patch
@workflow/rollup Patch
@workflow/sveltekit Patch
@workflow/vite Patch
@workflow/nuxt Patch

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

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

Project Deployment Actions Updated (UTC)
example-nextjs-workflow-turbopack Ready Ready Preview, v0 Aug 27, 2026 4:34pm
example-nextjs-workflow-webpack Ready Ready Preview, v0 Aug 27, 2026 4:34pm
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🧪 E2E Test Results

❌ Some tests failed

❌ Failed E2E Tests

▲ Vercel Production (8 failed)

python-node (8 failed):

  • promiseAllWorkflow | wrun_41M1213GJS0GKEJZ508MYC3B58 | 🔍 observability
  • sleepingWorkflow | wrun_41M12143770GP2H8E97SNB1KCH | 🔍 observability
  • parallelSleepWorkflow | wrun_41M12143MB0GK7TGB3TY5D1JS3 | 🔍 observability
  • nullByteWorkflow | wrun_41M12149NG0GYB0P5SMXPR7F5W | 🔍 observability
  • cancelRun - cancelling a running workflow | wrun_41M1218AY40GJEVKXGGDZZXWHY | 🔍 observability
  • cancelRun via CLI - cancelling a running workflow | wrun_41M1218BMN0GH9RTJRD6QH8DEK | 🔍 observability
  • sleepInLoopWorkflow - sleep inside loop with steps actually delays each iteration | wrun_41M1218GYT0GJG8A4EH3RCGWQX | 🔍 observability
  • resilient start: addTenWorkflow completes when run_created returns 500 | wrun_41M121923R0GW62HC7GV5V8099 | 🔍 observability

🌐 Cross-language Conformance (9 failed)

python (9 failed):

  • deploymentId: 'latest' is a no-op in non-Vercel worlds | wrun_01M121D9TND7284XZVAK91FT03
  • promiseAllWorkflow | wrun_41M1213GJS0GKEJZ508MYC3B58
  • sleepingWorkflow | wrun_41M12143770GP2H8E97SNB1KCH
  • parallelSleepWorkflow | wrun_41M12143MB0GK7TGB3TY5D1JS3
  • nullByteWorkflow | wrun_41M12149NG0GYB0P5SMXPR7F5W
  • cancelRun - cancelling a running workflow | wrun_41M1218AY40GJEVKXGGDZZXWHY
  • cancelRun via CLI - cancelling a running workflow | wrun_41M1218BMN0GH9RTJRD6QH8DEK
  • sleepInLoopWorkflow - sleep inside loop with steps actually delays each iteration | wrun_41M1218GYT0GJG8A4EH3RCGWQX
  • resilient start: addTenWorkflow completes when run_created returns 500 | wrun_41M121923R0GW62HC7GV5V8099

⚠️ 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 (hono)
  • cancelRun via CLI - cancelling a running workflow (nitro)
  • concurrent hook token conflict - two workflows cannot use the same hook token simultaneously (astro)
  • deploymentId: 'latest' is a no-op in non-Vercel worlds (fastify)
  • hookWithSleepFinalStepWorkflow - step only on final payload (nextjs-webpack)
  • hookWorkflow (sveltekit)
  • hookWorkflow (tanstack-start)
  • hookWorkflow (vite)

🛠 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.

33 infra events
  • cold-start-warmup · suite warmup (python) · at 16:34:23Z · abandoned wrun_41M1211GA50GPGVFT9JA2YMHA7 · (+7 more)
  • run-pickup-stall · sleepingWorkflow (python) · at 16:34:39Z · abandoned wrun_41M121550M0GNDHJDY27BW71KT
  • run-pickup-stall · parallelSleepWorkflow (python) · at 16:34:39Z · abandoned wrun_41M121550M0GNDHJDY27BW71KV
  • run-pickup-stall · cancelRun - cancelling a running workflow (python) · at 16:34:39Z · abandoned wrun_41M12155A60GPAMCTC4YE202Y9
  • run-pickup-stall · nullByteWorkflow (python) · at 16:34:39Z · abandoned wrun_41M121550R0GN4EKX2WNAX4YXZ
  • run-pickup-stall · promiseAllWorkflow (python) · at 16:34:40Z · abandoned wrun_41M121550E0GV6HG2GXFK06K37
  • run-pickup-stall · cancelRun - cancelling a running workflow (python) · at 16:35:12Z · abandoned wrun_41M12164S20GVYBNPPWCTT4KRE
  • run-pickup-stall · nullByteWorkflow (python) · at 16:35:40Z · abandoned wrun_41M12170DC0GRDA5F94NK7TGBN
  • run-pickup-stall · sleepingWorkflow (python) · at 16:35:40Z · abandoned wrun_41M12170E40GP6HEPXA8WH6DX0
  • run-pickup-stall · parallelSleepWorkflow (python) · at 16:35:40Z · abandoned wrun_41M12170EC0GKV255EZM11HP19
  • run-pickup-stall · promiseAllWorkflow (python) · at 16:35:40Z · abandoned wrun_41M12170F10GZKFZN2ZR7A5EQV
  • cold-start-warmup · suite warmup (tanstack-start) · at 16:36:24Z · abandoned wrun_01M12180SGAV9AGMYMQX7C5F05
  • run-pickup-stall · cancelRun via CLI - cancelling a running workflow (python) · at 16:36:30Z · abandoned wrun_41M12173XJ0GX076RMR9QNDHMY
  • cold-start-warmup · suite warmup (python) · at 16:37:35Z · abandoned wrun_01M1217BCRYX9VD93DFQCWR9NA · (+7 more)
  • run-pickup-stall · promiseAllWorkflow (python) · at 16:37:50Z · abandoned wrun_01M121B0HG9PM2RF8XXXJTNFZ5
  • run-pickup-stall · parallelSleepWorkflow (python) · at 16:37:50Z · abandoned wrun_01M121B0HQCXM5BTW9C5SSE2GS
  • run-pickup-stall · deploymentId: 'latest' is a no-op in non-Vercel worlds (python) · at 16:37:50Z · abandoned wrun_01M121B0HG9PM2RF8XXXJTNFZ4
  • run-pickup-stall · sleepingWorkflow (python) · at 16:37:50Z · abandoned wrun_01M121B0HN6NW9FMYWRDEJM3MA
  • run-pickup-stall · nullByteWorkflow (python) · at 16:37:50Z · abandoned wrun_01M121B0HTQQ8ZEHEYY85Q1ZJF
  • run-pickup-stall · cancelRun via CLI - cancelling a running workflow (python) · at 16:38:11Z · abandoned wrun_41M1219VT30GWV53B51TW334GW
  • run-pickup-stall · sleepInLoopWorkflow - sleep inside loop with steps actually delays each iteration (python) · at 16:38:11Z · abandoned wrun_41M1219R9Y0GW7ZQJG2A25VXFD
  • run-pickup-stall · promiseAllWorkflow (python) · at 16:38:50Z · abandoned wrun_01M121CV5BTNYVW1SZDE3P3FJV
  • run-pickup-stall · sleepingWorkflow (python) · at 16:38:50Z · abandoned wrun_01M121CV5F8WY6822ANP1QM4A4
  • run-pickup-stall · deploymentId: 'latest' is a no-op in non-Vercel worlds (python) · at 16:38:50Z · abandoned wrun_01M121CV59Y40CW71RTTB2SX1F
  • run-pickup-stall · parallelSleepWorkflow (python) · at 16:38:50Z · abandoned wrun_01M121CV5KAGK1871VP6HT1673
  • run-pickup-stall · nullByteWorkflow (python) · at 16:38:50Z · abandoned wrun_01M121CV5QQWXMDA3XS0XZR0SX
  • run-pickup-stall · cancelRun - cancelling a running workflow (python) · at 16:39:50Z · abandoned wrun_01M121ENRVFWKZDQ6BC14ANRYM
  • run-pickup-stall · cancelRun via CLI - cancelling a running workflow (python) · at 16:39:50Z · abandoned wrun_01M121ENS367D49TBR1SKBS650
  • run-pickup-stall · sleepInLoopWorkflow - sleep inside loop with steps actually delays each iteration (python) · at 16:39:50Z · abandoned wrun_01M121ENS6XXHMNS0JY4DP59HN
  • run-pickup-stall · cancelRun - cancelling a running workflow (python) · at 16:40:20Z · abandoned wrun_01M121FK4C5D73E67TR9ZAKFW4
  • run-pickup-stall · cancelRun via CLI - cancelling a running workflow (python) · at 16:40:20Z · abandoned wrun_01M121FK4HM6QQWJ86GT0ZKCPH
  • run-pickup-stall · sleepInLoopWorkflow - sleep inside loop with steps actually delays each iteration (python) · at 16:40:50Z · abandoned wrun_01M121GGCAA4YW6KC5XBV80Q4H
  • run-pickup-stall · hookWithSleepWorkflow - hook payloads delivered correctly with concurrent sleep (nextjs-webpack) · at 16:41:47Z · abandoned wrun_01M121J7RG4W57GGYQ2JYXETJA

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

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📊 Workflow Benchmarks

commit 9bdc6be · Thu, 27 Aug 2026 16:48:26 GMT · run logs

Backend: vercel · app: nextjs-turbopack

Metric Scenario Best (ms) P75 (ms) P90 (ms) P99 (ms) Samples
TTFS step 245 (+14%) 1347 🔴 (+22%) 🔻 1376 🔴 (+20%) 🔻 1419 🔴 (+21%) 🔻 30
TTFS stream 1212 (+509%) 🔻 1331 🔴 (+21%) 🔻 1350 🔴 (+16%) 🔻 1393 🔴 (-3.9%) 30
TTFS hook + stream 1505 (+41%) 🔻 1677 🔴 (+22%) 🔻 1823 🔴 (+29%) 🔻 5993 🔴 (+245%) 🔻 30
Fan-out TTFS Promise.all(100 steps) 593 (-8.1%) 981 (-45%) 💚 1742 (-4.4%) 1950 (+5.8%) 10
Fan-out TTLS Promise.all(100 steps) 1796 (-13%) 4594 (+15%) 5159 (+25%) 🔻 8031 (+83%) 🔻 10
STSO 1020 steps (inline) 80 (-19%) 💚 114 (-31%) 💚 125 (-38%) 💚 209 (-39%) 💚 1019
WO 1020 steps 115486 (-28%) 💚 115486 (-28%) 💚 115486 (-28%) 💚 115486 (-28%) 💚 1
CRTT first chunk (pooled) 75 (-26%) 💚 154 (-7.2%) 351 (+74%) 🔻 387 (-88%) 💚 28

Streams

Scenario CRTT 1st p75 p90 p99 CDV max iters
paced control (100/s, 60B) 98 (-34%) 106 (-49%) 141 (-53%) 446 (-14%) 85.5 (-52%) 10
size sweep (100/s, 160B-12KB) 97 (-32%) 115 (-55%) 199 (-50%) 593 (-55%) 102 (-62%) 10
replay gateway-gpt-5.4-nano-2000t (1x) 150 (-5%) 101 (-61%) 130 (-91%) 461 (-85%) 176 (-50%) 3
replay eve-gpt-5.6-sol-2000t (1x) 104 (-24%) 126 (-34%) 352 (+35%) 3988 (+806%) 2104 (+357%) 2
replay eve-gpt-5.6-sol-2000t (2x) 351 (+111%) 164 (-99%) 219 (-99%) 397 (-98%) 253 (-62%) 3
📈 STSO distribution vs main (inline / queue-hop histograms)

1020 steps (inline)

Cumulative STSO time: main 160359ms → this run 115275ms (Δ -45084ms, -28%)

 50-100 ms  ┃                         main   1  this  44   +43
100-150 ms  ███████████████░░░░░░░░┃  main 591  this 934  +343
150-200 ms  ┃███████                  main 314  this  25  -289
200-250 ms  ┃█                        main  78  this  13   -65
250-300 ms  ┃                         main  19  this   2   -17
300-350 ms  ┃                         main   7  this   1    -6
350-400 ms  ┃                         main   3  this   0    -3
400-450 ms  ┃                         main   2  this   0    -2
450-500 ms  ┃                         main   2  this   0    -2
500-550 ms  ┃                         main   1  this   0    -1
550-600 ms  ┃                         main   1  this   0    -1
📈 CRTT drill-down vs main (RTT distributions & profiles)
variant  RTT 1ms→5s+             avg         p50         p90           p99     n
control  ·····▁█▄▁····   98.1 (-40%)   87 (-40%)  141 (-53%)    446 (-14%)  3000
sweep    ·····▁█▅▁▁···  103.4 (-50%)   92 (-43%)  199 (-50%)    593 (-55%)  3000
gw 1x    ·····▁█▃▁▁···   92.4 (-63%)   84 (-40%)  130 (-91%)    461 (-85%)  5295
eve 1x   ·····▁█▄▁▁▁▁·  213.6 (+36%)   84 (-36%)  352 (+35%)  3988 (+806%)  5186
eve 2x   ·····▁▇█▂▁···  126.3 (-96%)  108 (-41%)  219 (-99%)    397 (-98%)  7779

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

control  ▇▃█▆▄▂▂▂▂▁  83–124ms
sweep    ▇▅▂▇█▃▁▂▄▂  88–123ms
gw 1x    █▂▂▁▃▂▁▃▂▂  82–129ms
eve 1x   █▁▁▁▁▁▁▁▁▁  78–1251ms
eve 2x   ▄▂▂▂▂▃▄█▁▄  113–156ms

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

sweep  █▇▅▂▁▁▃  101–107ms

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

control  ▄▃▆█▃▃▃▃▄▁  22–34ms
sweep    ▄▂▄█▅▆▃▃▇▁  32–43ms
gw 1x    █▄▂▁▅▄▄▄▃▄  20–31ms
eve 1x   █▂▂▁▂▁▁▂▂▂  17–60ms
eve 2x   ▆▅▃▅█▄▄▆▁▆  17–25ms
ℹ️ Metric definitions & methodology

Streams: first-chunk RTT (the stream-open path, before any buffering/backpressure), CRTT percentiles, and worst delivery stall (CDV max). Cells are medians across iterations; per-run values in the artifacts. No 🔴/🟢 marks until targets attach.

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

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

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

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

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

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

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

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

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

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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

Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>
Comment thread packages/world-vercel/src/events-v4.ts Outdated
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Backport to stable failed for 1c44cc8 due to a workflow error (backport job run).

This is usually an infrastructure problem (e.g. the configured AI model could not be found, an AI Gateway error, or an opencode crash) rather than a merge conflict. Check the job logs linked above for details.

Once the underlying issue is fixed, re-run the Backport to stable workflow manually via workflow_dispatch and paste this commit SHA into the ref input:

1c44cc8c3f76f81553d04d21f56da1d2adbc1746

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