[backport] [world-vercel] Use stream control frame for transparent reconnection - #1766

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[backport] [world-vercel] Use stream control frame for transparent reconnection#1766
VaguelySerious merged 5 commits into
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Summary

Backport of #1742 to stable.

  • Adds hold-back buffer to readFromStream that detects the 13-byte stream control frame appended by workflow-server on timeout
  • When the server signals a timeout (done=false), the client transparently reconnects from the next chunk index using ?controlFrame=1
  • Caps reconnections at 50 (~100 min of streaming at 2-min server timeout)
  • Network errors propagate to consumers via controller.error() instead of silently closing

Test plan

  • Unit tests for parseStreamControlFrame (8 tests)
  • Integration tests for reconnection, backward compat, and error propagation (3 tests)

🤖 Generated with Claude Code

@VaguelySerious@claude
[world-vercel] Use stream control frame for transparent reconnection
911431c
Add hold-back buffer to readFromStream that detects the 13-byte stream
control frame appended by workflow-server on timeout. When the server
signals a timeout (done=false), the client transparently reconnects
from the next chunk index. Caps reconnections at 50 (~100 min).
Network errors propagate to consumers via controller.error() instead
of silently closing.
Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>
@VaguelySerious
VaguelySerious requested a review from a team as a code ownerApril 16, 2026 02:54
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🦋 Changeset detected

Latest commit: d78a4d4

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

This PR includes changesets to release 18 packages
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@workflow/world-vercelPatch
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🧪 E2E Test Results

❌ Some tests failed

Summary

PassedFailedSkippedTotal
❌ ▲ Vercel Production8891267968
✅ 💻 Local Development9700861056
✅ 📦 Local Production9700861056
✅ 🐘 Local Postgres9700861056
✅ 🪟 Windows880088
❌ 🌍 Community Worlds1668084
✅ 📋 Other246018264
Total4149803434572

❌ Failed Tests

▲ Vercel Production (12 failed)

astro (1 failed):

  • importMetaUrlWorkflow - import.meta.url is available in step bundles | wrun_01KPBW3QV1YR1HYCBEQACJZXMC | 🔍 observability

fastify (1 failed):

  • instanceMethodStepWorkflow - instance methods with "use step" directive | wrun_01KPBW0RPQJWQD8XX6WT388358 | 🔍 observability

hono (1 failed):

  • outputStreamInsideStepWorkflow - getWritable() called inside step functions | wrun_01KPBVMG655K9S7SR3J0B4SPG3 | 🔍 observability

nextjs-turbopack (3 failed):

  • DurableAgent e2e core multiple sequential tool calls
  • addTenWorkflow | wrun_01KPBVDY4X04RNEQM3N84AWM63 | 🔍 observability
  • outputStreamWorkflow no startIndex (reads all chunks)

nextjs-webpack (3 failed):

  • wellKnownAgentWorkflow (.well-known/agent) | wrun_01KPBVEK284DTN2TSAQDEXZQTV | 🔍 observability
  • outputStreamWorkflow no startIndex (reads all chunks)
  • crossContextSerdeWorkflow - classes defined in step code are deserializable in workflow context | wrun_01KPBW18RXBXVAWVFY9EVH1DAJ | 🔍 observability

sveltekit (1 failed):

  • DurableAgent e2e core basic text response

vite (2 failed):

  • addTenWorkflow | wrun_01KPBVDY4X04RNEQM3N84AWM63 | 🔍 observability
  • stepFunctionPassingWorkflow - step function references can be passed as arguments (without closure vars) | wrun_01KPBVW9JQR18S4AYFFFHVBF92 | 🔍 observability
🌍 Community Worlds (68 failed)

mongodb-dev (1 failed):

  • dev e2e should rebuild on imported step dependency change

redis-dev (1 failed):

  • dev e2e should rebuild on imported step dependency change

turso-dev (1 failed):

  • dev e2e should rebuild on imported step dependency change

turso (65 failed):

  • addTenWorkflow | wrun_01KPBVDY4X04RNEQM3N84AWM63
  • addTenWorkflow | wrun_01KPBVDY4X04RNEQM3N84AWM63
  • wellKnownAgentWorkflow (.well-known/agent) | wrun_01KPBVEK284DTN2TSAQDEXZQTV
  • should work with react rendering in step
  • promiseAllWorkflow | wrun_01KPBVFS7XZNCF7EPS70TNTSC6
  • promiseRaceWorkflow | wrun_01KPBVFXSMG6DWV8H4E8373YZ9
  • promiseAnyWorkflow | wrun_01KPBVG018YH5WD53N66TW9EHY
  • importedStepOnlyWorkflow | wrun_01KPBVGRNKABXQH08KT40RFHNW
  • readableStreamWorkflow | wrun_01KPBVG260RNCWKZCWNHG155PA
  • hookWorkflow | wrun_01KPBVGCSQ4BWAXC6DAM138HA5
  • hookWorkflow is not resumable via public webhook endpoint | wrun_01KPBVGR3K1FJX1P7Z18SKGVTG
  • webhookWorkflow | wrun_01KPBVH1RX158NTANJ3G67CAVY
  • sleepingWorkflow | wrun_01KPBVH7R2QTVWZSMHWRBAXDZP
  • parallelSleepWorkflow | wrun_01KPBVHM8KRQCHESSJ00121DVT
  • nullByteWorkflow | wrun_01KPBVHQJJ3NRATJJR0BSM9NBX
  • workflowAndStepMetadataWorkflow | wrun_01KPBVHT3SZHPAQHJHMPTFF0CV
  • outputStreamWorkflow no startIndex (reads all chunks)
  • outputStreamWorkflow positive startIndex (skips first chunk)
  • outputStreamWorkflow negative startIndex (reads from end)
  • outputStreamWorkflow - getTailIndex and getStreamChunks getTailIndex returns correct index after stream completes
  • outputStreamWorkflow - getTailIndex and getStreamChunks getTailIndex returns -1 before any chunks are written
  • outputStreamWorkflow - getTailIndex and getStreamChunks getStreamChunks returns same content as reading the stream
  • outputStreamInsideStepWorkflow - getWritable() called inside step functions | wrun_01KPBVMG655K9S7SR3J0B4SPG3
  • fetchWorkflow | wrun_01KPBVNGFM3Y4VR9963M7M5VDX
  • promiseRaceStressTestWorkflow | wrun_01KPBVP6Z5SKG0AKMYA1YBGH4P
  • error handling error propagation workflow errors nested function calls preserve message and stack trace
  • error handling error propagation workflow errors cross-file imports preserve message and stack trace
  • error handling error propagation step errors basic step error preserves message and stack trace
  • error handling error propagation step errors cross-file step error preserves message and function names in stack
  • error handling retry behavior regular Error retries until success
  • error handling retry behavior FatalError fails immediately without retries
  • error handling retry behavior RetryableError respects custom retryAfter delay
  • error handling retry behavior maxRetries=0 disables retries
  • error handling catchability FatalError can be caught and detected with FatalError.is()
  • error handling not registered WorkflowNotRegisteredError fails the run when workflow does not exist
  • error handling not registered StepNotRegisteredError fails the step but workflow can catch it
  • error handling not registered StepNotRegisteredError fails the run when not caught in workflow
  • hookCleanupTestWorkflow - hook token reuse after workflow completion | wrun_01KPBVTARB8H5MYMWDGMQKV130
  • concurrent hook token conflict - two workflows cannot use the same hook token simultaneously | wrun_01KPBVTZ8QY29TGD3X00R2SZY5
  • hookDisposeTestWorkflow - hook token reuse after explicit disposal while workflow still running | wrun_01KPBVVMYEQBMJM0Z4ACZWK16Y
  • stepFunctionPassingWorkflow - step function references can be passed as arguments (without closure vars) | wrun_01KPBVW9JQR18S4AYFFFHVBF92
  • stepFunctionWithClosureWorkflow - step function with closure variables passed as argument | wrun_01KPBVY4NRHE6JN8FC3SF207QD
  • closureVariableWorkflow - nested step functions with closure variables | wrun_01KPBVYAF3BX06ENR9QV6FD2G7
  • spawnWorkflowFromStepWorkflow - spawning a child workflow using start() inside a step | wrun_01KPBVYCJR9VSMY5AW9T7Y8EV9
  • health check (queue-based) - workflow and step endpoints respond to health check messages
  • pathsAliasWorkflow - TypeScript path aliases resolve correctly | wrun_01KPBVYW5RFX6WX736FV6YCNVS
  • Calculator.calculate - static workflow method using static step methods from another class | wrun_01KPBVZ1WFVBKETMF6NB8R659D
  • AllInOneService.processNumber - static workflow method using sibling static step methods | wrun_01KPBVZ8WZWNMNE0WG23YT0ENV
  • ChainableService.processWithThis - static step methods using this to reference the class | wrun_01KPBW01PW0S7KND4T74KCFE18
  • thisSerializationWorkflow - step function invoked with .call() and .apply() | wrun_01KPBW08RZVQH6136T11JWJ96E
  • customSerializationWorkflow - custom class serialization with WORKFLOW_SERIALIZE/WORKFLOW_DESERIALIZE | wrun_01KPBW0HQSGQG9Y80A6V8XGA85
  • instanceMethodStepWorkflow - instance methods with "use step" directive | wrun_01KPBW0RPQJWQD8XX6WT388358
  • crossContextSerdeWorkflow - classes defined in step code are deserializable in workflow context | wrun_01KPBW18RXBXVAWVFY9EVH1DAJ
  • stepFunctionAsStartArgWorkflow - step function reference passed as start() argument | wrun_01KPBW1J3ZH787GXWV8PS9DRWX
  • cancelRun - cancelling a running workflow | wrun_01KPBW1V6Y7NZY48XHGJ0MC340
  • cancelRun via CLI - cancelling a running workflow | wrun_01KPBW2615R61B09JPQVVR93AV
  • pages router addTenWorkflow via pages router
  • pages router promiseAllWorkflow via pages router
  • pages router sleepingWorkflow via pages router
  • hookWithSleepWorkflow - hook payloads delivered correctly with concurrent sleep | wrun_01KPBW2J64D1PBDWZ3D42SVW7N
  • sleepInLoopWorkflow - sleep inside loop with steps actually delays each iteration | wrun_01KPBW36T2QYNVQ8MSSCTPYMVN
  • sleepWithSequentialStepsWorkflow - sequential steps work with concurrent sleep (control) | wrun_01KPBW3H2AC0V39WSHAJEFYNRF
  • importMetaUrlWorkflow - import.meta.url is available in step bundles | wrun_01KPBW3QV1YR1HYCBEQACJZXMC
  • metadataFromHelperWorkflow - getWorkflowMetadata/getStepMetadata work from module-level helper (#1577) | wrun_01KPBW3WEP3T5WPRMFKXVZZJRV
  • resilient start: addTenWorkflow completes when run_created returns 500 | wrun_01KPBW3YM7947XTQ24QE9J9BHE

Details by Category

❌ ▲ Vercel Production
AppPassedFailedSkipped
❌ astro8017
✅ example8107
✅ express8107
❌ fastify8017
❌ hono8017
❌ nextjs-turbopack8332
❌ nextjs-webpack8332
✅ nitro8107
✅ nuxt8107
❌ sveltekit8017
❌ vite7927
✅ 💻 Local Development
AppPassedFailedSkipped
✅ astro-stable8206
✅ express-stable8206
✅ fastify-stable8206
✅ hono-stable8206
✅ nextjs-turbopack-canary69019
✅ nextjs-turbopack-stable8800
✅ nextjs-webpack-canary69019
✅ nextjs-webpack-stable8800
✅ nitro-stable8206
✅ nuxt-stable8206
✅ sveltekit-stable8206
✅ vite-stable8206
✅ 📦 Local Production
AppPassedFailedSkipped
✅ astro-stable8206
✅ express-stable8206
✅ fastify-stable8206
✅ hono-stable8206
✅ nextjs-turbopack-canary69019
✅ nextjs-turbopack-stable8800
✅ nextjs-webpack-canary69019
✅ nextjs-webpack-stable8800
✅ nitro-stable8206
✅ nuxt-stable8206
✅ sveltekit-stable8206
✅ vite-stable8206
✅ 🐘 Local Postgres
AppPassedFailedSkipped
✅ astro-stable8206
✅ express-stable8206
✅ fastify-stable8206
✅ hono-stable8206
✅ nextjs-turbopack-canary69019
✅ nextjs-turbopack-stable8800
✅ nextjs-webpack-canary69019
✅ nextjs-webpack-stable8800
✅ nitro-stable8206
✅ nuxt-stable8206
✅ sveltekit-stable8206
✅ vite-stable8206
✅ 🪟 Windows
AppPassedFailedSkipped
✅ nextjs-turbopack8800
❌ 🌍 Community Worlds
AppPassedFailedSkipped
❌ mongodb-dev410
❌ redis-dev410
❌ turso-dev410
❌ turso4650
✅ 📋 Other
AppPassedFailedSkipped
✅ e2e-local-dev-nest-stable8206
✅ e2e-local-postgres-nest-stable8206
✅ e2e-local-prod-nest-stable8206

📋 View full workflow run

❌ Some E2E test jobs failed:

  • Vercel Prod: failure
  • Local Dev: success
  • Local Prod: success
  • Local Postgres: success
  • Windows: success

Check the workflow run for details.

@VaguelySeriousVaguelySerious changed the title [world-vercel] Use stream control frame for transparent reconnection[backport] [world-vercel] Use stream control frame for transparent reconnectionApr 16, 2026
TooTallNate
TooTallNate requested changes Apr 16, 2026
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The code itself is a clean backport of the reconnection logic from #1742, but there's a fundamental protocol mismatch that makes it non-functional.

Re: why not use the backport Action: The repo has a Backport to stable workflow (.github/workflows/backport.yml) that triggers on merged PRs with the backport-stable label. PR #1742 has no labels and hasn't been merged yet, so the action was never triggered. Once #1742 is merged with the backport-stable label, the action would cherry-pick it automatically (or use OpenCode to resolve conflicts if the cherry-pick fails). That said, cherry-picking #1742 would have the same protocol mismatch described below, so a manual backport with adaptation is the right call — it just needs a different approach to signal control frame support.

Changes reviewed:

  1. parseStreamControlFrame, concatUint8Arrays, STREAM_CONTROL_FRAME_SIZE — identical to main, correct.
  2. Hold-back buffer + reconnection loop in readFromStream — identical logic to main's streams.get, with MAX_RECONNECTS=50 and controller.error(err) on network errors. All good.
  3. Unit tests for parseStreamControlFrame — identical to main, 8 tests. Good.
  4. Integration tests for reconnection — 3 tests (reconnect, backward compat, error propagation). Good coverage.
  5. Changeset — correct.

Comment threadpackages/world-vercel/src/streamer.ts
});
if (!response.ok) {
throw new Error(`Failed to fetch stream: ${response.status}`);
}

@TooTallNateTooTallNateApr 16, 2026•
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Blocking: ?controlFrame=1 is not supported by the backend. The backend decides whether to append the trailing control frame based solely on which API version path the request came in on — a query parameter has no effect.

On main, PR #1742 solved this by switching getStreamUrl to the /v3/runs/:runId/stream/:name route. But on stable, readFromStream uses the deprecated no-runId route (/v2/stream/:name), and that deprecated route shape is not available under /v3 — so there is no v3 URL this code path can call.

As a result, the control frame will never be emitted for this code path, and the reconnection logic is dead code.

Options to fix:

  1. If readFromStream on stable has access to a runId somewhere (even via a different caller), thread it through and use the run-scoped /v3 route
  2. Add backend support for signaling control-frame opt-in on the deprecated route (requires a backend change)
  3. Expose the deprecated no-runId route under /v3 on the backend (requires a backend change)

@VaguelySeriousVaguelySeriousApr 16, 2026

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Fixed in 8781b5f — switched to /v3/stream/:name (option 3). Companion server PR: vercel/workflow-server#387 registers the deprecated stream route on the v3 sub-app.

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I suppose you did a "manual" backport because the World API is different on stable (readFromStream, etc.). Still though, I'd be curious to see how the AI does at trying to backport #1742 from the GH Action 😄

@VaguelySerious@claude
Use v3 stream route instead of controlFrame query param
8781b5f
The server enables control frames based on API version (v3+), not a
query param. Use the v3 deprecated stream route which will be
registered on the server via vercel/workflow-server#387.
Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>
vercel[bot]
vercelBot reviewed Apr 16, 2026
View reviewed changes
Comment threadpackages/world-vercel/src/streamer.ts Outdated
VaguelySeriousand others added 2 commits April 16, 2026 12:11
@VaguelySerious@vercel
Update packages/world-vercel/src/streamer.ts
8e9247c
Co-authored-by: vercel[bot] <35613825+vercel[bot]@users.noreply.github.com>
Signed-off-by: Peter Wielander <mittgfu@gmail.com>
@VaguelySerious
Merge branch 'stable' into peter/stream-reconnect-stable
d78a4d4
@VaguelySerious
VaguelySerious merged commit 3737caa into stableApr 16, 2026
77 of 86 checks passed
@VaguelySerious
VaguelySerious deleted the peter/stream-reconnect-stable branch April 16, 2026 19:33
@ghostghost mentioned this pull request Apr 16, 2026
Merged
TooTallNate pushed a commit that referenced this pull request Apr 16, 2026
@VaguelySerious@TooTallNate
[backport] [world-vercel] Use stream control frame for transparent re…
f2f9dbc
…connection (#1766)
VaguelySerious added a commit that referenced this pull request Apr 17, 2026
@VaguelySerious
Revert "[backport] [world-vercel] Use stream control frame for transp…
ac792cd
…arent reconnection (#1766)"
This reverts commit 3737caa.
VaguelySerious added a commit that referenced this pull request Apr 17, 2026
@VaguelySerious
Revert#1766(Use stream control frame for transparent reconnection) (#…
7be05b9
…1788)
VaguelySerious added a commit that referenced this pull request Apr 17, 2026
@VaguelySerious@claude
[world-vercel] Use stream control frame for transparent reconnection,…
d76d170
… with streaming hold-back buffer
Re-applies #1742's reconnect feature on stable, without the arrayBuffer()
rewrite that shipped in 4.2.3 (#1766) and defeated incremental streaming.
- readFromStream returns the ReadableStream promptly; a hold-back buffer
inside the pull loop holds only the last 13 bytes, forwarding surplus
bytes as they arrive. This preserves incremental delivery for AI UIs.
- On upstream close, the tail is parsed for a stream control frame
(done=true → close; done=false → reconnect from nextIndex; no frame →
forward tail as data for older servers).
- Network errors propagate via controller.error() rather than silent close.
- Caps reconnections at 50 (~100 min of streaming at 2-min server timeout).
Adds a regression test that asserts data reaches the consumer before
upstream close — any buffer-then-replay implementation fails it.
Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>
@VaguelySeriousVaguelySerious mentioned this pull request Apr 17, 2026
Merged
5 tasks
VaguelySerious added a commit that referenced this pull request Apr 17, 2026
@VaguelySerious@claude
[world-vercel] Use stream control frame for transparent reconnection,…
ee258dc
… with streaming hold-back buffer
Re-applies #1742's reconnect feature on stable, without the arrayBuffer()
rewrite that shipped in 4.2.3 (#1766) and defeated incremental streaming.
- readFromStream returns the ReadableStream promptly; a hold-back buffer
inside the pull loop holds only the last 13 bytes, forwarding surplus
bytes as they arrive. This preserves incremental delivery for AI UIs.
- On upstream close, the tail is parsed for a stream control frame
(done=true → close; done=false → reconnect from nextIndex; no frame →
forward tail as data for older servers).
- Network errors propagate via controller.error() rather than silent close.
- Caps reconnections at 50 (~100 min of streaming at 2-min server timeout).
Adds a regression test that asserts data reaches the consumer before
upstream close — any buffer-then-replay implementation fails it.
Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>
Signed-off-by: Peter Wielander <mittgfu@gmail.com>
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[backport] [world-vercel] Use stream control frame for transparent reconnection - #1766
Merged
VaguelySerious merged 5 commits into
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peter/stream-reconnect-stable
Apr 16, 2026
Merged
[backport] [world-vercel] Use stream control frame for transparent reconnection#1766
VaguelySerious merged 5 commits into
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peter/stream-reconnect-stable
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Summary
Backport of #1742 to stable.
  • Adds hold-back buffer to readFromStream that detects the 13-byte stream control frame appended by workflow-server on timeout
  • When the server signals a timeout (done=false), the client transparently reconnects from the next chunk index using ?controlFrame=1
  • Caps reconnections at 50 (~100 min of streaming at 2-min server timeout)
  • Network errors propagate to consumers via controller.error() instead of silently closing
Test plan
  •  Unit tests for parseStreamControlFrame (8 tests)
  •  Integration tests for reconnection, backward compat, and error propagation (3 tests)
🤖 Generated with Claude Code
@VaguelySerious@claude
[world-vercel] Use stream control frame for transparent reconnection
911431c
Add hold-back buffer to readFromStream that detects the 13-byte stream
control frame appended by workflow-server on timeout. When the server
signals a timeout (done=false), the client transparently reconnects
from the next chunk index. Caps reconnections at 50 (~100 min).
Network errors propagate to consumers via controller.error() instead
of silently closing.
Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>
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🦋 Changeset detected
Latest commit: d78a4d4
The changes in this PR will be included in the next version bump.
This PR includes changesets to release 18 packages
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🧪 E2E Test Results
❌ Some tests failed
Summary
PassedFailedSkippedTotal
❌ ▲ Vercel Production8891267968
✅ 💻 Local Development9700861056
✅ 📦 Local Production9700861056
✅ 🐘 Local Postgres9700861056
✅ 🪟 Windows880088
❌ 🌍 Community Worlds1668084
✅ 📋 Other246018264
Total4149803434572
❌ Failed Tests
▲ Vercel Production (12 failed)
astro (1 failed):
  • importMetaUrlWorkflow - import.meta.url is available in step bundles | wrun_01KPBW3QV1YR1HYCBEQACJZXMC | 🔍 observability
fastify (1 failed):
  • instanceMethodStepWorkflow - instance methods with "use step" directive | wrun_01KPBW0RPQJWQD8XX6WT388358 | 🔍 observability
hono (1 failed):
  • outputStreamInsideStepWorkflow - getWritable() called inside step functions | wrun_01KPBVMG655K9S7SR3J0B4SPG3 | 🔍 observability
nextjs-turbopack (3 failed):
  • DurableAgent e2e core multiple sequential tool calls
  • addTenWorkflow | wrun_01KPBVDY4X04RNEQM3N84AWM63 | 🔍 observability
  • outputStreamWorkflow no startIndex (reads all chunks)
nextjs-webpack (3 failed):
  • wellKnownAgentWorkflow (.well-known/agent) | wrun_01KPBVEK284DTN2TSAQDEXZQTV | 🔍 observability
  • outputStreamWorkflow no startIndex (reads all chunks)
  • crossContextSerdeWorkflow - classes defined in step code are deserializable in workflow context | wrun_01KPBW18RXBXVAWVFY9EVH1DAJ | 🔍 observability
sveltekit (1 failed):
  • DurableAgent e2e core basic text response
vite (2 failed):
  • addTenWorkflow | wrun_01KPBVDY4X04RNEQM3N84AWM63 | 🔍 observability
  • stepFunctionPassingWorkflow - step function references can be passed as arguments (without closure vars) | wrun_01KPBVW9JQR18S4AYFFFHVBF92 | 🔍 observability
🌍 Community Worlds (68 failed)
mongodb-dev (1 failed):
  • dev e2e should rebuild on imported step dependency change
redis-dev (1 failed):
  • dev e2e should rebuild on imported step dependency change
turso-dev (1 failed):
  • dev e2e should rebuild on imported step dependency change
turso (65 failed):
  • addTenWorkflow | wrun_01KPBVDY4X04RNEQM3N84AWM63
  • addTenWorkflow | wrun_01KPBVDY4X04RNEQM3N84AWM63
  • wellKnownAgentWorkflow (.well-known/agent) | wrun_01KPBVEK284DTN2TSAQDEXZQTV
  • should work with react rendering in step
  • promiseAllWorkflow | wrun_01KPBVFS7XZNCF7EPS70TNTSC6
  • promiseRaceWorkflow | wrun_01KPBVFXSMG6DWV8H4E8373YZ9
  • promiseAnyWorkflow | wrun_01KPBVG018YH5WD53N66TW9EHY
  • importedStepOnlyWorkflow | wrun_01KPBVGRNKABXQH08KT40RFHNW
  • readableStreamWorkflow | wrun_01KPBVG260RNCWKZCWNHG155PA
  • hookWorkflow | wrun_01KPBVGCSQ4BWAXC6DAM138HA5
  • hookWorkflow is not resumable via public webhook endpoint | wrun_01KPBVGR3K1FJX1P7Z18SKGVTG
  • webhookWorkflow | wrun_01KPBVH1RX158NTANJ3G67CAVY
  • sleepingWorkflow | wrun_01KPBVH7R2QTVWZSMHWRBAXDZP
  • parallelSleepWorkflow | wrun_01KPBVHM8KRQCHESSJ00121DVT
  • nullByteWorkflow | wrun_01KPBVHQJJ3NRATJJR0BSM9NBX
  • workflowAndStepMetadataWorkflow | wrun_01KPBVHT3SZHPAQHJHMPTFF0CV
  • outputStreamWorkflow no startIndex (reads all chunks)
  • outputStreamWorkflow positive startIndex (skips first chunk)
  • outputStreamWorkflow negative startIndex (reads from end)
  • outputStreamWorkflow - getTailIndex and getStreamChunks getTailIndex returns correct index after stream completes
  • outputStreamWorkflow - getTailIndex and getStreamChunks getTailIndex returns -1 before any chunks are written
  • outputStreamWorkflow - getTailIndex and getStreamChunks getStreamChunks returns same content as reading the stream
  • outputStreamInsideStepWorkflow - getWritable() called inside step functions | wrun_01KPBVMG655K9S7SR3J0B4SPG3
  • fetchWorkflow | wrun_01KPBVNGFM3Y4VR9963M7M5VDX
  • promiseRaceStressTestWorkflow | wrun_01KPBVP6Z5SKG0AKMYA1YBGH4P
  • error handling error propagation workflow errors nested function calls preserve message and stack trace
  • error handling error propagation workflow errors cross-file imports preserve message and stack trace
  • error handling error propagation step errors basic step error preserves message and stack trace
  • error handling error propagation step errors cross-file step error preserves message and function names in stack
  • error handling retry behavior regular Error retries until success
  • error handling retry behavior FatalError fails immediately without retries
  • error handling retry behavior RetryableError respects custom retryAfter delay
  • error handling retry behavior maxRetries=0 disables retries
  • error handling catchability FatalError can be caught and detected with FatalError.is()
  • error handling not registered WorkflowNotRegisteredError fails the run when workflow does not exist
  • error handling not registered StepNotRegisteredError fails the step but workflow can catch it
  • error handling not registered StepNotRegisteredError fails the run when not caught in workflow
  • hookCleanupTestWorkflow - hook token reuse after workflow completion | wrun_01KPBVTARB8H5MYMWDGMQKV130
  • concurrent hook token conflict - two workflows cannot use the same hook token simultaneously | wrun_01KPBVTZ8QY29TGD3X00R2SZY5
  • hookDisposeTestWorkflow - hook token reuse after explicit disposal while workflow still running | wrun_01KPBVVMYEQBMJM0Z4ACZWK16Y
  • stepFunctionPassingWorkflow - step function references can be passed as arguments (without closure vars) | wrun_01KPBVW9JQR18S4AYFFFHVBF92
  • stepFunctionWithClosureWorkflow - step function with closure variables passed as argument | wrun_01KPBVY4NRHE6JN8FC3SF207QD
  • closureVariableWorkflow - nested step functions with closure variables | wrun_01KPBVYAF3BX06ENR9QV6FD2G7
  • spawnWorkflowFromStepWorkflow - spawning a child workflow using start() inside a step | wrun_01KPBVYCJR9VSMY5AW9T7Y8EV9
  • health check (queue-based) - workflow and step endpoints respond to health check messages
  • pathsAliasWorkflow - TypeScript path aliases resolve correctly | wrun_01KPBVYW5RFX6WX736FV6YCNVS
  • Calculator.calculate - static workflow method using static step methods from another class | wrun_01KPBVZ1WFVBKETMF6NB8R659D
  • AllInOneService.processNumber - static workflow method using sibling static step methods | wrun_01KPBVZ8WZWNMNE0WG23YT0ENV
  • ChainableService.processWithThis - static step methods using this to reference the class | wrun_01KPBW01PW0S7KND4T74KCFE18
  • thisSerializationWorkflow - step function invoked with .call() and .apply() | wrun_01KPBW08RZVQH6136T11JWJ96E
  • customSerializationWorkflow - custom class serialization with WORKFLOW_SERIALIZE/WORKFLOW_DESERIALIZE | wrun_01KPBW0HQSGQG9Y80A6V8XGA85
  • instanceMethodStepWorkflow - instance methods with "use step" directive | wrun_01KPBW0RPQJWQD8XX6WT388358
  • crossContextSerdeWorkflow - classes defined in step code are deserializable in workflow context | wrun_01KPBW18RXBXVAWVFY9EVH1DAJ
  • stepFunctionAsStartArgWorkflow - step function reference passed as start() argument | wrun_01KPBW1J3ZH787GXWV8PS9DRWX
  • cancelRun - cancelling a running workflow | wrun_01KPBW1V6Y7NZY48XHGJ0MC340
  • cancelRun via CLI - cancelling a running workflow | wrun_01KPBW2615R61B09JPQVVR93AV
  • pages router addTenWorkflow via pages router
  • pages router promiseAllWorkflow via pages router
  • pages router sleepingWorkflow via pages router
  • hookWithSleepWorkflow - hook payloads delivered correctly with concurrent sleep | wrun_01KPBW2J64D1PBDWZ3D42SVW7N
  • sleepInLoopWorkflow - sleep inside loop with steps actually delays each iteration | wrun_01KPBW36T2QYNVQ8MSSCTPYMVN
  • sleepWithSequentialStepsWorkflow - sequential steps work with concurrent sleep (control) | wrun_01KPBW3H2AC0V39WSHAJEFYNRF
  • importMetaUrlWorkflow - import.meta.url is available in step bundles | wrun_01KPBW3QV1YR1HYCBEQACJZXMC
  • metadataFromHelperWorkflow - getWorkflowMetadata/getStepMetadata work from module-level helper (#1577) | wrun_01KPBW3WEP3T5WPRMFKXVZZJRV
  • resilient start: addTenWorkflow completes when run_created returns 500 | wrun_01KPBW3YM7947XTQ24QE9J9BHE
Details by Category
❌ ▲ Vercel Production
AppPassedFailedSkipped
❌ astro8017
✅ example8107
✅ express8107
❌ fastify8017
❌ hono8017
❌ nextjs-turbopack8332
❌ nextjs-webpack8332
✅ nitro8107
✅ nuxt8107
❌ sveltekit8017
❌ vite7927
✅ 💻 Local Development
AppPassedFailedSkipped
✅ astro-stable8206
✅ express-stable8206
✅ fastify-stable8206
✅ hono-stable8206
✅ nextjs-turbopack-canary69019
✅ nextjs-turbopack-stable8800
✅ nextjs-webpack-canary69019
✅ nextjs-webpack-stable8800
✅ nitro-stable8206
✅ nuxt-stable8206
✅ sveltekit-stable8206
✅ vite-stable8206
✅ 📦 Local Production
AppPassedFailedSkipped
✅ astro-stable8206
✅ express-stable8206
✅ fastify-stable8206
✅ hono-stable8206
✅ nextjs-turbopack-canary69019
✅ nextjs-turbopack-stable8800
✅ nextjs-webpack-canary69019
✅ nextjs-webpack-stable8800
✅ nitro-stable8206
✅ nuxt-stable8206
✅ sveltekit-stable8206
✅ vite-stable8206
✅ 🐘 Local Postgres
AppPassedFailedSkipped
✅ astro-stable8206
✅ express-stable8206
✅ fastify-stable8206
✅ hono-stable8206
✅ nextjs-turbopack-canary69019
✅ nextjs-turbopack-stable8800
✅ nextjs-webpack-canary69019
✅ nextjs-webpack-stable8800
✅ nitro-stable8206
✅ nuxt-stable8206
✅ sveltekit-stable8206
✅ vite-stable8206
✅ 🪟 Windows
AppPassedFailedSkipped
✅ nextjs-turbopack8800
❌ 🌍 Community Worlds
AppPassedFailedSkipped
❌ mongodb-dev410
❌ redis-dev410
❌ turso-dev410
❌ turso4650
✅ 📋 Other
AppPassedFailedSkipped
✅ e2e-local-dev-nest-stable8206
✅ e2e-local-postgres-nest-stable8206
✅ e2e-local-prod-nest-stable8206
📋 View full workflow run
❌ Some E2E test jobs failed:
  • Vercel Prod: failure
  • Local Dev: success
  • Local Prod: success
  • Local Postgres: success
  • Windows: success
Check the workflow run for details.
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changed the title
[world-vercel] Use stream control frame for transparent reconnection[backport] [world-vercel] Use stream control frame for transparent reconnectionApr 16, 2026
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The code itself is a clean backport of the reconnection logic from #1742, but there's a fundamental protocol mismatch that makes it non-functional.
Re: why not use the backport Action: The repo has a Backport to stable workflow (.github/workflows/backport.yml) that triggers on merged PRs with the backport-stable label. PR #1742 has no labels and hasn't been merged yet, so the action was never triggered. Once #1742 is merged with the backport-stable label, the action would cherry-pick it automatically (or use OpenCode to resolve conflicts if the cherry-pick fails). That said, cherry-picking #1742 would have the same protocol mismatch described below, so a manual backport with adaptation is the right call — it just needs a different approach to signal control frame support.
Changes reviewed:
  1. parseStreamControlFrame, concatUint8Arrays, STREAM_CONTROL_FRAME_SIZE — identical to main, correct.
  2. Hold-back buffer + reconnection loop in readFromStream — identical logic to main's streams.get, with MAX_RECONNECTS=50 and controller.error(err) on network errors. All good.
  3. Unit tests for parseStreamControlFrame — identical to main, 8 tests. Good.
  4. Integration tests for reconnection — 3 tests (reconnect, backward compat, error propagation). Good coverage.
  5. Changeset — correct.
Comment threadpackages/world-vercel/src/streamer.ts
 });
 if (!response.ok) {
 throw new Error(`Failed to fetch stream: ${response.status}`);
 }
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Blocking: ?controlFrame=1 is not supported by the backend. The backend decides whether to append the trailing control frame based solely on which API version path the request came in on — a query parameter has no effect.
On main, PR #1742 solved this by switching getStreamUrl to the /v3/runs/:runId/stream/:name route. But on stable, readFromStream uses the deprecated no-runId route (/v2/stream/:name), and that deprecated route shape is not available under /v3 — so there is no v3 URL this code path can call.
As a result, the control frame will never be emitted for this code path, and the reconnection logic is dead code.
Options to fix:
  1. If readFromStream on stable has access to a runId somewhere (even via a different caller), thread it through and use the run-scoped /v3 route
  2. Add backend support for signaling control-frame opt-in on the deprecated route (requires a backend change)
  3. Expose the deprecated no-runId route under /v3 on the backend (requires a backend change)
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Fixed in 8781b5f — switched to /v3/stream/:name (option 3). Companion server PR: vercel/workflow-server#387 registers the deprecated stream route on the v3 sub-app.
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I suppose you did a "manual" backport because the World API is different on stable (readFromStream, etc.). Still though, I'd be curious to see how the AI does at trying to backport #1742 from the GH Action 😄
@VaguelySerious@claude
Use v3 stream route instead of controlFrame query param
8781b5f
The server enables control frames based on API version (v3+), not a
query param. Use the v3 deprecated stream route which will be
registered on the server via vercel/workflow-server#387.
Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>
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Comment threadpackages/world-vercel/src/streamer.ts
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Update packages/world-vercel/src/streamer.ts
8e9247c
Co-authored-by: vercel[bot] <35613825+vercel[bot]@users.noreply.github.com>
Signed-off-by: Peter Wielander <mittgfu@gmail.com>
@VaguelySerious
Merge branch 'stable' into peter/stream-reconnect-stable
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[backport] [world-vercel] Use stream control frame for transparent re…
f2f9dbc
…connection (#1766)
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Revert "[backport] [world-vercel] Use stream control frame for transp…
ac792cd
…arent reconnection (#1766)"
This reverts commit 3737caa.
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Revert#1766(Use stream control frame for transparent reconnection) (#…
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@VaguelySerious@claude
[world-vercel] Use stream control frame for transparent reconnection,…
d76d170
… with streaming hold-back buffer
Re-applies #1742's reconnect feature on stable, without the arrayBuffer()
rewrite that shipped in 4.2.3 (#1766) and defeated incremental streaming.
- readFromStream returns the ReadableStream promptly; a hold-back buffer
inside the pull loop holds only the last 13 bytes, forwarding surplus
bytes as they arrive. This preserves incremental delivery for AI UIs.
- On upstream close, the tail is parsed for a stream control frame
(done=true → close; done=false → reconnect from nextIndex; no frame →
forward tail as data for older servers).
- Network errors propagate via controller.error() rather than silent close.
- Caps reconnections at 50 (~100 min of streaming at 2-min server timeout).
Adds a regression test that asserts data reaches the consumer before
upstream close — any buffer-then-replay implementation fails it.
Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>
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@VaguelySerious@claude
[world-vercel] Use stream control frame for transparent reconnection,…
ee258dc
… with streaming hold-back buffer
Re-applies #1742's reconnect feature on stable, without the arrayBuffer()
rewrite that shipped in 4.2.3 (#1766) and defeated incremental streaming.
- readFromStream returns the ReadableStream promptly; a hold-back buffer
inside the pull loop holds only the last 13 bytes, forwarding surplus
bytes as they arrive. This preserves incremental delivery for AI UIs.
- On upstream close, the tail is parsed for a stream control frame
(done=true → close; done=false → reconnect from nextIndex; no frame →
forward tail as data for older servers).
- Network errors propagate via controller.error() rather than silent close.
- Caps reconnections at 50 (~100 min of streaming at 2-min server timeout).
Adds a regression test that asserts data reaches the consumer before
upstream close — any buffer-then-replay implementation fails it.
Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>
Signed-off-by: Peter Wielander <mittgfu@gmail.com>
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[backport] [world-vercel] Use stream control frame for transparent reconnection - #1766
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Apr 16, 2026
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[backport] [world-vercel] Use stream control frame for transparent reconnection#1766
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Summary
Backport of #1742 to stable.
  • Adds hold-back buffer to readFromStream that detects the 13-byte stream control frame appended by workflow-server on timeout
  • When the server signals a timeout (done=false), the client transparently reconnects from the next chunk index using ?controlFrame=1
  • Caps reconnections at 50 (~100 min of streaming at 2-min server timeout)
  • Network errors propagate to consumers via controller.error() instead of silently closing
Test plan
  •  Unit tests for parseStreamControlFrame (8 tests)
  •  Integration tests for reconnection, backward compat, and error propagation (3 tests)
🤖 Generated with Claude Code
@VaguelySerious@claude
[world-vercel] Use stream control frame for transparent reconnection
911431c
Add hold-back buffer to readFromStream that detects the 13-byte stream
control frame appended by workflow-server on timeout. When the server
signals a timeout (done=false), the client transparently reconnects
from the next chunk index. Caps reconnections at 50 (~100 min).
Network errors propagate to consumers via controller.error() instead
of silently closing.
Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>
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The changes in this PR will be included in the next version bump.
This PR includes changesets to release 18 packages
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🧪 E2E Test Results
❌ Some tests failed
Summary
PassedFailedSkippedTotal
❌ ▲ Vercel Production8891267968
✅ 💻 Local Development9700861056
✅ 📦 Local Production9700861056
✅ 🐘 Local Postgres9700861056
✅ 🪟 Windows880088
❌ 🌍 Community Worlds1668084
✅ 📋 Other246018264
Total4149803434572
❌ Failed Tests
▲ Vercel Production (12 failed)
astro (1 failed):
  • importMetaUrlWorkflow - import.meta.url is available in step bundles | wrun_01KPBW3QV1YR1HYCBEQACJZXMC | 🔍 observability
fastify (1 failed):
  • instanceMethodStepWorkflow - instance methods with "use step" directive | wrun_01KPBW0RPQJWQD8XX6WT388358 | 🔍 observability
hono (1 failed):
  • outputStreamInsideStepWorkflow - getWritable() called inside step functions | wrun_01KPBVMG655K9S7SR3J0B4SPG3 | 🔍 observability
nextjs-turbopack (3 failed):
  • DurableAgent e2e core multiple sequential tool calls
  • addTenWorkflow | wrun_01KPBVDY4X04RNEQM3N84AWM63 | 🔍 observability
  • outputStreamWorkflow no startIndex (reads all chunks)
nextjs-webpack (3 failed):
  • wellKnownAgentWorkflow (.well-known/agent) | wrun_01KPBVEK284DTN2TSAQDEXZQTV | 🔍 observability
  • outputStreamWorkflow no startIndex (reads all chunks)
  • crossContextSerdeWorkflow - classes defined in step code are deserializable in workflow context | wrun_01KPBW18RXBXVAWVFY9EVH1DAJ | 🔍 observability
sveltekit (1 failed):
  • DurableAgent e2e core basic text response
vite (2 failed):
  • addTenWorkflow | wrun_01KPBVDY4X04RNEQM3N84AWM63 | 🔍 observability
  • stepFunctionPassingWorkflow - step function references can be passed as arguments (without closure vars) | wrun_01KPBVW9JQR18S4AYFFFHVBF92 | 🔍 observability
🌍 Community Worlds (68 failed)
mongodb-dev (1 failed):
  • dev e2e should rebuild on imported step dependency change
redis-dev (1 failed):
  • dev e2e should rebuild on imported step dependency change
turso-dev (1 failed):
  • dev e2e should rebuild on imported step dependency change
turso (65 failed):
  • addTenWorkflow | wrun_01KPBVDY4X04RNEQM3N84AWM63
  • addTenWorkflow | wrun_01KPBVDY4X04RNEQM3N84AWM63
  • wellKnownAgentWorkflow (.well-known/agent) | wrun_01KPBVEK284DTN2TSAQDEXZQTV
  • should work with react rendering in step
  • promiseAllWorkflow | wrun_01KPBVFS7XZNCF7EPS70TNTSC6
  • promiseRaceWorkflow | wrun_01KPBVFXSMG6DWV8H4E8373YZ9
  • promiseAnyWorkflow | wrun_01KPBVG018YH5WD53N66TW9EHY
  • importedStepOnlyWorkflow | wrun_01KPBVGRNKABXQH08KT40RFHNW
  • readableStreamWorkflow | wrun_01KPBVG260RNCWKZCWNHG155PA
  • hookWorkflow | wrun_01KPBVGCSQ4BWAXC6DAM138HA5
  • hookWorkflow is not resumable via public webhook endpoint | wrun_01KPBVGR3K1FJX1P7Z18SKGVTG
  • webhookWorkflow | wrun_01KPBVH1RX158NTANJ3G67CAVY
  • sleepingWorkflow | wrun_01KPBVH7R2QTVWZSMHWRBAXDZP
  • parallelSleepWorkflow | wrun_01KPBVHM8KRQCHESSJ00121DVT
  • nullByteWorkflow | wrun_01KPBVHQJJ3NRATJJR0BSM9NBX
  • workflowAndStepMetadataWorkflow | wrun_01KPBVHT3SZHPAQHJHMPTFF0CV
  • outputStreamWorkflow no startIndex (reads all chunks)
  • outputStreamWorkflow positive startIndex (skips first chunk)
  • outputStreamWorkflow negative startIndex (reads from end)
  • outputStreamWorkflow - getTailIndex and getStreamChunks getTailIndex returns correct index after stream completes
  • outputStreamWorkflow - getTailIndex and getStreamChunks getTailIndex returns -1 before any chunks are written
  • outputStreamWorkflow - getTailIndex and getStreamChunks getStreamChunks returns same content as reading the stream
  • outputStreamInsideStepWorkflow - getWritable() called inside step functions | wrun_01KPBVMG655K9S7SR3J0B4SPG3
  • fetchWorkflow | wrun_01KPBVNGFM3Y4VR9963M7M5VDX
  • promiseRaceStressTestWorkflow | wrun_01KPBVP6Z5SKG0AKMYA1YBGH4P
  • error handling error propagation workflow errors nested function calls preserve message and stack trace
  • error handling error propagation workflow errors cross-file imports preserve message and stack trace
  • error handling error propagation step errors basic step error preserves message and stack trace
  • error handling error propagation step errors cross-file step error preserves message and function names in stack
  • error handling retry behavior regular Error retries until success
  • error handling retry behavior FatalError fails immediately without retries
  • error handling retry behavior RetryableError respects custom retryAfter delay
  • error handling retry behavior maxRetries=0 disables retries
  • error handling catchability FatalError can be caught and detected with FatalError.is()
  • error handling not registered WorkflowNotRegisteredError fails the run when workflow does not exist
  • error handling not registered StepNotRegisteredError fails the step but workflow can catch it
  • error handling not registered StepNotRegisteredError fails the run when not caught in workflow
  • hookCleanupTestWorkflow - hook token reuse after workflow completion | wrun_01KPBVTARB8H5MYMWDGMQKV130
  • concurrent hook token conflict - two workflows cannot use the same hook token simultaneously | wrun_01KPBVTZ8QY29TGD3X00R2SZY5
  • hookDisposeTestWorkflow - hook token reuse after explicit disposal while workflow still running | wrun_01KPBVVMYEQBMJM0Z4ACZWK16Y
  • stepFunctionPassingWorkflow - step function references can be passed as arguments (without closure vars) | wrun_01KPBVW9JQR18S4AYFFFHVBF92
  • stepFunctionWithClosureWorkflow - step function with closure variables passed as argument | wrun_01KPBVY4NRHE6JN8FC3SF207QD
  • closureVariableWorkflow - nested step functions with closure variables | wrun_01KPBVYAF3BX06ENR9QV6FD2G7
  • spawnWorkflowFromStepWorkflow - spawning a child workflow using start() inside a step | wrun_01KPBVYCJR9VSMY5AW9T7Y8EV9
  • health check (queue-based) - workflow and step endpoints respond to health check messages
  • pathsAliasWorkflow - TypeScript path aliases resolve correctly | wrun_01KPBVYW5RFX6WX736FV6YCNVS
  • Calculator.calculate - static workflow method using static step methods from another class | wrun_01KPBVZ1WFVBKETMF6NB8R659D
  • AllInOneService.processNumber - static workflow method using sibling static step methods | wrun_01KPBVZ8WZWNMNE0WG23YT0ENV
  • ChainableService.processWithThis - static step methods using this to reference the class | wrun_01KPBW01PW0S7KND4T74KCFE18
  • thisSerializationWorkflow - step function invoked with .call() and .apply() | wrun_01KPBW08RZVQH6136T11JWJ96E
  • customSerializationWorkflow - custom class serialization with WORKFLOW_SERIALIZE/WORKFLOW_DESERIALIZE | wrun_01KPBW0HQSGQG9Y80A6V8XGA85
  • instanceMethodStepWorkflow - instance methods with "use step" directive | wrun_01KPBW0RPQJWQD8XX6WT388358
  • crossContextSerdeWorkflow - classes defined in step code are deserializable in workflow context | wrun_01KPBW18RXBXVAWVFY9EVH1DAJ
  • stepFunctionAsStartArgWorkflow - step function reference passed as start() argument | wrun_01KPBW1J3ZH787GXWV8PS9DRWX
  • cancelRun - cancelling a running workflow | wrun_01KPBW1V6Y7NZY48XHGJ0MC340
  • cancelRun via CLI - cancelling a running workflow | wrun_01KPBW2615R61B09JPQVVR93AV
  • pages router addTenWorkflow via pages router
  • pages router promiseAllWorkflow via pages router
  • pages router sleepingWorkflow via pages router
  • hookWithSleepWorkflow - hook payloads delivered correctly with concurrent sleep | wrun_01KPBW2J64D1PBDWZ3D42SVW7N
  • sleepInLoopWorkflow - sleep inside loop with steps actually delays each iteration | wrun_01KPBW36T2QYNVQ8MSSCTPYMVN
  • sleepWithSequentialStepsWorkflow - sequential steps work with concurrent sleep (control) | wrun_01KPBW3H2AC0V39WSHAJEFYNRF
  • importMetaUrlWorkflow - import.meta.url is available in step bundles | wrun_01KPBW3QV1YR1HYCBEQACJZXMC
  • metadataFromHelperWorkflow - getWorkflowMetadata/getStepMetadata work from module-level helper (#1577) | wrun_01KPBW3WEP3T5WPRMFKXVZZJRV
  • resilient start: addTenWorkflow completes when run_created returns 500 | wrun_01KPBW3YM7947XTQ24QE9J9BHE
Details by Category
❌ ▲ Vercel Production
AppPassedFailedSkipped
❌ astro8017
✅ example8107
✅ express8107
❌ fastify8017
❌ hono8017
❌ nextjs-turbopack8332
❌ nextjs-webpack8332
✅ nitro8107
✅ nuxt8107
❌ sveltekit8017
❌ vite7927
✅ 💻 Local Development
AppPassedFailedSkipped
✅ astro-stable8206
✅ express-stable8206
✅ fastify-stable8206
✅ hono-stable8206
✅ nextjs-turbopack-canary69019
✅ nextjs-turbopack-stable8800
✅ nextjs-webpack-canary69019
✅ nextjs-webpack-stable8800
✅ nitro-stable8206
✅ nuxt-stable8206
✅ sveltekit-stable8206
✅ vite-stable8206
✅ 📦 Local Production
AppPassedFailedSkipped
✅ astro-stable8206
✅ express-stable8206
✅ fastify-stable8206
✅ hono-stable8206
✅ nextjs-turbopack-canary69019
✅ nextjs-turbopack-stable8800
✅ nextjs-webpack-canary69019
✅ nextjs-webpack-stable8800
✅ nitro-stable8206
✅ nuxt-stable8206
✅ sveltekit-stable8206
✅ vite-stable8206
✅ 🐘 Local Postgres
AppPassedFailedSkipped
✅ astro-stable8206
✅ express-stable8206
✅ fastify-stable8206
✅ hono-stable8206
✅ nextjs-turbopack-canary69019
✅ nextjs-turbopack-stable8800
✅ nextjs-webpack-canary69019
✅ nextjs-webpack-stable8800
✅ nitro-stable8206
✅ nuxt-stable8206
✅ sveltekit-stable8206
✅ vite-stable8206
✅ 🪟 Windows
AppPassedFailedSkipped
✅ nextjs-turbopack8800
❌ 🌍 Community Worlds
AppPassedFailedSkipped
❌ mongodb-dev410
❌ redis-dev410
❌ turso-dev410
❌ turso4650
✅ 📋 Other
AppPassedFailedSkipped
✅ e2e-local-dev-nest-stable8206
✅ e2e-local-postgres-nest-stable8206
✅ e2e-local-prod-nest-stable8206
📋 View full workflow run
❌ Some E2E test jobs failed:
  • Vercel Prod: failure
  • Local Dev: success
  • Local Prod: success
  • Local Postgres: success
  • Windows: success
Check the workflow run for details.
@VaguelySeriousVaguelySerious
changed the title
[world-vercel] Use stream control frame for transparent reconnection[backport] [world-vercel] Use stream control frame for transparent reconnectionApr 16, 2026
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The code itself is a clean backport of the reconnection logic from #1742, but there's a fundamental protocol mismatch that makes it non-functional.
Re: why not use the backport Action: The repo has a Backport to stable workflow (.github/workflows/backport.yml) that triggers on merged PRs with the backport-stable label. PR #1742 has no labels and hasn't been merged yet, so the action was never triggered. Once #1742 is merged with the backport-stable label, the action would cherry-pick it automatically (or use OpenCode to resolve conflicts if the cherry-pick fails). That said, cherry-picking #1742 would have the same protocol mismatch described below, so a manual backport with adaptation is the right call — it just needs a different approach to signal control frame support.
Changes reviewed:
  1. parseStreamControlFrame, concatUint8Arrays, STREAM_CONTROL_FRAME_SIZE — identical to main, correct.
  2. Hold-back buffer + reconnection loop in readFromStream — identical logic to main's streams.get, with MAX_RECONNECTS=50 and controller.error(err) on network errors. All good.
  3. Unit tests for parseStreamControlFrame — identical to main, 8 tests. Good.
  4. Integration tests for reconnection — 3 tests (reconnect, backward compat, error propagation). Good coverage.
  5. Changeset — correct.
Comment threadpackages/world-vercel/src/streamer.ts
 });
 if (!response.ok) {
 throw new Error(`Failed to fetch stream: ${response.status}`);
 }
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Blocking: ?controlFrame=1 is not supported by the backend. The backend decides whether to append the trailing control frame based solely on which API version path the request came in on — a query parameter has no effect.
On main, PR #1742 solved this by switching getStreamUrl to the /v3/runs/:runId/stream/:name route. But on stable, readFromStream uses the deprecated no-runId route (/v2/stream/:name), and that deprecated route shape is not available under /v3 — so there is no v3 URL this code path can call.
As a result, the control frame will never be emitted for this code path, and the reconnection logic is dead code.
Options to fix:
  1. If readFromStream on stable has access to a runId somewhere (even via a different caller), thread it through and use the run-scoped /v3 route
  2. Add backend support for signaling control-frame opt-in on the deprecated route (requires a backend change)
  3. Expose the deprecated no-runId route under /v3 on the backend (requires a backend change)
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Fixed in 8781b5f — switched to /v3/stream/:name (option 3). Companion server PR: vercel/workflow-server#387 registers the deprecated stream route on the v3 sub-app.
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I suppose you did a "manual" backport because the World API is different on stable (readFromStream, etc.). Still though, I'd be curious to see how the AI does at trying to backport #1742 from the GH Action 😄
@VaguelySerious@claude
Use v3 stream route instead of controlFrame query param
8781b5f
The server enables control frames based on API version (v3+), not a
query param. Use the v3 deprecated stream route which will be
registered on the server via vercel/workflow-server#387.
Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>
vercel[bot]
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Comment threadpackages/world-vercel/src/streamer.ts
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April 16, 2026 12:11
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Update packages/world-vercel/src/streamer.ts
8e9247c
Co-authored-by: vercel[bot] <35613825+vercel[bot]@users.noreply.github.com>
Signed-off-by: Peter Wielander <mittgfu@gmail.com>
@VaguelySerious
Merge branch 'stable' into peter/stream-reconnect-stable
d78a4d4
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[backport] [world-vercel] Use stream control frame for transparent re…
f2f9dbc
…connection (#1766)
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@VaguelySerious
Revert "[backport] [world-vercel] Use stream control frame for transp…
ac792cd
…arent reconnection (#1766)"
This reverts commit 3737caa.
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Revert#1766(Use stream control frame for transparent reconnection) (#…
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…1788)
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@VaguelySerious@claude
[world-vercel] Use stream control frame for transparent reconnection,…
d76d170
… with streaming hold-back buffer
Re-applies #1742's reconnect feature on stable, without the arrayBuffer()
rewrite that shipped in 4.2.3 (#1766) and defeated incremental streaming.
- readFromStream returns the ReadableStream promptly; a hold-back buffer
inside the pull loop holds only the last 13 bytes, forwarding surplus
bytes as they arrive. This preserves incremental delivery for AI UIs.
- On upstream close, the tail is parsed for a stream control frame
(done=true → close; done=false → reconnect from nextIndex; no frame →
forward tail as data for older servers).
- Network errors propagate via controller.error() rather than silent close.
- Caps reconnections at 50 (~100 min of streaming at 2-min server timeout).
Adds a regression test that asserts data reaches the consumer before
upstream close — any buffer-then-replay implementation fails it.
Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>
@VaguelySeriousVaguelySerious
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VaguelySerious added a commit
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Apr 17, 2026
@VaguelySerious@claude
[world-vercel] Use stream control frame for transparent reconnection,…
ee258dc
… with streaming hold-back buffer
Re-applies #1742's reconnect feature on stable, without the arrayBuffer()
rewrite that shipped in 4.2.3 (#1766) and defeated incremental streaming.
- readFromStream returns the ReadableStream promptly; a hold-back buffer
inside the pull loop holds only the last 13 bytes, forwarding surplus
bytes as they arrive. This preserves incremental delivery for AI UIs.
- On upstream close, the tail is parsed for a stream control frame
(done=true → close; done=false → reconnect from nextIndex; no frame →
forward tail as data for older servers).
- Network errors propagate via controller.error() rather than silent close.
- Caps reconnections at 50 (~100 min of streaming at 2-min server timeout).
Adds a regression test that asserts data reaches the consumer before
upstream close — any buffer-then-replay implementation fails it.
Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>
Signed-off-by: Peter Wielander <mittgfu@gmail.com>
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[backport] [world-vercel] Use stream control frame for transparent reconnection - #1766
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peter/stream-reconnect-stable
Apr 16, 2026
Merged
[backport] [world-vercel] Use stream control frame for transparent reconnection#1766
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Summary
Backport of #1742 to stable.
  • Adds hold-back buffer to readFromStream that detects the 13-byte stream control frame appended by workflow-server on timeout
  • When the server signals a timeout (done=false), the client transparently reconnects from the next chunk index using ?controlFrame=1
  • Caps reconnections at 50 (~100 min of streaming at 2-min server timeout)
  • Network errors propagate to consumers via controller.error() instead of silently closing
Test plan
  •  Unit tests for parseStreamControlFrame (8 tests)
  •  Integration tests for reconnection, backward compat, and error propagation (3 tests)
🤖 Generated with Claude Code
@VaguelySerious@claude
[world-vercel] Use stream control frame for transparent reconnection
911431c
Add hold-back buffer to readFromStream that detects the 13-byte stream
control frame appended by workflow-server on timeout. When the server
signals a timeout (done=false), the client transparently reconnects
from the next chunk index. Caps reconnections at 50 (~100 min).
Network errors propagate to consumers via controller.error() instead
of silently closing.
Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>
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🦋 Changeset detected
Latest commit: d78a4d4
The changes in this PR will be included in the next version bump.
This PR includes changesets to release 18 packages
NameType
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@workflow/cliPatch
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🧪 E2E Test Results
❌ Some tests failed
Summary
PassedFailedSkippedTotal
❌ ▲ Vercel Production8891267968
✅ 💻 Local Development9700861056
✅ 📦 Local Production9700861056
✅ 🐘 Local Postgres9700861056
✅ 🪟 Windows880088
❌ 🌍 Community Worlds1668084
✅ 📋 Other246018264
Total4149803434572
❌ Failed Tests
▲ Vercel Production (12 failed)
astro (1 failed):
  • importMetaUrlWorkflow - import.meta.url is available in step bundles | wrun_01KPBW3QV1YR1HYCBEQACJZXMC | 🔍 observability
fastify (1 failed):
  • instanceMethodStepWorkflow - instance methods with "use step" directive | wrun_01KPBW0RPQJWQD8XX6WT388358 | 🔍 observability
hono (1 failed):
  • outputStreamInsideStepWorkflow - getWritable() called inside step functions | wrun_01KPBVMG655K9S7SR3J0B4SPG3 | 🔍 observability
nextjs-turbopack (3 failed):
  • DurableAgent e2e core multiple sequential tool calls
  • addTenWorkflow | wrun_01KPBVDY4X04RNEQM3N84AWM63 | 🔍 observability
  • outputStreamWorkflow no startIndex (reads all chunks)
nextjs-webpack (3 failed):
  • wellKnownAgentWorkflow (.well-known/agent) | wrun_01KPBVEK284DTN2TSAQDEXZQTV | 🔍 observability
  • outputStreamWorkflow no startIndex (reads all chunks)
  • crossContextSerdeWorkflow - classes defined in step code are deserializable in workflow context | wrun_01KPBW18RXBXVAWVFY9EVH1DAJ | 🔍 observability
sveltekit (1 failed):
  • DurableAgent e2e core basic text response
vite (2 failed):
  • addTenWorkflow | wrun_01KPBVDY4X04RNEQM3N84AWM63 | 🔍 observability
  • stepFunctionPassingWorkflow - step function references can be passed as arguments (without closure vars) | wrun_01KPBVW9JQR18S4AYFFFHVBF92 | 🔍 observability
🌍 Community Worlds (68 failed)
mongodb-dev (1 failed):
  • dev e2e should rebuild on imported step dependency change
redis-dev (1 failed):
  • dev e2e should rebuild on imported step dependency change
turso-dev (1 failed):
  • dev e2e should rebuild on imported step dependency change
turso (65 failed):
  • addTenWorkflow | wrun_01KPBVDY4X04RNEQM3N84AWM63
  • addTenWorkflow | wrun_01KPBVDY4X04RNEQM3N84AWM63
  • wellKnownAgentWorkflow (.well-known/agent) | wrun_01KPBVEK284DTN2TSAQDEXZQTV
  • should work with react rendering in step
  • promiseAllWorkflow | wrun_01KPBVFS7XZNCF7EPS70TNTSC6
  • promiseRaceWorkflow | wrun_01KPBVFXSMG6DWV8H4E8373YZ9
  • promiseAnyWorkflow | wrun_01KPBVG018YH5WD53N66TW9EHY
  • importedStepOnlyWorkflow | wrun_01KPBVGRNKABXQH08KT40RFHNW
  • readableStreamWorkflow | wrun_01KPBVG260RNCWKZCWNHG155PA
  • hookWorkflow | wrun_01KPBVGCSQ4BWAXC6DAM138HA5
  • hookWorkflow is not resumable via public webhook endpoint | wrun_01KPBVGR3K1FJX1P7Z18SKGVTG
  • webhookWorkflow | wrun_01KPBVH1RX158NTANJ3G67CAVY
  • sleepingWorkflow | wrun_01KPBVH7R2QTVWZSMHWRBAXDZP
  • parallelSleepWorkflow | wrun_01KPBVHM8KRQCHESSJ00121DVT
  • nullByteWorkflow | wrun_01KPBVHQJJ3NRATJJR0BSM9NBX
  • workflowAndStepMetadataWorkflow | wrun_01KPBVHT3SZHPAQHJHMPTFF0CV
  • outputStreamWorkflow no startIndex (reads all chunks)
  • outputStreamWorkflow positive startIndex (skips first chunk)
  • outputStreamWorkflow negative startIndex (reads from end)
  • outputStreamWorkflow - getTailIndex and getStreamChunks getTailIndex returns correct index after stream completes
  • outputStreamWorkflow - getTailIndex and getStreamChunks getTailIndex returns -1 before any chunks are written
  • outputStreamWorkflow - getTailIndex and getStreamChunks getStreamChunks returns same content as reading the stream
  • outputStreamInsideStepWorkflow - getWritable() called inside step functions | wrun_01KPBVMG655K9S7SR3J0B4SPG3
  • fetchWorkflow | wrun_01KPBVNGFM3Y4VR9963M7M5VDX
  • promiseRaceStressTestWorkflow | wrun_01KPBVP6Z5SKG0AKMYA1YBGH4P
  • error handling error propagation workflow errors nested function calls preserve message and stack trace
  • error handling error propagation workflow errors cross-file imports preserve message and stack trace
  • error handling error propagation step errors basic step error preserves message and stack trace
  • error handling error propagation step errors cross-file step error preserves message and function names in stack
  • error handling retry behavior regular Error retries until success
  • error handling retry behavior FatalError fails immediately without retries
  • error handling retry behavior RetryableError respects custom retryAfter delay
  • error handling retry behavior maxRetries=0 disables retries
  • error handling catchability FatalError can be caught and detected with FatalError.is()
  • error handling not registered WorkflowNotRegisteredError fails the run when workflow does not exist
  • error handling not registered StepNotRegisteredError fails the step but workflow can catch it
  • error handling not registered StepNotRegisteredError fails the run when not caught in workflow
  • hookCleanupTestWorkflow - hook token reuse after workflow completion | wrun_01KPBVTARB8H5MYMWDGMQKV130
  • concurrent hook token conflict - two workflows cannot use the same hook token simultaneously | wrun_01KPBVTZ8QY29TGD3X00R2SZY5
  • hookDisposeTestWorkflow - hook token reuse after explicit disposal while workflow still running | wrun_01KPBVVMYEQBMJM0Z4ACZWK16Y
  • stepFunctionPassingWorkflow - step function references can be passed as arguments (without closure vars) | wrun_01KPBVW9JQR18S4AYFFFHVBF92
  • stepFunctionWithClosureWorkflow - step function with closure variables passed as argument | wrun_01KPBVY4NRHE6JN8FC3SF207QD
  • closureVariableWorkflow - nested step functions with closure variables | wrun_01KPBVYAF3BX06ENR9QV6FD2G7
  • spawnWorkflowFromStepWorkflow - spawning a child workflow using start() inside a step | wrun_01KPBVYCJR9VSMY5AW9T7Y8EV9
  • health check (queue-based) - workflow and step endpoints respond to health check messages
  • pathsAliasWorkflow - TypeScript path aliases resolve correctly | wrun_01KPBVYW5RFX6WX736FV6YCNVS
  • Calculator.calculate - static workflow method using static step methods from another class | wrun_01KPBVZ1WFVBKETMF6NB8R659D
  • AllInOneService.processNumber - static workflow method using sibling static step methods | wrun_01KPBVZ8WZWNMNE0WG23YT0ENV
  • ChainableService.processWithThis - static step methods using this to reference the class | wrun_01KPBW01PW0S7KND4T74KCFE18
  • thisSerializationWorkflow - step function invoked with .call() and .apply() | wrun_01KPBW08RZVQH6136T11JWJ96E
  • customSerializationWorkflow - custom class serialization with WORKFLOW_SERIALIZE/WORKFLOW_DESERIALIZE | wrun_01KPBW0HQSGQG9Y80A6V8XGA85
  • instanceMethodStepWorkflow - instance methods with "use step" directive | wrun_01KPBW0RPQJWQD8XX6WT388358
  • crossContextSerdeWorkflow - classes defined in step code are deserializable in workflow context | wrun_01KPBW18RXBXVAWVFY9EVH1DAJ
  • stepFunctionAsStartArgWorkflow - step function reference passed as start() argument | wrun_01KPBW1J3ZH787GXWV8PS9DRWX
  • cancelRun - cancelling a running workflow | wrun_01KPBW1V6Y7NZY48XHGJ0MC340
  • cancelRun via CLI - cancelling a running workflow | wrun_01KPBW2615R61B09JPQVVR93AV
  • pages router addTenWorkflow via pages router
  • pages router promiseAllWorkflow via pages router
  • pages router sleepingWorkflow via pages router
  • hookWithSleepWorkflow - hook payloads delivered correctly with concurrent sleep | wrun_01KPBW2J64D1PBDWZ3D42SVW7N
  • sleepInLoopWorkflow - sleep inside loop with steps actually delays each iteration | wrun_01KPBW36T2QYNVQ8MSSCTPYMVN
  • sleepWithSequentialStepsWorkflow - sequential steps work with concurrent sleep (control) | wrun_01KPBW3H2AC0V39WSHAJEFYNRF
  • importMetaUrlWorkflow - import.meta.url is available in step bundles | wrun_01KPBW3QV1YR1HYCBEQACJZXMC
  • metadataFromHelperWorkflow - getWorkflowMetadata/getStepMetadata work from module-level helper (#1577) | wrun_01KPBW3WEP3T5WPRMFKXVZZJRV
  • resilient start: addTenWorkflow completes when run_created returns 500 | wrun_01KPBW3YM7947XTQ24QE9J9BHE
Details by Category
❌ ▲ Vercel Production
AppPassedFailedSkipped
❌ astro8017
✅ example8107
✅ express8107
❌ fastify8017
❌ hono8017
❌ nextjs-turbopack8332
❌ nextjs-webpack8332
✅ nitro8107
✅ nuxt8107
❌ sveltekit8017
❌ vite7927
✅ 💻 Local Development
AppPassedFailedSkipped
✅ astro-stable8206
✅ express-stable8206
✅ fastify-stable8206
✅ hono-stable8206
✅ nextjs-turbopack-canary69019
✅ nextjs-turbopack-stable8800
✅ nextjs-webpack-canary69019
✅ nextjs-webpack-stable8800
✅ nitro-stable8206
✅ nuxt-stable8206
✅ sveltekit-stable8206
✅ vite-stable8206
✅ 📦 Local Production
AppPassedFailedSkipped
✅ astro-stable8206
✅ express-stable8206
✅ fastify-stable8206
✅ hono-stable8206
✅ nextjs-turbopack-canary69019
✅ nextjs-turbopack-stable8800
✅ nextjs-webpack-canary69019
✅ nextjs-webpack-stable8800
✅ nitro-stable8206
✅ nuxt-stable8206
✅ sveltekit-stable8206
✅ vite-stable8206
✅ 🐘 Local Postgres
AppPassedFailedSkipped
✅ astro-stable8206
✅ express-stable8206
✅ fastify-stable8206
✅ hono-stable8206
✅ nextjs-turbopack-canary69019
✅ nextjs-turbopack-stable8800
✅ nextjs-webpack-canary69019
✅ nextjs-webpack-stable8800
✅ nitro-stable8206
✅ nuxt-stable8206
✅ sveltekit-stable8206
✅ vite-stable8206
✅ 🪟 Windows
AppPassedFailedSkipped
✅ nextjs-turbopack8800
❌ 🌍 Community Worlds
AppPassedFailedSkipped
❌ mongodb-dev410
❌ redis-dev410
❌ turso-dev410
❌ turso4650
✅ 📋 Other
AppPassedFailedSkipped
✅ e2e-local-dev-nest-stable8206
✅ e2e-local-postgres-nest-stable8206
✅ e2e-local-prod-nest-stable8206
📋 View full workflow run
❌ Some E2E test jobs failed:
  • Vercel Prod: failure
  • Local Dev: success
  • Local Prod: success
  • Local Postgres: success
  • Windows: success
Check the workflow run for details.
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changed the title
[world-vercel] Use stream control frame for transparent reconnection[backport] [world-vercel] Use stream control frame for transparent reconnectionApr 16, 2026
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The code itself is a clean backport of the reconnection logic from #1742, but there's a fundamental protocol mismatch that makes it non-functional.
Re: why not use the backport Action: The repo has a Backport to stable workflow (.github/workflows/backport.yml) that triggers on merged PRs with the backport-stable label. PR #1742 has no labels and hasn't been merged yet, so the action was never triggered. Once #1742 is merged with the backport-stable label, the action would cherry-pick it automatically (or use OpenCode to resolve conflicts if the cherry-pick fails). That said, cherry-picking #1742 would have the same protocol mismatch described below, so a manual backport with adaptation is the right call — it just needs a different approach to signal control frame support.
Changes reviewed:
  1. parseStreamControlFrame, concatUint8Arrays, STREAM_CONTROL_FRAME_SIZE — identical to main, correct.
  2. Hold-back buffer + reconnection loop in readFromStream — identical logic to main's streams.get, with MAX_RECONNECTS=50 and controller.error(err) on network errors. All good.
  3. Unit tests for parseStreamControlFrame — identical to main, 8 tests. Good.
  4. Integration tests for reconnection — 3 tests (reconnect, backward compat, error propagation). Good coverage.
  5. Changeset — correct.
Comment threadpackages/world-vercel/src/streamer.ts
 });
 if (!response.ok) {
 throw new Error(`Failed to fetch stream: ${response.status}`);
 }
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Blocking: ?controlFrame=1 is not supported by the backend. The backend decides whether to append the trailing control frame based solely on which API version path the request came in on — a query parameter has no effect.
On main, PR #1742 solved this by switching getStreamUrl to the /v3/runs/:runId/stream/:name route. But on stable, readFromStream uses the deprecated no-runId route (/v2/stream/:name), and that deprecated route shape is not available under /v3 — so there is no v3 URL this code path can call.
As a result, the control frame will never be emitted for this code path, and the reconnection logic is dead code.
Options to fix:
  1. If readFromStream on stable has access to a runId somewhere (even via a different caller), thread it through and use the run-scoped /v3 route
  2. Add backend support for signaling control-frame opt-in on the deprecated route (requires a backend change)
  3. Expose the deprecated no-runId route under /v3 on the backend (requires a backend change)
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Fixed in 8781b5f — switched to /v3/stream/:name (option 3). Companion server PR: vercel/workflow-server#387 registers the deprecated stream route on the v3 sub-app.
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I suppose you did a "manual" backport because the World API is different on stable (readFromStream, etc.). Still though, I'd be curious to see how the AI does at trying to backport #1742 from the GH Action 😄
@VaguelySerious@claude
Use v3 stream route instead of controlFrame query param
8781b5f
The server enables control frames based on API version (v3+), not a
query param. Use the v3 deprecated stream route which will be
registered on the server via vercel/workflow-server#387.
Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>
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Comment threadpackages/world-vercel/src/streamer.ts
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Update packages/world-vercel/src/streamer.ts
8e9247c
Co-authored-by: vercel[bot] <35613825+vercel[bot]@users.noreply.github.com>
Signed-off-by: Peter Wielander <mittgfu@gmail.com>
@VaguelySerious
Merge branch 'stable' into peter/stream-reconnect-stable
d78a4d4
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[backport] [world-vercel] Use stream control frame for transparent re…
f2f9dbc
…connection (#1766)
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@VaguelySerious
Revert "[backport] [world-vercel] Use stream control frame for transp…
ac792cd
…arent reconnection (#1766)"
This reverts commit 3737caa.
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Revert#1766(Use stream control frame for transparent reconnection) (#…
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@VaguelySerious@claude
[world-vercel] Use stream control frame for transparent reconnection,…
d76d170
… with streaming hold-back buffer
Re-applies #1742's reconnect feature on stable, without the arrayBuffer()
rewrite that shipped in 4.2.3 (#1766) and defeated incremental streaming.
- readFromStream returns the ReadableStream promptly; a hold-back buffer
inside the pull loop holds only the last 13 bytes, forwarding surplus
bytes as they arrive. This preserves incremental delivery for AI UIs.
- On upstream close, the tail is parsed for a stream control frame
(done=true → close; done=false → reconnect from nextIndex; no frame →
forward tail as data for older servers).
- Network errors propagate via controller.error() rather than silent close.
- Caps reconnections at 50 (~100 min of streaming at 2-min server timeout).
Adds a regression test that asserts data reaches the consumer before
upstream close — any buffer-then-replay implementation fails it.
Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>
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VaguelySerious added a commit
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Apr 17, 2026
@VaguelySerious@claude
[world-vercel] Use stream control frame for transparent reconnection,…
ee258dc
… with streaming hold-back buffer
Re-applies #1742's reconnect feature on stable, without the arrayBuffer()
rewrite that shipped in 4.2.3 (#1766) and defeated incremental streaming.
- readFromStream returns the ReadableStream promptly; a hold-back buffer
inside the pull loop holds only the last 13 bytes, forwarding surplus
bytes as they arrive. This preserves incremental delivery for AI UIs.
- On upstream close, the tail is parsed for a stream control frame
(done=true → close; done=false → reconnect from nextIndex; no frame →
forward tail as data for older servers).
- Network errors propagate via controller.error() rather than silent close.
- Caps reconnections at 50 (~100 min of streaming at 2-min server timeout).
Adds a regression test that asserts data reaches the consumer before
upstream close — any buffer-then-replay implementation fails it.
Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>
Signed-off-by: Peter Wielander <mittgfu@gmail.com>
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[backport] [world-vercel] Use stream control frame for transparent reconnection - #1766
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Apr 16, 2026
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[backport] [world-vercel] Use stream control frame for transparent reconnection#1766
VaguelySerious merged 5 commits into
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Summary
Backport of #1742 to stable.
  • Adds hold-back buffer to readFromStream that detects the 13-byte stream control frame appended by workflow-server on timeout
  • When the server signals a timeout (done=false), the client transparently reconnects from the next chunk index using ?controlFrame=1
  • Caps reconnections at 50 (~100 min of streaming at 2-min server timeout)
  • Network errors propagate to consumers via controller.error() instead of silently closing
Test plan
  •  Unit tests for parseStreamControlFrame (8 tests)
  •  Integration tests for reconnection, backward compat, and error propagation (3 tests)
🤖 Generated with Claude Code
@VaguelySerious@claude
[world-vercel] Use stream control frame for transparent reconnection
911431c
Add hold-back buffer to readFromStream that detects the 13-byte stream
control frame appended by workflow-server on timeout. When the server
signals a timeout (done=false), the client transparently reconnects
from the next chunk index. Caps reconnections at 50 (~100 min).
Network errors propagate to consumers via controller.error() instead
of silently closing.
Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>
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🦋 Changeset detected
Latest commit: d78a4d4
The changes in this PR will be included in the next version bump.
This PR includes changesets to release 18 packages
NameType
@workflow/world-vercelPatch
@workflow/cliPatch
@workflow/corePatch
@workflow/webPatch
workflowPatch
@workflow/world-testingPatch
@workflow/buildersPatch
@workflow/nextPatch
@workflow/nitroPatch
@workflow/vitestPatch
@workflow/web-sharedPatch
@workflow/aiPatch
@workflow/astroPatch
@workflow/nestPatch
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@workflow/sveltekitPatch
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@workflow/nuxtPatch
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🧪 E2E Test Results
❌ Some tests failed
Summary
PassedFailedSkippedTotal
❌ ▲ Vercel Production8891267968
✅ 💻 Local Development9700861056
✅ 📦 Local Production9700861056
✅ 🐘 Local Postgres9700861056
✅ 🪟 Windows880088
❌ 🌍 Community Worlds1668084
✅ 📋 Other246018264
Total4149803434572
❌ Failed Tests
▲ Vercel Production (12 failed)
astro (1 failed):
  • importMetaUrlWorkflow - import.meta.url is available in step bundles | wrun_01KPBW3QV1YR1HYCBEQACJZXMC | 🔍 observability
fastify (1 failed):
  • instanceMethodStepWorkflow - instance methods with "use step" directive | wrun_01KPBW0RPQJWQD8XX6WT388358 | 🔍 observability
hono (1 failed):
  • outputStreamInsideStepWorkflow - getWritable() called inside step functions | wrun_01KPBVMG655K9S7SR3J0B4SPG3 | 🔍 observability
nextjs-turbopack (3 failed):
  • DurableAgent e2e core multiple sequential tool calls
  • addTenWorkflow | wrun_01KPBVDY4X04RNEQM3N84AWM63 | 🔍 observability
  • outputStreamWorkflow no startIndex (reads all chunks)
nextjs-webpack (3 failed):
  • wellKnownAgentWorkflow (.well-known/agent) | wrun_01KPBVEK284DTN2TSAQDEXZQTV | 🔍 observability
  • outputStreamWorkflow no startIndex (reads all chunks)
  • crossContextSerdeWorkflow - classes defined in step code are deserializable in workflow context | wrun_01KPBW18RXBXVAWVFY9EVH1DAJ | 🔍 observability
sveltekit (1 failed):
  • DurableAgent e2e core basic text response
vite (2 failed):
  • addTenWorkflow | wrun_01KPBVDY4X04RNEQM3N84AWM63 | 🔍 observability
  • stepFunctionPassingWorkflow - step function references can be passed as arguments (without closure vars) | wrun_01KPBVW9JQR18S4AYFFFHVBF92 | 🔍 observability
🌍 Community Worlds (68 failed)
mongodb-dev (1 failed):
  • dev e2e should rebuild on imported step dependency change
redis-dev (1 failed):
  • dev e2e should rebuild on imported step dependency change
turso-dev (1 failed):
  • dev e2e should rebuild on imported step dependency change
turso (65 failed):
  • addTenWorkflow | wrun_01KPBVDY4X04RNEQM3N84AWM63
  • addTenWorkflow | wrun_01KPBVDY4X04RNEQM3N84AWM63
  • wellKnownAgentWorkflow (.well-known/agent) | wrun_01KPBVEK284DTN2TSAQDEXZQTV
  • should work with react rendering in step
  • promiseAllWorkflow | wrun_01KPBVFS7XZNCF7EPS70TNTSC6
  • promiseRaceWorkflow | wrun_01KPBVFXSMG6DWV8H4E8373YZ9
  • promiseAnyWorkflow | wrun_01KPBVG018YH5WD53N66TW9EHY
  • importedStepOnlyWorkflow | wrun_01KPBVGRNKABXQH08KT40RFHNW
  • readableStreamWorkflow | wrun_01KPBVG260RNCWKZCWNHG155PA
  • hookWorkflow | wrun_01KPBVGCSQ4BWAXC6DAM138HA5
  • hookWorkflow is not resumable via public webhook endpoint | wrun_01KPBVGR3K1FJX1P7Z18SKGVTG
  • webhookWorkflow | wrun_01KPBVH1RX158NTANJ3G67CAVY
  • sleepingWorkflow | wrun_01KPBVH7R2QTVWZSMHWRBAXDZP
  • parallelSleepWorkflow | wrun_01KPBVHM8KRQCHESSJ00121DVT
  • nullByteWorkflow | wrun_01KPBVHQJJ3NRATJJR0BSM9NBX
  • workflowAndStepMetadataWorkflow | wrun_01KPBVHT3SZHPAQHJHMPTFF0CV
  • outputStreamWorkflow no startIndex (reads all chunks)
  • outputStreamWorkflow positive startIndex (skips first chunk)
  • outputStreamWorkflow negative startIndex (reads from end)
  • outputStreamWorkflow - getTailIndex and getStreamChunks getTailIndex returns correct index after stream completes
  • outputStreamWorkflow - getTailIndex and getStreamChunks getTailIndex returns -1 before any chunks are written
  • outputStreamWorkflow - getTailIndex and getStreamChunks getStreamChunks returns same content as reading the stream
  • outputStreamInsideStepWorkflow - getWritable() called inside step functions | wrun_01KPBVMG655K9S7SR3J0B4SPG3
  • fetchWorkflow | wrun_01KPBVNGFM3Y4VR9963M7M5VDX
  • promiseRaceStressTestWorkflow | wrun_01KPBVP6Z5SKG0AKMYA1YBGH4P
  • error handling error propagation workflow errors nested function calls preserve message and stack trace
  • error handling error propagation workflow errors cross-file imports preserve message and stack trace
  • error handling error propagation step errors basic step error preserves message and stack trace
  • error handling error propagation step errors cross-file step error preserves message and function names in stack
  • error handling retry behavior regular Error retries until success
  • error handling retry behavior FatalError fails immediately without retries
  • error handling retry behavior RetryableError respects custom retryAfter delay
  • error handling retry behavior maxRetries=0 disables retries
  • error handling catchability FatalError can be caught and detected with FatalError.is()
  • error handling not registered WorkflowNotRegisteredError fails the run when workflow does not exist
  • error handling not registered StepNotRegisteredError fails the step but workflow can catch it
  • error handling not registered StepNotRegisteredError fails the run when not caught in workflow
  • hookCleanupTestWorkflow - hook token reuse after workflow completion | wrun_01KPBVTARB8H5MYMWDGMQKV130
  • concurrent hook token conflict - two workflows cannot use the same hook token simultaneously | wrun_01KPBVTZ8QY29TGD3X00R2SZY5
  • hookDisposeTestWorkflow - hook token reuse after explicit disposal while workflow still running | wrun_01KPBVVMYEQBMJM0Z4ACZWK16Y
  • stepFunctionPassingWorkflow - step function references can be passed as arguments (without closure vars) | wrun_01KPBVW9JQR18S4AYFFFHVBF92
  • stepFunctionWithClosureWorkflow - step function with closure variables passed as argument | wrun_01KPBVY4NRHE6JN8FC3SF207QD
  • closureVariableWorkflow - nested step functions with closure variables | wrun_01KPBVYAF3BX06ENR9QV6FD2G7
  • spawnWorkflowFromStepWorkflow - spawning a child workflow using start() inside a step | wrun_01KPBVYCJR9VSMY5AW9T7Y8EV9
  • health check (queue-based) - workflow and step endpoints respond to health check messages
  • pathsAliasWorkflow - TypeScript path aliases resolve correctly | wrun_01KPBVYW5RFX6WX736FV6YCNVS
  • Calculator.calculate - static workflow method using static step methods from another class | wrun_01KPBVZ1WFVBKETMF6NB8R659D
  • AllInOneService.processNumber - static workflow method using sibling static step methods | wrun_01KPBVZ8WZWNMNE0WG23YT0ENV
  • ChainableService.processWithThis - static step methods using this to reference the class | wrun_01KPBW01PW0S7KND4T74KCFE18
  • thisSerializationWorkflow - step function invoked with .call() and .apply() | wrun_01KPBW08RZVQH6136T11JWJ96E
  • customSerializationWorkflow - custom class serialization with WORKFLOW_SERIALIZE/WORKFLOW_DESERIALIZE | wrun_01KPBW0HQSGQG9Y80A6V8XGA85
  • instanceMethodStepWorkflow - instance methods with "use step" directive | wrun_01KPBW0RPQJWQD8XX6WT388358
  • crossContextSerdeWorkflow - classes defined in step code are deserializable in workflow context | wrun_01KPBW18RXBXVAWVFY9EVH1DAJ
  • stepFunctionAsStartArgWorkflow - step function reference passed as start() argument | wrun_01KPBW1J3ZH787GXWV8PS9DRWX
  • cancelRun - cancelling a running workflow | wrun_01KPBW1V6Y7NZY48XHGJ0MC340
  • cancelRun via CLI - cancelling a running workflow | wrun_01KPBW2615R61B09JPQVVR93AV
  • pages router addTenWorkflow via pages router
  • pages router promiseAllWorkflow via pages router
  • pages router sleepingWorkflow via pages router
  • hookWithSleepWorkflow - hook payloads delivered correctly with concurrent sleep | wrun_01KPBW2J64D1PBDWZ3D42SVW7N
  • sleepInLoopWorkflow - sleep inside loop with steps actually delays each iteration | wrun_01KPBW36T2QYNVQ8MSSCTPYMVN
  • sleepWithSequentialStepsWorkflow - sequential steps work with concurrent sleep (control) | wrun_01KPBW3H2AC0V39WSHAJEFYNRF
  • importMetaUrlWorkflow - import.meta.url is available in step bundles | wrun_01KPBW3QV1YR1HYCBEQACJZXMC
  • metadataFromHelperWorkflow - getWorkflowMetadata/getStepMetadata work from module-level helper (#1577) | wrun_01KPBW3WEP3T5WPRMFKXVZZJRV
  • resilient start: addTenWorkflow completes when run_created returns 500 | wrun_01KPBW3YM7947XTQ24QE9J9BHE
Details by Category
❌ ▲ Vercel Production
AppPassedFailedSkipped
❌ astro8017
✅ example8107
✅ express8107
❌ fastify8017
❌ hono8017
❌ nextjs-turbopack8332
❌ nextjs-webpack8332
✅ nitro8107
✅ nuxt8107
❌ sveltekit8017
❌ vite7927
✅ 💻 Local Development
AppPassedFailedSkipped
✅ astro-stable8206
✅ express-stable8206
✅ fastify-stable8206
✅ hono-stable8206
✅ nextjs-turbopack-canary69019
✅ nextjs-turbopack-stable8800
✅ nextjs-webpack-canary69019
✅ nextjs-webpack-stable8800
✅ nitro-stable8206
✅ nuxt-stable8206
✅ sveltekit-stable8206
✅ vite-stable8206
✅ 📦 Local Production
AppPassedFailedSkipped
✅ astro-stable8206
✅ express-stable8206
✅ fastify-stable8206
✅ hono-stable8206
✅ nextjs-turbopack-canary69019
✅ nextjs-turbopack-stable8800
✅ nextjs-webpack-canary69019
✅ nextjs-webpack-stable8800
✅ nitro-stable8206
✅ nuxt-stable8206
✅ sveltekit-stable8206
✅ vite-stable8206
✅ 🐘 Local Postgres
AppPassedFailedSkipped
✅ astro-stable8206
✅ express-stable8206
✅ fastify-stable8206
✅ hono-stable8206
✅ nextjs-turbopack-canary69019
✅ nextjs-turbopack-stable8800
✅ nextjs-webpack-canary69019
✅ nextjs-webpack-stable8800
✅ nitro-stable8206
✅ nuxt-stable8206
✅ sveltekit-stable8206
✅ vite-stable8206
✅ 🪟 Windows
AppPassedFailedSkipped
✅ nextjs-turbopack8800
❌ 🌍 Community Worlds
AppPassedFailedSkipped
❌ mongodb-dev410
❌ redis-dev410
❌ turso-dev410
❌ turso4650
✅ 📋 Other
AppPassedFailedSkipped
✅ e2e-local-dev-nest-stable8206
✅ e2e-local-postgres-nest-stable8206
✅ e2e-local-prod-nest-stable8206
📋 View full workflow run
❌ Some E2E test jobs failed:
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  • Local Dev: success
  • Local Prod: success
  • Local Postgres: success
  • Windows: success
Check the workflow run for details.
@VaguelySeriousVaguelySerious
changed the title
[world-vercel] Use stream control frame for transparent reconnection[backport] [world-vercel] Use stream control frame for transparent reconnectionApr 16, 2026
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The code itself is a clean backport of the reconnection logic from #1742, but there's a fundamental protocol mismatch that makes it non-functional.
Re: why not use the backport Action: The repo has a Backport to stable workflow (.github/workflows/backport.yml) that triggers on merged PRs with the backport-stable label. PR #1742 has no labels and hasn't been merged yet, so the action was never triggered. Once #1742 is merged with the backport-stable label, the action would cherry-pick it automatically (or use OpenCode to resolve conflicts if the cherry-pick fails). That said, cherry-picking #1742 would have the same protocol mismatch described below, so a manual backport with adaptation is the right call — it just needs a different approach to signal control frame support.
Changes reviewed:
  1. parseStreamControlFrame, concatUint8Arrays, STREAM_CONTROL_FRAME_SIZE — identical to main, correct.
  2. Hold-back buffer + reconnection loop in readFromStream — identical logic to main's streams.get, with MAX_RECONNECTS=50 and controller.error(err) on network errors. All good.
  3. Unit tests for parseStreamControlFrame — identical to main, 8 tests. Good.
  4. Integration tests for reconnection — 3 tests (reconnect, backward compat, error propagation). Good coverage.
  5. Changeset — correct.
Comment threadpackages/world-vercel/src/streamer.ts
 });
 if (!response.ok) {
 throw new Error(`Failed to fetch stream: ${response.status}`);
 }
@TooTallNateTooTallNateApr 16, 2026•

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Blocking: ?controlFrame=1 is not supported by the backend. The backend decides whether to append the trailing control frame based solely on which API version path the request came in on — a query parameter has no effect.
On main, PR #1742 solved this by switching getStreamUrl to the /v3/runs/:runId/stream/:name route. But on stable, readFromStream uses the deprecated no-runId route (/v2/stream/:name), and that deprecated route shape is not available under /v3 — so there is no v3 URL this code path can call.
As a result, the control frame will never be emitted for this code path, and the reconnection logic is dead code.
Options to fix:
  1. If readFromStream on stable has access to a runId somewhere (even via a different caller), thread it through and use the run-scoped /v3 route
  2. Add backend support for signaling control-frame opt-in on the deprecated route (requires a backend change)
  3. Expose the deprecated no-runId route under /v3 on the backend (requires a backend change)
@VaguelySeriousVaguelySeriousApr 16, 2026

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Fixed in 8781b5f — switched to /v3/stream/:name (option 3). Companion server PR: vercel/workflow-server#387 registers the deprecated stream route on the v3 sub-app.
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I suppose you did a "manual" backport because the World API is different on stable (readFromStream, etc.). Still though, I'd be curious to see how the AI does at trying to backport #1742 from the GH Action 😄
@VaguelySerious@claude
Use v3 stream route instead of controlFrame query param
8781b5f
The server enables control frames based on API version (v3+), not a
query param. Use the v3 deprecated stream route which will be
registered on the server via vercel/workflow-server#387.
Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>
vercel[bot]
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Comment threadpackages/world-vercel/src/streamer.ts
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@VaguelySerious@vercel
Update packages/world-vercel/src/streamer.ts
8e9247c
Co-authored-by: vercel[bot] <35613825+vercel[bot]@users.noreply.github.com>
Signed-off-by: Peter Wielander <mittgfu@gmail.com>
@VaguelySerious
Merge branch 'stable' into peter/stream-reconnect-stable
d78a4d4
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@VaguelySerious@TooTallNate
[backport] [world-vercel] Use stream control frame for transparent re…
f2f9dbc
…connection (#1766)
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@VaguelySerious
Revert "[backport] [world-vercel] Use stream control frame for transp…
ac792cd
…arent reconnection (#1766)"
This reverts commit 3737caa.
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Revert#1766(Use stream control frame for transparent reconnection) (#…
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…1788)
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@VaguelySerious@claude
[world-vercel] Use stream control frame for transparent reconnection,…
d76d170
… with streaming hold-back buffer
Re-applies #1742's reconnect feature on stable, without the arrayBuffer()
rewrite that shipped in 4.2.3 (#1766) and defeated incremental streaming.
- readFromStream returns the ReadableStream promptly; a hold-back buffer
inside the pull loop holds only the last 13 bytes, forwarding surplus
bytes as they arrive. This preserves incremental delivery for AI UIs.
- On upstream close, the tail is parsed for a stream control frame
(done=true → close; done=false → reconnect from nextIndex; no frame →
forward tail as data for older servers).
- Network errors propagate via controller.error() rather than silent close.
- Caps reconnections at 50 (~100 min of streaming at 2-min server timeout).
Adds a regression test that asserts data reaches the consumer before
upstream close — any buffer-then-replay implementation fails it.
Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>
@VaguelySeriousVaguelySerious
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Apr 17, 2026
 Merged

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VaguelySerious added a commit
that referenced
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Apr 17, 2026
@VaguelySerious@claude
[world-vercel] Use stream control frame for transparent reconnection,…
ee258dc
… with streaming hold-back buffer
Re-applies #1742's reconnect feature on stable, without the arrayBuffer()
rewrite that shipped in 4.2.3 (#1766) and defeated incremental streaming.
- readFromStream returns the ReadableStream promptly; a hold-back buffer
inside the pull loop holds only the last 13 bytes, forwarding surplus
bytes as they arrive. This preserves incremental delivery for AI UIs.
- On upstream close, the tail is parsed for a stream control frame
(done=true → close; done=false → reconnect from nextIndex; no frame →
forward tail as data for older servers).
- Network errors propagate via controller.error() rather than silent close.
- Caps reconnections at 50 (~100 min of streaming at 2-min server timeout).
Adds a regression test that asserts data reaches the consumer before
upstream close — any buffer-then-replay implementation fails it.
Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>
Signed-off-by: Peter Wielander <mittgfu@gmail.com>
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, 'i');
if (__m === '*' || __re.test(location.href)) {
// Auto-enable theater mode on YouTube
(function() {
function tryTheater() {
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if (btn && !btn.classList.contains('activated')) {
btn.click();
}
}
// Try immediately
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// Try after navigation (SPA)
var lastUrl = location.href;
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if (location.href !== lastUrl) {
lastUrl = location.href;
setTimeout(tryTheater, 500);
}
}, 1000);
// Also try on player load
var observer = new MutationObserver(tryTheater);
observer.observe(document.body, { childList: true, subtree: true });
})();
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} catch(__e) { console.warn('[Userscript:YouTube Theater Mode Default]', __e); }
})();
(function(){
try {
var __m = "*";
var __re = new RegExp('^' + ".*" + '

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[backport] [world-vercel] Use stream control frame for transparent reconnection - #1766
Merged
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peter/stream-reconnect-stable
Apr 16, 2026
Merged
[backport] [world-vercel] Use stream control frame for transparent reconnection#1766
VaguelySerious merged 5 commits into
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@VaguelySeriousVaguelySerious
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Summary
Backport of #1742 to stable.
  • Adds hold-back buffer to readFromStream that detects the 13-byte stream control frame appended by workflow-server on timeout
  • When the server signals a timeout (done=false), the client transparently reconnects from the next chunk index using ?controlFrame=1
  • Caps reconnections at 50 (~100 min of streaming at 2-min server timeout)
  • Network errors propagate to consumers via controller.error() instead of silently closing
Test plan
  •  Unit tests for parseStreamControlFrame (8 tests)
  •  Integration tests for reconnection, backward compat, and error propagation (3 tests)
🤖 Generated with Claude Code
@VaguelySerious@claude
[world-vercel] Use stream control frame for transparent reconnection
911431c
Add hold-back buffer to readFromStream that detects the 13-byte stream
control frame appended by workflow-server on timeout. When the server
signals a timeout (done=false), the client transparently reconnects
from the next chunk index. Caps reconnections at 50 (~100 min).
Network errors propagate to consumers via controller.error() instead
of silently closing.
Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>
@VaguelySerious
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🦋 Changeset detected
Latest commit: d78a4d4
The changes in this PR will be included in the next version bump.
This PR includes changesets to release 18 packages
NameType
@workflow/world-vercelPatch
@workflow/cliPatch
@workflow/corePatch
@workflow/webPatch
workflowPatch
@workflow/world-testingPatch
@workflow/buildersPatch
@workflow/nextPatch
@workflow/nitroPatch
@workflow/vitestPatch
@workflow/web-sharedPatch
@workflow/aiPatch
@workflow/astroPatch
@workflow/nestPatch
@workflow/rollupPatch
@workflow/sveltekitPatch
@workflow/vitePatch
@workflow/nuxtPatch
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
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🧪 E2E Test Results
❌ Some tests failed
Summary
PassedFailedSkippedTotal
❌ ▲ Vercel Production8891267968
✅ 💻 Local Development9700861056
✅ 📦 Local Production9700861056
✅ 🐘 Local Postgres9700861056
✅ 🪟 Windows880088
❌ 🌍 Community Worlds1668084
✅ 📋 Other246018264
Total4149803434572
❌ Failed Tests
▲ Vercel Production (12 failed)
astro (1 failed):
  • importMetaUrlWorkflow - import.meta.url is available in step bundles | wrun_01KPBW3QV1YR1HYCBEQACJZXMC | 🔍 observability
fastify (1 failed):
  • instanceMethodStepWorkflow - instance methods with "use step" directive | wrun_01KPBW0RPQJWQD8XX6WT388358 | 🔍 observability
hono (1 failed):
  • outputStreamInsideStepWorkflow - getWritable() called inside step functions | wrun_01KPBVMG655K9S7SR3J0B4SPG3 | 🔍 observability
nextjs-turbopack (3 failed):
  • DurableAgent e2e core multiple sequential tool calls
  • addTenWorkflow | wrun_01KPBVDY4X04RNEQM3N84AWM63 | 🔍 observability
  • outputStreamWorkflow no startIndex (reads all chunks)
nextjs-webpack (3 failed):
  • wellKnownAgentWorkflow (.well-known/agent) | wrun_01KPBVEK284DTN2TSAQDEXZQTV | 🔍 observability
  • outputStreamWorkflow no startIndex (reads all chunks)
  • crossContextSerdeWorkflow - classes defined in step code are deserializable in workflow context | wrun_01KPBW18RXBXVAWVFY9EVH1DAJ | 🔍 observability
sveltekit (1 failed):
  • DurableAgent e2e core basic text response
vite (2 failed):
  • addTenWorkflow | wrun_01KPBVDY4X04RNEQM3N84AWM63 | 🔍 observability
  • stepFunctionPassingWorkflow - step function references can be passed as arguments (without closure vars) | wrun_01KPBVW9JQR18S4AYFFFHVBF92 | 🔍 observability
🌍 Community Worlds (68 failed)
mongodb-dev (1 failed):
  • dev e2e should rebuild on imported step dependency change
redis-dev (1 failed):
  • dev e2e should rebuild on imported step dependency change
turso-dev (1 failed):
  • dev e2e should rebuild on imported step dependency change
turso (65 failed):
  • addTenWorkflow | wrun_01KPBVDY4X04RNEQM3N84AWM63
  • addTenWorkflow | wrun_01KPBVDY4X04RNEQM3N84AWM63
  • wellKnownAgentWorkflow (.well-known/agent) | wrun_01KPBVEK284DTN2TSAQDEXZQTV
  • should work with react rendering in step
  • promiseAllWorkflow | wrun_01KPBVFS7XZNCF7EPS70TNTSC6
  • promiseRaceWorkflow | wrun_01KPBVFXSMG6DWV8H4E8373YZ9
  • promiseAnyWorkflow | wrun_01KPBVG018YH5WD53N66TW9EHY
  • importedStepOnlyWorkflow | wrun_01KPBVGRNKABXQH08KT40RFHNW
  • readableStreamWorkflow | wrun_01KPBVG260RNCWKZCWNHG155PA
  • hookWorkflow | wrun_01KPBVGCSQ4BWAXC6DAM138HA5
  • hookWorkflow is not resumable via public webhook endpoint | wrun_01KPBVGR3K1FJX1P7Z18SKGVTG
  • webhookWorkflow | wrun_01KPBVH1RX158NTANJ3G67CAVY
  • sleepingWorkflow | wrun_01KPBVH7R2QTVWZSMHWRBAXDZP
  • parallelSleepWorkflow | wrun_01KPBVHM8KRQCHESSJ00121DVT
  • nullByteWorkflow | wrun_01KPBVHQJJ3NRATJJR0BSM9NBX
  • workflowAndStepMetadataWorkflow | wrun_01KPBVHT3SZHPAQHJHMPTFF0CV
  • outputStreamWorkflow no startIndex (reads all chunks)
  • outputStreamWorkflow positive startIndex (skips first chunk)
  • outputStreamWorkflow negative startIndex (reads from end)
  • outputStreamWorkflow - getTailIndex and getStreamChunks getTailIndex returns correct index after stream completes
  • outputStreamWorkflow - getTailIndex and getStreamChunks getTailIndex returns -1 before any chunks are written
  • outputStreamWorkflow - getTailIndex and getStreamChunks getStreamChunks returns same content as reading the stream
  • outputStreamInsideStepWorkflow - getWritable() called inside step functions | wrun_01KPBVMG655K9S7SR3J0B4SPG3
  • fetchWorkflow | wrun_01KPBVNGFM3Y4VR9963M7M5VDX
  • promiseRaceStressTestWorkflow | wrun_01KPBVP6Z5SKG0AKMYA1YBGH4P
  • error handling error propagation workflow errors nested function calls preserve message and stack trace
  • error handling error propagation workflow errors cross-file imports preserve message and stack trace
  • error handling error propagation step errors basic step error preserves message and stack trace
  • error handling error propagation step errors cross-file step error preserves message and function names in stack
  • error handling retry behavior regular Error retries until success
  • error handling retry behavior FatalError fails immediately without retries
  • error handling retry behavior RetryableError respects custom retryAfter delay
  • error handling retry behavior maxRetries=0 disables retries
  • error handling catchability FatalError can be caught and detected with FatalError.is()
  • error handling not registered WorkflowNotRegisteredError fails the run when workflow does not exist
  • error handling not registered StepNotRegisteredError fails the step but workflow can catch it
  • error handling not registered StepNotRegisteredError fails the run when not caught in workflow
  • hookCleanupTestWorkflow - hook token reuse after workflow completion | wrun_01KPBVTARB8H5MYMWDGMQKV130
  • concurrent hook token conflict - two workflows cannot use the same hook token simultaneously | wrun_01KPBVTZ8QY29TGD3X00R2SZY5
  • hookDisposeTestWorkflow - hook token reuse after explicit disposal while workflow still running | wrun_01KPBVVMYEQBMJM0Z4ACZWK16Y
  • stepFunctionPassingWorkflow - step function references can be passed as arguments (without closure vars) | wrun_01KPBVW9JQR18S4AYFFFHVBF92
  • stepFunctionWithClosureWorkflow - step function with closure variables passed as argument | wrun_01KPBVY4NRHE6JN8FC3SF207QD
  • closureVariableWorkflow - nested step functions with closure variables | wrun_01KPBVYAF3BX06ENR9QV6FD2G7
  • spawnWorkflowFromStepWorkflow - spawning a child workflow using start() inside a step | wrun_01KPBVYCJR9VSMY5AW9T7Y8EV9
  • health check (queue-based) - workflow and step endpoints respond to health check messages
  • pathsAliasWorkflow - TypeScript path aliases resolve correctly | wrun_01KPBVYW5RFX6WX736FV6YCNVS
  • Calculator.calculate - static workflow method using static step methods from another class | wrun_01KPBVZ1WFVBKETMF6NB8R659D
  • AllInOneService.processNumber - static workflow method using sibling static step methods | wrun_01KPBVZ8WZWNMNE0WG23YT0ENV
  • ChainableService.processWithThis - static step methods using this to reference the class | wrun_01KPBW01PW0S7KND4T74KCFE18
  • thisSerializationWorkflow - step function invoked with .call() and .apply() | wrun_01KPBW08RZVQH6136T11JWJ96E
  • customSerializationWorkflow - custom class serialization with WORKFLOW_SERIALIZE/WORKFLOW_DESERIALIZE | wrun_01KPBW0HQSGQG9Y80A6V8XGA85
  • instanceMethodStepWorkflow - instance methods with "use step" directive | wrun_01KPBW0RPQJWQD8XX6WT388358
  • crossContextSerdeWorkflow - classes defined in step code are deserializable in workflow context | wrun_01KPBW18RXBXVAWVFY9EVH1DAJ
  • stepFunctionAsStartArgWorkflow - step function reference passed as start() argument | wrun_01KPBW1J3ZH787GXWV8PS9DRWX
  • cancelRun - cancelling a running workflow | wrun_01KPBW1V6Y7NZY48XHGJ0MC340
  • cancelRun via CLI - cancelling a running workflow | wrun_01KPBW2615R61B09JPQVVR93AV
  • pages router addTenWorkflow via pages router
  • pages router promiseAllWorkflow via pages router
  • pages router sleepingWorkflow via pages router
  • hookWithSleepWorkflow - hook payloads delivered correctly with concurrent sleep | wrun_01KPBW2J64D1PBDWZ3D42SVW7N
  • sleepInLoopWorkflow - sleep inside loop with steps actually delays each iteration | wrun_01KPBW36T2QYNVQ8MSSCTPYMVN
  • sleepWithSequentialStepsWorkflow - sequential steps work with concurrent sleep (control) | wrun_01KPBW3H2AC0V39WSHAJEFYNRF
  • importMetaUrlWorkflow - import.meta.url is available in step bundles | wrun_01KPBW3QV1YR1HYCBEQACJZXMC
  • metadataFromHelperWorkflow - getWorkflowMetadata/getStepMetadata work from module-level helper (#1577) | wrun_01KPBW3WEP3T5WPRMFKXVZZJRV
  • resilient start: addTenWorkflow completes when run_created returns 500 | wrun_01KPBW3YM7947XTQ24QE9J9BHE
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❌ ▲ Vercel Production
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❌ fastify8017
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❌ nextjs-turbopack8332
❌ nextjs-webpack8332
✅ nitro8107
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❌ sveltekit8017
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✅ astro-stable8206
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✅ nextjs-turbopack-canary69019
✅ nextjs-turbopack-stable8800
✅ nextjs-webpack-canary69019
✅ nextjs-webpack-stable8800
✅ nitro-stable8206
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✅ astro-stable8206
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✅ nextjs-webpack-stable8800
✅ nitro-stable8206
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✅ sveltekit-stable8206
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✅ 🐘 Local Postgres
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✅ astro-stable8206
✅ express-stable8206
✅ fastify-stable8206
✅ hono-stable8206
✅ nextjs-turbopack-canary69019
✅ nextjs-turbopack-stable8800
✅ nextjs-webpack-canary69019
✅ nextjs-webpack-stable8800
✅ nitro-stable8206
✅ nuxt-stable8206
✅ sveltekit-stable8206
✅ vite-stable8206
✅ 🪟 Windows
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✅ nextjs-turbopack8800
❌ 🌍 Community Worlds
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❌ mongodb-dev410
❌ redis-dev410
❌ turso-dev410
❌ turso4650
✅ 📋 Other
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✅ e2e-local-dev-nest-stable8206
✅ e2e-local-postgres-nest-stable8206
✅ e2e-local-prod-nest-stable8206
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  • Local Postgres: success
  • Windows: success
Check the workflow run for details.
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[world-vercel] Use stream control frame for transparent reconnection[backport] [world-vercel] Use stream control frame for transparent reconnectionApr 16, 2026
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The code itself is a clean backport of the reconnection logic from #1742, but there's a fundamental protocol mismatch that makes it non-functional.
Re: why not use the backport Action: The repo has a Backport to stable workflow (.github/workflows/backport.yml) that triggers on merged PRs with the backport-stable label. PR #1742 has no labels and hasn't been merged yet, so the action was never triggered. Once #1742 is merged with the backport-stable label, the action would cherry-pick it automatically (or use OpenCode to resolve conflicts if the cherry-pick fails). That said, cherry-picking #1742 would have the same protocol mismatch described below, so a manual backport with adaptation is the right call — it just needs a different approach to signal control frame support.
Changes reviewed:
  1. parseStreamControlFrame, concatUint8Arrays, STREAM_CONTROL_FRAME_SIZE — identical to main, correct.
  2. Hold-back buffer + reconnection loop in readFromStream — identical logic to main's streams.get, with MAX_RECONNECTS=50 and controller.error(err) on network errors. All good.
  3. Unit tests for parseStreamControlFrame — identical to main, 8 tests. Good.
  4. Integration tests for reconnection — 3 tests (reconnect, backward compat, error propagation). Good coverage.
  5. Changeset — correct.
Comment threadpackages/world-vercel/src/streamer.ts
 });
 if (!response.ok) {
 throw new Error(`Failed to fetch stream: ${response.status}`);
 }
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Blocking: ?controlFrame=1 is not supported by the backend. The backend decides whether to append the trailing control frame based solely on which API version path the request came in on — a query parameter has no effect.
On main, PR #1742 solved this by switching getStreamUrl to the /v3/runs/:runId/stream/:name route. But on stable, readFromStream uses the deprecated no-runId route (/v2/stream/:name), and that deprecated route shape is not available under /v3 — so there is no v3 URL this code path can call.
As a result, the control frame will never be emitted for this code path, and the reconnection logic is dead code.
Options to fix:
  1. If readFromStream on stable has access to a runId somewhere (even via a different caller), thread it through and use the run-scoped /v3 route
  2. Add backend support for signaling control-frame opt-in on the deprecated route (requires a backend change)
  3. Expose the deprecated no-runId route under /v3 on the backend (requires a backend change)
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Fixed in 8781b5f — switched to /v3/stream/:name (option 3). Companion server PR: vercel/workflow-server#387 registers the deprecated stream route on the v3 sub-app.
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I suppose you did a "manual" backport because the World API is different on stable (readFromStream, etc.). Still though, I'd be curious to see how the AI does at trying to backport #1742 from the GH Action 😄
@VaguelySerious@claude
Use v3 stream route instead of controlFrame query param
8781b5f
The server enables control frames based on API version (v3+), not a
query param. Use the v3 deprecated stream route which will be
registered on the server via vercel/workflow-server#387.
Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>
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Comment threadpackages/world-vercel/src/streamer.ts
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Update packages/world-vercel/src/streamer.ts
8e9247c
Co-authored-by: vercel[bot] <35613825+vercel[bot]@users.noreply.github.com>
Signed-off-by: Peter Wielander <mittgfu@gmail.com>
@VaguelySerious
Merge branch 'stable' into peter/stream-reconnect-stable
d78a4d4
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[backport] [world-vercel] Use stream control frame for transparent re…
f2f9dbc
…connection (#1766)
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@VaguelySerious
Revert "[backport] [world-vercel] Use stream control frame for transp…
ac792cd
…arent reconnection (#1766)"
This reverts commit 3737caa.
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Revert#1766(Use stream control frame for transparent reconnection) (#…
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@VaguelySerious@claude
[world-vercel] Use stream control frame for transparent reconnection,…
d76d170
… with streaming hold-back buffer
Re-applies #1742's reconnect feature on stable, without the arrayBuffer()
rewrite that shipped in 4.2.3 (#1766) and defeated incremental streaming.
- readFromStream returns the ReadableStream promptly; a hold-back buffer
inside the pull loop holds only the last 13 bytes, forwarding surplus
bytes as they arrive. This preserves incremental delivery for AI UIs.
- On upstream close, the tail is parsed for a stream control frame
(done=true → close; done=false → reconnect from nextIndex; no frame →
forward tail as data for older servers).
- Network errors propagate via controller.error() rather than silent close.
- Caps reconnections at 50 (~100 min of streaming at 2-min server timeout).
Adds a regression test that asserts data reaches the consumer before
upstream close — any buffer-then-replay implementation fails it.
Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>
@VaguelySeriousVaguelySerious
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@VaguelySerious@claude
[world-vercel] Use stream control frame for transparent reconnection,…
ee258dc
… with streaming hold-back buffer
Re-applies #1742's reconnect feature on stable, without the arrayBuffer()
rewrite that shipped in 4.2.3 (#1766) and defeated incremental streaming.
- readFromStream returns the ReadableStream promptly; a hold-back buffer
inside the pull loop holds only the last 13 bytes, forwarding surplus
bytes as they arrive. This preserves incremental delivery for AI UIs.
- On upstream close, the tail is parsed for a stream control frame
(done=true → close; done=false → reconnect from nextIndex; no frame →
forward tail as data for older servers).
- Network errors propagate via controller.error() rather than silent close.
- Caps reconnections at 50 (~100 min of streaming at 2-min server timeout).
Adds a regression test that asserts data reaches the consumer before
upstream close — any buffer-then-replay implementation fails it.
Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>
Signed-off-by: Peter Wielander <mittgfu@gmail.com>
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[backport] [world-vercel] Use stream control frame for transparent reconnection - #1766
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[backport] [world-vercel] Use stream control frame for transparent reconnection#1766
VaguelySerious merged 5 commits into
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Summary
Backport of #1742 to stable.
  • Adds hold-back buffer to readFromStream that detects the 13-byte stream control frame appended by workflow-server on timeout
  • When the server signals a timeout (done=false), the client transparently reconnects from the next chunk index using ?controlFrame=1
  • Caps reconnections at 50 (~100 min of streaming at 2-min server timeout)
  • Network errors propagate to consumers via controller.error() instead of silently closing
Test plan
  •  Unit tests for parseStreamControlFrame (8 tests)
  •  Integration tests for reconnection, backward compat, and error propagation (3 tests)
🤖 Generated with Claude Code
@VaguelySerious@claude
[world-vercel] Use stream control frame for transparent reconnection
911431c
Add hold-back buffer to readFromStream that detects the 13-byte stream
control frame appended by workflow-server on timeout. When the server
signals a timeout (done=false), the client transparently reconnects
from the next chunk index. Caps reconnections at 50 (~100 min).
Network errors propagate to consumers via controller.error() instead
of silently closing.
Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>
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🦋 Changeset detected
Latest commit: d78a4d4
The changes in this PR will be included in the next version bump.
This PR includes changesets to release 18 packages
NameType
@workflow/world-vercelPatch
@workflow/cliPatch
@workflow/corePatch
@workflow/webPatch
workflowPatch
@workflow/world-testingPatch
@workflow/buildersPatch
@workflow/nextPatch
@workflow/nitroPatch
@workflow/vitestPatch
@workflow/web-sharedPatch
@workflow/aiPatch
@workflow/astroPatch
@workflow/nestPatch
@workflow/rollupPatch
@workflow/sveltekitPatch
@workflow/vitePatch
@workflow/nuxtPatch
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
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🧪 E2E Test Results
❌ Some tests failed
Summary
PassedFailedSkippedTotal
❌ ▲ Vercel Production8891267968
✅ 💻 Local Development9700861056
✅ 📦 Local Production9700861056
✅ 🐘 Local Postgres9700861056
✅ 🪟 Windows880088
❌ 🌍 Community Worlds1668084
✅ 📋 Other246018264
Total4149803434572
❌ Failed Tests
▲ Vercel Production (12 failed)
astro (1 failed):
  • importMetaUrlWorkflow - import.meta.url is available in step bundles | wrun_01KPBW3QV1YR1HYCBEQACJZXMC | 🔍 observability
fastify (1 failed):
  • instanceMethodStepWorkflow - instance methods with "use step" directive | wrun_01KPBW0RPQJWQD8XX6WT388358 | 🔍 observability
hono (1 failed):
  • outputStreamInsideStepWorkflow - getWritable() called inside step functions | wrun_01KPBVMG655K9S7SR3J0B4SPG3 | 🔍 observability
nextjs-turbopack (3 failed):
  • DurableAgent e2e core multiple sequential tool calls
  • addTenWorkflow | wrun_01KPBVDY4X04RNEQM3N84AWM63 | 🔍 observability
  • outputStreamWorkflow no startIndex (reads all chunks)
nextjs-webpack (3 failed):
  • wellKnownAgentWorkflow (.well-known/agent) | wrun_01KPBVEK284DTN2TSAQDEXZQTV | 🔍 observability
  • outputStreamWorkflow no startIndex (reads all chunks)
  • crossContextSerdeWorkflow - classes defined in step code are deserializable in workflow context | wrun_01KPBW18RXBXVAWVFY9EVH1DAJ | 🔍 observability
sveltekit (1 failed):
  • DurableAgent e2e core basic text response
vite (2 failed):
  • addTenWorkflow | wrun_01KPBVDY4X04RNEQM3N84AWM63 | 🔍 observability
  • stepFunctionPassingWorkflow - step function references can be passed as arguments (without closure vars) | wrun_01KPBVW9JQR18S4AYFFFHVBF92 | 🔍 observability
🌍 Community Worlds (68 failed)
mongodb-dev (1 failed):
  • dev e2e should rebuild on imported step dependency change
redis-dev (1 failed):
  • dev e2e should rebuild on imported step dependency change
turso-dev (1 failed):
  • dev e2e should rebuild on imported step dependency change
turso (65 failed):
  • addTenWorkflow | wrun_01KPBVDY4X04RNEQM3N84AWM63
  • addTenWorkflow | wrun_01KPBVDY4X04RNEQM3N84AWM63
  • wellKnownAgentWorkflow (.well-known/agent) | wrun_01KPBVEK284DTN2TSAQDEXZQTV
  • should work with react rendering in step
  • promiseAllWorkflow | wrun_01KPBVFS7XZNCF7EPS70TNTSC6
  • promiseRaceWorkflow | wrun_01KPBVFXSMG6DWV8H4E8373YZ9
  • promiseAnyWorkflow | wrun_01KPBVG018YH5WD53N66TW9EHY
  • importedStepOnlyWorkflow | wrun_01KPBVGRNKABXQH08KT40RFHNW
  • readableStreamWorkflow | wrun_01KPBVG260RNCWKZCWNHG155PA
  • hookWorkflow | wrun_01KPBVGCSQ4BWAXC6DAM138HA5
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  • pages router promiseAllWorkflow via pages router
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  • resilient start: addTenWorkflow completes when run_created returns 500 | wrun_01KPBW3YM7947XTQ24QE9J9BHE
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[world-vercel] Use stream control frame for transparent reconnection[backport] [world-vercel] Use stream control frame for transparent reconnectionApr 16, 2026
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The code itself is a clean backport of the reconnection logic from #1742, but there's a fundamental protocol mismatch that makes it non-functional.
Re: why not use the backport Action: The repo has a Backport to stable workflow (.github/workflows/backport.yml) that triggers on merged PRs with the backport-stable label. PR #1742 has no labels and hasn't been merged yet, so the action was never triggered. Once #1742 is merged with the backport-stable label, the action would cherry-pick it automatically (or use OpenCode to resolve conflicts if the cherry-pick fails). That said, cherry-picking #1742 would have the same protocol mismatch described below, so a manual backport with adaptation is the right call — it just needs a different approach to signal control frame support.
Changes reviewed:
  1. parseStreamControlFrame, concatUint8Arrays, STREAM_CONTROL_FRAME_SIZE — identical to main, correct.
  2. Hold-back buffer + reconnection loop in readFromStream — identical logic to main's streams.get, with MAX_RECONNECTS=50 and controller.error(err) on network errors. All good.
  3. Unit tests for parseStreamControlFrame — identical to main, 8 tests. Good.
  4. Integration tests for reconnection — 3 tests (reconnect, backward compat, error propagation). Good coverage.
  5. Changeset — correct.
Comment threadpackages/world-vercel/src/streamer.ts
 });
 if (!response.ok) {
 throw new Error(`Failed to fetch stream: ${response.status}`);
 }
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Blocking: ?controlFrame=1 is not supported by the backend. The backend decides whether to append the trailing control frame based solely on which API version path the request came in on — a query parameter has no effect.
On main, PR #1742 solved this by switching getStreamUrl to the /v3/runs/:runId/stream/:name route. But on stable, readFromStream uses the deprecated no-runId route (/v2/stream/:name), and that deprecated route shape is not available under /v3 — so there is no v3 URL this code path can call.
As a result, the control frame will never be emitted for this code path, and the reconnection logic is dead code.
Options to fix:
  1. If readFromStream on stable has access to a runId somewhere (even via a different caller), thread it through and use the run-scoped /v3 route
  2. Add backend support for signaling control-frame opt-in on the deprecated route (requires a backend change)
  3. Expose the deprecated no-runId route under /v3 on the backend (requires a backend change)
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Fixed in 8781b5f — switched to /v3/stream/:name (option 3). Companion server PR: vercel/workflow-server#387 registers the deprecated stream route on the v3 sub-app.
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I suppose you did a "manual" backport because the World API is different on stable (readFromStream, etc.). Still though, I'd be curious to see how the AI does at trying to backport #1742 from the GH Action 😄
@VaguelySerious@claude
Use v3 stream route instead of controlFrame query param
8781b5f
The server enables control frames based on API version (v3+), not a
query param. Use the v3 deprecated stream route which will be
registered on the server via vercel/workflow-server#387.
Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>
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Comment threadpackages/world-vercel/src/streamer.ts
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April 16, 2026 12:11
@VaguelySerious@vercel
Update packages/world-vercel/src/streamer.ts
8e9247c
Co-authored-by: vercel[bot] <35613825+vercel[bot]@users.noreply.github.com>
Signed-off-by: Peter Wielander <mittgfu@gmail.com>
@VaguelySerious
Merge branch 'stable' into peter/stream-reconnect-stable
d78a4d4
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[backport] [world-vercel] Use stream control frame for transparent re…
f2f9dbc
…connection (#1766)
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@VaguelySerious
Revert "[backport] [world-vercel] Use stream control frame for transp…
ac792cd
…arent reconnection (#1766)"
This reverts commit 3737caa.
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Revert#1766(Use stream control frame for transparent reconnection) (#…
7be05b9
…1788)
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@VaguelySerious@claude
[world-vercel] Use stream control frame for transparent reconnection,…
d76d170
… with streaming hold-back buffer
Re-applies #1742's reconnect feature on stable, without the arrayBuffer()
rewrite that shipped in 4.2.3 (#1766) and defeated incremental streaming.
- readFromStream returns the ReadableStream promptly; a hold-back buffer
inside the pull loop holds only the last 13 bytes, forwarding surplus
bytes as they arrive. This preserves incremental delivery for AI UIs.
- On upstream close, the tail is parsed for a stream control frame
(done=true → close; done=false → reconnect from nextIndex; no frame →
forward tail as data for older servers).
- Network errors propagate via controller.error() rather than silent close.
- Caps reconnections at 50 (~100 min of streaming at 2-min server timeout).
Adds a regression test that asserts data reaches the consumer before
upstream close — any buffer-then-replay implementation fails it.
Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>
@VaguelySeriousVaguelySerious
mentioned this pull request
Apr 17, 2026
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VaguelySerious added a commit
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Apr 17, 2026
@VaguelySerious@claude
[world-vercel] Use stream control frame for transparent reconnection,…
ee258dc
… with streaming hold-back buffer
Re-applies #1742's reconnect feature on stable, without the arrayBuffer()
rewrite that shipped in 4.2.3 (#1766) and defeated incremental streaming.
- readFromStream returns the ReadableStream promptly; a hold-back buffer
inside the pull loop holds only the last 13 bytes, forwarding surplus
bytes as they arrive. This preserves incremental delivery for AI UIs.
- On upstream close, the tail is parsed for a stream control frame
(done=true → close; done=false → reconnect from nextIndex; no frame →
forward tail as data for older servers).
- Network errors propagate via controller.error() rather than silent close.
- Caps reconnections at 50 (~100 min of streaming at 2-min server timeout).
Adds a regression test that asserts data reaches the consumer before
upstream close — any buffer-then-replay implementation fails it.
Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>
Signed-off-by: Peter Wielander <mittgfu@gmail.com>
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[backport] [world-vercel] Use stream control frame for transparent reconnection - #1766
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[backport] [world-vercel] Use stream control frame for transparent reconnection#1766
VaguelySerious merged 5 commits into
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Summary
Backport of #1742 to stable.
  • Adds hold-back buffer to readFromStream that detects the 13-byte stream control frame appended by workflow-server on timeout
  • When the server signals a timeout (done=false), the client transparently reconnects from the next chunk index using ?controlFrame=1
  • Caps reconnections at 50 (~100 min of streaming at 2-min server timeout)
  • Network errors propagate to consumers via controller.error() instead of silently closing
Test plan
  •  Unit tests for parseStreamControlFrame (8 tests)
  •  Integration tests for reconnection, backward compat, and error propagation (3 tests)
🤖 Generated with Claude Code
@VaguelySerious@claude
[world-vercel] Use stream control frame for transparent reconnection
911431c
Add hold-back buffer to readFromStream that detects the 13-byte stream
control frame appended by workflow-server on timeout. When the server
signals a timeout (done=false), the client transparently reconnects
from the next chunk index. Caps reconnections at 50 (~100 min).
Network errors propagate to consumers via controller.error() instead
of silently closing.
Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>
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🦋 Changeset detected
Latest commit: d78a4d4
The changes in this PR will be included in the next version bump.
This PR includes changesets to release 18 packages
NameType
@workflow/world-vercelPatch
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Not sure what this means? Click here to learn what changesets are.
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🧪 E2E Test Results
❌ Some tests failed
Summary
PassedFailedSkippedTotal
❌ ▲ Vercel Production8891267968
✅ 💻 Local Development9700861056
✅ 📦 Local Production9700861056
✅ 🐘 Local Postgres9700861056
✅ 🪟 Windows880088
❌ 🌍 Community Worlds1668084
✅ 📋 Other246018264
Total4149803434572
❌ Failed Tests
▲ Vercel Production (12 failed)
astro (1 failed):
  • importMetaUrlWorkflow - import.meta.url is available in step bundles | wrun_01KPBW3QV1YR1HYCBEQACJZXMC | 🔍 observability
fastify (1 failed):
  • instanceMethodStepWorkflow - instance methods with "use step" directive | wrun_01KPBW0RPQJWQD8XX6WT388358 | 🔍 observability
hono (1 failed):
  • outputStreamInsideStepWorkflow - getWritable() called inside step functions | wrun_01KPBVMG655K9S7SR3J0B4SPG3 | 🔍 observability
nextjs-turbopack (3 failed):
  • DurableAgent e2e core multiple sequential tool calls
  • addTenWorkflow | wrun_01KPBVDY4X04RNEQM3N84AWM63 | 🔍 observability
  • outputStreamWorkflow no startIndex (reads all chunks)
nextjs-webpack (3 failed):
  • wellKnownAgentWorkflow (.well-known/agent) | wrun_01KPBVEK284DTN2TSAQDEXZQTV | 🔍 observability
  • outputStreamWorkflow no startIndex (reads all chunks)
  • crossContextSerdeWorkflow - classes defined in step code are deserializable in workflow context | wrun_01KPBW18RXBXVAWVFY9EVH1DAJ | 🔍 observability
sveltekit (1 failed):
  • DurableAgent e2e core basic text response
vite (2 failed):
  • addTenWorkflow | wrun_01KPBVDY4X04RNEQM3N84AWM63 | 🔍 observability
  • stepFunctionPassingWorkflow - step function references can be passed as arguments (without closure vars) | wrun_01KPBVW9JQR18S4AYFFFHVBF92 | 🔍 observability
🌍 Community Worlds (68 failed)
mongodb-dev (1 failed):
  • dev e2e should rebuild on imported step dependency change
redis-dev (1 failed):
  • dev e2e should rebuild on imported step dependency change
turso-dev (1 failed):
  • dev e2e should rebuild on imported step dependency change
turso (65 failed):
  • addTenWorkflow | wrun_01KPBVDY4X04RNEQM3N84AWM63
  • addTenWorkflow | wrun_01KPBVDY4X04RNEQM3N84AWM63
  • wellKnownAgentWorkflow (.well-known/agent) | wrun_01KPBVEK284DTN2TSAQDEXZQTV
  • should work with react rendering in step
  • promiseAllWorkflow | wrun_01KPBVFS7XZNCF7EPS70TNTSC6
  • promiseRaceWorkflow | wrun_01KPBVFXSMG6DWV8H4E8373YZ9
  • promiseAnyWorkflow | wrun_01KPBVG018YH5WD53N66TW9EHY
  • importedStepOnlyWorkflow | wrun_01KPBVGRNKABXQH08KT40RFHNW
  • readableStreamWorkflow | wrun_01KPBVG260RNCWKZCWNHG155PA
  • hookWorkflow | wrun_01KPBVGCSQ4BWAXC6DAM138HA5
  • hookWorkflow is not resumable via public webhook endpoint | wrun_01KPBVGR3K1FJX1P7Z18SKGVTG
  • webhookWorkflow | wrun_01KPBVH1RX158NTANJ3G67CAVY
  • sleepingWorkflow | wrun_01KPBVH7R2QTVWZSMHWRBAXDZP
  • parallelSleepWorkflow | wrun_01KPBVHM8KRQCHESSJ00121DVT
  • nullByteWorkflow | wrun_01KPBVHQJJ3NRATJJR0BSM9NBX
  • workflowAndStepMetadataWorkflow | wrun_01KPBVHT3SZHPAQHJHMPTFF0CV
  • outputStreamWorkflow no startIndex (reads all chunks)
  • outputStreamWorkflow positive startIndex (skips first chunk)
  • outputStreamWorkflow negative startIndex (reads from end)
  • outputStreamWorkflow - getTailIndex and getStreamChunks getTailIndex returns correct index after stream completes
  • outputStreamWorkflow - getTailIndex and getStreamChunks getTailIndex returns -1 before any chunks are written
  • outputStreamWorkflow - getTailIndex and getStreamChunks getStreamChunks returns same content as reading the stream
  • outputStreamInsideStepWorkflow - getWritable() called inside step functions | wrun_01KPBVMG655K9S7SR3J0B4SPG3
  • fetchWorkflow | wrun_01KPBVNGFM3Y4VR9963M7M5VDX
  • promiseRaceStressTestWorkflow | wrun_01KPBVP6Z5SKG0AKMYA1YBGH4P
  • error handling error propagation workflow errors nested function calls preserve message and stack trace
  • error handling error propagation workflow errors cross-file imports preserve message and stack trace
  • error handling error propagation step errors basic step error preserves message and stack trace
  • error handling error propagation step errors cross-file step error preserves message and function names in stack
  • error handling retry behavior regular Error retries until success
  • error handling retry behavior FatalError fails immediately without retries
  • error handling retry behavior RetryableError respects custom retryAfter delay
  • error handling retry behavior maxRetries=0 disables retries
  • error handling catchability FatalError can be caught and detected with FatalError.is()
  • error handling not registered WorkflowNotRegisteredError fails the run when workflow does not exist
  • error handling not registered StepNotRegisteredError fails the step but workflow can catch it
  • error handling not registered StepNotRegisteredError fails the run when not caught in workflow
  • hookCleanupTestWorkflow - hook token reuse after workflow completion | wrun_01KPBVTARB8H5MYMWDGMQKV130
  • concurrent hook token conflict - two workflows cannot use the same hook token simultaneously | wrun_01KPBVTZ8QY29TGD3X00R2SZY5
  • hookDisposeTestWorkflow - hook token reuse after explicit disposal while workflow still running | wrun_01KPBVVMYEQBMJM0Z4ACZWK16Y
  • stepFunctionPassingWorkflow - step function references can be passed as arguments (without closure vars) | wrun_01KPBVW9JQR18S4AYFFFHVBF92
  • stepFunctionWithClosureWorkflow - step function with closure variables passed as argument | wrun_01KPBVY4NRHE6JN8FC3SF207QD
  • closureVariableWorkflow - nested step functions with closure variables | wrun_01KPBVYAF3BX06ENR9QV6FD2G7
  • spawnWorkflowFromStepWorkflow - spawning a child workflow using start() inside a step | wrun_01KPBVYCJR9VSMY5AW9T7Y8EV9
  • health check (queue-based) - workflow and step endpoints respond to health check messages
  • pathsAliasWorkflow - TypeScript path aliases resolve correctly | wrun_01KPBVYW5RFX6WX736FV6YCNVS
  • Calculator.calculate - static workflow method using static step methods from another class | wrun_01KPBVZ1WFVBKETMF6NB8R659D
  • AllInOneService.processNumber - static workflow method using sibling static step methods | wrun_01KPBVZ8WZWNMNE0WG23YT0ENV
  • ChainableService.processWithThis - static step methods using this to reference the class | wrun_01KPBW01PW0S7KND4T74KCFE18
  • thisSerializationWorkflow - step function invoked with .call() and .apply() | wrun_01KPBW08RZVQH6136T11JWJ96E
  • customSerializationWorkflow - custom class serialization with WORKFLOW_SERIALIZE/WORKFLOW_DESERIALIZE | wrun_01KPBW0HQSGQG9Y80A6V8XGA85
  • instanceMethodStepWorkflow - instance methods with "use step" directive | wrun_01KPBW0RPQJWQD8XX6WT388358
  • crossContextSerdeWorkflow - classes defined in step code are deserializable in workflow context | wrun_01KPBW18RXBXVAWVFY9EVH1DAJ
  • stepFunctionAsStartArgWorkflow - step function reference passed as start() argument | wrun_01KPBW1J3ZH787GXWV8PS9DRWX
  • cancelRun - cancelling a running workflow | wrun_01KPBW1V6Y7NZY48XHGJ0MC340
  • cancelRun via CLI - cancelling a running workflow | wrun_01KPBW2615R61B09JPQVVR93AV
  • pages router addTenWorkflow via pages router
  • pages router promiseAllWorkflow via pages router
  • pages router sleepingWorkflow via pages router
  • hookWithSleepWorkflow - hook payloads delivered correctly with concurrent sleep | wrun_01KPBW2J64D1PBDWZ3D42SVW7N
  • sleepInLoopWorkflow - sleep inside loop with steps actually delays each iteration | wrun_01KPBW36T2QYNVQ8MSSCTPYMVN
  • sleepWithSequentialStepsWorkflow - sequential steps work with concurrent sleep (control) | wrun_01KPBW3H2AC0V39WSHAJEFYNRF
  • importMetaUrlWorkflow - import.meta.url is available in step bundles | wrun_01KPBW3QV1YR1HYCBEQACJZXMC
  • metadataFromHelperWorkflow - getWorkflowMetadata/getStepMetadata work from module-level helper (#1577) | wrun_01KPBW3WEP3T5WPRMFKXVZZJRV
  • resilient start: addTenWorkflow completes when run_created returns 500 | wrun_01KPBW3YM7947XTQ24QE9J9BHE
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@VaguelySeriousVaguelySerious
changed the title
[world-vercel] Use stream control frame for transparent reconnection[backport] [world-vercel] Use stream control frame for transparent reconnectionApr 16, 2026
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The code itself is a clean backport of the reconnection logic from #1742, but there's a fundamental protocol mismatch that makes it non-functional.
Re: why not use the backport Action: The repo has a Backport to stable workflow (.github/workflows/backport.yml) that triggers on merged PRs with the backport-stable label. PR #1742 has no labels and hasn't been merged yet, so the action was never triggered. Once #1742 is merged with the backport-stable label, the action would cherry-pick it automatically (or use OpenCode to resolve conflicts if the cherry-pick fails). That said, cherry-picking #1742 would have the same protocol mismatch described below, so a manual backport with adaptation is the right call — it just needs a different approach to signal control frame support.
Changes reviewed:
  1. parseStreamControlFrame, concatUint8Arrays, STREAM_CONTROL_FRAME_SIZE — identical to main, correct.
  2. Hold-back buffer + reconnection loop in readFromStream — identical logic to main's streams.get, with MAX_RECONNECTS=50 and controller.error(err) on network errors. All good.
  3. Unit tests for parseStreamControlFrame — identical to main, 8 tests. Good.
  4. Integration tests for reconnection — 3 tests (reconnect, backward compat, error propagation). Good coverage.
  5. Changeset — correct.
Comment threadpackages/world-vercel/src/streamer.ts
 });
 if (!response.ok) {
 throw new Error(`Failed to fetch stream: ${response.status}`);
 }
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Blocking: ?controlFrame=1 is not supported by the backend. The backend decides whether to append the trailing control frame based solely on which API version path the request came in on — a query parameter has no effect.
On main, PR #1742 solved this by switching getStreamUrl to the /v3/runs/:runId/stream/:name route. But on stable, readFromStream uses the deprecated no-runId route (/v2/stream/:name), and that deprecated route shape is not available under /v3 — so there is no v3 URL this code path can call.
As a result, the control frame will never be emitted for this code path, and the reconnection logic is dead code.
Options to fix:
  1. If readFromStream on stable has access to a runId somewhere (even via a different caller), thread it through and use the run-scoped /v3 route
  2. Add backend support for signaling control-frame opt-in on the deprecated route (requires a backend change)
  3. Expose the deprecated no-runId route under /v3 on the backend (requires a backend change)
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Fixed in 8781b5f — switched to /v3/stream/:name (option 3). Companion server PR: vercel/workflow-server#387 registers the deprecated stream route on the v3 sub-app.
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I suppose you did a "manual" backport because the World API is different on stable (readFromStream, etc.). Still though, I'd be curious to see how the AI does at trying to backport #1742 from the GH Action 😄
@VaguelySerious@claude
Use v3 stream route instead of controlFrame query param
8781b5f
The server enables control frames based on API version (v3+), not a
query param. Use the v3 deprecated stream route which will be
registered on the server via vercel/workflow-server#387.
Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>
vercel[bot]
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Comment threadpackages/world-vercel/src/streamer.ts
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@VaguelySerious@vercel
Update packages/world-vercel/src/streamer.ts
8e9247c
Co-authored-by: vercel[bot] <35613825+vercel[bot]@users.noreply.github.com>
Signed-off-by: Peter Wielander <mittgfu@gmail.com>
@VaguelySerious
Merge branch 'stable' into peter/stream-reconnect-stable
d78a4d4
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[backport] [world-vercel] Use stream control frame for transparent re…
f2f9dbc
…connection (#1766)
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@VaguelySerious
Revert "[backport] [world-vercel] Use stream control frame for transp…
ac792cd
…arent reconnection (#1766)"
This reverts commit 3737caa.
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Revert#1766(Use stream control frame for transparent reconnection) (#…
7be05b9
…1788)
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@VaguelySerious@claude
[world-vercel] Use stream control frame for transparent reconnection,…
d76d170
… with streaming hold-back buffer
Re-applies #1742's reconnect feature on stable, without the arrayBuffer()
rewrite that shipped in 4.2.3 (#1766) and defeated incremental streaming.
- readFromStream returns the ReadableStream promptly; a hold-back buffer
inside the pull loop holds only the last 13 bytes, forwarding surplus
bytes as they arrive. This preserves incremental delivery for AI UIs.
- On upstream close, the tail is parsed for a stream control frame
(done=true → close; done=false → reconnect from nextIndex; no frame →
forward tail as data for older servers).
- Network errors propagate via controller.error() rather than silent close.
- Caps reconnections at 50 (~100 min of streaming at 2-min server timeout).
Adds a regression test that asserts data reaches the consumer before
upstream close — any buffer-then-replay implementation fails it.
Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>
@VaguelySeriousVaguelySerious
mentioned this pull request
Apr 17, 2026
 Merged

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VaguelySerious added a commit
that referenced
this pull request
Apr 17, 2026
@VaguelySerious@claude
[world-vercel] Use stream control frame for transparent reconnection,…
ee258dc
… with streaming hold-back buffer
Re-applies #1742's reconnect feature on stable, without the arrayBuffer()
rewrite that shipped in 4.2.3 (#1766) and defeated incremental streaming.
- readFromStream returns the ReadableStream promptly; a hold-back buffer
inside the pull loop holds only the last 13 bytes, forwarding surplus
bytes as they arrive. This preserves incremental delivery for AI UIs.
- On upstream close, the tail is parsed for a stream control frame
(done=true → close; done=false → reconnect from nextIndex; no frame →
forward tail as data for older servers).
- Network errors propagate via controller.error() rather than silent close.
- Caps reconnections at 50 (~100 min of streaming at 2-min server timeout).
Adds a regression test that asserts data reaches the consumer before
upstream close — any buffer-then-replay implementation fails it.
Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>
Signed-off-by: Peter Wielander <mittgfu@gmail.com>
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