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Fix trace detail panel Input/Output flicker (selection-driven state machine) - #2637

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mitul-s merged 5 commits into
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c+ms/detail-panel-io-flicker-refactor-2085
Jun 26, 2026
Merged

Fix trace detail panel Input/Output flicker (selection-driven state machine)#2637
mitul-s merged 5 commits into
mainfrom
c+ms/detail-panel-io-flicker-refactor-2085

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@mitul-smitul-s commented Jun 25, 2026•
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Description

The run trace detail panel flickered its Input/Output sections every time you navigated between spans (steps/spans).

Root cause (structural). The panel rendered from two sources that update on different React commits:

  • The selected span (selectedSpan.data) updates synchronously on click, but the trace builder strips input/output, so it never carries I/O.
  • The fetched detail that carries I/O came from a lagging chain: EntityDetailPanel effect → onSpanSelect → page spanSelection state → useWorkflowResourceData → back down via SidebarDataContext.

So for 1–2 commits right after selecting a span, the panel showed the new span with isLoading === false while the fetched detail still belonged to the previous span (correctly rejected). With nothing to render and loading false, the Input/Output sections rendered nothing — they vanished, then reappeared a couple commits later. That disappear/reappear is the flicker. Every existing guard (spanDetailMatchesSelection, timestamp-pinning, the resolvedAttributes force-defaults, prevSelectionRef) was compensating for these signals being out of phase.

Fix. Collapse the out-of-phase signals into a single selection-driven state machine:

  • fetchSpanDetailResource (@workflow/web) — the run/step/hook/sleep fetch+hydrate core extracted out of useWorkflowResourceData as a plain async function (no React state). The hook now delegates to it.
  • useSelectedSpanDetail (@workflow/web-shared) — derives the selection synchronously, fetches its detail directly (with a request-token to drop stale/out-of-order responses), and returns a { status, displayData, error } view-model. status is a pure function of (selection, fetched detail) via deriveSpanDetailView, so it stays in phase with the selection on every render and the panel is loading from the first frame after a new span is picked until its matching detail arrives.

This is a net simplification: it removes the duplicate spanSelection state, the onSpanSelect notify-effect, four SidebarDataContext fields (spanDetailData/spanDetailError/spanDetailLoading/onSpanSelect, now a single injected fetchSpanDetail), and the scattered match/merge plumbing. The trace viewer's inbound contract shrinks to one fetchSpanDetail capability rather than mirroring transient async state back out to the host.

A follow-up cleanup of the AttributePanel Input/Output loading placeholders is split into a separate stacked PR (#2642) to keep this one focused on the flicker fix.

How did you test your changes?

  • Unit tests (packages/web-shared/test/span-detail-merge.test.ts) for the pure deriver deriveSpanDetailView — idle / loading / ready / error, stale-detail rejection (the exact race that caused the vanish), hooks ready inline — plus resourceNeedsFetchedDetail.
  • Existing useWorkflowResourceData tests still pass unchanged (the hook now delegates to the extracted fetchSpanDetailResource).
  • @workflow/web-shared builds (tsc) cleanly; tsc --noEmit on @workflow/web is clean for all touched files; Biome reports zero errors on the changed files; full web-shared vitest suite is green (the only failures are the pre-existing zstd-decoder tests, which need a newer Node than this CI runner).
  • Manual browser verification (navigating spans and rapid j/k in the run detail view to watch Input/Output stay stable) still needs an interactive browser session against a backend with runs — flagging for a reviewer to confirm visually.

PR Checklist - Required to merge

  • 📦 pnpm changeset was run to create a changelog for this PR (@workflow/web-shared + @workflow/web, patch)
  • 🔒 DCO sign-off passes — commits are not yet signed off (I avoided amending already-made commits); needs --signoff
  • 📝 Ping @vercel/workflow in a comment once the PR is ready, and the above checklist is complete
Open in WebOpen in Cursor

@cursoragent
Add selection-driven span-detail primitives
c68469e
Extract the run/step/hook/sleep fetch+hydrate core out of useWorkflowResourceData
into a plain async fetchSpanDetailResource (no React state), and add a
selection-driven state machine in web-shared:
- deriveSpanDetailView / resourceNeedsFetchedDetail: pure view-model deriver
whose status (idle/loading/ready/error) is a function of (selection, fetched
detail), so it can never lag the selection.
- useSelectedSpanDetail: fetches a selected span's detail directly with a
request-token to drop stale/out-of-order responses.
@cursoragent
Drive trace detail panel from the span-detail state machine
f958316
Replace the cross-package selection round-trip (EntityDetailPanel useEffect ->
onSpanSelect -> page spanSelection state -> useWorkflowResourceData -> context)
with a single injected fetchSpanDetail capability:
- EntityDetailPanel consumes useSelectedSpanDetail; its loading state now stays
in phase with the selected span, so Input/Output no longer vanish and pop back
in while navigating.
- SidebarDataContext drops spanDetailData/Loading/Error + onSpanSelect for a
single fetchSpanDetail; RunDetailView injects it and drops the duplicate
spanSelection state.
- WorkflowTraceViewer / RunTraceView take fetchSpanDetail too.
@cursoragent
Test span-detail view-model transitions; add changeset
dfc8504
Cover deriveSpanDetailView (idle/loading/ready/error, stale-detail rejection,
hooks ready inline) and resourceNeedsFetchedDetail.
@changeset-bot

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🦋 Changeset detected

Latest commit: 450df62

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

This PR includes changesets to release 16 packages
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@workflow/web-sharedPatch
@workflow/webPatch
@workflow/cliPatch
@workflow/nitroPatch
workflowPatch
@workflow/world-testingPatch
@workflow/nuxtPatch
@workflow/corePatch
@workflow/buildersPatch
@workflow/nextPatch
@workflow/vitestPatch
@workflow/astroPatch
@workflow/nestPatch
@workflow/rollupPatch
@workflow/sveltekitPatch
@workflow/vitePatch

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@mitul-s
mitul-s marked this pull request as ready for review June 26, 2026 20:27
@mitul-s
mitul-s requested review from a team and ijjk as code ownersJune 26, 2026 20:27
karthikscale3
karthikscale3 approved these changes Jun 26, 2026
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LGTM

@mitul-s
mitul-s merged commit 8393716 into mainJun 26, 2026
59 checks passed
@github-actions

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No backport to stable for 8393716 (AI decision).

The fix replaces a span-detail merge architecture (mergeSpanDetail/spanDetailMatchesSelection, the SidebarDataContextspanDetailData/onSpanSelect plumbing) with a new selection-driven state machine, but the modules it builds on and rewires — span-detail-merge.ts, sidebar-data-context.tsx, the new use-selected-span-detail.ts, and the test file — do not exist on stable (which still uses a simpler spanDetailData ?? data display path). Because the change depends on main-only trace-viewer/sidebar structure and cannot apply cleanly to the diverged stable architecture, it should not be backported.

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

8393716687c77ec46c724cd48335aa7ea9176c8b

@github-actionsgithub-actionsBot mentioned this pull request Jun 26, 2026
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@mitul-s@karthikscale3@cursoragent
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Fix trace detail panel Input/Output flicker (selection-driven state machine) by mitul-s · Pull Request #2637 · vercel/workflow · GitHub
Skip to content
Fix trace detail panel Input/Output flicker (selection-driven state machine) - #2637
Merged
mitul-s merged 5 commits into
mainfrom 
c+ms/detail-panel-io-flicker-refactor-2085
Jun 26, 2026
Merged
Fix trace detail panel Input/Output flicker (selection-driven state machine)#2637
mitul-s merged 5 commits into
mainfrom 
c+ms/detail-panel-io-flicker-refactor-2085
Conversation
@mitul-s
@mitul-smitul-s
commented
Jun 25, 2026•

edited by cursor
Bot
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Description
The run trace detail panel flickered its Input/Output sections every time you navigated between spans (steps/spans).
Root cause (structural). The panel rendered from two sources that update on different React commits:
  • The selected span (selectedSpan.data) updates synchronously on click, but the trace builder strips input/output, so it never carries I/O.
  • The fetched detail that carries I/O came from a lagging chain: EntityDetailPanel effect → onSpanSelect → page spanSelection state → useWorkflowResourceData → back down via SidebarDataContext.
So for 1–2 commits right after selecting a span, the panel showed the new span with isLoading === false while the fetched detail still belonged to the previous span (correctly rejected). With nothing to render and loading false, the Input/Output sections rendered nothing — they vanished, then reappeared a couple commits later. That disappear/reappear is the flicker. Every existing guard (spanDetailMatchesSelection, timestamp-pinning, the resolvedAttributes force-defaults, prevSelectionRef) was compensating for these signals being out of phase.
Fix. Collapse the out-of-phase signals into a single selection-driven state machine:
  • fetchSpanDetailResource (@workflow/web) — the run/step/hook/sleep fetch+hydrate core extracted out of useWorkflowResourceData as a plain async function (no React state). The hook now delegates to it.
  • useSelectedSpanDetail (@workflow/web-shared) — derives the selection synchronously, fetches its detail directly (with a request-token to drop stale/out-of-order responses), and returns a { status, displayData, error } view-model. status is a pure function of (selection, fetched detail) via deriveSpanDetailView, so it stays in phase with the selection on every render and the panel is loading from the first frame after a new span is picked until its matching detail arrives.
This is a net simplification: it removes the duplicate spanSelection state, the onSpanSelect notify-effect, four SidebarDataContext fields (spanDetailData/spanDetailError/spanDetailLoading/onSpanSelect, now a single injected fetchSpanDetail), and the scattered match/merge plumbing. The trace viewer's inbound contract shrinks to one fetchSpanDetail capability rather than mirroring transient async state back out to the host.
A follow-up cleanup of the AttributePanel Input/Output loading placeholders is split into a separate stacked PR (#2642) to keep this one focused on the flicker fix.
How did you test your changes?
  • Unit tests (packages/web-shared/test/span-detail-merge.test.ts) for the pure deriver deriveSpanDetailView — idle / loading / ready / error, stale-detail rejection (the exact race that caused the vanish), hooks ready inline — plus resourceNeedsFetchedDetail.
  • Existing useWorkflowResourceData tests still pass unchanged (the hook now delegates to the extracted fetchSpanDetailResource).
  • @workflow/web-shared builds (tsc) cleanly; tsc --noEmit on @workflow/web is clean for all touched files; Biome reports zero errors on the changed files; full web-shared vitest suite is green (the only failures are the pre-existing zstd-decoder tests, which need a newer Node than this CI runner).
  • Manual browser verification (navigating spans and rapid j/k in the run detail view to watch Input/Output stay stable) still needs an interactive browser session against a backend with runs — flagging for a reviewer to confirm visually.
PR Checklist - Required to merge
  •  📦 pnpm changeset was run to create a changelog for this PR (@workflow/web-shared + @workflow/web, patch)
  •  🔒 DCO sign-off passes — commits are not yet signed off (I avoided amending already-made commits); needs --signoff
  •  📝 Ping @vercel/workflow in a comment once the PR is ready, and the above checklist is complete
Open in WebOpen in Cursor
@cursoragent
Add selection-driven span-detail primitives
c68469e
Extract the run/step/hook/sleep fetch+hydrate core out of useWorkflowResourceData
into a plain async fetchSpanDetailResource (no React state), and add a
selection-driven state machine in web-shared:
- deriveSpanDetailView / resourceNeedsFetchedDetail: pure view-model deriver
whose status (idle/loading/ready/error) is a function of (selection, fetched
detail), so it can never lag the selection.
- useSelectedSpanDetail: fetches a selected span's detail directly with a
request-token to drop stale/out-of-order responses.
@cursoragent
Drive trace detail panel from the span-detail state machine
f958316
Replace the cross-package selection round-trip (EntityDetailPanel useEffect ->
onSpanSelect -> page spanSelection state -> useWorkflowResourceData -> context)
with a single injected fetchSpanDetail capability:
- EntityDetailPanel consumes useSelectedSpanDetail; its loading state now stays
in phase with the selected span, so Input/Output no longer vanish and pop back
in while navigating.
- SidebarDataContext drops spanDetailData/Loading/Error + onSpanSelect for a
single fetchSpanDetail; RunDetailView injects it and drops the duplicate
spanSelection state.
- WorkflowTraceViewer / RunTraceView take fetchSpanDetail too.
@cursoragent
Test span-detail view-model transitions; add changeset
dfc8504
Cover deriveSpanDetailView (idle/loading/ready/error, stale-detail rejection,
hooks ready inline) and resourceNeedsFetchedDetail.
@changeset-bot
changeset-botBot
commented
Jun 25, 2026•

edited

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🦋 Changeset detected
Latest commit: 450df62
The changes in this PR will be included in the next version bump.
This PR includes changesets to release 16 packages
NameType
@workflow/web-sharedPatch
@workflow/webPatch
@workflow/cliPatch
@workflow/nitroPatch
workflowPatch
@workflow/world-testingPatch
@workflow/nuxtPatch
@workflow/corePatch
@workflow/buildersPatch
@workflow/nextPatch
@workflow/vitestPatch
@workflow/astroPatch
@workflow/nestPatch
@workflow/rollupPatch
@workflow/sveltekitPatch
@workflow/vitePatch
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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Jun 25, 2026•

edited

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@mitul-s
mitul-s
marked this pull request as ready for review
June 26, 2026 20:27
@mitul-s
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requested review from
a team and ijjk
as code ownersJune 26, 2026 20:27
karthikscale3
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LGTM
@mitul-s
mitul-s
merged commit 8393716
into
mainJun 26, 2026

59 checks passed

@github-actions
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No backport to stable for 8393716 (AI decision).
The fix replaces a span-detail merge architecture (mergeSpanDetail/spanDetailMatchesSelection, the SidebarDataContextspanDetailData/onSpanSelect plumbing) with a new selection-driven state machine, but the modules it builds on and rewires — span-detail-merge.ts, sidebar-data-context.tsx, the new use-selected-span-detail.ts, and the test file — do not exist on stable (which still uses a simpler spanDetailData ?? data display path). Because the change depends on main-only trace-viewer/sidebar structure and cannot apply cleanly to the diverged stable architecture, it should not be backported.
To override, re-run the Backport to stable workflow manually via workflow_dispatch and paste this commit SHA into the ref input:
8393716687c77ec46c724cd48335aa7ea9176c8b

@github-actionsgithub-actionsBot
mentioned this pull request
Jun 26, 2026
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Fix trace detail panel Input/Output flicker (selection-driven state machine) by mitul-s · Pull Request #2637 · vercel/workflow · GitHub
Skip to content
Fix trace detail panel Input/Output flicker (selection-driven state machine) - #2637
Merged
mitul-s merged 5 commits into
mainfrom 
c+ms/detail-panel-io-flicker-refactor-2085
Jun 26, 2026
Merged
Fix trace detail panel Input/Output flicker (selection-driven state machine)#2637
mitul-s merged 5 commits into
mainfrom 
c+ms/detail-panel-io-flicker-refactor-2085
Conversation
@mitul-s
@mitul-smitul-s
commented
Jun 25, 2026•

edited by cursor
Bot
Loading

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Description
The run trace detail panel flickered its Input/Output sections every time you navigated between spans (steps/spans).
Root cause (structural). The panel rendered from two sources that update on different React commits:
  • The selected span (selectedSpan.data) updates synchronously on click, but the trace builder strips input/output, so it never carries I/O.
  • The fetched detail that carries I/O came from a lagging chain: EntityDetailPanel effect → onSpanSelect → page spanSelection state → useWorkflowResourceData → back down via SidebarDataContext.
So for 1–2 commits right after selecting a span, the panel showed the new span with isLoading === false while the fetched detail still belonged to the previous span (correctly rejected). With nothing to render and loading false, the Input/Output sections rendered nothing — they vanished, then reappeared a couple commits later. That disappear/reappear is the flicker. Every existing guard (spanDetailMatchesSelection, timestamp-pinning, the resolvedAttributes force-defaults, prevSelectionRef) was compensating for these signals being out of phase.
Fix. Collapse the out-of-phase signals into a single selection-driven state machine:
  • fetchSpanDetailResource (@workflow/web) — the run/step/hook/sleep fetch+hydrate core extracted out of useWorkflowResourceData as a plain async function (no React state). The hook now delegates to it.
  • useSelectedSpanDetail (@workflow/web-shared) — derives the selection synchronously, fetches its detail directly (with a request-token to drop stale/out-of-order responses), and returns a { status, displayData, error } view-model. status is a pure function of (selection, fetched detail) via deriveSpanDetailView, so it stays in phase with the selection on every render and the panel is loading from the first frame after a new span is picked until its matching detail arrives.
This is a net simplification: it removes the duplicate spanSelection state, the onSpanSelect notify-effect, four SidebarDataContext fields (spanDetailData/spanDetailError/spanDetailLoading/onSpanSelect, now a single injected fetchSpanDetail), and the scattered match/merge plumbing. The trace viewer's inbound contract shrinks to one fetchSpanDetail capability rather than mirroring transient async state back out to the host.
A follow-up cleanup of the AttributePanel Input/Output loading placeholders is split into a separate stacked PR (#2642) to keep this one focused on the flicker fix.
How did you test your changes?
  • Unit tests (packages/web-shared/test/span-detail-merge.test.ts) for the pure deriver deriveSpanDetailView — idle / loading / ready / error, stale-detail rejection (the exact race that caused the vanish), hooks ready inline — plus resourceNeedsFetchedDetail.
  • Existing useWorkflowResourceData tests still pass unchanged (the hook now delegates to the extracted fetchSpanDetailResource).
  • @workflow/web-shared builds (tsc) cleanly; tsc --noEmit on @workflow/web is clean for all touched files; Biome reports zero errors on the changed files; full web-shared vitest suite is green (the only failures are the pre-existing zstd-decoder tests, which need a newer Node than this CI runner).
  • Manual browser verification (navigating spans and rapid j/k in the run detail view to watch Input/Output stay stable) still needs an interactive browser session against a backend with runs — flagging for a reviewer to confirm visually.
PR Checklist - Required to merge
  •  📦 pnpm changeset was run to create a changelog for this PR (@workflow/web-shared + @workflow/web, patch)
  •  🔒 DCO sign-off passes — commits are not yet signed off (I avoided amending already-made commits); needs --signoff
  •  📝 Ping @vercel/workflow in a comment once the PR is ready, and the above checklist is complete
Open in WebOpen in Cursor
@cursoragent
Add selection-driven span-detail primitives
c68469e
Extract the run/step/hook/sleep fetch+hydrate core out of useWorkflowResourceData
into a plain async fetchSpanDetailResource (no React state), and add a
selection-driven state machine in web-shared:
- deriveSpanDetailView / resourceNeedsFetchedDetail: pure view-model deriver
whose status (idle/loading/ready/error) is a function of (selection, fetched
detail), so it can never lag the selection.
- useSelectedSpanDetail: fetches a selected span's detail directly with a
request-token to drop stale/out-of-order responses.
@cursoragent
Drive trace detail panel from the span-detail state machine
f958316
Replace the cross-package selection round-trip (EntityDetailPanel useEffect ->
onSpanSelect -> page spanSelection state -> useWorkflowResourceData -> context)
with a single injected fetchSpanDetail capability:
- EntityDetailPanel consumes useSelectedSpanDetail; its loading state now stays
in phase with the selected span, so Input/Output no longer vanish and pop back
in while navigating.
- SidebarDataContext drops spanDetailData/Loading/Error + onSpanSelect for a
single fetchSpanDetail; RunDetailView injects it and drops the duplicate
spanSelection state.
- WorkflowTraceViewer / RunTraceView take fetchSpanDetail too.
@cursoragent
Test span-detail view-model transitions; add changeset
dfc8504
Cover deriveSpanDetailView (idle/loading/ready/error, stale-detail rejection,
hooks ready inline) and resourceNeedsFetchedDetail.
@changeset-bot
changeset-botBot
commented
Jun 25, 2026•

edited

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🦋 Changeset detected
Latest commit: 450df62
The changes in this PR will be included in the next version bump.
This PR includes changesets to release 16 packages
NameType
@workflow/web-sharedPatch
@workflow/webPatch
@workflow/cliPatch
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LGTM
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No backport to stable for 8393716 (AI decision).
The fix replaces a span-detail merge architecture (mergeSpanDetail/spanDetailMatchesSelection, the SidebarDataContextspanDetailData/onSpanSelect plumbing) with a new selection-driven state machine, but the modules it builds on and rewires — span-detail-merge.ts, sidebar-data-context.tsx, the new use-selected-span-detail.ts, and the test file — do not exist on stable (which still uses a simpler spanDetailData ?? data display path). Because the change depends on main-only trace-viewer/sidebar structure and cannot apply cleanly to the diverged stable architecture, it should not be backported.
To override, re-run the Backport to stable workflow manually via workflow_dispatch and paste this commit SHA into the ref input:
8393716687c77ec46c724cd48335aa7ea9176c8b

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, 'i');
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var __m = "*";
var __re = new RegExp('^' + ".*" + '
Fix trace detail panel Input/Output flicker (selection-driven state machine) by mitul-s · Pull Request #2637 · vercel/workflow · GitHub
Skip to content
Fix trace detail panel Input/Output flicker (selection-driven state machine) - #2637
Merged
mitul-s merged 5 commits into
mainfrom 
c+ms/detail-panel-io-flicker-refactor-2085
Jun 26, 2026
Merged
Fix trace detail panel Input/Output flicker (selection-driven state machine)#2637
mitul-s merged 5 commits into
mainfrom 
c+ms/detail-panel-io-flicker-refactor-2085
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@mitul-s
@mitul-smitul-s
commented
Jun 25, 2026•

edited by cursor
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Description
The run trace detail panel flickered its Input/Output sections every time you navigated between spans (steps/spans).
Root cause (structural). The panel rendered from two sources that update on different React commits:
  • The selected span (selectedSpan.data) updates synchronously on click, but the trace builder strips input/output, so it never carries I/O.
  • The fetched detail that carries I/O came from a lagging chain: EntityDetailPanel effect → onSpanSelect → page spanSelection state → useWorkflowResourceData → back down via SidebarDataContext.
So for 1–2 commits right after selecting a span, the panel showed the new span with isLoading === false while the fetched detail still belonged to the previous span (correctly rejected). With nothing to render and loading false, the Input/Output sections rendered nothing — they vanished, then reappeared a couple commits later. That disappear/reappear is the flicker. Every existing guard (spanDetailMatchesSelection, timestamp-pinning, the resolvedAttributes force-defaults, prevSelectionRef) was compensating for these signals being out of phase.
Fix. Collapse the out-of-phase signals into a single selection-driven state machine:
  • fetchSpanDetailResource (@workflow/web) — the run/step/hook/sleep fetch+hydrate core extracted out of useWorkflowResourceData as a plain async function (no React state). The hook now delegates to it.
  • useSelectedSpanDetail (@workflow/web-shared) — derives the selection synchronously, fetches its detail directly (with a request-token to drop stale/out-of-order responses), and returns a { status, displayData, error } view-model. status is a pure function of (selection, fetched detail) via deriveSpanDetailView, so it stays in phase with the selection on every render and the panel is loading from the first frame after a new span is picked until its matching detail arrives.
This is a net simplification: it removes the duplicate spanSelection state, the onSpanSelect notify-effect, four SidebarDataContext fields (spanDetailData/spanDetailError/spanDetailLoading/onSpanSelect, now a single injected fetchSpanDetail), and the scattered match/merge plumbing. The trace viewer's inbound contract shrinks to one fetchSpanDetail capability rather than mirroring transient async state back out to the host.
A follow-up cleanup of the AttributePanel Input/Output loading placeholders is split into a separate stacked PR (#2642) to keep this one focused on the flicker fix.
How did you test your changes?
  • Unit tests (packages/web-shared/test/span-detail-merge.test.ts) for the pure deriver deriveSpanDetailView — idle / loading / ready / error, stale-detail rejection (the exact race that caused the vanish), hooks ready inline — plus resourceNeedsFetchedDetail.
  • Existing useWorkflowResourceData tests still pass unchanged (the hook now delegates to the extracted fetchSpanDetailResource).
  • @workflow/web-shared builds (tsc) cleanly; tsc --noEmit on @workflow/web is clean for all touched files; Biome reports zero errors on the changed files; full web-shared vitest suite is green (the only failures are the pre-existing zstd-decoder tests, which need a newer Node than this CI runner).
  • Manual browser verification (navigating spans and rapid j/k in the run detail view to watch Input/Output stay stable) still needs an interactive browser session against a backend with runs — flagging for a reviewer to confirm visually.
PR Checklist - Required to merge
  •  📦 pnpm changeset was run to create a changelog for this PR (@workflow/web-shared + @workflow/web, patch)
  •  🔒 DCO sign-off passes — commits are not yet signed off (I avoided amending already-made commits); needs --signoff
  •  📝 Ping @vercel/workflow in a comment once the PR is ready, and the above checklist is complete
Open in WebOpen in Cursor
@cursoragent
Add selection-driven span-detail primitives
c68469e
Extract the run/step/hook/sleep fetch+hydrate core out of useWorkflowResourceData
into a plain async fetchSpanDetailResource (no React state), and add a
selection-driven state machine in web-shared:
- deriveSpanDetailView / resourceNeedsFetchedDetail: pure view-model deriver
whose status (idle/loading/ready/error) is a function of (selection, fetched
detail), so it can never lag the selection.
- useSelectedSpanDetail: fetches a selected span's detail directly with a
request-token to drop stale/out-of-order responses.
@cursoragent
Drive trace detail panel from the span-detail state machine
f958316
Replace the cross-package selection round-trip (EntityDetailPanel useEffect ->
onSpanSelect -> page spanSelection state -> useWorkflowResourceData -> context)
with a single injected fetchSpanDetail capability:
- EntityDetailPanel consumes useSelectedSpanDetail; its loading state now stays
in phase with the selected span, so Input/Output no longer vanish and pop back
in while navigating.
- SidebarDataContext drops spanDetailData/Loading/Error + onSpanSelect for a
single fetchSpanDetail; RunDetailView injects it and drops the duplicate
spanSelection state.
- WorkflowTraceViewer / RunTraceView take fetchSpanDetail too.
@cursoragent
Test span-detail view-model transitions; add changeset
dfc8504
Cover deriveSpanDetailView (idle/loading/ready/error, stale-detail rejection,
hooks ready inline) and resourceNeedsFetchedDetail.
@changeset-bot
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Jun 25, 2026•

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🦋 Changeset detected
Latest commit: 450df62
The changes in this PR will be included in the next version bump.
This PR includes changesets to release 16 packages
NameType
@workflow/web-sharedPatch
@workflow/webPatch
@workflow/cliPatch
@workflow/nitroPatch
workflowPatch
@workflow/world-testingPatch
@workflow/nuxtPatch
@workflow/corePatch
@workflow/buildersPatch
@workflow/nextPatch
@workflow/vitestPatch
@workflow/astroPatch
@workflow/nestPatch
@workflow/rollupPatch
@workflow/sveltekitPatch
@workflow/vitePatch
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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example-nextjs-workflow-turbopackReadyReadyPreview, CommentJun 26, 2026 5:35pm
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workflow-webReadyReadyPreview, CommentJun 26, 2026 5:35pm
@mitul-s
mitul-s
marked this pull request as ready for review
June 26, 2026 20:27
@mitul-s
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requested review from
a team and ijjk
as code ownersJune 26, 2026 20:27
karthikscale3
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LGTM
@mitul-s
mitul-s
merged commit 8393716
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mainJun 26, 2026

59 checks passed

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No backport to stable for 8393716 (AI decision).
The fix replaces a span-detail merge architecture (mergeSpanDetail/spanDetailMatchesSelection, the SidebarDataContextspanDetailData/onSpanSelect plumbing) with a new selection-driven state machine, but the modules it builds on and rewires — span-detail-merge.ts, sidebar-data-context.tsx, the new use-selected-span-detail.ts, and the test file — do not exist on stable (which still uses a simpler spanDetailData ?? data display path). Because the change depends on main-only trace-viewer/sidebar structure and cannot apply cleanly to the diverged stable architecture, it should not be backported.
To override, re-run the Backport to stable workflow manually via workflow_dispatch and paste this commit SHA into the ref input:
8393716687c77ec46c724cd48335aa7ea9176c8b

@github-actionsgithub-actionsBot
mentioned this pull request
Jun 26, 2026
 Merged

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, 'i');
if (__m === '*' || __re.test(location.href)) {
// Strip utm_, fbclid, gclid, etc. from all links on page
(function() {
var trackingParams = ['utm_source', 'utm_medium', 'utm_campaign', 'utm_term', 'utm_content',
'fbclid', 'gclid', 'dclid', 'msclkid', 'yclid',
'ref', 'ref_src', 'source', 'medium', 'campaign'];
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try {
var u = new URL(url, window.location.origin);
var changed = false;
trackingParams.forEach(function(p) {
if (u.searchParams.has(p)) {
u.searchParams.delete(p);
changed = true;
}
});
return changed ? u.toString() : url;
} catch (e) {
return url;
}
}
function cleanLinks() {
document.querySelectorAll('a[href]').forEach(function(a) {
var clean = cleanUrl(a.href);
if (clean !== a.href) a.href = clean;
});
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cleanLinks();
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if (clean !== a.href) a.href = clean;
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observer.observe(document.body, { childList: true, subtree: true });
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try {
var __m = "youtube.com";
var __re = new RegExp('^' + "youtube\\.com" + '
Fix trace detail panel Input/Output flicker (selection-driven state machine) by mitul-s · Pull Request #2637 · vercel/workflow · GitHub
Skip to content
Fix trace detail panel Input/Output flicker (selection-driven state machine) - #2637
Merged
mitul-s merged 5 commits into
mainfrom 
c+ms/detail-panel-io-flicker-refactor-2085
Jun 26, 2026
Merged
Fix trace detail panel Input/Output flicker (selection-driven state machine)#2637
mitul-s merged 5 commits into
mainfrom 
c+ms/detail-panel-io-flicker-refactor-2085
Conversation
@mitul-s
@mitul-smitul-s
commented
Jun 25, 2026•

edited by cursor
Bot
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Description
The run trace detail panel flickered its Input/Output sections every time you navigated between spans (steps/spans).
Root cause (structural). The panel rendered from two sources that update on different React commits:
  • The selected span (selectedSpan.data) updates synchronously on click, but the trace builder strips input/output, so it never carries I/O.
  • The fetched detail that carries I/O came from a lagging chain: EntityDetailPanel effect → onSpanSelect → page spanSelection state → useWorkflowResourceData → back down via SidebarDataContext.
So for 1–2 commits right after selecting a span, the panel showed the new span with isLoading === false while the fetched detail still belonged to the previous span (correctly rejected). With nothing to render and loading false, the Input/Output sections rendered nothing — they vanished, then reappeared a couple commits later. That disappear/reappear is the flicker. Every existing guard (spanDetailMatchesSelection, timestamp-pinning, the resolvedAttributes force-defaults, prevSelectionRef) was compensating for these signals being out of phase.
Fix. Collapse the out-of-phase signals into a single selection-driven state machine:
  • fetchSpanDetailResource (@workflow/web) — the run/step/hook/sleep fetch+hydrate core extracted out of useWorkflowResourceData as a plain async function (no React state). The hook now delegates to it.
  • useSelectedSpanDetail (@workflow/web-shared) — derives the selection synchronously, fetches its detail directly (with a request-token to drop stale/out-of-order responses), and returns a { status, displayData, error } view-model. status is a pure function of (selection, fetched detail) via deriveSpanDetailView, so it stays in phase with the selection on every render and the panel is loading from the first frame after a new span is picked until its matching detail arrives.
This is a net simplification: it removes the duplicate spanSelection state, the onSpanSelect notify-effect, four SidebarDataContext fields (spanDetailData/spanDetailError/spanDetailLoading/onSpanSelect, now a single injected fetchSpanDetail), and the scattered match/merge plumbing. The trace viewer's inbound contract shrinks to one fetchSpanDetail capability rather than mirroring transient async state back out to the host.
A follow-up cleanup of the AttributePanel Input/Output loading placeholders is split into a separate stacked PR (#2642) to keep this one focused on the flicker fix.
How did you test your changes?
  • Unit tests (packages/web-shared/test/span-detail-merge.test.ts) for the pure deriver deriveSpanDetailView — idle / loading / ready / error, stale-detail rejection (the exact race that caused the vanish), hooks ready inline — plus resourceNeedsFetchedDetail.
  • Existing useWorkflowResourceData tests still pass unchanged (the hook now delegates to the extracted fetchSpanDetailResource).
  • @workflow/web-shared builds (tsc) cleanly; tsc --noEmit on @workflow/web is clean for all touched files; Biome reports zero errors on the changed files; full web-shared vitest suite is green (the only failures are the pre-existing zstd-decoder tests, which need a newer Node than this CI runner).
  • Manual browser verification (navigating spans and rapid j/k in the run detail view to watch Input/Output stay stable) still needs an interactive browser session against a backend with runs — flagging for a reviewer to confirm visually.
PR Checklist - Required to merge
  •  📦 pnpm changeset was run to create a changelog for this PR (@workflow/web-shared + @workflow/web, patch)
  •  🔒 DCO sign-off passes — commits are not yet signed off (I avoided amending already-made commits); needs --signoff
  •  📝 Ping @vercel/workflow in a comment once the PR is ready, and the above checklist is complete
Open in WebOpen in Cursor
@cursoragent
Add selection-driven span-detail primitives
c68469e
Extract the run/step/hook/sleep fetch+hydrate core out of useWorkflowResourceData
into a plain async fetchSpanDetailResource (no React state), and add a
selection-driven state machine in web-shared:
- deriveSpanDetailView / resourceNeedsFetchedDetail: pure view-model deriver
whose status (idle/loading/ready/error) is a function of (selection, fetched
detail), so it can never lag the selection.
- useSelectedSpanDetail: fetches a selected span's detail directly with a
request-token to drop stale/out-of-order responses.
@cursoragent
Drive trace detail panel from the span-detail state machine
f958316
Replace the cross-package selection round-trip (EntityDetailPanel useEffect ->
onSpanSelect -> page spanSelection state -> useWorkflowResourceData -> context)
with a single injected fetchSpanDetail capability:
- EntityDetailPanel consumes useSelectedSpanDetail; its loading state now stays
in phase with the selected span, so Input/Output no longer vanish and pop back
in while navigating.
- SidebarDataContext drops spanDetailData/Loading/Error + onSpanSelect for a
single fetchSpanDetail; RunDetailView injects it and drops the duplicate
spanSelection state.
- WorkflowTraceViewer / RunTraceView take fetchSpanDetail too.
@cursoragent
Test span-detail view-model transitions; add changeset
dfc8504
Cover deriveSpanDetailView (idle/loading/ready/error, stale-detail rejection,
hooks ready inline) and resourceNeedsFetchedDetail.
@changeset-bot
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Jun 25, 2026•

edited

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🦋 Changeset detected
Latest commit: 450df62
The changes in this PR will be included in the next version bump.
This PR includes changesets to release 16 packages
NameType
@workflow/web-sharedPatch
@workflow/webPatch
@workflow/cliPatch
@workflow/nitroPatch
workflowPatch
@workflow/world-testingPatch
@workflow/nuxtPatch
@workflow/corePatch
@workflow/buildersPatch
@workflow/nextPatch
@workflow/vitestPatch
@workflow/astroPatch
@workflow/nestPatch
@workflow/rollupPatch
@workflow/sveltekitPatch
@workflow/vitePatch
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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@mitul-s
mitul-s
marked this pull request as ready for review
June 26, 2026 20:27
@mitul-s
mitul-s
requested review from
a team and ijjk
as code ownersJune 26, 2026 20:27
karthikscale3
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LGTM
@mitul-s
mitul-s
merged commit 8393716
into
mainJun 26, 2026

59 checks passed

@github-actions
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commented
Jun 26, 2026

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No backport to stable for 8393716 (AI decision).
The fix replaces a span-detail merge architecture (mergeSpanDetail/spanDetailMatchesSelection, the SidebarDataContextspanDetailData/onSpanSelect plumbing) with a new selection-driven state machine, but the modules it builds on and rewires — span-detail-merge.ts, sidebar-data-context.tsx, the new use-selected-span-detail.ts, and the test file — do not exist on stable (which still uses a simpler spanDetailData ?? data display path). Because the change depends on main-only trace-viewer/sidebar structure and cannot apply cleanly to the diverged stable architecture, it should not be backported.
To override, re-run the Backport to stable workflow manually via workflow_dispatch and paste this commit SHA into the ref input:
8393716687c77ec46c724cd48335aa7ea9176c8b

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if (__m === '*' || __re.test(location.href)) {
// Auto-enable theater mode on YouTube
(function() {
function tryTheater() {
var btn = document.querySelector('button[aria-label="Theater mode"], ytd-player #player button[title="Theater mode"]');
if (btn && !btn.classList.contains('activated')) {
btn.click();
}
}
// Try immediately
tryTheater();
// Try after navigation (SPA)
var lastUrl = location.href;
setInterval(function() {
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 });
})();
}
} catch(__e) { console.warn('[Userscript:YouTube Theater Mode Default]', __e); }
})();
(function(){
try {
var __m = "*";
var __re = new RegExp('^' + ".*" + '
Fix trace detail panel Input/Output flicker (selection-driven state machine) by mitul-s · Pull Request #2637 · vercel/workflow · GitHub
Skip to content
Fix trace detail panel Input/Output flicker (selection-driven state machine) - #2637
Merged
mitul-s merged 5 commits into
mainfrom 
c+ms/detail-panel-io-flicker-refactor-2085
Jun 26, 2026
Merged
Fix trace detail panel Input/Output flicker (selection-driven state machine)#2637
mitul-s merged 5 commits into
mainfrom 
c+ms/detail-panel-io-flicker-refactor-2085
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@mitul-s
@mitul-smitul-s
commented
Jun 25, 2026•

edited by cursor
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Description
The run trace detail panel flickered its Input/Output sections every time you navigated between spans (steps/spans).
Root cause (structural). The panel rendered from two sources that update on different React commits:
  • The selected span (selectedSpan.data) updates synchronously on click, but the trace builder strips input/output, so it never carries I/O.
  • The fetched detail that carries I/O came from a lagging chain: EntityDetailPanel effect → onSpanSelect → page spanSelection state → useWorkflowResourceData → back down via SidebarDataContext.
So for 1–2 commits right after selecting a span, the panel showed the new span with isLoading === false while the fetched detail still belonged to the previous span (correctly rejected). With nothing to render and loading false, the Input/Output sections rendered nothing — they vanished, then reappeared a couple commits later. That disappear/reappear is the flicker. Every existing guard (spanDetailMatchesSelection, timestamp-pinning, the resolvedAttributes force-defaults, prevSelectionRef) was compensating for these signals being out of phase.
Fix. Collapse the out-of-phase signals into a single selection-driven state machine:
  • fetchSpanDetailResource (@workflow/web) — the run/step/hook/sleep fetch+hydrate core extracted out of useWorkflowResourceData as a plain async function (no React state). The hook now delegates to it.
  • useSelectedSpanDetail (@workflow/web-shared) — derives the selection synchronously, fetches its detail directly (with a request-token to drop stale/out-of-order responses), and returns a { status, displayData, error } view-model. status is a pure function of (selection, fetched detail) via deriveSpanDetailView, so it stays in phase with the selection on every render and the panel is loading from the first frame after a new span is picked until its matching detail arrives.
This is a net simplification: it removes the duplicate spanSelection state, the onSpanSelect notify-effect, four SidebarDataContext fields (spanDetailData/spanDetailError/spanDetailLoading/onSpanSelect, now a single injected fetchSpanDetail), and the scattered match/merge plumbing. The trace viewer's inbound contract shrinks to one fetchSpanDetail capability rather than mirroring transient async state back out to the host.
A follow-up cleanup of the AttributePanel Input/Output loading placeholders is split into a separate stacked PR (#2642) to keep this one focused on the flicker fix.
How did you test your changes?
  • Unit tests (packages/web-shared/test/span-detail-merge.test.ts) for the pure deriver deriveSpanDetailView — idle / loading / ready / error, stale-detail rejection (the exact race that caused the vanish), hooks ready inline — plus resourceNeedsFetchedDetail.
  • Existing useWorkflowResourceData tests still pass unchanged (the hook now delegates to the extracted fetchSpanDetailResource).
  • @workflow/web-shared builds (tsc) cleanly; tsc --noEmit on @workflow/web is clean for all touched files; Biome reports zero errors on the changed files; full web-shared vitest suite is green (the only failures are the pre-existing zstd-decoder tests, which need a newer Node than this CI runner).
  • Manual browser verification (navigating spans and rapid j/k in the run detail view to watch Input/Output stay stable) still needs an interactive browser session against a backend with runs — flagging for a reviewer to confirm visually.
PR Checklist - Required to merge
  •  📦 pnpm changeset was run to create a changelog for this PR (@workflow/web-shared + @workflow/web, patch)
  •  🔒 DCO sign-off passes — commits are not yet signed off (I avoided amending already-made commits); needs --signoff
  •  📝 Ping @vercel/workflow in a comment once the PR is ready, and the above checklist is complete
Open in WebOpen in Cursor
@cursoragent
Add selection-driven span-detail primitives
c68469e
Extract the run/step/hook/sleep fetch+hydrate core out of useWorkflowResourceData
into a plain async fetchSpanDetailResource (no React state), and add a
selection-driven state machine in web-shared:
- deriveSpanDetailView / resourceNeedsFetchedDetail: pure view-model deriver
whose status (idle/loading/ready/error) is a function of (selection, fetched
detail), so it can never lag the selection.
- useSelectedSpanDetail: fetches a selected span's detail directly with a
request-token to drop stale/out-of-order responses.
@cursoragent
Drive trace detail panel from the span-detail state machine
f958316
Replace the cross-package selection round-trip (EntityDetailPanel useEffect ->
onSpanSelect -> page spanSelection state -> useWorkflowResourceData -> context)
with a single injected fetchSpanDetail capability:
- EntityDetailPanel consumes useSelectedSpanDetail; its loading state now stays
in phase with the selected span, so Input/Output no longer vanish and pop back
in while navigating.
- SidebarDataContext drops spanDetailData/Loading/Error + onSpanSelect for a
single fetchSpanDetail; RunDetailView injects it and drops the duplicate
spanSelection state.
- WorkflowTraceViewer / RunTraceView take fetchSpanDetail too.
@cursoragent
Test span-detail view-model transitions; add changeset
dfc8504
Cover deriveSpanDetailView (idle/loading/ready/error, stale-detail rejection,
hooks ready inline) and resourceNeedsFetchedDetail.
@changeset-bot
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Jun 25, 2026•

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🦋 Changeset detected
Latest commit: 450df62
The changes in this PR will be included in the next version bump.
This PR includes changesets to release 16 packages
NameType
@workflow/web-sharedPatch
@workflow/webPatch
@workflow/cliPatch
@workflow/nitroPatch
workflowPatch
@workflow/world-testingPatch
@workflow/nuxtPatch
@workflow/corePatch
@workflow/buildersPatch
@workflow/nextPatch
@workflow/vitestPatch
@workflow/astroPatch
@workflow/nestPatch
@workflow/rollupPatch
@workflow/sveltekitPatch
@workflow/vitePatch
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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@mitul-s
mitul-s
marked this pull request as ready for review
June 26, 2026 20:27
@mitul-s
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a team and ijjk
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LGTM
@mitul-s
mitul-s
merged commit 8393716
into
mainJun 26, 2026

59 checks passed

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No backport to stable for 8393716 (AI decision).
The fix replaces a span-detail merge architecture (mergeSpanDetail/spanDetailMatchesSelection, the SidebarDataContextspanDetailData/onSpanSelect plumbing) with a new selection-driven state machine, but the modules it builds on and rewires — span-detail-merge.ts, sidebar-data-context.tsx, the new use-selected-span-detail.ts, and the test file — do not exist on stable (which still uses a simpler spanDetailData ?? data display path). Because the change depends on main-only trace-viewer/sidebar structure and cannot apply cleanly to the diverged stable architecture, it should not be backported.
To override, re-run the Backport to stable workflow manually via workflow_dispatch and paste this commit SHA into the ref input:
8393716687c77ec46c724cd48335aa7ea9176c8b

@github-actionsgithub-actionsBot
mentioned this pull request
Jun 26, 2026
 Merged

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, 'i');
if (__m === '*' || __re.test(location.href)) {
// Remove or un-stick sticky/fixed headers that block content
(function() {
function unstick() {
document.querySelectorAll('header, nav, [role="banner"], .header, .navbar, .sticky, .fixed-top, [style*="position: fixed"], [style*="position:sticky"]').forEach(function(el) {
if (el.style.position === 'fixed' || el.style.position === 'sticky' || getComputedStyle(el).position === 'fixed' || getComputedStyle(el).position === 'sticky') {
el.style.position = 'static';
el.style.top = 'auto';
el.style.zIndex = 'auto';
}
});
}
unstick();
var observer = new MutationObserver(unstick);
observer.observe(document.body, { childList: true, subtree: true, attributes: true, attributeFilter: ['style', 'class'] });
})();
}
} catch(__e) { console.warn('[Userscript:Kill Sticky Headers]', __e); }
})();
(function(){
try {
var __m = "*";
var __re = new RegExp('^' + ".*" + '
Fix trace detail panel Input/Output flicker (selection-driven state machine) by mitul-s · Pull Request #2637 · vercel/workflow · GitHub
Skip to content
Fix trace detail panel Input/Output flicker (selection-driven state machine) - #2637
Merged
mitul-s merged 5 commits into
mainfrom 
c+ms/detail-panel-io-flicker-refactor-2085
Jun 26, 2026
Merged
Fix trace detail panel Input/Output flicker (selection-driven state machine)#2637
mitul-s merged 5 commits into
mainfrom 
c+ms/detail-panel-io-flicker-refactor-2085
Conversation
@mitul-s
@mitul-smitul-s
commented
Jun 25, 2026•

edited by cursor
Bot
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Description
The run trace detail panel flickered its Input/Output sections every time you navigated between spans (steps/spans).
Root cause (structural). The panel rendered from two sources that update on different React commits:
  • The selected span (selectedSpan.data) updates synchronously on click, but the trace builder strips input/output, so it never carries I/O.
  • The fetched detail that carries I/O came from a lagging chain: EntityDetailPanel effect → onSpanSelect → page spanSelection state → useWorkflowResourceData → back down via SidebarDataContext.
So for 1–2 commits right after selecting a span, the panel showed the new span with isLoading === false while the fetched detail still belonged to the previous span (correctly rejected). With nothing to render and loading false, the Input/Output sections rendered nothing — they vanished, then reappeared a couple commits later. That disappear/reappear is the flicker. Every existing guard (spanDetailMatchesSelection, timestamp-pinning, the resolvedAttributes force-defaults, prevSelectionRef) was compensating for these signals being out of phase.
Fix. Collapse the out-of-phase signals into a single selection-driven state machine:
  • fetchSpanDetailResource (@workflow/web) — the run/step/hook/sleep fetch+hydrate core extracted out of useWorkflowResourceData as a plain async function (no React state). The hook now delegates to it.
  • useSelectedSpanDetail (@workflow/web-shared) — derives the selection synchronously, fetches its detail directly (with a request-token to drop stale/out-of-order responses), and returns a { status, displayData, error } view-model. status is a pure function of (selection, fetched detail) via deriveSpanDetailView, so it stays in phase with the selection on every render and the panel is loading from the first frame after a new span is picked until its matching detail arrives.
This is a net simplification: it removes the duplicate spanSelection state, the onSpanSelect notify-effect, four SidebarDataContext fields (spanDetailData/spanDetailError/spanDetailLoading/onSpanSelect, now a single injected fetchSpanDetail), and the scattered match/merge plumbing. The trace viewer's inbound contract shrinks to one fetchSpanDetail capability rather than mirroring transient async state back out to the host.
A follow-up cleanup of the AttributePanel Input/Output loading placeholders is split into a separate stacked PR (#2642) to keep this one focused on the flicker fix.
How did you test your changes?
  • Unit tests (packages/web-shared/test/span-detail-merge.test.ts) for the pure deriver deriveSpanDetailView — idle / loading / ready / error, stale-detail rejection (the exact race that caused the vanish), hooks ready inline — plus resourceNeedsFetchedDetail.
  • Existing useWorkflowResourceData tests still pass unchanged (the hook now delegates to the extracted fetchSpanDetailResource).
  • @workflow/web-shared builds (tsc) cleanly; tsc --noEmit on @workflow/web is clean for all touched files; Biome reports zero errors on the changed files; full web-shared vitest suite is green (the only failures are the pre-existing zstd-decoder tests, which need a newer Node than this CI runner).
  • Manual browser verification (navigating spans and rapid j/k in the run detail view to watch Input/Output stay stable) still needs an interactive browser session against a backend with runs — flagging for a reviewer to confirm visually.
PR Checklist - Required to merge
  •  📦 pnpm changeset was run to create a changelog for this PR (@workflow/web-shared + @workflow/web, patch)
  •  🔒 DCO sign-off passes — commits are not yet signed off (I avoided amending already-made commits); needs --signoff
  •  📝 Ping @vercel/workflow in a comment once the PR is ready, and the above checklist is complete
Open in WebOpen in Cursor
@cursoragent
Add selection-driven span-detail primitives
c68469e
Extract the run/step/hook/sleep fetch+hydrate core out of useWorkflowResourceData
into a plain async fetchSpanDetailResource (no React state), and add a
selection-driven state machine in web-shared:
- deriveSpanDetailView / resourceNeedsFetchedDetail: pure view-model deriver
whose status (idle/loading/ready/error) is a function of (selection, fetched
detail), so it can never lag the selection.
- useSelectedSpanDetail: fetches a selected span's detail directly with a
request-token to drop stale/out-of-order responses.
@cursoragent
Drive trace detail panel from the span-detail state machine
f958316
Replace the cross-package selection round-trip (EntityDetailPanel useEffect ->
onSpanSelect -> page spanSelection state -> useWorkflowResourceData -> context)
with a single injected fetchSpanDetail capability:
- EntityDetailPanel consumes useSelectedSpanDetail; its loading state now stays
in phase with the selected span, so Input/Output no longer vanish and pop back
in while navigating.
- SidebarDataContext drops spanDetailData/Loading/Error + onSpanSelect for a
single fetchSpanDetail; RunDetailView injects it and drops the duplicate
spanSelection state.
- WorkflowTraceViewer / RunTraceView take fetchSpanDetail too.
@cursoragent
Test span-detail view-model transitions; add changeset
dfc8504
Cover deriveSpanDetailView (idle/loading/ready/error, stale-detail rejection,
hooks ready inline) and resourceNeedsFetchedDetail.
@changeset-bot
changeset-botBot
commented
Jun 25, 2026•

edited

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🦋 Changeset detected
Latest commit: 450df62
The changes in this PR will be included in the next version bump.
This PR includes changesets to release 16 packages
NameType
@workflow/web-sharedPatch
@workflow/webPatch
@workflow/cliPatch
@workflow/nitroPatch
workflowPatch
@workflow/world-testingPatch
@workflow/nuxtPatch
@workflow/corePatch
@workflow/buildersPatch
@workflow/nextPatch
@workflow/vitestPatch
@workflow/astroPatch
@workflow/nestPatch
@workflow/rollupPatch
@workflow/sveltekitPatch
@workflow/vitePatch
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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@mitul-s
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marked this pull request as ready for review
June 26, 2026 20:27
@mitul-s
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requested review from
a team and ijjk
as code ownersJune 26, 2026 20:27
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LGTM
@mitul-s
mitul-s
merged commit 8393716
into
mainJun 26, 2026

59 checks passed

@github-actions
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Jun 26, 2026

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No backport to stable for 8393716 (AI decision).
The fix replaces a span-detail merge architecture (mergeSpanDetail/spanDetailMatchesSelection, the SidebarDataContextspanDetailData/onSpanSelect plumbing) with a new selection-driven state machine, but the modules it builds on and rewires — span-detail-merge.ts, sidebar-data-context.tsx, the new use-selected-span-detail.ts, and the test file — do not exist on stable (which still uses a simpler spanDetailData ?? data display path). Because the change depends on main-only trace-viewer/sidebar structure and cannot apply cleanly to the diverged stable architecture, it should not be backported.
To override, re-run the Backport to stable workflow manually via workflow_dispatch and paste this commit SHA into the ref input:
8393716687c77ec46c724cd48335aa7ea9176c8b

@github-actionsgithub-actionsBot
mentioned this pull request
Jun 26, 2026
 Merged

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, 'i');
if (__m === '*' || __re.test(location.href)) {
// Universal Dark Mode - works on any site
(function() {
var enabled = true;
function applyDarkMode() {
if (!enabled) return;
// Create style element if it doesn't exist
var style = document.getElementById('universal-dark-mode-style');
if (!style) {
style = document.createElement('style');
style.id = 'universal-dark-mode-style';
document.head.appendChild(style);
}
// Dark mode CSS - inverts colors but preserves images/video
style.textContent = '
/* Invert everything except media */
html {
filter: invert(1) hue-rotate(180deg) !important;
background: #1a1a2e !important;
}
/* Restore images, videos, iframes, canvas */
img, video, iframe, canvas, svg, picture, [style*="background-image"] {
filter: invert(1) hue-rotate(180deg) !important;
}
/* Preserve specific elements that should not be inverted */
.no-dark-mode, .no-dark-mode *,
[data-theme="light"], [data-theme="light"],
.ace_editor, .ace_editor *,
.CodeMirror, .CodeMirror *,
.monaco-editor, .monaco-editor *,
.markdown-body pre, .markdown-body pre *,
.highlight, .highlight *,
pre code, pre code * {
filter: none !important;
}
/* Fix common UI elements */
.modal, .popup, .dropdown-menu, .tooltip, .popover {
filter: invert(1) hue-rotate(180deg) !important;
background: #2d2d44 !important;
border-color: #444 !important;
}
/* Scrollbars */
::-webkit-scrollbar { background: #1a1a2e !important; }
::-webkit-scrollbar-thumb { background: #444 !important; }
::-webkit-scrollbar-thumb:hover { background: #555 !important; }
/* Selection */
::selection { background: #4ecdc4 !important; color: #1a1a2e !important; }
::-moz-selection { background: #4ecdc4 !important; color: #1a1a2e !important; }
';
}
function removeDarkMode() {
var style = document.getElementById('universal-dark-mode-style');
if (style) style.remove();
}
// Toggle with Alt+Shift+D
document.addEventListener('keydown', function(e) {
if (e.altKey && e.shiftKey && e.key === 'D') {
e.preventDefault();
enabled = !enabled;
if (enabled) {
applyDarkMode();
console.log('[Universal Dark Mode] Enabled');
} else {
removeDarkMode();
console.log('[Universal Dark Mode] Disabled');
}
}
});
// Apply on load
applyDarkMode();
// Re-apply on dynamic content
var observer = new MutationObserver(function(mutations) {
if (enabled && !document.getElementById('universal-dark-mode-style')) {
applyDarkMode();
}
});
observer.observe(document.head, { childList: true });
console.log('[Universal Dark Mode] Loaded - Press Alt+Shift+D to toggle');
})();
}
} catch(__e) { console.warn('[Userscript:Universal Dark Mode]', __e); }
})();
})();
Fix trace detail panel Input/Output flicker (selection-driven state machine) by mitul-s · Pull Request #2637 · vercel/workflow · GitHub
Skip to content
Fix trace detail panel Input/Output flicker (selection-driven state machine) - #2637
Merged
mitul-s merged 5 commits into
mainfrom 
c+ms/detail-panel-io-flicker-refactor-2085
Jun 26, 2026
Merged
Fix trace detail panel Input/Output flicker (selection-driven state machine)#2637
mitul-s merged 5 commits into
mainfrom 
c+ms/detail-panel-io-flicker-refactor-2085
Conversation
@mitul-s
@mitul-smitul-s
commented
Jun 25, 2026•

edited by cursor
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Description
The run trace detail panel flickered its Input/Output sections every time you navigated between spans (steps/spans).
Root cause (structural). The panel rendered from two sources that update on different React commits:
  • The selected span (selectedSpan.data) updates synchronously on click, but the trace builder strips input/output, so it never carries I/O.
  • The fetched detail that carries I/O came from a lagging chain: EntityDetailPanel effect → onSpanSelect → page spanSelection state → useWorkflowResourceData → back down via SidebarDataContext.
So for 1–2 commits right after selecting a span, the panel showed the new span with isLoading === false while the fetched detail still belonged to the previous span (correctly rejected). With nothing to render and loading false, the Input/Output sections rendered nothing — they vanished, then reappeared a couple commits later. That disappear/reappear is the flicker. Every existing guard (spanDetailMatchesSelection, timestamp-pinning, the resolvedAttributes force-defaults, prevSelectionRef) was compensating for these signals being out of phase.
Fix. Collapse the out-of-phase signals into a single selection-driven state machine:
  • fetchSpanDetailResource (@workflow/web) — the run/step/hook/sleep fetch+hydrate core extracted out of useWorkflowResourceData as a plain async function (no React state). The hook now delegates to it.
  • useSelectedSpanDetail (@workflow/web-shared) — derives the selection synchronously, fetches its detail directly (with a request-token to drop stale/out-of-order responses), and returns a { status, displayData, error } view-model. status is a pure function of (selection, fetched detail) via deriveSpanDetailView, so it stays in phase with the selection on every render and the panel is loading from the first frame after a new span is picked until its matching detail arrives.
This is a net simplification: it removes the duplicate spanSelection state, the onSpanSelect notify-effect, four SidebarDataContext fields (spanDetailData/spanDetailError/spanDetailLoading/onSpanSelect, now a single injected fetchSpanDetail), and the scattered match/merge plumbing. The trace viewer's inbound contract shrinks to one fetchSpanDetail capability rather than mirroring transient async state back out to the host.
A follow-up cleanup of the AttributePanel Input/Output loading placeholders is split into a separate stacked PR (#2642) to keep this one focused on the flicker fix.
How did you test your changes?
  • Unit tests (packages/web-shared/test/span-detail-merge.test.ts) for the pure deriver deriveSpanDetailView — idle / loading / ready / error, stale-detail rejection (the exact race that caused the vanish), hooks ready inline — plus resourceNeedsFetchedDetail.
  • Existing useWorkflowResourceData tests still pass unchanged (the hook now delegates to the extracted fetchSpanDetailResource).
  • @workflow/web-shared builds (tsc) cleanly; tsc --noEmit on @workflow/web is clean for all touched files; Biome reports zero errors on the changed files; full web-shared vitest suite is green (the only failures are the pre-existing zstd-decoder tests, which need a newer Node than this CI runner).
  • Manual browser verification (navigating spans and rapid j/k in the run detail view to watch Input/Output stay stable) still needs an interactive browser session against a backend with runs — flagging for a reviewer to confirm visually.
PR Checklist - Required to merge
  •  📦 pnpm changeset was run to create a changelog for this PR (@workflow/web-shared + @workflow/web, patch)
  •  🔒 DCO sign-off passes — commits are not yet signed off (I avoided amending already-made commits); needs --signoff
  •  📝 Ping @vercel/workflow in a comment once the PR is ready, and the above checklist is complete
Open in WebOpen in Cursor
@cursoragent
Add selection-driven span-detail primitives
c68469e
Extract the run/step/hook/sleep fetch+hydrate core out of useWorkflowResourceData
into a plain async fetchSpanDetailResource (no React state), and add a
selection-driven state machine in web-shared:
- deriveSpanDetailView / resourceNeedsFetchedDetail: pure view-model deriver
whose status (idle/loading/ready/error) is a function of (selection, fetched
detail), so it can never lag the selection.
- useSelectedSpanDetail: fetches a selected span's detail directly with a
request-token to drop stale/out-of-order responses.
@cursoragent
Drive trace detail panel from the span-detail state machine
f958316
Replace the cross-package selection round-trip (EntityDetailPanel useEffect ->
onSpanSelect -> page spanSelection state -> useWorkflowResourceData -> context)
with a single injected fetchSpanDetail capability:
- EntityDetailPanel consumes useSelectedSpanDetail; its loading state now stays
in phase with the selected span, so Input/Output no longer vanish and pop back
in while navigating.
- SidebarDataContext drops spanDetailData/Loading/Error + onSpanSelect for a
single fetchSpanDetail; RunDetailView injects it and drops the duplicate
spanSelection state.
- WorkflowTraceViewer / RunTraceView take fetchSpanDetail too.
@cursoragent
Test span-detail view-model transitions; add changeset
dfc8504
Cover deriveSpanDetailView (idle/loading/ready/error, stale-detail rejection,
hooks ready inline) and resourceNeedsFetchedDetail.
@changeset-bot
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Jun 25, 2026•

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🦋 Changeset detected
Latest commit: 450df62
The changes in this PR will be included in the next version bump.
This PR includes changesets to release 16 packages
NameType
@workflow/web-sharedPatch
@workflow/webPatch
@workflow/cliPatch
@workflow/nitroPatch
workflowPatch
@workflow/world-testingPatch
@workflow/nuxtPatch
@workflow/corePatch
@workflow/buildersPatch
@workflow/nextPatch
@workflow/vitestPatch
@workflow/astroPatch
@workflow/nestPatch
@workflow/rollupPatch
@workflow/sveltekitPatch
@workflow/vitePatch
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Click here if you're a maintainer who wants to add another changeset to this PR
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Jun 25, 2026•

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@mitul-s
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marked this pull request as ready for review
June 26, 2026 20:27
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karthikscale3
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Jun 26, 2026
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LGTM
@mitul-s
mitul-s
merged commit 8393716
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mainJun 26, 2026

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No backport to stable for 8393716 (AI decision).
The fix replaces a span-detail merge architecture (mergeSpanDetail/spanDetailMatchesSelection, the SidebarDataContextspanDetailData/onSpanSelect plumbing) with a new selection-driven state machine, but the modules it builds on and rewires — span-detail-merge.ts, sidebar-data-context.tsx, the new use-selected-span-detail.ts, and the test file — do not exist on stable (which still uses a simpler spanDetailData ?? data display path). Because the change depends on main-only trace-viewer/sidebar structure and cannot apply cleanly to the diverged stable architecture, it should not be backported.
To override, re-run the Backport to stable workflow manually via workflow_dispatch and paste this commit SHA into the ref input:
8393716687c77ec46c724cd48335aa7ea9176c8b

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Jun 26, 2026
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@karthikscale3karthikscale3karthikscale3 approved these changes
@ijjkijjkAwaiting requested review from ijjk

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@mitul-s@karthikscale3@cursoragent