🤖 fix: collapse settled operation bundles in hyper density

[ThomasK33]

Summary

Collapse completed hyper-density operational bundles by default while keeping active/running operational bundles expanded for live progress visibility.

Background

Hyper transcript density already groups low-signal reasoning/tool details behind operation summaries. Completed summaries could still start expanded at the active turn tail, which let settled details consume viewport space before the user chose to inspect them.

Implementation

• Simplified operational bundle default expansion to state === "active".
• Removed the settled-tail visible-event exception and its now-unused helper.
• Added projection and app-level UI regressions proving completed summaries start collapsed and hide details until clicked.

Validation

• bun test src/browser/utils/messages/transcriptRenderProjection.test.ts
• bun test src/browser/features/Messages/OperationalBundleMessage.test.tsx
• make version
• bun x jest tests/ui/chat/transcriptDensity.test.ts -t "expands work bundles and nested operational bundles through the app render path"
• make typecheck
• make static-check
• Storybook dogfood of App/Chat/Transcript Density / HyperCollapsedBundles with screenshots and a WebM recording verifying collapsed, expanded, and re-collapsed states.

Risks

Low. The change only affects the default expansion flag for operational bundle summaries; manual expand/collapse state and active/running visibility are preserved.

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📋 Implementation Plan

Plan: collapse hyper-density operation summaries by default

Goal

When transcript density is hyper, grouped operation summaries like Ran 59 operations · ... should start collapsed so completed tool/reasoning details do not consume the viewport. Manual expand/collapse should continue to work.

Evidence gathered

• ChatPaneContent in src/browser/components/ChatPane/ChatPane.tsx only computes/renders operational bundles when transcriptDensity === "hyper".
• The summary copy and default expansion are produced by computeOperationalBundleInfos() in src/browser/utils/messages/transcriptRenderProjection.ts.
• Current settled-tail behavior expands operation bundles by default while the turn is active: state === "active" || (options.isTurnActive && !hasSubsequentVisibleEvent).
• OperationalBundleMessage in src/browser/features/Messages/OperationalBundleMessage.tsx already supports collapsed rendering via expanded / onToggle.
• Existing validation targets:
  • src/browser/utils/messages/transcriptRenderProjection.test.ts
  • src/browser/features/Messages/OperationalBundleMessage.test.tsx
  • tests/ui/chat/transcriptDensity.test.ts
  • src/browser/features/Messages/TranscriptDensity.stories.tsx

Recommended approach

Approach A — simplify operational bundle default expansion
Product code net LoC estimate: -8 to -12 LoC

1. Update src/browser/utils/messages/transcriptRenderProjection.ts so completed operational bundles default collapsed:
   • keep active/running bundles expanded: defaultExpanded: state === "active";
   • remove the settled-tail exception that expands when isTurnActive && !hasSubsequentVisibleEvent;
   • remove now-unused hasVisibleEventAfter() helper if no other local use remains.
2. Preserve ChatPaneContent manual override behavior:
   • operationalBundleOverride ?? operationalBundle.defaultExpanded remains the expansion source;
   • user clicks still override the default for the current component lifetime.
3. Update src/browser/utils/messages/transcriptRenderProjection.test.ts:
   • assert active bundles still default expanded;
   • assert just-settled tail bundles default collapsed even while the turn is active;
   • keep or simplify existing older-settled collapse assertions.
4. Add/adjust a regression assertion in tests/ui/chat/transcriptDensity.test.ts if needed so the full app hyper-density path proves the operational-bundle button starts with aria-expanded="false" and hides details until clicked.

Why this is preferred: the Ran N operations bundle only renders in hyper density today, so making settled operational bundles collapsed in the projection is the smallest change and avoids adding a new density option or duplicated expansion logic.

Alternative considered

Approach B — density-aware override in ChatPaneContent
Product code net LoC estimate: +3 to +12 LoC

Add a hyper-density override near isOperationalBundleExpanded, leaving computeOperationalBundleInfos() unchanged. This is more explicit about density but adds a second policy layer and makes projection tests less representative of actual default behavior. I would only use this if another caller needs the old settled-tail expansion semantics.

Acceptance criteria

• In hyper transcript density, any completed Ran N operations bundle starts collapsed by default.
• Operation details under that summary are not visible until the user expands the bundle.
• Clicking the summary toggles expanded/collapsed state exactly as before.
• Active/running operational bundles remain expanded by default unless explicitly requested otherwise, so live progress is not hidden.
• Normal transcript density behavior is unchanged.
• No persisted-state or migration changes are introduced.

Quality gates and validation

1. Targeted unit tests:

   bun test src/browser/utils/messages/transcriptRenderProjection.test.ts
   bun test src/browser/features/Messages/OperationalBundleMessage.test.tsx

2. Targeted full-app UI test:

   bun x jest tests/ui/chat/transcriptDensity.test.ts -t "expands work bundles and nested operational bundles through the app render path"

3. Type/static validation:

   make typecheck
   make static-check

4. If test runtime or environment blocks a command, capture the exact failure and validate the closest targeted subset instead before reporting.

Dogfooding plan

1. Start Storybook:

   make storybook

2. Use agent-browser to open the transcript density Storybook story that displays hyper-density operation bundles, preferably TranscriptDensity.stories.tsx / HyperExpandedBundle.
3. Record a short video and take screenshots showing:
   • hyper density enabled;
   • the Ran N operations row visible with aria-expanded="false" by default;
   • operation details hidden before interaction;
   • details visible after clicking the operation summary;
   • details hidden again after a second click.
4. Optionally repeat in the desktop sandbox for the real app shell:

   MUX_E2E=1 make dev-desktop-sandbox DEV_DESKTOP_SANDBOX_ARGS="--clean-projects"

   Then use Electron/agent-browser automation to capture screenshots/video of the same collapsed-by-default and expand/collapse flow.

Implementation notes

• Keep the change surgical; do not introduce persistent expansion state.
• Do not alter summary text, counts, icons, or category copy.
• If active/running bundles are later requested to collapse too, treat that as a separate UX decision because it hides live progress.

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Generated with mux • Model: openai:gpt-5.5 • Thinking: xhigh • Cost: $10.61

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[ThomasK33]

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