[juliusmarminge]

The sidebar body and useSidebarProjectGroups both subscribed to every thread shell. A running thread bumps its shell's updatedAt on every update, so each update re-rendered the whole sidebar: the header, the project-scope picker, every sortable row wrapper and every shelf marker. That happened even when the streaming thread was not the one on screen.

How this PR fixes it:

• Quiet shell list. A new quietThreadShellsAtom in client-runtime lists the existing per-thread quietThreadShellAtom values. A quiet shell stays the same while only streaming fields change (updatedAt, item counts, latest message), and the list keeps its identity with it. The web exposes it as useQuietThreadShells.
• The sidebar reads the quiet list. The sidebar's partition and useSidebarProjectGroups now read that list. Any real change (runtime, title, pin, settle, snooze, a new run) still produces a new shell, so sections and order still update.
• Each row reads its own live shell. SortableThreadRow and the search-result row read their thread's live shell, so a streaming thread re-renders only its own row: the relative time, the working state and so on.

One visible difference: with "sort projects by activity", the project order inside one running turn follows the turn's last real change, not every streaming tick. Turn start and turn end are real changes, so the project still moves up when the run starts.

Measured on a dev server seeded with migrate-dev-db: 9 visible rows, React Compiler build, render counter counting only fibers React rendered, median of 3 runs.

Thread A streams a reply while thread B is open, counted over 15 s:

component renders	main	this PR
all sidebar components	286	27
Sidebar	7	0
SortableThreadRow	63	2
SidebarThreadRow (memo)	6	2
SortableSidebarMarker	42	0

Switching threads (4 clicks): 363 → 364 sidebar component renders, Sidebar 14 → 13, SidebarThreadRow 10 → 14. That is unchanged within noise, which is expected: a route change is a real change for the sidebar.

Tests run:

• threadShell.test.ts, including a new test: the quiet list keeps its identity through a streaming tick and follows a rename.
• React Compiler coverage for the sidebar and entities files (0 bailouts).
• entities.relationshipShells.test.ts
• Sidebar.logic.test.ts
• tsc for apps/web and client-runtime
• oxlint on the changed files

Claude Opus 5.5 in Claude Code.

🤖 Generated with Claude Code

[macroscopeapp]

Approvability

Verdict: Approved at e1c4bdc

Macroscope's review found this PR approvable — This is a focused sidebar performance optimization that isolates streaming updates to the affected row while preserving meaningful ordering and grouping updates. Its intentional activity-ordering delay during streaming is narrow, documented, and covered by targeted tests.

No code changes detected at bb23117. Prior analysis still applies.

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📒 Files selected for processing: 6

• apps/web/src/components/Sidebar.tsx
• apps/web/src/components/sidebar/SidebarThreadRow.tsx
• apps/web/src/hooks/useSidebarProjectGroups.ts
• apps/web/src/state/entities.ts
• packages/client-runtime/src/state/threadShell.test.ts
• packages/client-runtime/src/state/threadShell.ts

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📝 Walkthrough

The change adds an aggregate quiet-thread-shell atom and a public hook. Sidebar thread lists and project groups use the quiet-shell collection. Sidebar rows resolve current thread shells by environment and thread ID, with supplied data as a fallback.

Changes: Sidebar thread-shell updates

Layer / File(s)	Summary
Aggregate quiet thread shells packages/client-runtime/src/state/threadShell.ts, apps/web/src/state/entities.ts, packages/client-runtime/src/state/threadShell.test.ts	The new atom aggregates non-null quiet thread shells and reuses the prior array when its elements are unchanged. The public hook exposes the collection. Tests cover streaming updates and title changes.
Sidebar thread-shell consumers apps/web/src/components/Sidebar.tsx, apps/web/src/hooks/useSidebarProjectGroups.ts, apps/web/src/components/sidebar/SidebarThreadRow.tsx	The sidebar thread list and project groups use quiet thread shells. Sortable and search-result rows resolve the current scoped shell, with supplied thread data as a fallback.

Priority: ⬇️ Low

Estimated code review effort: 2 (Simple) | ~10 minutes

Change: Refactor

Suggested reviewers: maria-rcks

Merge Risk: ⚪ Minimal · up to e1c4b

The sidebar subscription change has no established user-visible regression and is mergeable after normal checks.

Pre-merge checks: 4

Check name	Status	Explanation
Title check		The title clearly and concisely describes the primary performance change: streaming updates re-render only the affected sidebar row.
Description check		The description clearly explains the problem, implementation, behavior change, performance measurements, and verification steps. It does not include an explicit Scope and approval section or UI eviden…
Linked Issues check		Check skipped because no linked issues were found for this pull request.
Out of Scope Changes check		Check skipped because no linked issues were found for this pull request.

Full details: Description check

Explanation

The description clearly explains the problem, implementation, behavior change, performance measurements, and verification steps. It does not include an explicit Scope and approval section or UI evidence, but the core description is mostly complete.

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