perf(mobile): streaming re-renders less on the open thread screen

[juliusmarminge]

While a thread streams, every delta bumps its shell's updatedAt. The open thread screen read the full shell through useResolvedThreadSelection, so ThreadRouteScreen and its header (IconButton, AndroidAnchoredMenu, Stop) re-rendered on every tick even though only the visit watermark uses that timestamp.

The thread selection now reads the quiet shell, which ignores the streaming timestamps. The visit watermark moves into a ThreadVisitWatermark leaf that still reads the live shell, so visits and unread state work the same as before.

The earlier version of this PR also moved 11 config readers to the provider-free serverConfigsAtom, and changed SubagentRow and the outbox status atom. Measured below, none of them moved a number, so they're gone.

Measurements

Pixel 9 API 36 emulator (nucbox-1), Metro and an isolated seeded server on cups, apps/mobile/scripts/measure-renders.mts. Both sides are on the same base (c274a25151), with a fresh Metro --clear per side, median of 3. Each run's thread was deleted afterwards so Home stays the same size. Values are renders / commits (renders per commit).

(a) The open thread streams

	run 1	run 2	run 3	median renders/commit
main	965/33 (29)	1256/38 (33)	1304/37 (35)	33
this PR, before trim	1252/41 (31)	963/37 (26)	928/35 (27)	27
this PR (trimmed, this head)	857/31 (28)	857/30 (29)	851/30 (28)	28

A second session on the same base agreed: main 34, this PR 27. Top components on main include ThreadRouteScreen 7, ThreadRouteContent 7, Stop 14, IconButton 12, AndroidAnchoredMenu 9. On this PR ThreadRouteScreen, IconButton and AndroidAnchoredMenu fall out of the top 20 and Stop is 7. Host View renders go from 556 to 428.

(b) Another thread streams while a different thread is open (--route /threads/<env>/<thread> --server)

	run 1	run 2	run 3	median renders/commit
main	66/2	66/2	66/2	33
this PR	66/2	66/2	165/5	33

(c) Another thread streams while on Home (--route / --server)

	run 1	run 2	run 3	median renders/commit
main	334/6 (56)	337/8 (42)	501/9 (56)	56
this PR	334/6 (56)	334/6 (56)	168/4 (42)	56

(d) Provider refresh while the thread screen is open (server.refreshProviders, 10 s window; this trigger is a local harness edit and isn't part of this PR)

	run 1	run 2	run 3	median renders/commit
main	326/9 (36)	267/7 (38)	255/5 (51)	38
this PR, before trim	324/10 (32)	265/6 (44)	265/6 (44)	44

Median renders are 267 and 265. The component tables match except ThreadOutboxDrainWorker (2 → 0). The per-commit gap comes from the commit count, not from renders. The serverConfigsAtom half was dropped for that reason.

Why web won more from the same idea

In web's #20823, components near the root (FirstRunGate, AppSidebarLayout through useThreadVisitedMigration, ThreadRelationshipsPanel) subscribed to the whole threadShellsAtom. Each push from an unrelated thread re-rendered about 180 components. Mobile has no such subscriber.

• In (b), the open thread screen doesn't render at all on main. The two commits per window are ThreadOutboxDrainWorker state#8 and the composer subtree. No screen component appears. Mobile's screen already reads per-thread atoms, so another thread's stream had nothing to narrow.
• In (c), Home renders because the streaming thread is a Home row: Container2 state#1 (list row containers), PositionViewState2, and HomeScreen 2. Narrowing can't remove that.
• So the expected explanation (the compiler makes a broad re-render cheap) doesn't hold on mobile, because no broad re-render happens there. The earlier 220 and 433 renders per commit came from unstable props in rows, which #21255 fixed. The one broad subscription left was the open thread's own shell ticking, and this PR removes it.

Ready for review. Measured with Claude Opus 5.5 through Claude Code.

🤖 Generated with Claude Code

[macroscopeapp]

Approvability

Verdict: Approved at 43147d3

Macroscope's review found this PR approvable — This is a narrowly scoped mobile performance optimization that isolates live visit tracking and suppresses only redundant streaming-driven shell updates. It introduces no new capability, schema or infrastructure change, product-default change, or static-analysis override.

Notes:

• All code in this push has already been reviewed. Approvability was decided on eligibility alone.

^{You can add or adjust custom eligibility rules. Learn more.}

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• apps/mobile/src/features/threads/ThreadDetailScreen.tsx

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📝 Walkthrough

The mobile app adds quiet thread-shell and presentation configuration readers, migrates thread and configuration consumers, reads shell status directly, and moves thread-visit watermark tracking into a dedicated component.

Changes: Mobile state readers and consumers

Layer / File(s)	Summary
Add thread-shell and configuration readers apps/mobile/src/state/entities.ts	Adds useQuietThreadShell. useServerConfigs reads presentation configurations, while useServerConfigsWithProviders retains the provider-inclusive read.
Migrate thread-shell consumers apps/mobile/src/features/keyboard/*, apps/mobile/src/features/shortcuts/useAppShortcuts.ts, apps/mobile/src/features/threads/*, apps/mobile/src/native/useOpenPullRequest.ts, apps/mobile/src/state/use-thread-selection.ts	These consumers now read thread shells with useQuietThreadShell instead of useThreadShell.
Update configuration and outbox reads apps/mobile/src/features/prompt-links/usePromptLinkResolver.ts, apps/mobile/src/features/settings/scheduled-task-editor.tsx, apps/mobile/src/state/use-thread-outbox.ts	Prompt-link and scheduled-task code uses provider-aware configurations. The outbox reads each environment’s status atom directly.

Thread visit tracking

Layer / File(s)	Summary
Extract thread visit-watermark tracking apps/mobile/src/features/threads/ThreadDetailScreen.tsx	Moves visit validation, deduplication, and dispatch timing into ThreadVisitWatermark, which is rendered with the environment, selected thread, and content-visibility state.

Priority: ⬇️ Low

Estimated code review effort: 3 (Moderate) | ~20 minutes

Change: Refactor

Suggested reviewers: maria-rcks, t3dotgg

Merge Risk: ⚪ Minimal · up to b8377

No actionable merge-blocking issue remains. Native render performance and visit behavior still need the planned device verification.

Pre-merge checks: 3 · 1

Failed checks: 1 warning

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Passed checks: 3 passed

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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.
Title check		The title clearly describes the main change: reducing streaming re-renders on the mobile open-thread screen.

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[juliusmarminge]

Render measurement with the device harness from #21001, scenario stream-reply: an open thread streams a Claude Haiku 5.5 turn while the composer is idle, with a 12 s window mid-stream. Median of 3 on the same base (main 13aa882, then main + this branch merged). Device: Android emulator, Pixel 9 API 36, on nucbox-1. The dev build counts every component React rendered in a commit, using the bailout-aware fiber walk.

	main	+#20963	Δ
feed	633	741	+17%
composer	425	595	+40%
header	470	470	0%
other	863	923	+7%
total	2391	3001	+26%
commits	35	41	+17%
renders per commit	68	73	+7%

Runs (total renders / commits): main 2391/35, 2379/35, 2398/33; +#20963 3001/41, 3089/42, 2136/34.

Component (excluding host primitives)	main	+#20963
AnimatedComponent(View	88	106
AppSymbolView	50	68
IconButton	57	66
PressabilityDebugView	30	44
Host	31	37
TextInputHostProvider	31	37
HostView	31	37
RNHostView	32	36
NativeThemeHost	28	32
SlotView	24	29
AppText	12	18
AnimatedComponent(Component	16	17
WorkingTimer	17	17
AndroidAnchoredMenu	14	17
GlassSurface	10	14

Top causes, main (excluding host primitives):

• AnimatedComponent(View props:style,children: 51
• AppSymbolView parent-same-props<-View: 32
• TextInputHostProvider props:children: 30
• PressabilityDebugView parent-same-props<-View: 30
• HostView props:style,children: 26
• RNHostView props:children: 20
• NativeThemeHost props:style,children: 19
• Host props:style,children: 19

Top causes, +#20963 (excluding host primitives):

• AnimatedComponent(View props:style,children: 66
• PressabilityDebugView parent-same-props<-View: 44
• AppSymbolView parent-same-props<-View: 42
• TextInputHostProvider props:children: 36
• HostView props:style,children: 30
• NativeThemeHost props:style,children: 22
• Host props:style,children: 22
• IconButton props:modifiers,onGlobalEvent,onButtonPressed: 22

The thread shell components rendered the same number of times on both: ThreadRouteScreen, ThreadDetailScreen, ThreadFeed and ThreadHeader at 5 per window on main and 4–6 here. The composer subtree went from 5 to 7 renders in two of three runs (ThreadComposer, ComposerSurface, the dictation toolbar). ThreadVisitWatermark appeared with 7 renders. Total renders per commit barely moved (68 → 73); most of the total difference comes from more commits in the window, which depends on provider pace.

Caveat on the scenario: Haiku streamed its reasoning item, then delivered the reply text in one update, so the window covers reasoning deltas. The quiet-shell benefit may show more on a provider that streams reply text token by token.

Claude Opus 5.5 via Claude Code.

[github-actions]

Thread transfer impact

⚠️ The latest CI run did not produce a thread transfer result for 50431ca.

This comment will update automatically after the next completed run.

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Actionable comments posted: 1

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Inline comments:
Review comments at @apps/mobile/src/state/use-thread-outbox-drain.ts:
- Line 605: Update the server-config hook used by the drain logic to use
useServerConfigs instead of useServerConfigsWithProviders, since serverConfigs
is only needed for maxUploadBytes and provider-status updates should not trigger
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• apps/mobile/src/state/use-thread-outbox-drain.permissions.test.ts
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[juliusmarminge]

Taking over this one. I'll resolve conflicts with current main, retain the live visit tracking and provider-dependent paths, and push the focused change to this branch.

Dismissing prior approval to re-evaluate 8cad314