perf(mobile): remove unused Home project sorting

[juliusmarminge]

Home scanned every thread to sort project groups on each streaming update. It then used the sorted groups only to find the selected project and build a title map; it never displayed that order.

Use the existing project groups directly. This removes the scan, sort and downstream memo invalidations without adding a cache or changing thread order. The sorted project picker in the new-task flow is unchanged. Selected-group lookup now prefers an exact scope key before falling back to legacy project-ref keys, avoiding collisions with caller-supplied project IDs.

Release measurements

Two alternating before/after pairs with Home visible and its settled shelf expanded. Each run restores the same server fixture and saved app cache: 1,210 shells and five concurrent streams at 20 Hz for 15 seconds, 1,500 emitted events. Same optimized native Release binary, Hermes -O, dev=false, no Metro. These captures used cb8b899. Their source maps differ only in HomeScreen.tsx; baseline is 4a0c6b2.

Measurement	Before 1	After 1	Before 2	After 2
Project-sort inclusive samples	158	0	138	0
Active JS samples	2,871	2,698	2,855	2,722
Total samples	14,626	15,058	15,172	15,028
GC samples	387	352	394	341
Process CPU seconds	5.42	4.77	5.04	4.92
Capture seconds	22.98	22.96	22.87	22.86

Mean process CPU fell from 5.23 s to 4.85 s, about 7% for this loaded-Home workload. Both pairs improved, but two pairs are not a confidence interval. Process CPU includes native threads and profiler overhead; generated text and batching vary. This is not a whole-app latency or battery claim.

Measurement details · Before 1 · After 1 · Before 2 · After 2

The subsequent project-key collision correction is covered by a regression test. It retains the immediate null result for All projects, the selection used in these captures. The profiles were not rerun after that correction.

Verification and scope

• 19 focused Home/project-grouping tests passed, including a collision test that fails with the old lookup; mobile typechecking passed. Targeted lint has 13 pre-existing warnings, down from 14. Formatting passed.
• Grouping deduplicates project refs, so the title map is independent of group order. Reviewed selected-group and legacy scoped-project-key lookup paths. Neither consumer renders group order.
• In the release simulator, choosing the server project showed only its thread; returning to All projects restored the loaded list. No visual or interaction change is intended, and no navigation-timing claim is made.
• This affects the shared iOS/Android Home component; runtime verification was iOS only. Web, desktop, contracts, providers and the new-task picker are unchanged. Unrelated widget edits are excluded. No wiring-only test or new documentation was added.

Julius requested this maintainer performance audit with one PR per measured hotspot. There is no separate public issue or approval link.

Implementation: Claude Opus 5.5 through T3 Code. Integration, review and release profiling: GPT-6 Astra through the Codex harness.

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[macroscopeapp]

Approvability

Verdict: Approved at fbb9943

Macroscope's review found this PR approvable — This is an isolated mobile performance cleanup that removes an unused project-scope sort and adds a small, tested lookup helper. Existing list behavior remains bounded to the same scopes, with no defaults, deployment settings, or static-analysis suppressions changed.

No code changes detected at d443e39. Prior analysis still applies.

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[github-actions]

Thread transfer impact

✅ Thread transfer remains within every enforced ceiling.

ℹ️ No successful main baseline artifact is available yet. This run establishes the initial measurement.

Provider	Metric	Main baseline	This PR	Impact	PR ceiling
Codex	Total thread wire	—	5.0 KiB	—	6.8 KiB	✅
Codex	Thread snapshot wire	—	3.8 KiB	—	4.9 KiB	✅
Codex	Live turn WebSocket wire	—	1.2 KiB	—	2.0 KiB	✅
Codex	Live turn WebSocket decoded	—	20.9 KiB	—	29.3 KiB	✅
Codex	Live turn messages	—	2	—	8	✅
Claude	Total thread wire	—	5.0 KiB	—	6.8 KiB	✅
Claude	Thread snapshot wire	—	3.8 KiB	—	4.9 KiB	✅
Claude	Live turn WebSocket wire	—	1.2 KiB	—	2.0 KiB	✅
Claude	Live turn WebSocket decoded	—	21.2 KiB	—	29.3 KiB	✅
Claude	Live turn messages	—	1	—	8	✅

Baseline: unavailable · PR result: d443e39 · Source CI: success

Scenario and decoded snapshot size

10 historical turns, 5 command tools per turn, 878.9 KiB retained MCP result per historical turn, and a 1.05 MiB retained result in the measured turn.

• Codex decoded thread snapshot: 108.5 KiB
• Claude decoded thread snapshot: 108.8 KiB

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📒 Files selected for processing (3)

• apps/mobile/src/features/home/HomeScreen.tsx
• apps/mobile/src/features/home/homeThreadList.test.ts
• apps/mobile/src/features/home/homeThreadList.ts

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📝 Walkthrough

Walkthrough

HomeScreen no longer sorts project scopes using threads, pending tasks, or the configured project sort order. It uses projectScopes for selected-scope lookup and project-title mappings. A new helper resolves scopes by exact key or environment-scoped project reference.

Changes

Home project scope lookup

Layer / File(s)	Summary
Resolve project scopes apps/mobile/src/features/home/homeThreadList.ts, apps/mobile/src/features/home/homeThreadList.test.ts	findHomeProjectScope returns null for null or unmatched keys. It prefers exact scope-key matches over environment-scoped project references. Tests cover key collisions and missing keys.
Use project scopes directly apps/mobile/src/features/home/HomeScreen.tsx	HomeScreen uses projectScopes for selected-scope lookup and project-title mappings instead of sorted scopes.

Priority: ➖ Normal

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

Change: Refactor

Merge Risk: ⚪ Minimal · up to fbb99

No actionable issue is identified in the Home project-scope lookup change; it is mergeable after normal checks.

🚥 Pre-merge checks | ✅ 4 | ❌ 1

❌ Failed checks (1 warning)

Check name	Status	Explanation	Resolution
Docstring Coverage	⚠️ Warning	Docstring coverage is 40.00% which is insufficient. The required threshold is 80.00%. Docstring coverage is scoped to functions touched by this diff. Analyzed 5 functions across 3 files.	Write docstrings for the functions missing them to satisfy the coverage threshold.

✅ Passed checks (4 passed)

Check name	Status	Explanation
Linked Issues check	✅ Passed	Check skipped because no linked issues were found for this pull request.
Out of Scope Changes check	✅ Passed	Check skipped because no linked issues were found for this pull request.
Title check	✅ Passed	The title clearly summarizes the main change: removing unused project sorting from the mobile Home screen.
Description check	✅ Passed	The description covers the problem, change, scope and approval context, and verification. It also reports measured results with appropriate limitations. The maintainer audit is identified, although no…

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Inline comments:
Review comments at @apps/mobile/src/features/home/HomeScreen.tsx:
- Around line 336-349: Update the v2ScopedProjectGroup lookup to search
projectScopes for an exact scope.key match first, then fall back to matching
member projectRefs with scopedProjectKey. Preserve the null result when
v2ProjectScopeKey is null or neither lookup finds a match.

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• apps/mobile/src/features/home/HomeScreen.tsx

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