perf(clients): sort projects and settled threads without re-parsing dates per comparison

[t3dotgg]

With thousands of threads, every shell update re-sorts the sidebar's projects and the settled shelf. While agents stream, that can be up to about 20 updates a second. Both sorts parsed dates inside the comparator. The project sort was the worst: on every comparison it walked all of a project's threads and parsed their dates again. On a synthetic set of 5,191 threads and 130 projects, the project sort took about 5.3 ms per update. The settled sort took 1.6 to 19 ms, based on how many rows have no settledAt.

Fix

• Compute each project's timestamp and each settled thread's timestamp once, then sort by that key. The comparisons and tie-breaks do not change, so the order is the same.
• The keyed settled sort moves to client-runtime as sortSettledThreads, so web and mobile use the same function.
• On the same synthetic set, the keyed project sort takes about 0.9 ms and the keyed settled sort 0.9 to 1.6 ms.

Behavior change on mobile: settled rows with the exact same timestamp now sort by id, not by input order. This is what web already did.

Verification

• New tests compare each keyed sort against the old per-comparison comparator on a shuffled list with ties and invalid stamps (project sort for updated_at and created_at, and the settled sort). Removing the tie-break makes them fail.
• vp test run on threadSort.test.ts, Sidebar.logic.test.ts and threadListV2.test.ts: 282 pass.
• vp lint (no new warnings) and vp fmt on the changed files. Typecheck passes for @t3tools/client-runtime, @t3tools/web and @t3tools/mobile.

Made by Claude Opus 5.5 (1M context) in Claude Code, running in T3 Code.

🤖 Generated with Claude Code

Summary by CodeRabbit

• Bug Fixes
  • Settled threads are now ordered consistently in the mobile and web sidebars, including when previewing their position during drag-and-drop.
  • Project ordering continues to honor activity timestamps and existing tie-break rules, including when timestamps are tied or unavailable.

[github-actions]

Thread transfer impact

✅ Thread transfer remains within every enforced ceiling.

Provider	Metric	Main baseline	This PR	Impact	PR ceiling
Codex	Total thread wire	13.5 KiB	13.5 KiB	+29 B (+0.2%)	15.1 KiB	✅
Codex	Thread snapshot wire	7.1 KiB	7.1 KiB	0 B (0.0%)	7.3 KiB	✅
Codex	Live turn WebSocket wire	6.4 KiB	6.5 KiB	+29 B (+0.4%)	7.8 KiB	✅
Codex	Live turn WebSocket decoded	56.2 KiB	56.3 KiB	+44 B (+0.1%)	66.4 KiB	✅
Codex	Live turn messages	9	10	+1 (+11.1%)	21	✅
Claude	Total thread wire	13.5 KiB	13.5 KiB	−23 B (−0.2%)	15.1 KiB	✅
Claude	Thread snapshot wire	7.1 KiB	7.1 KiB	+9 B (+0.1%)	7.3 KiB	✅
Claude	Live turn WebSocket wire	6.5 KiB	6.4 KiB	−32 B (−0.5%)	7.8 KiB	✅
Claude	Live turn WebSocket decoded	57.0 KiB	57.0 KiB	0 B (0.0%)	66.4 KiB	✅
Claude	Live turn messages	9	9	0 (0.0%)	21	✅

Baseline: 92f0af2 · PR result: ea49c2f · 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: 114.0 KiB
• Claude decoded thread snapshot: 114.7 KiB

Updated in place by a trusted workflow. PR artifacts are strictly validated and never executed.

[macroscopeapp]

Approvability

Verdict: Approved at 486fe34

Macroscope's review found this PR approvable — This is a contained client-side performance refactor that caches sort keys while preserving existing project and web thread ordering. It adds shared test coverage and only makes the low-risk, deterministic change of ID tie-breaking for equal-timestamp mobile rows.

No code changes detected at ea49c2f. Prior analysis still applies.

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📒 Files selected for processing (7)

• apps/mobile/src/features/threads/threadListV2.ts
• apps/web/src/components/Sidebar.logic.test.ts
• apps/web/src/components/Sidebar.logic.ts
• apps/web/src/components/Sidebar.tsx
• apps/web/src/lib/threadSort.ts
• packages/client-runtime/src/state/threadSort.test.ts
• packages/client-runtime/src/state/threadSort.ts

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• apps/web/src/lib/threadSort.ts

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📝 Walkthrough

Walkthrough

The client runtime adds shared settled-thread ordering. Mobile and web use the shared sorter instead of the sidebar-specific function. Sidebar project activity sorting also computes each project timestamp once before sorting.

Changes

Settled-thread sorting

Layer / File(s)	Summary
Add shared settled-thread sorting packages/client-runtime/src/state/threadSort.ts, packages/client-runtime/src/state/threadSort.test.ts	Adds ordering by resolved timestamp descending, with ascending thread ID for ties. Tests cover timestamp fallbacks, tie-breaking, and shuffled inputs.
Use the shared sorter in mobile and web apps/mobile/src/features/threads/threadListV2.ts, apps/web/src/components/Sidebar.tsx, apps/web/src/components/Sidebar.logic.ts, apps/web/src/components/Sidebar.logic.test.ts, apps/web/src/lib/threadSort.ts	Replaces sidebar-specific settled-thread sorting in sidebar and mobile flows. Removes the old function and its re-exports. Updates sidebar tests to use the shared sorter.
Precompute project activity timestamps apps/web/src/components/Sidebar.logic.ts, apps/web/src/components/Sidebar.logic.test.ts	Computes project timestamps once before sorting. Tests cover both sort orders with tied or invalid timestamps and projects without threads.

Priority: ⬇️ Low

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

Change: Refactor

Suggested reviewers: juliusmarminge

Merge Risk: ⚪ Minimal · up to 486fe

The shared ordering and project-sort optimization have no identified merge-blocking issue; this change is ready for normal checks.

🚥 Pre-merge checks | ✅ 4 | ❌ 1

❌ Failed checks (1 warning)

Check name	Status	Explanation	Resolution
Docstring Coverage	⚠️ Warning	Docstring coverage is 37.50% which is insufficient. The required threshold is 80.00%. Docstring coverage is scoped to functions touched by this diff. Analyzed 8 functions across 6 files.	Write docstrings for the functions missing them to satisfy the coverage threshold.

✅ Passed checks (4 passed)

Check name	Status	Explanation
Title check	✅ Passed	The title clearly identifies the performance change: avoiding repeated date parsing when sorting projects and settled threads.
Description check	✅ Passed	The description explains what changed, why it changed, the measured performance impact, behavior differences, and verification results. It does not use the template headings or include the checklist, …
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.

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