perf(ci): run PR checks side by side and balance server shards

[t3dotgg]

PR checks take about 2 minutes on main-based PRs and about 3.5 minutes on PRs into t3code/codex-turn-mapping. Three things set that time:

• Check ran knip, lint, typecheck, an apt install, and the desktop build one after another (p50 112s).
• Test started the web suite last, so it ran alone for about 40s after everything else finished.
• Server shards split files by path hash into equal-count groups. On the v2 branch, the two slowest files (51s and 25s) land in the same shard, which takes 200s while the others take 135s.

This PR runs the work side by side and balances the shards. No check is removed.

• Check splits into Lint (knip, lint, format), Typecheck, and Build (desktop pipeline and preload check).
• Test splits into Test (every package except server and web) and Test Web.
• apt installs the libsecret headers in the background while Vite+ installs dependencies, in Build and Test, instead of taking about 16s on the critical path.
• Server tests move from 3 shards on 8 vCPU to 6 shards on 4 vCPU. fileParallelism: false keeps about 1.5 cores busy, so 4 vCPU loses nothing and the vCPU-minutes stay about the same. A small vitest sequencer (apps/server/src/testUtils/weightedShardSequencer.ts) gives each shard an equal share of recorded test time: longest file first, into the lightest shard. Every shard computes the same split, so each file still runs exactly once, and a test checks that. node apps/server/scripts/update-test-shard-weights.ts rewrites the recorded times. Files without a recorded time count as fast files.
• Check is now the last job. It fails when any other job fails, is cancelled, or is skipped without a reason. Only the macOS native lint may skip, when no native mobile code changed. Branch protection already requires Check by name, so every job in the workflow, including the new ones, is required with no ruleset change.

Measured on this PR's first CI run, against the last 60 successful runs:

Job	Before (p50)	After
Check (now Lint)	112s	47s
Typecheck	(in Check)	50s
Build	(in Check)	50s
Test	106s	59s
Test Web	(in Test)	57s
Test Server (slowest)	102s, 200s on v2 PRs	70s

The six server shards ran 37-41s of tests each. The background apt install finished before anything needed it. The slowest job went from about 112s to 70s. PRs into t3code/codex-turn-mapping get the balanced split after that branch merges main and reruns the weights script, since its v2 test files are not in main's recorded times yet.

Branch protection: the "Passing CI on main" ruleset already requires Check, Test, Test Server 1-3, Rust, Release Smoke, and Mobile Native Static Analysis. Check now covers every job, so nothing needs to change. Later, the ruleset could require only Check.

Verified with the new sequencer test, server typecheck, lint and format on changed files, knip:check, actionlint, and this PR's own CI run.

Created with Claude Opus 5.5 in Claude Code, running inside T3 Code.

🤖 Generated with Claude Code

[macroscopeapp]

Approvability

Verdict: Not approved

Macroscope's review found this PR not approvable — This PR primarily reorganizes CI and server test sharding without changing customer-facing runtime behavior. It also adds file-level @effect-diagnostics nodeBuiltinImport:off suppressions, so the static-analysis policy requires human review.

No code changes detected at 2647c4d. Prior analysis still applies.

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[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	−34 B (−0.2%)	15.1 KiB	✅
Codex	Thread snapshot wire	7.1 KiB	7.1 KiB	−3 B (−0.0%)	7.3 KiB	✅
Codex	Live turn WebSocket wire	6.5 KiB	6.4 KiB	−31 B (−0.5%)	7.8 KiB	✅
Codex	Live turn WebSocket decoded	56.3 KiB	56.2 KiB	−44 B (−0.1%)	66.4 KiB	✅
Codex	Live turn messages	10	9	−1 (−10.0%)	21	✅
Claude	Total thread wire	13.5 KiB	13.5 KiB	−4 B (−0.0%)	15.1 KiB	✅
Claude	Thread snapshot wire	7.1 KiB	7.1 KiB	−5 B (−0.1%)	7.3 KiB	✅
Claude	Live turn WebSocket wire	6.4 KiB	6.4 KiB	+1 B (+0.0%)	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: 67b175a · PR result: 25ed99a · 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.

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📝 Walkthrough

Walkthrough

CI runs checks and test suites in separate jobs. Server tests use duration-weighted sharding across six shards. An always-running CI job checks the results of required jobs.

Changes

CI testing

Layer / File(s)	Summary
Weighted server test sharding apps/server/scripts/update-test-shard-weights.ts, apps/server/src/testUtils/shardWeights.json, apps/server/src/testUtils/weightedShardSequencer.ts, apps/server/src/testUtils/weightedShardSequencer.test.ts, apps/server/vite.config.ts, knip.jsonc	A script records test durations in a weights file. WeightedShardSequencer uses those weights to assign test files to shards, and the server test configuration uses the sequencer. Tests check file coverage and assignment of the six slowest files.
Separate CI checks and test jobs .github/workflows/ci.yml	The workflow separates Typecheck, Build, non-server tests, Web tests, and Server tests. Server tests run in six shards on 4-vCPU runners. Build and non-server test setup installs browser-secret-helper libraries in the background and waits for completion before continuing.
Required CI result gate .github/workflows/ci.yml	An always-running job checks required job results and fails unless each result is success or skipped.

Priority: ➖ Normal

Estimated code review effort: 3 (Moderate) | ~25 minutes

Change: Refactor

Suggested reviewers: juliusmarminge

Merge Risk: ⚪ Minimal · up to 25ed9

The change splits CI jobs and balances server test shards. No concrete merge-blocking risk was identified.

🚥 Pre-merge checks | ✅ 5

✅ Passed checks (5 passed)

Check name	Status	Explanation
Docstring Coverage	✅ Passed	No functions found in the changed files to evaluate docstring coverage. Skipping docstring coverage check. Docstring coverage is scoped to functions touched by this diff. Analyzed 0 functions across 4…
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 and concisely describes the main changes: parallel CI checks and balanced server test shards.
Description check	✅ Passed	The description explains the CI performance problem, the workflow and shard-balancing changes, measured results, verification steps, and relevant scope. It does not include an explicit link to a triag…

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🧹 Nitpick comments (1)

apps/server/src/testUtils/weightedShardSequencer.test.ts (1)

13-17: 📐 Maintainability & Code Quality | 🔵 Trivial | ⚡ Quick win

Cover the three-shard release configuration.

The exactly-once test calls shardModuleIds(6) only. The release workflow runs WeightedShardSequencer with three shards. No other test invokes this sequencer with three shards. A regression in three-shard assignment can therefore pass the changed test.

Suggested fix

-  it("runs every file in exactly one shard", async () => {
-    const shards = await shardModuleIds(6);
+  it.each([3, 6])("runs every file in exactly one shard across %s shards", async (count) => {
+    const shards = await shardModuleIds(count);

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Review comment at @apps/server/src/testUtils/weightedShardSequencer.test.ts
around lines 13 - 17:
Update the exactly-once test that calls shardModuleIds to cover both three- and
six-shard configurations, ensuring it verifies every file is assigned to exactly
one shard in each case.

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Nitpick comments:
Review comments at @apps/server/src/testUtils/weightedShardSequencer.test.ts:
- Around line 13-17: Update the exactly-once test that calls shardModuleIds to
cover both three- and six-shard configurations, ensuring it verifies every file
is assigned to exactly one shard in each case.

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