ci: optimize PR pipeline — concurrency, fast gate, reduced matrix

[RtlZeroMemory]

Summary

• Concurrency groups on ci.yml and codeql.yml — cancel in-progress runs when a new push arrives on the same PR, freeing runners immediately
• Fast checks gate — lint, typecheck, codegen, portability, and unicode checks run once on Linux/Node 22 (~2 min); failures prevent the expensive matrix from starting at all
• Dynamic matrix — PRs use 5 runners (Linux × Node 18/20/22, macOS × 22, Windows × 22); push to main keeps the full 3×3 = 9
• Removed redundant work — lint/typecheck/codegen/biome-install stripped from each matrix cell and the bun job; duplicate docs job removed (already in docs.yml)

Before vs After (PR)

Metric	Before	After
Matrix runners	9	5
Total jobs	13	9
Time to lint failure	~3–5 min	~2 min
Redundant lint/typecheck runs	9	0
Cancel on re-push	No	Yes

Full 3×3 matrix still runs on push to main — no safety regression.

Test plan

• Verify CI passes on this PR (the new pipeline tests itself)
• Force-push to confirm stale run is cancelled
• Confirm docs required status check doesn't reference the removed ci.yml job (if applicable in branch protection)

🤖 Generated with Claude Code

Summary by CodeRabbit

• Chores
  • Optimized CI/CD pipeline with concurrency controls to prevent duplicate workflow runs
  • Enhanced workflow efficiency through improved job organization and platform-specific optimizations

[coderabbitai]

Caution

Review failed

The pull request is closed.

ℹ️ Recent review info

Configuration used: defaults

Review profile: CHILL

Plan: Pro

📥 Commits

Reviewing files that changed from the base of the PR and between 3fdcbb0 and 945caa0.

📒 Files selected for processing (2)

• .github/workflows/ci.yml
• .github/workflows/codeql.yml

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📝 Walkthrough

Walkthrough

The CI workflow is refactored to introduce concurrency controls, extract fast platform-independent checks into a dedicated job, and compute test matrices dynamically based on event type. The CodeQL workflow gains concurrency configuration to cancel redundant PR runs.

Changes

Cohort / File(s)	Summary
CI Workflow Restructuring .github/workflows/ci.yml	Reorganized pipeline with concurrency group for PRs, new checks job (codegen, lint, typecheck, portability, Unicode validation), new matrix-config job for dynamic matrix computation, rewired ci job dependencies on matrix output, conditional Linux/non-Linux steps, and removed docs job.
CodeQL Concurrency .github/workflows/codeql.yml	Added concurrency block with group key and pull-request-only cancellation.

Estimated code review effort

🎯 3 (Moderate) | ⏱️ ~25 minutes

Poem

🐰 A rabbit hops through CI lanes,
Fast checks first, no more delays,
Dynamic matrices adapt their way,
Concurrency curbs the wasteful race,
Workflows leap with newfound grace! 🚀

✨ Finishing Touches

🧪 Generate unit tests (beta)

• Create PR with unit tests
• Post copyable unit tests in a comment
• Commit unit tests in branch ci/optimize-pr-pipeline

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