GitHub Actions CI Tuning

Audit and improve GitHub Actions workflows. Focus on correctness first (jobs that error rather than fail), then speed (cache, parallelism), then reliability (flakiness, artifact guards).

Workflow

1. Inventory — list all .github/workflows/*.yml files and their trigger events, jobs, and rough durations (gh run list --workflow <file> --limit 5).
2. Audit against checklist — run through each section below and flag every gap.
3. Prioritise — group findings by impact: correctness bugs > cache misses > parallelism gains > cosmetic.
4. Propose changes — draft minimal diffs; do not refactor unrelated parts.
5. Verify — after applying, confirm via gh run list that the next run is green and faster.

Checklist

Package Manager Cache