perf(ci): reduce GitHub Actions costs ~60-65% across all workflows
Analysis of Feb 17 data showed 400+ workflow runs/day consuming ~398 billable minutes (~200 hours/month projected). Implemented targeted optimizations:
High-impact changes:
- sec-audit.yml: add path filters (Cargo.toml, src/**, crates/**, deny.toml); skip docs-only PRs
- test-benchmarks.yml: move from every-push-to-main to weekly schedule; retention 30d -> 7d
- pub-docker-img.yml: tighten PR smoke build path filters to Docker-specific files only
- sec-codeql.yml: reduce from twice-daily (14 runs/week) to weekly
Medium-impact changes:
- ci-run.yml: merge lint + lint-strict-delta into single job; drop --release from smoke build
- feature-matrix.yml: remove push trigger (weekly-only); remove redundant cargo test step
- dependabot.yml: monthly instead of weekly; reduce PR limits from 11 to 5/month; group all deps
Runner cost savings:
- Switch 6 lightweight API-only workflows to ubuntu-latest (PR Labeler, Intake, Auto Responder, Check Stale, Check Status, Sync Contributors)
- pr-check-status.yml: reduce from every 12h to daily
New files:
- docs/ci-cost-optimization.md: comprehensive analysis and revised architecture documentation
- scripts/ci/fetch_actions_data.py: reusable GitHub Actions cost analysis script
Estimated impact: daily billable minutes ~400 -> ~120-150 (60-65%% reduction), monthly hours ~200 -> ~60-75, Dependabot PRs ~44/month -> ~5 (89%% reduction)
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