harpoon — the build cache that survives the weekend
- Distributed compile cache — 68% median cache-hit rate across 200+ CI machines
- Cut a monorepo's cold CI from 22 minutes to 6.5 minutes; saves ~3,100 build-hours/month
- Rust + gRPC + S3; 2,400 GitHub Actions workflows reference it, 48 contributors
- 3.2k stars — the flagship, maintained on a written release schedule