Fast GitHub Actions Without Migrating Off GitHub Actions
joelclaw monorepo CI is the bottleneck between agent loop commits and deploy verification — faster runners means tighter loop feedback cycles
Blacksmith is a drop-in GitHub Actions runner service that promises meaningfully faster CI without touching your workflow YAML. Same .github/workflows/ files, same GitHub Actions syntax, same ecosystem — just runners that actually go fast because someone cared about the hardware.
The appeal here is obvious: most GitHub Actions alternatives (CircleCI, BuildKite, self-hosted runners) require a migration. You’re rewriting workflow files, learning new DSLs, managing new integrations. Blacksmith sidesteps all of that. You change one line — runs-on: blacksmith-... — and your builds speed up. That’s the entire value proposition, and it’s a good one.
For a TypeScript monorepo running Bun, the usual CI bottlenecks are install time, type-checking across packages, and test runs. Faster hardware hits all three. The joelclaw monorepo has a publish pipeline for the system-bus worker that goes source → Docker build → GHCR push → k8s rollout — every second of runner overhead compounds across that chain. And if the agent loop is shipping multiple stories per run, slow CI becomes a real tax on iteration speed.
Worth benchmarking against the current GitHub-hosted runners before committing, but as potential migration targets go, this is the least disruptive path to faster CI. No new orchestration layer, no new secrets management story, no new DSL to learn.
Key Ideas
- Drop-in replacement: change
runs-on:in your workflow YAML, nothing else — no workflow migration required - Purpose-built hardware: Blacksmith uses optimized runner infrastructure rather than commodity cloud VMs, which is where the speed gain comes from
- Monorepo-friendly: faster installs and TypeScript compilation matter most in large workspaces — joelclaw’s pnpm workspace is a prime candidate
- GitHub ecosystem preserved: GitHub Actions Marketplace, caching, secrets, OIDC — all still work because it’s still GitHub Actions under the hood
- Cost angle: typically positioned as faster and cheaper than GitHub’s hosted runners, though that depends on usage patterns
- Agent loop relevance: tighter CI feedback loops = faster agent loop iteration — the loop-nanny can act on test results sooner
Links
- Blacksmith
- Blacksmith Docs — runner configuration and migration guide
- GitHub Actions runner types — what you’re replacing
- joelclaw k8s publish script — the pipeline that would benefit most