github-actions-builder

# GitHub Actions Builder ## Overview Author production-grade GitHub Actions workflows that are fast, deterministic, and secure by default. Keywords: github actions, workflow, ci, cd, ci/cd, .github/workflows, jobs, steps, runs-on, matrix, build matrix, strategy, fail-fast, cache, actions/cache, setup-node, setup-python, setup-go, secrets, GITHUB_TOKEN, permissions, OIDC, environments, reusable workflow, workflow_call, composite action, concurrency, artifacts, upload-artifact, deploy, release, pinning SHA, dependabot. This skill covers the full lifecycle: choosing triggers, structuring jobs, caching dependencies correctly, fanning out across a matrix, passing secrets safely, gating deployments with environments, and factoring shared logic into reusable or composite workflows. Always prefer the patterns and pinning rules in `references/best-practices.md` and validate output structure with `scripts/validate_workflow.py`. ## Workflow 1. **Clarify intent.** Identify: project language/runtime, the events that should trigger CI (push, pull_request, tag, schedule, manual), and whether deployment is in scope. If the user only says "add CI", default to lint + test on `push` to the default branch and on `pull_request`. 2. **Pick triggers (`on:`).** Use `pull_request` for validation and `push` (filtered to the default branch) to avoid double-runs on PR branches. Add `workflow_dispatch` for manual runs and `tags` filters for release pipelines. See the trigger matrix in `references/...