patterns.md

Canonical Patterns

Load this reference only when you need concrete examples during implementation.

Dependency Cache

- uses: actions/cache@v4
  with:
    path: ~/.npm
    key: ${{ runner.os }}-node-${{ hashFiles('**/package-lock.json') }}
    restore-keys: |
      ${{ runner.os }}-node-

Adapt the cache path and invalidation file to the repo's ecosystem.

Cancel Stale Runs

concurrency:
  group: ${{ github.workflow }}-${{ github.ref }}
  cancel-in-progress: true

Scope Triggers

on:
  push:
    paths:
      - "src/**"
      - "tests/**"
      - "package.json"

Use paths-ignore when exclusion is easier to maintain than inclusion.

Job-Level Changed-File Gating

Use a small change-detection step that emits explicit outputs such as:

• docs_relevant
• runtime_relevant
• compat_relevant
• run_tests

Gate downstream jobs on those outputs when event-level filters are not expressive enough.

Matrix Reduction

Use the minimum matrix that matches the decision:

• Full matrix on release
• Reduced compatibility matrix on sensitive runtime surfaces
• Single representative leg for ordinary code changes

Optional Write-Back Job

Use label-driven or manual triggers for jobs that mutate the PR branch, such as formatting bots.