GitHub Actions Efficiency

references/actions.md

gh

.github/workflows/

gh run list --limit 10

Use This Skill When

• The user wants to reduce GitHub Actions runtime, CI cost, or wasted workflow runs.
• The repo has existing workflows in

  .github/workflows/

  or explicit GitHub Actions configuration questions.
• The user asks for caching, concurrency, path filters, matrix reduction, job optimization, or workflow-specific fixes.
• The user needs help creating a new GitHub Actions workflow or CI baseline from scratch.

Load Only What You Need

• references/actions.md

  — audits, job gating, matrix reduction, live validation, and workflow-specific fixes.

• references/reporting.md

  — when the user asks for a before/after efficiency report.

• references/patterns.md

  — full YAML examples when inline audit commands are not enough.

Core Workflow

1. Measure first

rg -n "on:|concurrency:|paths:|paths-ignore:|strategy:|matrix:|cache:" .github/workflows
gh run list --limit 10
run_id=$(gh run list --limit 1 --json databaseId --jq '.[0].databaseId')
gh run view "$run_id" --log-failed

concurrency

2. Apply guardrails

1. Does not hide required validation — drop any fix that removes release, schema, migration, or shared-library checks.
2. Does not reduce parallelism without justification — drop unless the user prioritised cost over latency and the new critical path stays within 1.25× the original.
3. Preserves only documented matrix legs — drop matrix legs with no explicit version or platform commitment.
4. Write-back jobs use opt-in triggers — flag (do not drop) formatter or bot jobs that run automatically; recommend an opt-in trigger instead.
5. Repo changes stay separate from org settings — split any fix that mixes repo-editable YAML with org-level or GitHub-account settings into two distinct recommendations.

3. Select the top 3 fixes

1. Add dependency caching with lockfile-based keys
2. Add or correct

   concurrency

   cancellation
3. Remove duplicate workflow coverage before merging jobs
4. Narrow workflow or job triggers safely
5. Reduce matrix breadth to match risk and event type
6. Parallelize independent jobs on the critical path

4. Verify

• If

  gh

  CLI access is available, validate path-gating and concurrency cancellation with a live test push on a non-protected branch.
• If live validation is not possible, state that explicitly in the output.
• Treat unexpected live behavior as a real bug even when the YAML looks correct.

Required Output

1. Waste sources — top cost or latency drivers found in step 1
2. Proposed fixes — top 3 (or all remaining) with supporting audit evidence
3. Validation — what was proven live, what was checked locally only, and any remaining risk
4. Impact — expected savings vs. measured savings; separate PR wall-clock time from total runner time

References

• references/actions.md

• references/reporting.md

• references/patterns.md

• references/review-rubric.md

  — load when reviewing completed efficiency work