GitHub Actions Branch Drift Audit

Use this skill to catch branch-specific CI reliability regressions before they spread into your mainline release flow.

What this skill does

• Reads GitHub Actions run JSON exports
• Groups runs by repository + workflow + branch
• Selects a baseline branch per repository/workflow (defaults to main|master)
• Compares each non-baseline branch against that baseline on:
  • failure-rate drift (percentage points)
  • average runtime drift (ratio)
• Flags warning/critical drift severity and supports CI fail gates
• Emits text or JSON output for pipeline checks and triage dashboards

Inputs

Optional:

• RUN_GLOB (default: artifacts/github-actions/*.json)
• TOP_N (default: 20)
• OUTPUT_FORMAT (text or json, default: text)
• MIN_RUNS_PER_BRANCH (default: 2)
• MIN_BRANCHES (default: 2)
• BASELINE_BRANCH_MATCH (default: ^(main|master)$)
• WORKFLOW_MATCH (regex, optional)
• WORKFLOW_EXCLUDE (regex, optional)
• REPO_MATCH (regex, optional)
• REPO_EXCLUDE (regex, optional)
• FAILURE_DRIFT_WARN_PP (default: 10)
• FAILURE_DRIFT_CRITICAL_PP (default: 25)
• RUNTIME_DRIFT_WARN_RATIO (default: 1.25)
• RUNTIME_DRIFT_CRITICAL_RATIO (default: 1.6)
• FAIL_ON_CRITICAL (0 or 1, default: 0)

Collect run JSON

gh run view <run-id> --json databaseId,workflowName,event,conclusion,headBranch,headSha,createdAt,updatedAt,startedAt,url,repository \
  > artifacts/github-actions/run-<run-id>.json

Run

Text report:

RUN_GLOB='artifacts/github-actions/*.json' \
BASELINE_BRANCH_MATCH='^(main|release/.*)$' \
MIN_RUNS_PER_BRANCH=3 \
bash skills/github-actions-branch-drift-audit/scripts/branch-drift-audit.sh

JSON output with fail gate:

RUN_GLOB='artifacts/github-actions/*.json' \
OUTPUT_FORMAT=json \
FAIL_ON_CRITICAL=1 \
bash skills/github-actions-branch-drift-audit/scripts/branch-drift-audit.sh

Run with bundled fixtures:

RUN_GLOB='skills/github-actions-branch-drift-audit/fixtures/*.json' \
bash skills/github-actions-branch-drift-audit/scripts/branch-drift-audit.sh

Output contract

• Exit 0 in report mode (default)
• Exit 1 when FAIL_ON_CRITICAL=1 and one or more drift rows are critical
• Text mode prints summary + ranked branch drift rows
• JSON mode prints summary + drift rows + critical-only slice