{
  "intent": "Stop the two Python CI workflows re-downloading ~80 packages from PyPI on every run, which was the single slowest step in both.",
  "scope": [
    ".github/workflows/python-tests.yml",
    ".github/workflows/pre-commit.yml",
    "Non-goal: pinning dependencies or trimming the requirements list"
  ],
  "changes": [
    "Added cache: pip with cache-dependency-path: meta/requirements.txt to actions/setup-python in both workflows. The path is the real file, not the root requirements.txt symlink, because the cache key is hashed from the file at the given path.",
    "Added an actions/cache@v4 step for ~/.cache/pre-commit in pre-commit.yml, keyed on .pre-commit-config.yaml, so hook virtualenvs are not rebuilt when no hook changed.",
    "The Node workflows (poker-stakes, reverse-survivors) already cached npm; the Python ones were the outliers."
  ],
  "verification": [
    {
      "command": "gh api .../actions/runs/32645134828/jobs -- per-step timings for Pre-commit checks",
      "result": "pass",
      "evidence": "Install dependencies = 63s, the dominant step; every other step 16s or less. This is the step the cache targets."
    },
    {
      "command": "gh api .../actions/runs/32645075080/jobs -- per-step timings for Python tests",
      "result": "pass",
      "evidence": "Install dependencies = 49s vs 35s actually running pytest; same dominant step"
    },
    {
      "command": "python3 -c \"import yaml; yaml.safe_load(...)\" on both workflow files",
      "result": "pass",
      "evidence": "both parse as valid YAML"
    },
    {
      "command": "pre-commit run --files .github/workflows/python-tests.yml .github/workflows/pre-commit.yml",
      "result": "pass",
      "evidence": "no hook reported a failure (prettier, check-yaml included)"
    }
  ],
  "risks": [
    "A stale pip cache could in principle serve an old wheel; mitigated because the key is a hash of the requirements file, so any dependency change invalidates it.",
    "The first run after this lands is a cache MISS and will be no faster; the saving appears from the second run onward."
  ],
  "rollback": [
    "Remove the cache lines from both setup-python blocks and delete the actions/cache step.",
    "After rollback, confirm the Install dependencies step returns to ~50-60s."
  ]
}