Risk score

This runs in CI, where something reads the JSON and decides whether a PR needs a second reviewer or can merge. That only works if the same diff gets the same score every time. So the score comes from scripts/score.py, never from you.

Your job is getting the right diff into the script and handing back what it prints, untouched. If a rule looks wrong for this PR, that's a change to the script, made in a PR of its own. Bending one score breaks the thing CI trusts.

1. Pick the diff

$ARGUMENTS decides:

• A number, or a GitHub PR URL: the PR.

  gh pr diff <number or url> --color=never

• Anything else non-empty: a base branch to compare the current branch with.

• Empty: the base is origin/$GITHUB_BASE_REF when that's set (GitHub Actions sets it on pull_request runs), else what git symbolic-ref --short refs/remotes/origin/HEAD prints, else main.

  git -c core.quotePath=false diff --no-color --no-ext-diff --find-renames <base>...HEAD

The flags pin the output format, so a user's git config can't change the score. Three dots means the diff since the branch left the base, which is what a PR shows. Uncommitted changes aren't part of a PR, so they aren't scored.

2. Score it

Pipe the diff straight in. Don't save, trim, or filter it first; the script already skips lockfiles and generated files where they shouldn't count.

git ... | python3 <this skill's directory>/scripts/score.py

The script reads only the diff, never git history, so a shallow CI checkout works as long as the diff command does.

3. Reply

Reply with exactly what the script printed: one JSON object, no code fence, nothing before or after. Something like jq parses your reply, so a sentence of commentary breaks the job that called you.

{
  "score": 7,
  "level": "high",
  "files_changed": 3,
  "lines_changed": 41,
  "signals": [
    {
      "rule": "migration",
      "points": 2,
      "reason": "Changes the database schema",
      "files": ["migrations/20261103_drop_legacy_status.js"]
    },
    {
      "rule": "destructive_migration",
      "points": 3,
      "reason": "Drops, renames, or rewrites existing columns, tables, or rows",
      "files": ["migrations/20261103_drop_legacy_status.js"]
    },
    {
      "rule": "untested_code",
      "points": 2,
      "reason": "Changes code without changing any tests",
      "files": ["src/orders.js"]
    }
  ]
}

That holds when the user calls the change small, safe, or urgent, too. Their read of the PR isn't an input to the score.

If the diff command fails, reply with one JSON object instead, and still nothing else:

{
  "error": "git diff origin/main...HEAD failed: no merge base",
  "hint": "Check out with fetch-depth: 0, or pass the PR number."
}

Use the command's own error message. "No merge base" in CI almost always means a shallow checkout; the hint above is the fix. Never score a different diff than the one asked for to get around an error.

Rules

For reading results, not for scoring by hand. Levels: 0–2 low, 3–5 medium, 6+ high.