caspar-create-pr

name	caspar-create_pr
description	Generate a high-quality pull request from the actual diff and open it via gh — derives What from the diff, Why from commits/linked issue/branch, Testing from real test changes, scales the template to PR size, self-verifies every claim against a diff hunk, then runs gh pr create. Use when wrapping up a branch and asked to open a PR or write a PR description. Do NOT use to commit/clean the diff first (caspar-sweep), to rebase history (caspar-rebase), or for the full autonomous brain-dump→PR flow (caspar-ship).
user-invocable	true

create_pr

Produce a reviewer-ready pull request grounded in the actual change. Every claim traces to a diff hunk, a commit message, or a linked issue — never invented. Scale the description to the size of the change. Then open the PR with gh.

Inputs

• $ARGUMENTS (optional): TARGET_BRANCH (default origin/main), feedback-focus hint, or --draft. Read the live repo state at runtime — never assume a prior phase ran.
• Resolve just-in-time:
  • BRANCH = git rev-parse --abbrev-ref HEAD. If on main/master → stop and ask (nothing to PR).
  • TARGET_BRANCH (default origin/main); git fetch so the diff base is current.
  • DIFF = git diff {TARGET_BRANCH}...HEAD; COMMITS = git log {TARGET_BRANCH}..HEAD; branch name; any issue ref found in branch name or commits (#123, PROJ-123).
  • gh availability + unpushed commits. If gh is absent → output the title + body for manual creation and say so.

Working Set

The diff between TARGET_BRANCH and HEAD, the commit log over that range, and any .github/pull_request_template.md / .github/PULL_REQUEST_TEMPLATE/. If a repo template exists, honor its required sections over the defaults below.

Outputs + DONE

• A PR title in conventional-commit form: type(scope): summary (<70 chars, imperative, lowercase after colon, no trailing period).
• A PR body grounded per the Method, scaled to PR size.
• An opened PR via gh pr create (--draft when requested); the PR URL output as the final deliverable. If gh is unavailable, the title + body are output for manual creation instead.

DONE when: every factual claim in the body traces to a diff hunk, a commit message, or a linked issue; the Testing section reflects whether test files actually changed (no claimed tests that don't exist in the diff); no "Why" was fabricated (placeholder used if no source); title follows conventional-commit form; PR opened (or body emitted with the gh-unavailable note) and URL returned.

Method / guardrails

1. Ground each section in a real source — never the model's prior knowledge of the codebase:
   • What ← summarize the behavioral change from DIFF. Describe what the code now does, not which files/lines moved. Never recite the diff.
   • Why ← linked issue body, then commit messages, then branch name. If no source exists, emit <!-- WHY: motivation not found in commits/issue — fill in --> rather than inventing rationale.
   • How / trade-offs ← decisions visible in commit messages or diff structure. Omit for trivial changes; never infer design intent from code shape alone.
   • Testing ← inspect the diff for test-file changes. If tests changed, summarize what they cover. If none changed, state that plainly — do not claim tests were added.
2. Scale the template to PR size (lines changed + concern count):
   • Trivial (small, single-concern): What + Why + Closes #.
   • Standard: Summary · Changes (behavioral bullets) · Testing · Closes #.
   • Complex (large/multi-area/risky): add How & Trade-offs, Breaking Changes / Rollback, Screenshots (UI/CLI), and a Feedback Requested line directing the reviewer (e.g. "focus on the data model in src/models/") — the highest-leverage section for review quality.
3. Title — derive type from the dominant change (feat/fix/refactor/docs/test/chore/perf), scope from the primary area touched.
4. Issue linking — if an issue ref was found, add Closes #NNN (or the tracker's pattern) as its own line. Do not invent issue numbers.
5. Self-verification pass (required) — before opening: re-read the diff and check each claim in the body maps to a specific hunk. Drop or flag any claim that doesn't. Confirm no secrets/keys/PII are quoted from the diff into the body.
6. Open the PR — push if there are unpushed commits (git push -u origin {BRANCH}), then gh pr create --title … --body … (--draft if requested). Output the URL.

Handoff

Terminal skill — output is the PR URL (or the body + gh-unavailable note). End with a one-line Next Steps pointer (e.g. request review / /caspar:code_review).

Escalate-If

• On main/master, or no commits ahead of TARGET_BRANCH → stop and ask; there is nothing to PR.
• A secret/credential/PII appears in the diff → surface it; do not embed it in the body or open the PR until resolved.
• The diff is large and intent cannot be grounded from commits/issue/branch → open as --draft with the WHY placeholder and flag the gap, rather than fabricating rationale.