ulpi-io PR Implement Skill
Fork-based implementation for open source contributions with mandatory isolation check.
Overview
Execute a contribution plan with fork isolation. Ensures PRs are clean and focused by running isolation checks before and during implementation.
Input: Plan artifact from $pr-plan or repo URL
When to Use:
- Implementing a planned OSS contribution
- Need isolation enforcement for clean PRs
- After completing
$pr-plan
When NOT to Use:
- Internal project work (use
$implement) - Haven't planned yet (run
$pr-planfirst)
Workflow
-1. Prior Work Check -> BLOCKING: Check for competing PRs
0. Input Discovery -> Find plan artifact or repo
1. Fork Setup -> Ensure fork exists and is current
2. Worktree Creation -> Create isolated worktree
3. Isolation Pre-Check -> BLOCK if mixed concerns
4. Implementation -> Execute plan
5. Isolation Post-Check -> BLOCK if scope creep
6. Commit Preparation -> Stage with proper commit type
7. Handoff -> Ready for $pr-prep
Phase -1: Prior Work Check (BLOCKING)
# Search for open PRs on this topic
gh pr list -R <owner/repo> --state open --search "<topic>" --limit 10
# Check target issue status
gh issue view <issue-number> -R <repo> --json state,assignees
| Finding | Action |
|---|---|
| Open PR exists | Coordinate or wait |
| Issue assigned | Coordinate or find alternative |
| No competing work | Proceed |
Phase 3: Isolation Pre-Check (BLOCKING)
# Commit type analysis
git log --oneline main..HEAD | sed 's/^[^ ]* //' | grep -oE '^[a-z]+(\([^)]+\))?:' | sort -u
# File theme analysis
git diff --name-only main..HEAD | cut -d'/' -f1-2 | sort -u
| Check | Pass Criteria |
|---|---|
| Single commit type | 0 or 1 prefix |
| Thematic files | All match plan scope |
| Branch fresh | Based on recent main |
DO NOT PROCEED IF PRE-CHECK FAILS.
Phase 4: Implementation
Guidelines
| Guideline | Why |
|---|---|
| Single concern | Each commit = one logical change |
| Match conventions | Follow project style exactly |
| Test incrementally | Run tests after each change |
Commit Convention
git commit -m "type(scope): brief description
Longer explanation if needed.
Related: #issue-number"
Phase 5: Isolation Post-Check (BLOCKING)
# Commit type analysis
git log --oneline main..HEAD | sed 's/^[^ ]* //' | grep -oE '^[a-z]+(\([^)]+\))?:' | sort -u
# Summary stats
git diff --stat main..HEAD
| Check | Pass Criteria |
|---|---|
| Single commit type | All commits share same prefix |
| Thematic files | All files relate to PR scope |
| Atomic scope | Can explain in one sentence |
Phase 7: Handoff
Implementation complete. Isolation checks passed.
Branch: origin/$BRANCH_NAME
Commits: N commits, +X/-Y lines
Next step: $pr-prep
Anti-Patterns
| DON'T | DO INSTEAD |
|---|---|
| Skip isolation pre-check | Run Phase 3 FIRST |
| Skip isolation post-check | Run Phase 5 before push |
| Mix concerns in commits | One type prefix per PR |
| Implement without plan | Run $pr-plan first |
Examples
Implement From Contribution Plan
User says: "Implement this external PR plan with isolation checks."
What happens:
- Run pre-checks for branch and scope isolation.
- Implement only in planned files/areas.
- Run post-checks and prepare handoff for PR prep.
Enforce Single-Concern Commit Set
User says: "Make sure this branch is still single-purpose before I prep the PR."
What happens:
- Inspect commit/file patterns against stated scope.
- Flag mixed concerns and suggest extraction steps.
- Produce a clean handoff to
$pr-prep.
Troubleshooting
| Problem | Cause | Solution |
|---|---|---|
| Isolation check fails | Unrelated changes on branch | Move unrelated edits to separate branch/PR |
| Commits mix concerns | Implementation drifted from plan | Re-split commits by concern and revalidate |
| Scope keeps expanding | Weak boundaries in plan | Re-anchor to Out of Scope and stop additional changes |
| Hard to hand off | Missing summary/test context | Add concise change summary and verification notes |