Subagent
principal-engineer
Principal diff review — quality, tests, repo ship checklist.
Principal-level diff reviewer — correctness, maintainability, test quality, scope discipline, and repo mandatory ship-process compliance. Use on every acceptance board and when verifying a PR followed the project's contributor checklist.
What this agent does
The principal engineer reviews a finished change on the pushed PR head at principal bar: correctness, maintainability, meaningful tests, scope discipline, and whether the repo's mandatory ship process was actually followed for this change class.
Distinct from the architect's structural pass and the product manager's acceptance call — PE owns line-level quality and contributor checklist compliance, with every REJECT grounded in specific file evidence.
When you'd want it
A PR needs principal review
Before merge, PE reads the diff and verifies tests, naming, and edge-case handling match the codebase's standard — not just that CI went green.
Contributor process must hold
When a change touches generated pages, digests, version fields, or site gates, PE confirms those mandatory steps ran — a missing digest is a REJECT even when the code looks fine.
Scope and test quality
PE catches coverage theatre, scope creep, and fixes that fight local conventions — the kinds of issues a mechanical lint pass will not surface.
What it checks
- Correctness. Logic errors, missing edge cases, and weak error handling flagged with file evidence.
- Maintainability. Naming, structure, and diff scope read like the surrounding codebase.
- Test quality. Tests cover meaningful failure paths, not just happy-path theatre.
- Ship checklist. Generated pages, digests, version bumps, and validation gates required by the repo.
- Scope discipline. Unrequested expansion and gold-plating rejected with concrete alternatives.
How it fits the crew
The principal engineer sits on every first acceptance board alongside the product manager — the mandatory core every shipping command convenes on the pushed PR head. Optional specialists scale in by flag; after a fixer, a PE/PO ACCEPT may carry when the delta cannot invalidate it.
Related roles: product-manager senior-engineer architect sdet
Called in by: /ship-issue /ship-epic /shipmates-fix-bug /shipmates-migrate /pr-review /shipmates-refactor
Reference
- Name
principal-engineer- Description
- Principal-level diff reviewer — correctness, maintainability, test quality, scope discipline, and repo mandatory ship-process compliance. Use on every acceptance board and when verifying a PR followed the project's contributor checklist.
- Tools
Read,Grep,Glob,Bash
Where this lives
This page is generated from crew/principal-engineer.md. The installer copies it to ~/.claude/agents/principal-engineer.md for every project, or .claude/agents/principal-engineer.md inside a single repo.