Simplify
Claude Code and Codex skills for daily engineering workflows: worktrees, merge requests, code review, YApi lookup, and Java DDD guidance.
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Review all changed files for reuse, quality, and efficiency, then fix any issues found. Spawns three parallel review agents and aggregates findings into actionable fixes.
SKILL.md
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Simplify: Code Review and Cleanup
Overview
Review all changed files for reuse, quality, and efficiency. Fix any issues found.
Core principle: Identify changes -> Spawn three review agents in parallel -> Fix issues.
Announce at start: "I'm using the simplify skill to review changed code for reuse, quality, and efficiency."
Prerequisites
- A git repository with uncommitted or recently committed changes.
Workflow
Phase 1: Identify Changes
Run git diff (or git diff HEAD if there are staged changes) to see what changed. If there are no git changes, review the most recently modified files that the user mentioned or that were edited earlier in this conversation.
Save the full diff output — it will be passed to each review agent.
Phase 2: Spawn Three Review Agents in Parallel
Launch all three agents concurrently in a single message. Pass each agent the full diff as context.
| Agent | Role |
|---|---|
code-reuse-reviewer | Finds duplicated logic and missed existing utilities |
code-quality-reviewer | Finds hacky patterns that hurt maintainability |
code-efficiency-reviewer | Finds performance and resource issues |
For Codex, if the Spellbook reviewer agent roles are available, use the namespaced role names:
| Codex Agent Role | Role |
|---|---|
spellbook-code-reuse-reviewer | Finds duplicated logic and missed existing utilities |
spellbook-code-quality-reviewer | Finds hacky patterns that hurt maintainability |
spellbook-code-efficiency-reviewer | Finds performance and resource issues |
Invocation example (Claude Code):
Use the Agent tool three times in a single message, each with the corresponding subagent_type:
code-reuse-reviewercode-quality-reviewercode-efficiency-reviewer
Pass each agent a prompt like:
Review the following diff for [reuse/quality/efficiency] issues.
<full diff here>
Invocation example (Codex):
If the namespaced role names are available in the spawn_agent tool, launch all three agents concurrently with the corresponding agent_type:
spellbook-code-reuse-reviewerspellbook-code-quality-reviewerspellbook-code-efficiency-reviewer
Pass each agent the same full diff.
For platforms without named agent support: run the three reviews sequentially using each agent's checklist from their definitions.
Phase 3: Fix Issues
Wait for all three agents to complete. Aggregate their findings and fix each issue directly. If a finding is a false positive or not worth addressing, note it and move on — do not argue with the finding, just skip it.
Phase 4: Summary
Briefly summarize what was fixed (or confirm the code was already clean).
Notes
- This is a cleanup pass, not a formal code review. After this skill, use a dedicated review skill or process when merge readiness needs to be judged.
- Keep fixes small and local — preserve behavior exactly.
- Run the narrowest practical verification for the touched area when possible.
Gives 0 of the 12 instructions most refactoring skills give
Counted across 521 of the 525 authors here whose files we hold, read 2026-08-06
- run tests after each changein 59 of 521, across 56 files
- write tests before refactoringin 27 of 521, across 24 files
- preserve external behaviorin 26 of 521, across 22 files
- remove dead codein 25 of 521, across 24 files
- make small incremental changesin 20 of 521, across 17 files
- break the implementation into tiny commitsin 18 of 521, across 5 files
- ask the user about alternative optionsin 17 of 521, across 4 files
- create a GitHub issue with the planin 17 of 521, across 4 files
- explore the repository to verify assertionsin 17 of 521, across 4 files
- interview the user about the refactorin 16 of 521, across 3 files
- check the codebase for test coveragein 16 of 521, across 3 files
- refactor one thing at a timein 16 of 521, across 12 files
Said here and by no other author read
- announce skill usage at start
- review recently modified files if no diff exists
- save the full diff output
- run three reviews sequentially if needed
- wait for all agents to complete
- fix each valid issue found
Grouped from the skills themselves: near-identical wordings counted once, and counted by distinct author, so one author publishing three of these counts once.