| name | review |
| description | Review code changes, check project health, verify contract compliance, or refresh living docs (PLAN.md, DECISIONS.md). Use for any review or project health task. |
Review Skill
Use for reviewing code changes, checking project health, verifying contract compliance, or refreshing living docs.
NOT for: implementing changes (use build skill), bootstrapping projects, or research tasks.
Central rules: this skill ships with the Kata Engineering repository. Resolve this skill directory's real path (it is usually symlinked into the agent's global skills directory); the rules live two levels up, at the repository root. The Simplify checklist cited below is in rules/coding.md.
Modes
Select based on what's needed:
FOCUSED → review specific changes (after a coding session, before merge)
HEALTH → broader project health check (periodic, or when something feels off)
TIER → verify project meets its declared tier requirements
REFRESH → update living docs to match current reality (periodic maintenance)
Focused, Health, and Tier are diagnostic — they produce findings, not edits. Refresh is the only mode that writes to files, and it writes only to living docs (PLAN.md, DECISIONS.md).
Mode 1 — Focused Review
When: After implementing changes. Before merging. When you want a second opinion on recent work.
Step 1: Observe
Walk through the changes neutrally. Describe what you see — don't hunt for problems.
Frame it as: "What does this code do?" — not "What's wrong with this code?"
This matters. If you look for bugs, you'll manufacture them (sycophancy). If you observe behavior, real issues surface naturally.
For each changed file:
- What is the intent of this change?
- How does it interact with the rest of the system?
- What state does it read or write?
Step 2: Check contracts
Read the project's CONTRACTS.md (or equivalent). For each invariant relevant to the changed area:
- Does the invariant still hold?
- If a new boundary was created, is there an invariant for it?
- Run verification commands if available
Step 3: Simplify
Run the Simplify checklist from rules/coding.md (First Principle section) against the change. The question isn't "can I find something to remove?" — it's "has this solution found its natural form?"
Step 4: Report
Structure findings by severity:
🔴 Must fix — breaks contracts, violates boundaries, introduces bugs, loses data
🟡 Should fix — unnecessary complexity, missing tests, unclear code, minor architectural violations
🔵 Consider — style improvements, potential simplifications, documentation gaps
For each finding:
- What: describe the issue with evidence (file, line, specific code)
- Why: explain the consequence — not "this is bad" but "this means X can happen"
- How: suggest a concrete fix, not a vague direction
If there are no findings: say so. "No issues found" is a valid review outcome. Don't manufacture findings to justify the review.
Mode 2 — Health Check
When: Periodic project review. When complexity feels like it's creeping. When a new person would struggle to understand the codebase.
Step 1: Architecture accuracy
Read ARCHITECTURE.md. Then read the actual code structure.
- Does the architecture doc describe the system as it actually is?
- Are there modules or patterns that exist in code but aren't documented?
- Are there documented boundaries that are violated in practice?
- Are there dead zones — code that doesn't belong to any described layer?
Step 2: Contract health
Read CONTRACTS.md. For each invariant:
- Does the invariant still apply? (requirements may have changed)
- Is there a passing test for it?
- Are there boundaries in the code that SHOULD have invariants but don't?
Step 3: Complexity audit
Walk through the codebase module by module:
- File count and size — are files growing too large? Are there too many files for the complexity?
- Abstraction count — how many layers of indirection between a request and its effect? Each layer should earn its existence
- Pattern consistency — is there one way to do things, or have multiple patterns accumulated?
- Dead code — files, functions, or modules that nothing uses
- Dependency health — unused dependencies, outdated dependencies, dependencies that could be inlined
- Earned existence — tests/fixtures protecting deleted or unchanged behavior → cut candidates. Files relocated to
docs/archive/ or similar → delete; archive lives in Git history
Step 4: Stagnation check
Look at recent changes (git log, conversation context):
- Is the same approach being tried repeatedly without success?
- Are workarounds accumulating instead of fixing root causes?
- Is the architecture being stretched beyond what it was designed for?
- Should the project tier be upgraded (or downgraded)?
Step 5: Report
Structure as:
- Architecture accuracy — match/drift between docs and code
- Contract health — coverage, freshness, gaps
- Complexity assessment — where is unnecessary complexity accumulating?
- Stagnation signals — patterns that suggest the project needs a different approach
- Recommendations — prioritized actions, each with concrete steps
Mode 3 — Tier Compliance
When: After a tier upgrade. Periodically for standard/full projects. When preparing for a handoff.
Check against tier requirements
Tier definitions are canonical in build Phase 0 Step 3. Verify the project meets every requirement listed there for its declared tier (in ARCHITECTURE.md frontmatter), plus:
Standard, beyond build's scaffold list:
Full, beyond build's scaffold list:
Report
List each requirement as ✅ met / ❌ not met / ⚠️ partially met.
For each gap: describe what's missing and what to do about it.
Mode 4 — Refresh
When: Periodically — when living docs have drifted from current reality, or at the start of a new session after multiple sessions of work have accumulated. Also useful after a Health Check flags stale living docs.
Scope: This mode edits living docs to match reality. It does not edit stable docs and does not write code. Stable drift is flagged, not fixed.
What this mode does and does not do
| Edits? | Scope |
|---|
PLAN.md | ✅ | mark completed items, update "Up Next", move deferred items, close answered open questions |
DECISIONS.md | ✅ | add missing entries for recent design choices visible in git history |
ARCHITECTURE.md | ❌ | flag drift, do not edit |
CONTRACTS.md | ❌ | flag drift, do not edit |
| Code / tests | ❌ | flag issues, do not edit |
If the project has no living docs, Refresh has nothing to do. Exit cleanly. If the project would benefit from one or both of them, suggest creating them directly from the templates in skills/build/templates/ (plan.md, decisions.md) — do not route back to Bootstrap, which only runs on projects without ARCHITECTURE.md.
Step 1: Gather reality
Establish what has changed since the living docs were last updated:
- Read recent git log (commits since the last update of each living doc)
- Read the current code structure at the level of modules/layers
- Read any Focused Review or Health Check reports that already exist
Do not read the entire codebase. You're looking for signals of change, not doing a full review.
Step 2: Refresh PLAN.md (if it exists)
- Check off completed items — anything in "Up Next" that is now built, tested, and shipped
- Move completed phases/milestones from "Up Next" to "Completed"
- Update "Up Next" to reflect what's actually next given the current state (not wishful thinking from three sessions ago)
- Move anything deferred to "Deferred" with a one-line reason
- Close answered Open Questions — promote durable answers to
DECISIONS.md
- Prune "Completed" if it has grown into archaeology — keep enough history to understand the journey, not every checkmark forever
Step 3: Refresh DECISIONS.md (if it exists)
- Scan recent commits for non-obvious architectural or design choices that were made but never recorded
- For each one, add an entry at the top (newest first): what was chosen, why, what was rejected
- Do not invent rationale — if you can't determine the "why" from context, flag it for the human instead of guessing
- Never rewrite old entries. Superseded decisions get a new entry that references the old one
Step 4: Fold legacy RESEARCH.md (if it exists)
RESEARCH.md is no longer a Kata artifact. If a project still has one: move its open questions into PLAN.md's Open Questions section, promote durable findings to DECISIONS.md entries, then delete the file (git history is the archive). Confirm with the human before deleting.
Step 5: Flag stable drift
If you noticed during Steps 1–4 that stable docs (ARCHITECTURE.md, CONTRACTS.md) no longer match the code, do not edit them. List the drift at the end of your summary. The human decides whether to fix it directly or run a Health Check.
Step 6: Report
Briefly state:
- Which living docs were refreshed and what was changed (file-by-file summary)
- What was flagged for the human (stable drift, missing rationale, questions without evidence)
- Suggested follow-ups (e.g. "consider running Health Check on the auth module —
ARCHITECTURE.md no longer describes its flow")
Commit the living doc updates as a single commit with a message like chore: refresh living docs.
Constraints
- One file at a time. Edit
PLAN.md fully before touching DECISIONS.md. This keeps the changes auditable.
- No speculation. If you don't have evidence for an edit, don't make it.
- No new content categories. Don't invent new sections. Work within the existing template structure.
- Terse. Living docs should shrink when possible, not grow indefinitely. If a section can be tightened, tighten it.
Review Principles
Neutral observation over bug hunting
Describe behavior. Real issues surface from honest observation. Manufactured issues surface from looking for trouble.
Evidence over opinion
Every finding needs a file, a line, a specific piece of code. "This feels wrong" is not a finding.
Actionable over vague
"Refactor this" is useless. "Extract the validation logic from handler.ts:42-67 into validators/input.ts because it's reused in api.ts:31" is actionable.
Simplicity bias
When in doubt, recommend removing code rather than adding it. The codebase that doesn't exist has zero bugs.
Proportional depth
A small utility doesn't need the same review depth as a core system module. Scale your effort with the risk.
