code-review

name

code-review

description

Review the changes since a fixed point (commit, branch, tag, or merge-base) along three axes — Correctness (does it break anything?), Standards (repo coding standards plus a smell baseline), and Spec (does it match what the originating task/issue asked for?). Runs the axes as parallel sub-agents and reports them side by side. Use when the user wants to review a branch, work-in-progress changes, or asks to "review since X".

Three-axis review of the diff between HEAD and a fixed point:

• Correctness — does the change work, without breaking callers, contracts, or edge cases?
• Standards — does it conform to the repo's documented standards and the smell baseline?
• Spec — does it faithfully implement the originating task / issue / spec?

The axes run as parallel sub-agents so they don't pollute each other's context; this skill aggregates their findings.

Process

1. Pin the fixed point

Whatever the user said is the fixed point — a commit SHA, branch name, tag, main, HEAD~5, etc. If they didn't specify one, ask for it.

Capture the diff command once: git diff <fixed-point>...HEAD (three-dot, so the comparison is against the merge-base). Also note the list of commits via git log <fixed-point>..HEAD --oneline.

Before going further, confirm the fixed point resolves (git rev-parse <fixed-point>) and the diff is non-empty. A bad ref or empty diff should fail here — not inside three parallel sub-agents.

2. Identify the spec source

Look for the originating spec, in this order:

1. A path, URL, or text the user passed as an argument.
2. Issue/PR references in the commit messages (#123, Closes #45) — fetch via gh.
3. A task or spec file: agent/tasks/, docs/, specs/ matching the branch name or feature.
4. If nothing is found, ask the user where the spec is. If they say there isn't one, the Spec sub-agent will skip and report "no spec available".

3. Identify the standards sources

Anything in the repo that documents how code should be written: CLAUDE.md, CODING_STANDARDS.md, CONTRIBUTING.md.

On top of whatever the repo documents, the Standards axis always carries the smell baseline below — a fixed set of code smells (Fowler, Refactoring, ch.3) that applies even when a repo documents nothing. Two rules bind it:

• The repo overrides. A documented repo standard always wins; where it endorses something the baseline would flag, suppress the smell.
• Always a judgement call. Each smell is a labelled heuristic ("possible Feature Envy"), never a hard violation — and, like any standard here, skip anything tooling already enforces.

Each smell reads what it is → how to fix; match it against the diff:

• Mysterious Name — a function, variable, or type whose name doesn't reveal what it does or holds. → rename it; if no honest name comes, the design's murky.
• Duplicated Code — the same logic shape appears in more than one hunk or file in the change. → extract the shared shape, call it from both.
• Feature Envy — a method that reaches into another object's data more than its own. → move the method onto the data it envies.
• Data Clumps — the same few fields or params keep travelling together (a type wanting to be born). → bundle them into one type, pass that.
• Primitive Obsession — a primitive or string standing in for a domain concept that deserves its own type. → give the concept its own small type.
• Repeated Switches — the same switch/if-cascade on the same type recurs across the change. → replace with polymorphism, or one map both sites share.
• Shotgun Surgery — one logical change forces scattered edits across many files in the diff. → gather what changes together into one module.
• Divergent Change — one file or module is edited for several unrelated reasons. → split so each module changes for one reason.
• Speculative Generality — abstraction, parameters, or hooks added for needs the spec doesn't have. → delete it; inline back until a real need shows.
• Message Chains — long a.b().c().d() navigation the caller shouldn't depend on. → hide the walk behind one method on the first object.
• Middle Man — a class or function that mostly just delegates onward. → cut it, call the real target direct.
• Refused Bequest — a subclass or implementer that ignores or overrides most of what it inherits. → drop the inheritance, use composition.
• Dishonest Types — code lying to the type checker: as any, non-null assertions on nullables, T[] holding nulls. → make the type tell the truth; if it can't, the design is off.
• Defensive Padding — try/except "just in case", or validation for inputs the system already guarantees. → delete it; let impossible failures be loud.
• Narrating Comments — comments restating the next line, meta-commentary, fluff. → delete; comment only non-obvious behaviour, warnings, complex algorithms.

4. Spawn the sub-agents in parallel

Send a single message with three Agent tool calls. Use the general-purpose subagent for all three.

Every brief opens with the same discipline line: "Read every touched file in full, plus the callers of anything changed — not just the hunks. Build the mental model before judging; a diff read in isolation lies."

Correctness sub-agent prompt — include:

• The full diff command and commit list.
• The brief: "Trace the change end to end: touched files in full, callers of changed functions, changed types/protocols/contracts, related tests. Report only findings that survive three filters: (a) it's a real problem, not an artifact of reading the diff in isolation — check surrounding code and existing patterns first; (b) you can name the concrete consequence — bug, security hole, data loss, perf regression, maintenance trap; no nameable consequence, no finding; (c) the codebase doesn't already handle it. Not findings: style the change is internally consistent about, validation for inputs that can't arrive, API semantics that match existing conventions, 'what if X' where the system prevents X. Each finding: the scenario that breaks, file:line, fix. Under 400 words."

Standards sub-agent prompt — include:

• The full diff command and commit list.
• The list of standards-source files you found in step 3, plus the smell baseline pasted in full — the sub-agent has no other access to it.
• The brief: "Report — per file/hunk where relevant — (a) every place the diff violates a documented standard: cite the standard (file + the rule); and (b) any baseline smell you spot: name it and quote the hunk. Distinguish hard violations from judgement calls — documented-standard breaches can be hard, but baseline smells are always judgement calls, and a documented repo standard overrides the baseline. Skip anything tooling enforces. Under 400 words."

Spec sub-agent prompt — include:

• The diff command and commit list.
• The path or fetched contents of the spec.
• The brief: "Report: (a) requirements the spec asked for that are missing or partial; (b) behaviour in the diff that wasn't asked for (scope creep); (c) requirements that look implemented but where the implementation looks wrong. Quote the spec line for each finding. Under 400 words."

If the spec is missing, skip the Spec sub-agent and note this in the final report.

5. Aggregate

Present the reports under ## Correctness, ## Standards, and ## Spec headings, verbatim or lightly cleaned. Do not merge or rerank findings — the axes are deliberately separate (see Why separate axes).

End with a one-line summary: total findings per axis, and the worst issue within each axis (if any). Don't pick a single winner across axes — that's the reranking the separation exists to prevent.

A clean diff gets a short review. Report the axes as they came back; empty is a valid result.

Why separate axes

A change can pass any axis and fail another:

• Code that follows every standard but implements the wrong thing → Standards pass, Spec fail.
• Code that does exactly what the issue asked but breaks a caller → Spec pass, Correctness fail.
• Code that does exactly what the issue asked but breaks the project's conventions → Spec pass, Standards fail.

Reporting them separately stops one axis from masking another.