code-review

by Matt Pocock · mattpocock/skills

Review the changes since a fixed point (commit, branch, tag, or merge-base) along two axes: Standards (does the code follow this repo's documented coding standards?) and Spec (does the code match what the originating issue/spec asked for?). Runs both reviews in parallel sub-agents and reports them side by side. Use when the user wants to review a branch, a PR, work-in-progress changes, or asks to "review since X".

Review & debuggingMIT3 files

What it tells an agent to do.

The author’s own instructions, as your agent receives them — the same bytes the endpoint serves.

Two-axis review of the diff between HEAD and a fixed point the user supplies:

  • Standards: does the code conform to this repo's documented coding standards?
  • Spec: does the code faithfully implement the originating issue / spec?

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

The issue tracker should have been provided to you. If docs/agents/issue-tracker.md is missing, tell the user to run /setup-matt-pocock-skills.

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 two parallel sub-agents.

2. Identify the spec source

Look for the originating spec, in this order:

  1. Issue references in the commit messages (#123, Closes #45, GitLab !67, etc.), fetched via the workflow in docs/agents/issue-tracker.md.
  2. A path the user passed as an argument.
  3. A spec file under docs/, specs/, or .scratch/ 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, such as CODING_STANDARDS.md or CONTRIBUTING.md.

On top of whatever the repo documents, the Standards axis always carries the smell baseline below: a fixed set of Fowler code smells (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. Like any standard here, skip anything tooling already enforces.

Each smell reads what it ishow 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.

4. Spawn both sub-agents in parallel

Standards sub-agent prompt should include:

  • The full diff command and commit list.
  • The list of standards-source files you found in step 3, plus the smell baseline from step 3 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 should 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 two reports under ## Standards and ## Spec headings, verbatim or lightly cleaned. Do not merge or rerank findings, because the two axes are deliberately separate (see Why two 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.

Why two axes

A change can pass one axis and fail the other:

  • Code that follows every standard but implements the wrong thing → Standards pass, Spec 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 the other.

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