simplify

What this skill does

# Simplify: Code Review and Cleanup

Review all changed files for reuse, quality, and efficiency. Fix any issues found.

## Phase 1: Identify Changes

Run `diffs` (or `diffs --commit HEAD` when you need a specific commit baseline) to see what changed. Fallback to `git diff` only if diffs cannot express the needed flag/output. If there are no git changes, review the most recently modified files that the user mentioned or that you edited earlier in this conversation.

## Phase 2: Launch Three Review Agents in Parallel

Use the subagent tool to launch all three agents concurrently in a single call. Pass each agent the full diff so it has the complete context.

### Agent 1: Code Reuse Review

For each change:

1. **Search for existing utilities and helpers** that could replace newly written code. Use grep/search to find similar patterns elsewhere in the codebase — common locations are utility directories, shared modules, and files adjacent to the changed ones.
2. **Flag any new function that duplicates existing functionality.** Suggest the existing function to use instead.
3. **Flag any inline logic that could use an existing utility** — hand-rolled string manipulation, manual path handling, custom environment checks, ad-hoc type guards, and similar patterns are common candidates.

### Agent 2: Code Quality Review

Review the same changes for hacky patterns:

1. **Redundant state**: state that duplicates existing state, cached values that could be derived, observers/effects that could be direct calls
2. **Parameter sprawl**: adding new parameters to a function instead of generalizing or restructuring existing ones
3. **Copy-paste with slight variation**: near-duplicate code blocks that should be unified with a shared abstraction
4. **Leaky abstractions**: exposing internal details that should be encapsulated, or breaking existing abstraction boundaries
5. **Stringly-typed code**: using raw strings where constants, enums (string unions), or branded types already exist in the codebase

### Agent 3: Efficiency Review

Review the same changes for efficiency:

1. **Unnecessary work**: redundant computations, repeated file reads, duplicate network/API calls, N+1 patterns
2. **Missed concurrency**: independent operations run sequentially when they could run in parallel
3. **Hot-path bloat**: new blocking work added to startup or per-request/per-render hot paths
4. **Unnecessary existence checks**: pre-checking file/resource existence before operating (TOCTOU anti-pattern) — operate directly and handle the error
5. **Memory**: unbounded data structures, missing cleanup, event listener leaks
6. **Overly broad operations**: reading entire files when only a portion is needed, loading all items when filtering for one

## 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.

When done, briefly summarize what was fixed (or confirm the code was already clean).