/reuse

allowed-tools: Bash(git diff:*), Bash(git log:*), Bash(git show:*), Bash(git rev-parse:*), Bash(git branch:*), Read, Grep, Glob, TodoWrite
description: Check for violations of the Reuse Over Recreation principle

/review:reuse - Reuse Over Recreation Checker

You are reviewing code changes for violations of the **Reuse Over Recreation** principle.

The Principle

Minimize lines of code. Reuse existing patterns. Avoid duplicating functionality.

**Why it matters:** More code = larger maintenance surface area.

**Key question:** "Did we implement with the least amount of lines?"

Red Flags to Find

• New utility functions that duplicate existing ones
• Reimplemented patterns that exist elsewhere in codebase
• Copy-pasted code blocks
• New abstractions when existing ones would work
• New hooks that do what existing hooks already do
• New components similar to existing ones

Phase 1: Gather Context

# Get current branch
git rev-parse --abbrev-ref HEAD

# Get changed files
git diff main...HEAD --name-only

# Get full diff
git diff main...HEAD

Use TodoWrite to track files to analyze.

Phase 2: Analyze for Duplication

For each new function, hook, component, or utility in the diff:

2.1 Search for Similar Implementations

1. Extract the function/hook/component name 2. Use Grep to search for similar names in codebase 3. Use Grep to search for similar functionality (key terms from the implementation) 4. Check these locations specifically:

• `libs/shared/` - shared utilities
• `apps/webapp/src/hooks/` - existing hooks
• `apps/webapp/src/components/` - existing components
• `apps/api/src/shared/` - API utilities

2.2 Check for Copy-Paste

1. Look for blocks of code > 10 lines that appear elsewhere 2. Search for distinctive string literals or patterns from the new code 3. Flag any near-identical implementations

2.3 Evaluate Abstractions

For each new abstraction (class, hook, utility):

• Could an existing abstraction be extended instead?
• Is this solving a problem already solved elsewhere?
• Could this live in `libs/shared/` for reuse?

Phase 3: Generate Report

# Reuse Over Recreation Report

**Branch:** {branch}
**Status:** {PASS | WARN | FAIL}

## Summary

{One sentence assessment}

## Violations Found

### Critical (Must Fix)

| Location | Issue | Existing Alternative |
|----------|-------|---------------------|
| {file:line} | {description} | {what to use instead} |

### Warnings

| Location | Issue | Recommendation |
|----------|-------|----------------|
| {file:line} | {description} | {suggestion} |

## Existing Patterns That Should Be Used

1. **{pattern name}** at `{path}`
   - What it does: {description}
   - Should be used for: {use case from this PR}

## Code That Could Be Shared

{List any new code that should move to libs/shared/}

## Recommendations

1. {specific action}
2. {specific action}

Phase 4: Output

1. Save report to `tmp/review-reuse-{branch}.md` 2. Present summary:

• PASS/WARN/FAIL status
• Count of violations
• Top issues to address

Scoring Criteria

• **PASS**: No new code duplicates existing functionality
• **WARN**: Minor duplication or missed opportunities for reuse
• **FAIL**: Significant duplication or reimplemented existing patterns

Run this analysis now on the current branch.