code-simplifier

name	code-simplifier
description	Use when asked to simplify, clean up, or refactor recently modified code. Use when reviewing recent commits or PRs for code quality improvements in JavaScript or TypeScript projects.
original	https://github.com/github/gh-aw/blob/main/.github/workflows/code-simplifier.md

Code Simplifier

Analyze recently modified code and simplify it for clarity, consistency, and maintainability while preserving functionality. Optionally create a PR with the changes.

When to Use

• User asks to simplify or clean up recent code changes
• After a burst of feature work, to tighten up what was merged
• Reviewing recent PRs for refactoring opportunities

Do NOT use for: rewriting entire modules, changes older than a few days, adding features or changing behavior.

Phase 1: Identify Recently Modified Code

# Recent commits
git log --since="24 hours ago" --pretty=format:"%H %s" --no-merges

# Changed files (source only)
git diff --name-only HEAD~5..HEAD -- '*.ts' '*.tsx' '*.js' '*.jsx'

Include: .ts, .tsx, .js, .jsx in app/, components/, hooks/, lib/

Exclude: *.test.*, pnpm-lock.yaml, deno.lock, .contentlayer/, components/ui/ (shadcn), lib/supabase/types.d.ts (generated), config files

If no source files changed — exit: "No code changes to simplify."

Phase 2: Analyze and Simplify

Project Conventions (from biome.jsonc)

This project uses Biome (not ESLint/Prettier) with ultracite presets. Key enforced rules:

Convention	Rule
Single quotes, 2-space indent, 80-char lines	Biome formatter
Trailing commas everywhere	trailingCommas: all
interface over type for object shapes	useConsistentTypeDefinitions
import type for type-only imports	useImportType / useExportType
const over let when not reassigned	useConst
No inferrable types on variables	noInferrableTypes
Template literals over string concatenation	useTemplate
Self-closing JSX elements	useSelfClosingElements
No parameter reassignment	noParameterAssign
Default parameters last	useDefaultParameterLast
No useless else after return	noUselessElse
Number.X over global isNaN/parseInt	useNumberNamespace

Additional Patterns

• Naming: camelCase variables, PascalCase components/types, UPPER_SNAKE constants
• Prefer early returns over deep nesting
• Prefer function keyword for top-level/exported functions
• Explicit return types on exported functions
• React components: explicit Props interfaces, 'use client' directive when needed
• Next.js App Router: server components by default, client components only when hooks/interactivity needed
• Supabase: use typed client from lib/supabase/, never raw SQL strings
• Run pnpm clean (Knip) to detect unused exports, files, and dependencies

Simplification Principles

1. NEVER change behavior — only how code expresses it
2. Enhance clarity — reduce nesting, eliminate dead code, improve names
3. Avoid nested ternaries — use if/else or switch
4. Clarity over brevity — explicit beats compact
5. Don't over-simplify — no clever one-liners, keep helpful abstractions
6. Don't add complexity for hypothetical futures

For Each Changed File

1. Read and understand the file's purpose
2. Identify: long functions, duplicated patterns, complex conditionals, unclear names, non-standard patterns
3. Ask: Is this a real improvement or just preference? Does it maintain all functionality?
4. Apply surgical edits — one logical improvement per change, don't touch unrelated code

Phase 3: Validate

Run all checks — if any fail, revert the offending change:

pnpm run lint          # Biome lint
pnpm run type-check    # tsc --noEmit
pnpm test              # Vitest
pnpm run build         # Next.js build

Also consider: pnpm run format to auto-fix formatting, pnpm clean to find unused code.

Phase 4: Create Pull Request (if requested)

Only create PR if: simplifications were made, all checks pass, no behavior changed.

Title prefix: [code-simplifier], labels: refactoring, code-quality.

PR body should list files simplified, improvements made, which recent PRs/commits they came from, and validation results.

Common Mistakes

Mistake	Fix
Refactoring unrelated code	Only touch files from recent commits
Changing behavior	Verify with tests before and after
Over-simplifying	If readability decreases, revert
Nested ternaries	Use if/else or switch
Removing types on exports	Keep explicit types on exported functions
Using type instead of interface	Biome enforces interface for object shapes
Forgetting 'use client'	Required for components using hooks/browser APIs
Editing components/ui/	These are shadcn generated — don't touch