Code Simplification

# Code Simplification

> Inspired by the [Claude Code Simplifier plugin](https://github.com/anthropics/claude-plugins-official/blob/main/plugins/code-simplifier/agents/code-simplifier.md). Adapted here as a model-agnostic, process-driven skill for any AI coding agent.

## Overview

Simplify code by reducing complexity while preserving exact behavior. The goal is not fewer lines — it's code that is easier to read, understand, modify, and debug. Every simplification must pass a simple test: "Would a new team member understand this faster than the original?"

## When to Use

- After a feature is working and tests pass, but the implementation feels heavier than it needs to be
- During code review when readability or complexity issues are flagged
- When you encounter deeply nested logic, long functions, or unclear names
- When refactoring code written under time pressure
- When consolidating related logic scattered across files
- After merging changes that introduced duplication or inconsistency

**When NOT to use:**

- Code is already clean and readable — don't simplify for the sake of it
- You don't understand what the code does yet — comprehend before you simplify
- The code is performance-critical and the "simpler" version would be measurably slower
- You're about to rewrite the module entirely — simplifying throwaway code wastes effort

## The Five Principles

### 1. Preserve Behavior Exactly

Don't change what the code does — only how it expresses it. All inputs, outputs, side effects, error behavior, and edge cases must remain identical. If you're not sure a simplification preserves behavior, don't make it.

```
ASK BEFORE EVERY CHANGE:
→ Does this produce the same output for every input?
→ Does this maintain the same error behavior?
→ Does this preserve the same side effects and ordering?
→ Do all existing tests still pass without modification?
```

### 2. Follow Project Conventions

Simplification means making code more consistent with the codebase, not imposing external preferences. Before simplifying:

```
1. Read CLAUDE.md / project conventions
2. Study how neighboring code handles similar patterns
3. Match the project's style for:
   - Import ordering and module system
   - Function declaration style
   - Naming conventions
   - Error handling patterns
   - Type annotation depth
```

Simplification that breaks project consistency is not simplification — it's churn.

### 3. Prefer Clarity Over Cleverness

Explicit code is better than compact code when the compact version requires a mental pause to parse.

```typescript
// UNCLEAR: Dense ternary chain
const label = isNew ? 'New' : isUpdated ? 'Updated' : isArchived ? 'Archived' : 'Active';

// CLEAR: Readable mapping
function getStatusLabel(item: Item): string {
  if (item.isNew) return 'New';
  if (item.isUpdated) return 'Updated';
  if (item.isArchived) return 'Archived';
  return 'Active';
}
```

```typescript
// UNCLEAR: Chained reduces with inline logic
const result = items.reduce((acc, item) => ({
  ...acc,
  [item.id]: { ...acc[item.id], count: (acc[item.id]?.count ?? 0) + 1 }
}), {});

// CLEAR: Named intermediate step
const countById = new Map<string, number>();
for (const item of items) {
  countById.set(item.id, (countById.get(item.id) ?? 0) + 1);
}
```

### 4. Maintain Balance

Simplification has a failure mode: over-simplification. Watch for these traps:

- **Inlining too aggressively** — removing a helper that gave a concept a name makes the call site harder to read
- **Combining unrelated logic** — two simple functions merged into one complex function is not simpler
- **Removing "unnecessary" abstraction** — some abstractions exist for extensibility or testability, not