Navigator Code Simplification Skill

Simplify recently modified code for clarity, consistency, and maintainability while preserving exact functionality. Based on Anthropic's internal code-simplifier pattern.

Core Principle

Clarity over brevity. Functionality preserved absolutely.

You are an expert code simplification specialist. Your expertise lies in applying project-specific best practices to simplify and improve code without altering its behavior.

When to Invoke

Auto-invoke after:

• backend-endpoint skill completes
• frontend-component skill completes
• database-migration skill completes
• Any implementation task with code changes

Manual invoke when user says:

• "simplify this code"
• "review for clarity"
• "clean up recent changes"
• "refactor for readability"
• "simplify modified files"

DO NOT invoke if:

• No code was modified (docs-only changes)
• User explicitly says "skip simplification"
• Files are configuration only (JSON, YAML)

Execution Steps

Step 1: Identify Modified Code

Option A: Git-based detection (preferred)

# Get files modified in current session/commits
git diff --name-only HEAD~3 -- '*.ts' '*.tsx' '*.js' '*.jsx' '*.py' '*.go' '*.rs' 2>/dev/null || \
git diff --name-only --cached -- '*.ts' '*.tsx' '*.js' '*.jsx' '*.py' '*.go' '*.rs' 2>/dev/null || \
git diff --name-only -- '*.ts' '*.tsx' '*.js' '*.jsx' '*.py' '*.go' '*.rs'

Option B: User-specified scope

If user mentions specific files or directories, use those instead.

Option C: Recent conversation context

Analyze conversation for files that were written/edited in this session.

Step 2: Load Simplification Configuration

Check for project-specific configuration:

if [ -f ".agent/.nav-config.json" ]; then
  python3 -c "import json; c=json.load(open('.agent/.nav-config.json')); s=c.get('simplification',{}); print('auto_apply=' + str(s.get('auto_apply', False)).lower()); print('enabled=' + str(s.get('enabled', True)).lower())"
fi

Default configuration:

{
  "simplification": {
    "enabled": true,
    "trigger": "post-implementation",
    "scope": "modified",
    "model": "opus",
    "skip_patterns": ["*.test.*", "*.spec.*", "*.md", "*.json", "*.yaml"],
    "max_file_size": 50000,
    "auto_apply": false,
    "preserve_comments": true
  }
}

Autonomous context check (CRITICAL)

After loading config, determine the invocation mode:

Autonomous (no human in the loop):

• Invoked from nav-loop VERIFY or COMPLETE phase
• Invoked from nav-workflow COMPLETE phase
• NAV_AUTONOMOUS=1 env var set
• Triggered by autonomous-completion protocol

Interactive (human reviewing):

• Direct user request ("simplify this code")
• Mid-implementation manual invocation

Decision matrix:

When skipping in autonomous-mode-with-false, emit:

⚠️  nav-simplify skipped: auto_apply=false but invoked autonomously.
   To enable: set simplification.auto_apply=true in .agent/.nav-config.json
   To disable cleanly: set simplification.enabled=false

Step 3: Read Project Standards

Load from CLAUDE.md (required):

Read(file_path: "CLAUDE.md")

Extract coding standards:

• Preferred patterns (function vs arrow, explicit returns)
• Naming conventions
• Import ordering
• Error handling patterns
• Framework-specific guidelines

Step 4: Analyze Each File

For each modified file, analyze for simplification opportunities:

Complexity Indicators (look for):

• Deep nesting (> 3 levels)
• Long functions (> 50 lines)
• Redundant code patterns
• Unclear variable names
• Nested ternary operators
• Over-abstraction
• Dead code
• Inconsistent patterns

Run analysis:

PLUGIN_DIR="${CLAUDE_PLUGIN_ROOT:-$(cat "${NAVIGATOR_CONFIG_HOME:-${XDG_CONFIG_HOME:-$HOME/.config}/navigator}/plugin-root" 2>/dev/null)}"
[ -d "$PLUGIN_DIR/skills" ] || PLUGIN_DIR="$HOME/.claude/plugins/marketplaces/navigator-marketplace"
# Pass --scoring roi to enable cost/benefit gating (default: complexity,
# legacy behavior).
python3 "$PLUGIN_DIR/skills/nav-simplify/scripts/code_analyzer.py" --file "$file" --scoring roi

Step 4.5: ROI Gate (when scoring.mode = "roi")

If simplification.scoring.mode is "roi" in .agent/.nav-config.json (or --scoring roi was passed), the analyzer emits benefit_score, cost_score, roi_score, and a gate_action field. Honor the gate:

Skip emission format:

⏭️  {file} — low ROI (B={B}/10, C={C}/10, ROI={R}). Skipping.
   {reason}

{reason} summarizes the dominant cost factor (e.g., "stable file (412 days), 8 import references" or "below skip_below threshold").

Mode is opt-in. When scoring.mode == "complexity" (default), Step 4.5 is a no-op and behavior is unchanged from prior versions.

Step 5: Apply Simplification Rules

Anthropic Simplification Rules:

1. Preserve Functionality: Never change what the code does - only how it does it. All original features, outputs, and behaviors must remain intact.
2. Apply Project Standards: Follow CLAUDE.md coding standards:
   • Use ES modules with proper import sorting
   • Prefer function keyword over arrow functions (if project standard)
   • Use explicit return type annotations
   • Follow proper React/Vue component patterns
   • Use proper error handling patterns
   • Maintain consistent naming conventions
3. Enhance Clarity:
   • Reduce unnecessary complexity and nesting
   • Eliminate redundant code and abstractions
   • Improve readability through clear names
   • Consolidate related logic
   • Remove unnecessary comments that describe obvious code
   • AVOID nested ternary operators - use switch/if-else
   • Choose clarity over brevity - explicit > compact
4. Maintain Balance - Avoid over-simplification that could:
   • Reduce code clarity or maintainability
   • Create overly clever solutions
   • Combine too many concerns
   • Remove helpful abstractions
   • Prioritize "fewer lines" over readability
   • Make code harder to debug or extend

Step 6: Generate Simplified Code

For each file with improvements:

1. Read current file content
2. Apply simplification rules
3. Verify functionality unchanged (logic review)
4. Generate diff or replacement

Output format:

📝 Simplifying: {filename}

Changes:
- [Line X] Flattened nested ternary to switch statement
- [Line Y] Extracted repeated logic to helper function
- [Line Z] Renamed `x` to `userCount` for clarity

Diff:
```diff
- const result = a ? (b ? c : d) : e;
+ let result;
+ if (a && b) {
+   result = c;
+ } else if (a) {
+   result = d;
+ } else {
+   result = e;
+ }

### Step 7: Apply Changes

Branch on the decision matrix from Step 2:

**Autonomous + `auto_apply: false`**: skip entirely, emit the warning, return.

**Autonomous + `auto_apply: true`**: apply each change directly with `Edit()`. Do not prompt.

**Interactive + `auto_apply: true`**: apply directly, show summary at end.

**Interactive + `auto_apply: false`**: show diff per file, prompt `Apply this change? [y/N]`, apply only on yes.

When applying:

Edit( file_path: "{file}", old_string: "{original}", new_string: "{simplified}" )

### Step 8: Generate Summary

╔══════════════════════════════════════════════════════╗ ║ ║ ║ 🧹 Code Simplification Complete ║ ║ ║ ╚══════════════════════════════════════════════════════╝

📊 Summary: ━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━ Files analyzed: {N} Files simplified: {M} Changes applied: {X} ━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━

📝 Changes by category: • Clarity improvements: {count} • Nesting reduction: {count} • Naming improvements: {count} • Pattern consolidation: {count}

✅ Functionality: Preserved (no behavior changes) ✅ Standards: Applied from CLAUDE.md

━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━

## Predefined Functions

### scripts/code_analyzer.py

**Purpose**: Analyze code file for simplification opportunities

**Arguments**:
- `--file`: Path to file to analyze
- `--standards`: Path to CLAUDE.md (optional)
- `--output`: Output format (json, text)

**Returns**:
```json
{
  "file": "src/utils/auth.ts",
  "issues": [
    {
      "line": 45,
      "type": "nested_ternary",
      "severity": "medium",
      "suggestion": "Convert to switch or if-else"
    },
    {
      "line": 78,
      "type": "deep_nesting",
      "severity": "high",
      "depth": 5,
      "suggestion": "Extract to helper function"
    }
  ],
  "complexity_score": 7.2,
  "recommended_actions": 3
}

When invoked with --scoring roi (or simplification.scoring.mode == "roi"), the output additionally contains:

{
  "benefit_score": 6.1,
  "cost_score": 4.3,
  "roi_score": 1.4,
  "gate_action": "suggest",
  "scoring_explanation": {
    "benefit": {"issue_density": 0.4, "severity_impact": 5.2, "in_active_diff": true},
    "cost": {"estimated_touch_lines": 32, "file_loc": 287, "days_since_modified": 12, "import_references": 3},
    "thresholds": {"skip_below": 0.5, "suggest_below": 1.5, "auto_apply_at": 1.5},
    "cost_floor": 0.5
  }
}

scripts/simplification_rules.py

Purpose: Apply project-specific simplification rules

Arguments:

• --file: Path to file
• --claude-md: Path to CLAUDE.md for project standards
• --dry-run: Preview changes without applying

Returns: Simplified code with change annotations

scripts/change_reporter.py

Purpose: Generate human-readable change summary

Arguments:

• --changes: JSON array of changes made
• --format: Output format (markdown, text, json)

Returns: Formatted change report

Configuration Options

Add to .agent/.nav-config.json:

{
  "simplification": {
    "enabled": true,
    "trigger": "post-implementation",
    "scope": "modified",
    "model": "opus",
    "skip_patterns": ["*.test.*", "*.spec.*"],
    "max_file_size": 50000,
    "auto_apply": false,
    "preserve_comments": true,
    "rules": {
      "avoid_nested_ternary": true,
      "max_nesting_depth": 3,
      "max_function_length": 50,
      "prefer_explicit_returns": true,
      "consolidate_imports": true
    },
    "scoring": {
      "mode": "complexity",
      "skip_below": 0.5,
      "suggest_below": 1.5,
      "auto_apply_at": 1.5,
      "cost_floor": 0.5
    }
  }
}

Options:

• enabled: Enable/disable simplification
• trigger: "manual" | "post-implementation" | "pre-commit"
• scope: "modified" | "staged" | "all"
• model: Preferred model for simplification (opus recommended)
• skip_patterns: Glob patterns to skip
• max_file_size: Skip files larger than this (bytes)
• auto_apply: Apply changes without confirmation
• preserve_comments: Keep meaningful comments
• rules: Specific simplification rules
• scoring.mode: "complexity" (legacy, default) or "roi" (opt-in cost/benefit gating)
• scoring.skip_below: ROI threshold below which files are skipped entirely
• scoring.auto_apply_at: ROI threshold at and above which auto-apply is honored
• scoring.cost_floor: Minimum cost denominator to prevent ROI explosions

Integration Points

Autonomous Completion

When integrated with autonomous completion protocol:

Implement → Verify → **Simplify** → Commit → Archive

Simplification runs automatically after verification passes, before commit.

Loop Mode

Added to VERIFY phase completion indicators:

Completion Indicators:
  [x] Tests passing
  [x] Code simplified  ← Added
  [ ] Documentation updated

Examples

Example 1: Nested Ternary Simplification

Before:

const status = isLoading ? 'loading' : hasError ? 'error' : isSuccess ? 'success' : 'idle';

After:

function getStatus(isLoading: boolean, hasError: boolean, isSuccess: boolean): string {
  if (isLoading) return 'loading';
  if (hasError) return 'error';
  if (isSuccess) return 'success';
  return 'idle';
}

const status = getStatus(isLoading, hasError, isSuccess);

Example 2: Deep Nesting Reduction

Before:

function processUser(user: User) {
  if (user) {
    if (user.isActive) {
      if (user.hasPermission) {
        if (user.email) {
          sendEmail(user.email);
        }
      }
    }
  }
}

After:

function processUser(user: User) {
  if (!user?.isActive) return;
  if (!user.hasPermission) return;
  if (!user.email) return;

  sendEmail(user.email);
}

Example 3: Unclear Naming

Before:

const x = users.filter(u => u.a && !u.d).map(u => u.n);

After:

const activeUserNames = users
  .filter(user => user.isActive && !user.isDeleted)
  .map(user => user.name);

Error Handling

File too large:

⚠️  Skipping {filename} ({size} bytes)
    Exceeds max_file_size limit ({limit} bytes)

    Override with: "simplify {filename} --force"

No changes needed:

✅ {filename} - Already follows best practices
   No simplification opportunities found.

Functionality risk detected:

⚠️  Potential behavior change detected in {filename}

    Line {N}: Changing conditional logic

    Review required before applying:
    [Show diff]

    Apply this change? [y/N]:

Success Criteria

Simplification is successful when:

• All modified files analyzed
• Functionality preserved (verified)
• Project standards applied (from CLAUDE.md)
• No nested ternaries remain
• Nesting depth ≤ 3 levels
• Clear variable/function names
• Change summary generated

Notes

• Model preference: Opus recommended for quality judgment
• Scope default: Only recently modified files (avoid churn)
• Skip tests: Test files usually follow different patterns
• Preserve intent: Comments explaining "why" should be kept
• No over-optimization: Clarity > minimal lines

This skill integrates Anthropic's internal code-simplifier pattern into Navigator's workflow, ensuring code quality before commit.