Dead Code Cleanup

Dead Code Cleanup Command

Purpose

Systematically identify and remove unused code while maintaining project integrity.

Target Code:

• Unused exports/functions/classes with no references
• Deprecated code without active migration plan
• Orphaned files (no imports from anywhere)
• Unreachable code paths

Critical Constraint: Project must build and pass all tests after cleanup.

User Input

$ARGUMENTS

Interpretation:

Preservation Rules (NEVER DELETE)

Absolute Preservation

Special Cases

Exported but unused internally:

• Public library → PRESERVE (external consumers unknown)
• Private app → Flag for review

Deprecated with timeline:

• Deadline NOT passed → PRESERVE
• Deadline passed + no usage → DELETE

Analysis Workflow

Phase 1: Context Gathering

1.1 Detect Project Type

# Framework detection
[ -f "next.config.js" ] && echo "Next.js"
[ -f "tsconfig.json" ] && echo "TypeScript"
[ -f "go.mod" ] && echo "Go"

1.2 Identify Package Scope

# Public library vs private app
grep '"private": false' package.json && echo "PUBLIC_LIBRARY"

1.3 Map Public API Surface

• Check package.json exports field
• Find index.ts re-exports
• List Go exported symbols (capital letter)

Phase 2: Dead Code Detection

2.1 Unused Exports

For each export statement:

1. Search for import references across codebase
2. Check dynamic import patterns
3. Verify not in public API surface

2.2 Deprecated Code

grep -rn "@deprecated" --include="*.ts" --include="*.go"
grep -rn "DEPRECATED" --include="*.ts" --include="*.go"

Evaluate:

• Has migration deadline? Check if passed
• Has replacement? Check usage migrated
• No timeline? Flag for review

2.3 Orphaned Files

Files not imported anywhere:

• Exclude: entry points, config files, scripts
• Exclude: test files, type declarations
• Flag: utility files with no imports

2.4 Unreachable Code

• Code after return/throw
• Always-false conditions
• Dead switch cases

Phase 3: Validation

For each candidate:

1. Cross-reference check: Search all possible import patterns
2. String reference check: Filename as string (dynamic loading)
3. Comment reference check: TODO/FIXME mentioning future use
4. Preservation rule check: Apply rules from above

Confidence Classification:

Phase 4: Safe Deletion

4.1 Pre-Deletion

# Warn if uncommitted changes
git status --porcelain | grep -q . && echo "⚠️ Uncommitted changes exist"

4.2 Incremental Deletion

• Delete in batches (5-10 items)
• Verify after each batch
• Stop on first failure

4.3 Post-Deletion Verification

# Must pass after each batch
{build_command}  # npm run build / go build ./...
{test_command}   # npm test / go test ./...
{lint_command}   # npm run lint / golangci-lint run

4.4 Rollback on Failure

git checkout -- {failed_files}

Output Format

Progress Updates (During Analysis)

🔍 Analyzing codebase...

**Project**: TypeScript (Next.js)
**Scope**: Entire codebase
**Mode**: Standard

---

## Context ✓

- Public API: 12 exports in src/index.ts
- Framework: Next.js (preserving pages/, app/, api/)
- Test utils: 5 shared utilities

## Detection Progress

- Scanning exports... (45/120)
- Checking deprecated markers...

Final Report

# 🧹 Dead Code Cleanup Report

**Generated**: {timestamp}
**Scope**: {analyzed_paths}

---

## 📊 Summary

| Category        | Count   | Lines       |
| --------------- | ------- | ----------- |
| Unused Exports  | {n}     | {lines}     |
| Deprecated Code | {n}     | {lines}     |
| Orphaned Files  | {n}     | {lines}     |
| **TOTAL**       | **{n}** | **{lines}** |

---

## 🔴 DELETED (HIGH Confidence)

### {file_path}:{line}

- **Type**: {function/class/variable}
- **Reason**: No references found
- **Verification**: Build ✓ Tests ✓

---

## 🟡 SKIPPED - Needs Review

### {file_path}:{line}

- **Type**: {function/class/variable}
- **Reason**: {why detected as dead}
- **Skip Reason**: {why preserved}
- **Action**: {recommended next step}

---

## 🟢 PRESERVED (Matched Rules)

### {file_path}:{line}

- **Rule**: {which preservation rule}
- **Detail**: {specifics}

---

## ⚠️ MANUAL REVIEW REQUIRED

Items requiring human decision:

1. **{file_path}:{line}**
   - Detected: {what was found}
   - Concern: {why uncertain}
   - Suggestion: {recommended action}

---

## ✅ Verification Results

- Build: {PASS/FAIL}
- Tests: {PASS/FAIL} ({passed}/{total})
- Lint: {PASS/FAIL}

---

## 📋 Next Steps

### Immediate

- [ ] Review {n} SKIPPED items
- [ ] Investigate {n} MANUAL REVIEW items

### Recommended

- [ ] Add deprecation notices before removing LOW confidence items
- [ ] Update documentation for removed APIs
- [ ] Configure lint rules to prevent future dead code

---

## 📝 Session Summary

- Analyzed: {total_files} files, {total_lines} lines
- Deleted: {deleted_count} items ({deleted_lines} lines)
- Skipped: {skipped_count} items (see reasons above)
- Preserved: {preserved_count} items (matched rules)

Key Rules

✅ Must Do

• Run build + tests after EVERY deletion batch
• Document skip reasons for every preserved item
• Report all skipped items in final summary
• Preserve items matching preservation rules

❌ Must Not Do

• Delete without verification
• Ignore preservation rules
• Skip final report generation
• Batch too many deletions (max 10 per batch)

🛡️ Safety First

• When uncertain → SKIP and report
• When ambiguous → Ask user
• When build fails → Rollback immediately

Execution Instructions

Step 1: Parse Input

• Check for --dry-run, --auto flags
• Determine target path (default: entire codebase)

Step 2: Safety Check

git status --porcelain

• Warn if uncommitted changes exist
• Suggest: "Consider committing or stashing changes first"

Step 3: Context Gathering (Phase 1)

1. Detect project type and framework
2. Identify if public library
3. Map public API surface
4. List test infrastructure

Step 4: Detection (Phase 2)

For TypeScript/JavaScript:

# Find exports
grep -rn "export \(function\|class\|const\|interface\|type\)" src/

# For each, check imports
grep -r "import.*{.*ExportName.*}" --exclude-dir=node_modules

For Go:

# Find exported symbols
grep -rn "^func [A-Z]" --include="*.go"
grep -rn "^type [A-Z]" --include="*.go"

Step 5: Validation (Phase 3)

For each candidate:

1. Run cross-reference checks
2. Apply preservation rules
3. Classify confidence level

Step 6: Action (Phase 4)

Based on mode:

• --dry-run: Generate report only
• --auto: Delete HIGH confidence, report rest
• Default: Ask confirmation for each deletion

Step 7: Verification

After each batch:

# Detect package manager and run
npm run build && npm test
# OR
pnpm build && pnpm test
# OR
go build ./... && go test ./...

Step 8: Final Report

Generate comprehensive report with:

• All deleted items
• All skipped items with reasons
• All preserved items with rules
• Manual review recommendations
• Verification results

CRITICAL: Always include skipped items in final report.

Example Usage

# Report only (no deletions)
/dead-code-cleanup --dry-run

# Analyze specific directory
/dead-code-cleanup src/legacy/

# Auto-delete HIGH confidence items
/dead-code-cleanup --auto

# Default: interactive mode
/dead-code-cleanup

Troubleshooting

False Positives

Symptom: Code flagged but actually needed

Check:

• Dynamic imports with variables
• Framework lifecycle methods
• External consumer usage

Build Failures

Action:

1. Rollback: git checkout -- .
2. Review failed item
3. Add to preservation rules if legitimate

Missed Dead Code

Solutions:

• Check if matches preservation rules incorrectly
• Run with more aggressive grep patterns
• Manual verification

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