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Dead Code Auditor (L3 Worker)

Specialized worker auditing unused and unreachable code.

Purpose & Scope

• Worker in ln-620 coordinator pipeline
• Audit dead code (Category 9: Low Priority)
• Find unused imports, variables, functions, commented-out code
• Calculate compliance score (X/10)

Inputs (from Coordinator)

Receives contextStore with tech stack, codebase root.

Workflow

1. Parse context
2. Run dead code detection (linters, grep)
3. Collect findings
4. Calculate score
5. Return JSON

Audit Rules

MANDATORY READ: Load shared/references/clean_code_checklist.md for universal dead code patterns and severity definitions.

1. Unreachable Code

Detection:

• Linter rules: no-unreachable (ESLint)
• Check code after return, throw, break

Severity: MEDIUM

2. Unused Imports/Variables/Functions

Detection:

• ESLint: no-unused-vars
• TypeScript: noUnusedLocals, noUnusedParameters
• Python: flake8 with F401, F841

Severity:

• MEDIUM: Unused functions (dead weight)
• LOW: Unused imports (cleanup needed)

3. Commented-Out Code

Detection:

• Grep for //.*{ or /*.*function patterns
• Large comment blocks (>10 lines) with code syntax

Severity: LOW

Recommendation: Delete (git preserves history)

4. Legacy Code & Backward Compatibility

What: Backward compatibility shims, deprecated patterns, old code that should be removed

Detection:

• Renamed variables/functions with old aliases:
  • Pattern: const oldName = newName or export { newModule as oldModule }
  • Pattern: function oldFunc() { return newFunc(); } (wrapper for backward compatibility)
• Deprecated exports/re-exports:
  • Grep for // DEPRECATED, @deprecated JSDoc tags
  • Pattern: export.*as.*old.* or export.*legacy.*
• Conditional code for old versions:
  • Pattern: if.*legacy.* or if.*old.*version.* or isOldVersion ? oldFunc() : newFunc()
• Migration shims and adapters:
  • Pattern: migrate.*, Legacy.*Adapter, .*Shim, .*Compat
• Comment markers:
  • Grep for // backward compatibility, // legacy support, // TODO: remove in v
  • Grep for // old implementation, // deprecated, // kept for backward

Severity:

• HIGH: Backward compatibility shims in critical paths (auth, payment, core features)
• MEDIUM: Deprecated exports still in use, migration code from >6 months ago
• LOW: Recent migration code (<3 months), planned deprecation with clear removal timeline

Recommendation:

• Remove backward compatibility shims – breaking changes are acceptable when properly versioned
• Delete old implementations – keep only the correct/new version
• Remove deprecated exports – update consumers to use new API
• Delete migration code after grace period (3-6 months)
• Clean legacy support comments – git history preserves old implementations

Effort:

• S: Remove simple aliases, delete deprecated exports
• M: Refactor code using old APIs to new APIs
• L: Remove complex backward compatibility layer affecting multiple modules

Scoring Algorithm

MANDATORY READ: Load shared/references/audit_scoring.md for unified scoring formula.

Output Format

{
  "category": "Dead Code",
  "score": 6,
  "total_issues": 12,
  "critical": 0,
  "high": 2,
  "medium": 3,
  "low": 7,
  "checks": [
    {"id": "unreachable_code", "name": "Unreachable Code", "status": "passed", "details": "No unreachable code detected"},
    {"id": "unused_exports", "name": "Unused Exports", "status": "failed", "details": "3 unused functions found"},
    {"id": "commented_code", "name": "Commented Code", "status": "warning", "details": "7 blocks of commented code"},
    {"id": "legacy_shims", "name": "Legacy Shims", "status": "failed", "details": "2 backward compatibility shims"}
  ],
  "findings": [
    {
      "severity": "MEDIUM",
      "location": "src/utils/helpers.ts:45",
      "issue": "Function 'formatDate' is never used",
      "principle": "Code Maintainability / Clean Code",
      "recommendation": "Remove unused function or export if needed elsewhere",
      "effort": "S"
    },
    {
      "severity": "HIGH",
      "location": "src/api/v1/auth.ts:12-15",
      "issue": "Backward compatibility shim for old password validation (6+ months old)",
      "principle": "No Legacy Code / Clean Architecture",
      "recommendation": "Remove old password validation, keep only new implementation. Update API version if breaking.",
      "effort": "M"
    }
  ]
}

Reference Files

• Clean code checklist: shared/references/clean_code_checklist.md
• Audit scoring formula: shared/references/audit_scoring.md
• Audit output schema: shared/references/audit_output_schema.md

Critical Rules

• Do not auto-fix: Report only, never delete code
• Age-aware severity: Legacy shims >6 months = MEDIUM, <3 months = LOW
• Effort realism: S = <1h, M = 1-4h, L = >4h
• Exclusions: Skip generated code, vendor, migrations, test fixtures
• Git-aware: Recommend deletion confidently — git history preserves old code

Definition of Done

• contextStore parsed
• All 4 checks completed (unreachable code, unused imports/vars/functions, commented-out code, legacy shims)
• Clean code checklist loaded from shared/references/clean_code_checklist.md
• Findings collected with severity, location, effort, recommendation
• Score calculated per shared/references/audit_scoring.md
• JSON returned to coordinator

Version: 3.0.0 Last Updated: 2025-12-23