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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)

MANDATORY READ: Load shared/references/task_delegation_pattern.md#audit-coordinator--worker-contract for contextStore structure.

Receives contextStore with tech stack, codebase root, output_dir.

Workflow

MANDATORY READ: Load shared/references/two_layer_detection.md for detection methodology.

1. Parse context + output_dir
2. Run dead code detection (Layer 1: linters, grep)
3. Analyze context per candidate (Layer 2):
   • Unused functions: used via dynamic import/reflection? Exported in public API? Used in other packages (monorepo)?
   • Commented code: TODO with context or algorithm explanation → FP. Truly dead code block → confirmed
   • Legacy shims: read git blame — age? Is there an issue/PR tracking removal?
4. Collect confirmed findings
5. Calculate score
6. Write Report: Build full markdown report in memory per shared/templates/audit_worker_report_template.md, write to {output_dir}/626-dead-code.md in single Write call
7. Return Summary: Return minimal summary to coordinator

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

MANDATORY READ: Load shared/templates/audit_worker_report_template.md for file format.

Write report to {output_dir}/626-dead-code.md with category: "Dead Code" and checks: unreachable_code, unused_exports, commented_code, legacy_shims.

Return summary to coordinator:

Report written: docs/project/.audit/ln-620/{YYYY-MM-DD}/626-dead-code.md
Score: X.X/10 | Issues: N (C:N H:N M:N L:N)

Reference Files

• Worker report template: shared/templates/audit_worker_report_template.md
• 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 (including output_dir)
• 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
• Report written to {output_dir}/626-dead-code.md (atomic single Write call)
• Summary returned to coordinator

Version: 3.0.0 Last Updated: 2025-12-23