ln-626-dead-code-auditor

name	ln-626-dead-code-auditor
description	Checks unreachable code, unused imports/variables/functions, commented-out code, unsupported patterns. Use when auditing dead code.
allowed-tools	Read, Grep, Glob, Bash, mcp__hex-graph__index_project, mcp__hex-graph__audit_workspace, mcp__hex-line__read_file, mcp__hex-line__grep_search, mcp__hex-line__outline
license	MIT

Paths: File paths (references/, ../ln-*) are relative to this skill directory.

Dead Code Auditor (L3 Worker)

Type: L3 Worker

Specialized worker auditing unused and unreachable code.

Purpose & Scope

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

Inputs

MANDATORY READ: Load references/audit_worker_core_contract.md. Tool policy: follow host AGENTS.md MCP preferences; load references/mcp_tool_preferences.md and references/mcp_integration_patterns.md only when host policy is absent or MCP behavior is unclear.

Receives contextStore with tech stack, codebase root, output_dir.

Use hex-graph first when export liveness or workspace hotspots materially improve the audit. Use hex-line first for local code reads when available. If MCP is unavailable, unsupported, or not indexed, continue with built-in Read/Grep/Glob/Bash and state the fallback in the report.

Workflow

Detection policy: use two-layer detection (candidate scan, then context verification); load references/two_layer_detection.md only when the verification method is ambiguous.

1. Parse context + output_dir
2. Run dead code detection (Layer 1: linters, grep)
   • Graph-capable projects: For JavaScript, TypeScript/TSX, Python, C#, and PHP, use index_project then bounded audit_workspace(verbosity="minimal", limit=5) as primary detection for unused exports when graph indexing is available. Raise limit only for deliberate drill-down.
   • Keep grep/linter fallback for unsupported languages, graph-unavailable runs, and checks outside export liveness.
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 references/templates/audit_worker_report_template.md, write to {output_dir}/ln-626--global.md in single Write call
7. Return Summary: Return minimal summary to coordinator

Audit Rules

MANDATORY READ: Load 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, unsupported 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)
• Unsupported exports/re-exports:
  • Grep for // DEPRECATED, @obsolete 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, // unsupported, // kept for backward

Severity:

• HIGH: Backward compatibility shims in critical paths (auth, payment, core features)
• MEDIUM: Unsupported 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 unsupported 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 unsupported exports
• M: Refactor code using old APIs to new APIs
• L: Remove complex backward compatibility layer affecting multiple modules

Scoring Algorithm

MANDATORY READ: Load references/audit_scoring.md.

Output Format

MANDATORY READ: Load references/templates/audit_worker_report_template.md.

Write JSON summary per references/audit_summary_contract.md. In managed mode the caller passes both runId and summaryArtifactPath; in standalone mode the worker generates its own run-scoped artifact path per shared contract.

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

Return summary per references/audit_summary_contract.md.

When summaryArtifactPath is absent, write the standalone runtime summary under .hex-skills/runtime-artifacts/runs/{run_id}/evaluation-worker/{worker}--{identifier}.json and optionally echo the same summary in structured output.

Report written: .hex-skills/runtime-artifacts/runs/{run_id}/audit-report/ln-626--global.md
Score: X.X/10 | Issues: N (C:N H:N M:N L:N)

Reference Files

• Clean code checklist: references/clean_code_checklist.md
• Audit output schema: references/audit_output_schema.md

Critical Rules

Apply the already-loaded references/audit_worker_core_contract.md.

• 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

Apply the already-loaded references/audit_worker_core_contract.md.

• 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 references/clean_code_checklist.md
• Findings collected with severity, location, effort, recommendation
• Score calculated per references/audit_scoring.md
• Report written to {output_dir}/ln-626--global.md (atomic single Write call)
• Summary written per contract

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Version: 3.0.0 Last Updated: 2025-12-23