Ln 512 Tech Debt Cleaner

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Tech Debt Cleaner (L3 Worker)

Automated cleanup of safe, low-risk tech debt findings from codebase audits.

Purpose & Scope

• Consume audit findings from docs/project/codebase_audit.md (ln-620 output) or ln-511 code quality output
• Filter to auto-fixable findings with confidence >=90%
• Apply safe fixes: remove unused imports, delete dead code, clean commented-out blocks, remove deprecated aliases
• Never touch business logic, complex refactoring, or architectural changes
• Create single commit with structured summary of all changes
• Invocable from ln-510 quality coordinator pipeline or standalone

Auto-Fixable Categories

NOT Auto-Fixable (skip always)

When to Use

• Invoked by ln-510-quality-coordinator Phase 3 (after ln-511 code quality check)
• Standalone: After ln-620 codebase audit completes (user triggers manually)
• Scheduled: As periodic "garbage collection" for codebase hygiene

Inputs

• Pipeline mode (ln-510): findings from ln-511 code quality output (passed via coordinator context)
• Standalone mode: docs/project/codebase_audit.md (ln-620 output)

Workflow

1. Load findings: Read docs/project/codebase_audit.md. Parse findings from Dead Code section (ln-626 results) and Code Quality section (ln-624 results).

2. Filter to auto-fixable:

   • Category must be in Auto-Fixable table above
   • Severity must be LOW or MEDIUM (no HIGH/CRITICAL)
   • Effort must be S (small)
   • Skip files in: node_modules/, vendor/, dist/, build/, *.min.*, generated code, test fixtures

3. Verify each finding (confidence check): MANDATORY READ: shared/references/clean_code_checklist.md For each candidate fix: a) Read the target file at specified location b) Confirm the finding still exists (file may have changed since audit) c) Confirm removal is safe:

   • For unused imports: grep codebase for usage (must have 0 references)
   • For unused functions: grep for function name (must have 0 call sites)
   • For commented-out code: verify block is code, not documentation
   • For deprecated aliases: verify no consumers remain d) Assign confidence score (0-100). Only proceed if confidence >=90

4. Apply fixes (bottom-up within each file):

   • Sort fixes by line number descending (bottom-up prevents line shift issues)
   • Apply each fix using Edit tool
   • Track: file, lines removed, category, original finding ID

5. Verify build integrity: Per shared/references/ci_tool_detection.md discovery hierarchy: detect and run lint + typecheck commands.

   • If ANY check fails: revert ALL changes (git checkout .), report failure
   • If no lint/type commands detected: skip verification with warning

6. Create commit:

   • Stage only modified files (explicit git add per file, not git add .)
   • Commit message format:

     chore: automated tech debt cleanup
     
     Removed {N} auto-fixable findings from codebase audit:
     - {count} unused imports
     - {count} dead functions
     - {count} commented-out code blocks
     - {count} deprecated aliases
     
     Source: docs/project/codebase_audit.md
     Confidence threshold: >=90%
     

7. Update audit report:

   • Add "Last Cleanup" section to docs/project/codebase_audit.md:

     ## Last Automated Cleanup
     **Date:** YYYY-MM-DD
     **Findings fixed:** N of M auto-fixable
     **Skipped:** K (confidence <90% or verification failed)
     **Build check:** PASSED / SKIPPED
     

Output Format

verdict: CLEANED | NOTHING_TO_CLEAN | BUILD_FAILED
stats:
  total_findings: {from audit}
  auto_fixable: {filtered count}
  applied: {actually fixed}
  skipped: {confidence <90 or stale}
  reverted: {if build failed, all}
fixes:
  - file: "src/utils/helpers.ts"
    line: 45
    category: "unused_function"
    removed: "formatDate()"
    finding_id: "MNT-DC-003"
  - file: "src/api/v1/auth.ts"
    line: 12
    category: "deprecated_alias"
    removed: "export { newAuth as oldAuth }"
    finding_id: "MNT-DC-007"
build_check: PASSED | SKIPPED | FAILED
commit_sha: "abc1234" | null

Critical Rules

• Safety first: Never fix if confidence <90%. When in doubt, skip.
• Bottom-up editing: Always apply fixes from bottom to top of file to avoid line number shifts.
• Build verification: If linter/type-checker fails after fixes, revert ALL changes immediately.
• No business logic: Never modify function bodies, conditionals, or control flow.
• Explicit staging: Stage files by name, never git add . or git add -A.
• Idempotent: Running twice produces no changes if audit report unchanged.
• Git-aware: Only operate on tracked files. Skip untracked or ignored files.
• Exclusions: Skip generated code, vendor directories, minified files, test fixtures.

Definition of Done

• Audit report loaded and parsed
• Findings filtered to auto-fixable categories
• Each finding verified with confidence >=90%
• Fixes applied bottom-up per file
• Build integrity verified (lint + type check) or skipped with warning
• Single commit created with structured message (or all reverted on build failure)
• Audit report updated with "Last Automated Cleanup" section
• Output YAML returned to caller

Reference Files

• Clean code checklist: shared/references/clean_code_checklist.md
• Audit output schema: shared/references/audit_output_schema.md
• Audit report template: shared/templates/codebase_audit_template.md

Version: 1.0.0 Last Updated: 2026-02-15