name: ln-640-pattern-evolution-auditor description: "Audits architectural patterns against best practices (MCP Ref, Context7, WebSearch). Maintains patterns catalog, calculates 4 scores, creates refactor Stories via ln-220. Use when user asks to: (1) Check architecture health, (2) Audit patterns before refactoring, (3) Find undocumented patterns in codebase."

Pattern Evolution Auditor

L2 Coordinator that analyzes implemented architectural patterns against current best practices, tracks evolution over time, and creates Stories for improvements.

Purpose & Scope

• Maintain docs/project/patterns_catalog.md with implemented patterns
• Research best practices via MCP Ref, Context7, WebSearch
• Audit layer boundaries via ln-642 (detect violations, check coverage)
• Calculate 4 scores per pattern via ln-641
• Create Stories for patterns with score < 70% via ln-220
• Track quality trends over time (improving/stable/declining)

4-Score Model

Worker Invocation

CRITICAL: All delegations use Task tool with subagent_type: "general-purpose" for context isolation.

Prompt template:

Task(description: "[Audit/Create] via ln-6XX",
     prompt: "Execute {skill-name}. Read skill from {skill-name}/SKILL.md. Pattern: {pattern}",
     subagent_type: "general-purpose")

Anti-Patterns:

• ❌ Direct Skill tool invocation without Task wrapper
• ❌ Any execution bypassing subagent context isolation

Workflow

Phase 1: Discovery

1. Load docs/project/patterns_catalog.md
   IF missing → create from shared/templates/patterns_template.md

2. Load docs/reference/adrs/*.md → link patterns to ADRs
   Load docs/reference/guides/*.md → link patterns to Guides

3. Auto-detect undocumented patterns
   Use patterns from common_patterns.md "Pattern Detection" table
   IF found but not in catalog → add as "Undocumented"

Phase 2: Best Practices Research

FOR EACH pattern WHERE last_audit > 30 days OR never:

  # MCP Ref + Context7 + WebSearch
  ref_search_documentation("{pattern} best practices {tech_stack}")
  IF pattern.library: query-docs(library_id, "{pattern}")
  WebSearch("{pattern} implementation best practices 2026")

  → Store: contextStore.bestPractices[pattern]

Phase 3: Layer Boundary Audit

Task(ln-642-layer-boundary-auditor)
  Input: architecture_path, codebase_root, skip_violations
  Output: violations[], coverage{}

# Apply deductions to affected patterns (per scoring_rules.md)
FOR EACH violation IN violations:
  affected_pattern = match_violation_to_pattern(violation)
  affected_pattern.issues.append(violation)
  affected_pattern.compliance_deduction += get_deduction(violation)

Phase 4: Pattern Analysis Loop

FOR EACH pattern IN catalog:
  Task(ln-641-pattern-analyzer)
    Input: pattern, locations, adr_reference, bestPractices
    Output: scores{}, issues[], gaps{}

  **Task tool result contract:**
  - ln-641 returns: `{scores: {compliance, completeness, quality, implementation}, issues: [], gaps: {}}`
  - ln-642 returns: `{violations: [{severity, location, code, suggestion}], coverage: {layer: %}}`

  # Merge layer violations from Phase 3
  pattern.issues += layer_violations.filter(v => v.pattern == pattern)
  pattern.scores.compliance -= compliance_deduction
  pattern.scores.quality -= quality_deduction

Phase 5: Gap Analysis

gaps = {
  undocumentedPatterns: found in code but not in catalog,
  implementationGaps: ADR decisions not implemented,
  layerViolations: code in wrong architectural layers,
  consistencyIssues: conflicting patterns
}

Phase 6: Story Creation (via ln-220)

REFACTORING PRINCIPLE (MANDATORY):

Stories MUST include: "Zero Legacy / Zero Backward Compatibility" — no compatibility hacks, clean architecture is priority.

refactorItems = patterns WHERE any_score < 70%

IF refactorItems.length > 0:
  # Auto-detect Epic (Architecture/Refactoring/Technical Debt)
  targetEpic = find_epic(["Architecture", "Refactoring", "Technical Debt"])
  IF not found → AskUserQuestion

  FOR EACH pattern IN refactorItems:
    Task(ln-220-story-coordinator)
      Create Story with AC from issues list
      MANDATORY AC: Zero Legacy principle

Phase 7: Report + Trend Analysis

1. Update patterns_catalog.md:
   - Pattern scores, dates, Story links
   - Layer Boundary Status section
   - Quick Wins section
   - Patterns Requiring Attention section

2. Calculate trend: compare current vs previous scores

3. Output summary:
   - Patterns analyzed: N
   - Layer violations: M
   - Architecture Health Score: X%
   - Trend: improving/stable/declining

Critical Rules

• MCP Ref first: Always research best practices before analysis
• Layer audit first: Run ln-642 before ln-641 pattern analysis
• 4 scores mandatory: Never skip any score calculation
• Layer deductions: Apply scoring_rules.md deductions for violations
• ln-220 for Stories: Create Stories, not standalone tasks
• Zero Legacy: Refactor Stories must include "no backward compatibility" AC
• Auto-detect Epic: Only ask user if cannot determine automatically

Definition of Done

• Pattern catalog loaded or created
• Best practices researched for all patterns needing audit
• Layer boundaries audited via ln-642 (violations detected, coverage calculated)
• All patterns analyzed via ln-641 (4 scores with layer deductions applied)
• Gaps identified (undocumented, unimplemented, layer violations, inconsistent)
• Stories created via ln-220 for patterns with score < 70%
• Catalog updated with scores, dates, Layer Boundary Status, Story links
• Trend analysis completed
• Summary report output

Reference Files

• Pattern catalog template: shared/templates/patterns_template.md
• Common patterns detection: references/common_patterns.md
• Scoring rules: references/scoring_rules.md
• Pattern analysis: ../ln-641-pattern-analyzer/SKILL.md
• Layer boundary audit: ../ln-642-layer-boundary-auditor/SKILL.md
• Story creation: ../ln-220-story-coordinator/SKILL.md

Version: 1.1.0 Last Updated: 2026-01-29