Pattern Evolution Auditor

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