Paths: File paths (shared/, references/, ../ln-*) are relative to skills repo root. If not found at CWD, locate this SKILL.md directory and go up one level for repo root.

Pattern Evolution Auditor

L2 Coordinator that analyzes implemented architectural patterns against current best practices and tracks evolution over time.

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
• Track quality trends over time (improving/stable/declining)
• Output: docs/project/patterns_catalog.md (file-based)

4-Score Model

Score	What it measures	Threshold
Compliance	Industry standards, naming, tech stack conventions, layer boundaries	70%
Completeness	All components, error handling, observability, tests	70%
Quality	Readability, maintainability, no smells, SOLID, no duplication	70%
Implementation	Code exists, production use, integrated, monitored	70%

Worker Invocation

MANDATORY READ: Load shared/references/task_delegation_pattern.md.

Worker	Purpose	Phase
ln-641-pattern-analyzer	Calculate 4 scores per pattern	Phase 5
ln-642-layer-boundary-auditor	Detect layer violations	Phase 4
ln-643-api-contract-auditor	Audit API contracts, DTOs, layer leakage	Phase 4
ln-644-dependency-graph-auditor	Build dependency graph, detect cycles, validate boundaries, calculate metrics	Phase 4
ln-645-open-source-replacer	Search OSS replacements for custom modules via MCP Research	Phase 4
ln-646-project-structure-auditor	Audit physical structure, hygiene, naming conventions	Phase 4

All delegations use Agent with subagent_type: "general-purpose". Keep Phase 4 workers parallel where inputs are independent; keep ln-641 in Phase 5 because pattern scoring depends on earlier boundary and graph evidence.

Workflow

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

Phase 1a: Baseline Detection

1. Load docs/project/patterns_catalog.md
   IF missing → create from shared/templates/patterns_template.md
   IF exists → verify template conformance:
     required_sections = ["Score Legend", "Pattern Inventory", "Discovered Patterns",
       "Layer Boundary Status", "API Contract Status", "Quick Wins",
       "Patterns Requiring Attention", "Pattern Recommendations",
       "Excluded Patterns", "Summary"]
     FOR EACH section IN required_sections:
       IF section NOT found in catalog:
         → Append section from shared/templates/patterns_template.md
     Verify table columns match template (e.g., Recommendation in Quick Wins)
     IF columns mismatch → update table headers, preserve existing data rows

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

3. Auto-detect baseline patterns
   FOR EACH pattern IN pattern_library.md "Pattern Detection" table:
     Grep(detection_keywords) on codebase
     IF found but not in catalog → add as "Undocumented (Baseline)"

Phase 1b: Adaptive Discovery

MANDATORY READ: Load references/pattern_library.md — use "Discovery Heuristics" section.

Predefined patterns are a seed, not a ceiling. Discover project-specific patterns beyond the baseline.

# Structural heuristics (from pattern_library.md)
1. Class naming: Grep GoF suffixes (Factory|Builder|Strategy|Adapter|Observer|...)
2. Abstract hierarchy: ABC/Protocol with 2+ implementations → Template Method/Strategy
3. Fluent interface: return self chains → Builder
4. Registration dict: _registry + register() → Registry
5. Middleware chain: app.use/add_middleware → Chain of Responsibility
6. Event listeners: @on_event/@receiver/signal → Observer
7. Decorator wrappers: @wraps/functools.wraps → Decorator

# Document-based heuristics
8. ADR/Guide filenames + H1 headers → extract pattern names not in library
9. Architecture.md → grep pattern terminology
10. Code comments → "pattern:|@pattern|design pattern"

# Output per discovered pattern:
  {name, evidence: [files], confidence: HIGH|MEDIUM|LOW, status: "Discovered"}
  → Add to catalog "Discovered Patterns (Adaptive)" section

Phase 1c: Pattern Recommendations

Suggest patterns that COULD improve architecture (advisory, NOT scored).

# Check conditions from pattern_library.md "Pattern Recommendations" table
# E.g., external API calls without retry → recommend Resilience
# E.g., 5+ constructor params → recommend Builder/Parameter Object
# E.g., direct DB access from API layer → recommend Repository

→ Add to catalog "Pattern Recommendations" section

Phase 1d: Applicability Verification

Verify each detected pattern is actually implemented, not just a keyword false positive.

MANDATORY READ: Load references/scoring_rules.md — use "Required components by pattern" table.

FOR EACH detected_pattern IN (baseline_detected + adaptive_discovered):
  IF pattern.source == "adaptive":
    # Adaptive patterns: check confidence + evidence volume
    IF pattern.confidence == "LOW" AND len(pattern.evidence.files) < 3:
      pattern.status = "EXCLUDED"
      pattern.exclusion_reason = "Low confidence, insufficient evidence"
      → Add to catalog "Excluded Patterns" section
      CONTINUE
  ELSE:
    # Baseline patterns: check minimum 2 structural components
    components = get_required_components(pattern, scoring_rules.md)
    found_count = 0
    FOR EACH component IN components:
      IF Grep(component.detection_grep, codebase) has matches:
        found_count += 1
    IF found_count < 2:
      pattern.status = "EXCLUDED"
      pattern.exclusion_reason = "Found {found_count}/{len(components)} components"
      → Add to catalog "Excluded Patterns" section
      CONTINUE

  pattern.status = "VERIFIED"

# Step 2: Semantic applicability via MCP Ref (after structural check passes)
FOR EACH pattern WHERE pattern.status == "VERIFIED":
  ref_search_documentation("{pattern.name} {tech_stack.language} idiom vs architectural pattern")
  WebSearch("{pattern.name} {tech_stack.language} — language feature or design pattern?")

  IF evidence shows pattern is language idiom / stdlib feature / framework built-in:
    pattern.status = "EXCLUDED"
    pattern.exclusion_reason = "Language idiom / built-in feature, not architectural pattern"
    → Add to catalog "Excluded Patterns" section

# Cleanup: remove stale patterns from previous audits
FOR EACH pattern IN existing_catalog WHERE NOT detected in current scan:
  → REMOVE from Pattern Inventory
  → Add to "Excluded Patterns" with reason "No longer detected in codebase"

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: Domain Discovery + Output Setup

MANDATORY READ: Load shared/references/audit_coordinator_domain_mode.md.

Use the shared domain discovery pattern to set domain_mode and all_domains. Then create docs/project/.audit/ln-640/{YYYY-MM-DD}/. Worker files are cleaned up after consolidation (see Phase 11).

Phase 4: Layer Boundary + API Contract + Dependency Graph Audit

IF domain_mode == "domain-aware":
  FOR EACH domain IN all_domains:
    domain_context = {
      ...contextStore,
      domain_mode: "domain-aware",
      current_domain: { name: domain.name, path: domain.path }
    }
    FOR EACH worker IN [ln-642, ln-643, ln-644, ln-645, ln-646]:
      Agent(description: "Audit " + domain.name + " via " + worker,
           prompt: "Execute audit worker.

Step 1: Invoke worker:
  Skill(skill: \"" + worker + "\")

CONTEXT:
" + JSON.stringify(domain_context),
           subagent_type: "general-purpose")
ELSE:
  FOR EACH worker IN [ln-642, ln-643, ln-644, ln-645, ln-646]:
    Agent(description: "Pattern evolution audit via " + worker,
         prompt: "Execute audit worker.

Step 1: Invoke worker:
  Skill(skill: \"" + worker + "\")

CONTEXT:
" + JSON.stringify(contextStore),
         subagent_type: "general-purpose")

# Apply layer deductions from ln-642 return values (score + issue counts)
# Detailed violations read from files in Phase 6

Phase 5: Pattern Analysis Loop

# ln-641 stays GLOBAL (patterns are cross-cutting, not per-domain)
# Only VERIFIED patterns from Phase 1d (skip EXCLUDED)
FOR EACH pattern IN catalog WHERE pattern.status == "VERIFIED":
  Agent(description: "Analyze " + pattern.name + " via ln-641",
       prompt: "Execute audit worker.

Step 1: Invoke worker:
  Skill(skill: \"ln-641-pattern-analyzer\")

CONTEXT:
" + JSON.stringify({...contextStore, pattern: pattern}),
       subagent_type: "general-purpose")

Worker Output Contract (file-based):

MANDATORY READ: Load shared/references/audit_worker_core_contract.md and shared/templates/audit_worker_report_template.md.

All workers write reports to {output_dir}/ and return minimal summary:

Worker	Return Format	File
ln-641	Score: X.X/10 (C:N K:N Q:N I:N) | Issues: N	641-pattern-{slug}.md
ln-642	Score: X.X/10 | Issues: N (C:N H:N M:N L:N)	642-layer-boundary[-{domain}].md
ln-643	Score: X.X/10 (C:N K:N Q:N I:N) | Issues: N	643-api-contract[-{domain}].md
ln-644	Score: X.X/10 | Issues: N (C:N H:N M:N L:N)	644-dep-graph[-{domain}].md
ln-645	Score: X.X/10 | Issues: N (C:N H:N M:N L:N)	645-open-source-replacer[-{domain}].md
ln-646	Score: X.X/10 | Issues: N (C:N H:N M:N L:N)	646-structure[-{domain}].md

Coordinator parses scores/counts from return values (0 file reads for aggregation tables). Reads files only for cross-domain aggregation (Phase 6) and report assembly (Phase 8).

Phase 6: Cross-Domain Aggregation (File-Based)

IF domain_mode == "domain-aware":
  # Step 1: Read DATA-EXTENDED from ln-642 files
  FOR EACH file IN Glob("{output_dir}/642-layer-boundary-*.md"):
    Read file → extract <!-- DATA-EXTENDED ... --> JSON + Findings table
  # Group findings by issue type across domains
  FOR EACH issue_type IN unique(ln642_findings.issue):
    domains_with_issue = ln642_findings.filter(f => f.issue == issue_type).map(f => f.domain)
    IF len(domains_with_issue) >= 2:
      systemic_findings.append({
        severity: "CRITICAL",
        issue: f"Systemic layer violation: {issue_type} in {len(domains_with_issue)} domains",
        domains: domains_with_issue,
        recommendation: "Address at architecture level, not per-domain"
      })

  # Step 2: Read DATA-EXTENDED from ln-643 files
  FOR EACH file IN Glob("{output_dir}/643-api-contract-*.md"):
    Read file → extract <!-- DATA-EXTENDED ... --> JSON (issues with principle + domain)
  # Group findings by rule across domains
  FOR EACH rule IN unique(ln643_issues.principle):
    domains_with_issue = ln643_issues.filter(i => i.principle == rule).map(i => i.domain)
    IF len(domains_with_issue) >= 2:
      systemic_findings.append({
        severity: "HIGH",
        issue: f"Systemic API contract issue: {rule} in {len(domains_with_issue)} domains",
        domains: domains_with_issue,
        recommendation: "Create cross-cutting architectural fix"
      })

  # Step 3: Read DATA-EXTENDED from ln-644 files
  FOR EACH file IN Glob("{output_dir}/644-dep-graph-*.md"):
    Read file → extract <!-- DATA-EXTENDED ... --> JSON (cycles, sdp_violations)
  # Cross-domain cycles
  FOR EACH cycle IN ln644_cycles:
    domains_in_cycle = unique(cycle.path.map(m => m.domain))
    IF len(domains_in_cycle) >= 2:
      systemic_findings.append({
        severity: "CRITICAL",
        issue: f"Cross-domain dependency cycle: {cycle.path} spans {len(domains_in_cycle)} domains",
        domains: domains_in_cycle,
        recommendation: "Decouple via domain events or extract shared module"
      })

  # Step 4: Read DATA-EXTENDED from ln-645 files
  FOR EACH file IN Glob("{output_dir}/645-open-source-replacer-*.md"):
    Read file → extract <!-- DATA-EXTENDED ... --> JSON (replacements array)
  # Group findings by goal/alternative across domains
  FOR EACH goal IN unique(ln645_replacements.goal):
    domains_with_same = ln645_replacements.filter(r => r.goal == goal).map(r => r.domain)
    IF len(domains_with_same) >= 2:
      systemic_findings.append({
        severity: "HIGH",
        issue: f"Systemic custom implementation: {goal} duplicated in {len(domains_with_same)} domains",
        domains: domains_with_same,
        recommendation: "Single migration across all domains using recommended OSS package"
      })

  # Step 5: Read DATA-EXTENDED from ln-646 files
  FOR EACH file IN Glob("{output_dir}/646-structure-*.md"):
    Read file -> extract <!-- DATA-EXTENDED ... --> JSON
  # Group findings by dimension across domains
  FOR EACH dimension IN ["junk_drawers", "naming_violations"]:
    domains_with_issue = ln646_data.filter(d => d.dimensions[dimension].issues > 0).map(d => d.domain)
    IF len(domains_with_issue) >= 2:
      systemic_findings.append({
        severity: "MEDIUM",
        issue: f"Systemic structure issue: {dimension} in {len(domains_with_issue)} domains",
        domains: domains_with_issue,
        recommendation: "Standardize project structure conventions across domains"
      })

  # Cross-domain SDP violations
  FOR EACH sdp IN ln644_sdp_violations:
    IF sdp.from.domain != sdp.to.domain:
      systemic_findings.append({
        severity: "HIGH",
        issue: f"Cross-domain stability violation: {sdp.from} (I={sdp.I_from}) depends on {sdp.to} (I={sdp.I_to})",
        domains: [sdp.from.domain, sdp.to.domain],
        recommendation: "Apply DIP: extract interface at domain boundary"
      })

Phase 7: Gap Analysis

gaps = {
  undocumentedPatterns: found in code but not in catalog,
  missingComponents: required components not found per scoring_rules.md,
  layerViolations: code in wrong architectural layers,
  consistencyIssues: conflicting patterns,
  systemicIssues: systemic_findings from Phase 6
}

Aggregation Algorithm

MANDATORY READ: Load shared/references/audit_coordinator_aggregation.md and shared/references/context_validation.md.

# Step 1: Parse scores from worker return values (already in-context)
# ln-641: "Score: 7.9/10 (C:72 K:85 Q:68 I:90) | Issues: 3 (H:1 M:2 L:0)"
# ln-642: "Score: 4.5/10 | Issues: 8 (C:1 H:3 M:4 L:0)"
# ln-643: "Score: 6.75/10 (C:65 K:70 Q:55 I:80) | Issues: 4 (H:2 M:1 L:1)"
# ln-644: "Score: 6.5/10 | Issues: 8 (C:1 H:3 M:3 L:1)"
pattern_scores = [parse_score(r) for r in ln641_returns]  # Each 0-10
layer_score = parse_score(ln642_return)                     # 0-10
api_score = parse_score(ln643_return)                       # 0-10
graph_score = parse_score(ln644_return)                     # 0-10
structure_score = parse_score(ln646_return)                   # 0-10

# Step 2: Calculate architecture_health_score (ln-645 NOT included — separate metric)
all_scores = pattern_scores + [layer_score, api_score, graph_score, structure_score]
architecture_health_score = round(average(all_scores) * 10)  # 0-100 scale

# Step 2b: Separate reuse opportunity score (informational, no SLA enforcement)
reuse_opportunity_score = parse_score(ln645_return)  # 0-10, NOT in architecture_health_score

# Status mapping:
# >= 80: "healthy"
# 70-79: "warning"
# < 70: "critical"

# Step 3: Context Validation (Post-Filter)
# Apply Rules 1, 3 to ln-641 anti-pattern findings:
#   Rule 1: Match god_class/large_file findings against ADR list
#   Rule 3: For god_class deductions (-5 compliance):
#     Read flagged file ONCE, check 4 cohesion indicators
#     (public_func_count <= 2, subdirs, shared_state > 60%, CC=1)
#     IF cohesion >= 3: restore deducted -5 points
#     Note in patterns_catalog.md: "[Advisory: high cohesion module]"
# Recalculate architecture_health_score with restored points

Phase 8: Report + Trend Analysis

1. Update patterns_catalog.md:
   - Pattern scores, dates
   - Layer Boundary Status section
   - Quick Wins section
   - Patterns Requiring Attention section
2. Calculate trend: compare current vs previous scores
3. Output summary (see Return Result below)

Phase 9: Return Result

{
  "audit_date": "2026-02-04",
  "architecture_health_score": 78,
  "trend": "improving",
  "patterns_analyzed": 5,
  "layer_audit": {
    "architecture_type": "Layered",
    "violations_total": 5,
    "violations_by_severity": {"high": 2, "medium": 3, "low": 0},
    "coverage": {"http_abstraction": 85, "error_centralization": true}
  },
  "patterns": [
    {
      "name": "Job Processing",
      "scores": {"compliance": 72, "completeness": 85, "quality": 68, "implementation": 90},
      "avg_score": 79,
      "status": "warning",
      "issues_count": 3
    }
  ],
  "quick_wins": [
    {"pattern": "Caching", "issue": "Add TTL config", "effort": "2h", "impact": "+10 completeness"}
  ],
  "requires_attention": [
    {"pattern": "Event-Driven", "avg_score": 58, "critical_issues": ["No DLQ", "No schema versioning"]}
  ],
  "project_structure": {
    "structure_score": 7.5,
    "tech_stack_detected": "react",
    "dimensions": {
      "file_hygiene": {"checks": 6, "issues": 1},
      "ignore_files": {"checks": 4, "issues": 0},
      "framework_conventions": {"checks": 3, "issues": 1},
      "domain_organization": {"checks": 3, "issues": 1},
      "naming_conventions": {"checks": 3, "issues": 0}
    },
    "junk_drawers": 1,
    "naming_violations_pct": 3
  },
  "reuse_opportunities": {
    "reuse_opportunity_score": 6.5,
    "modules_scanned": 15,
    "high_confidence_replacements": 3,
    "medium_confidence_replacements": 5,
    "systemic_custom_implementations": 1
  },
  "dependency_graph": {
    "architecture_detected": "hybrid",
    "architecture_confidence": "MEDIUM",
    "modules_analyzed": 12,
    "cycles_detected": 2,
    "boundary_violations": 3,
    "sdp_violations": 1,
    "nccd": 1.3,
    "score": 6.5
  },
  "cross_domain_issues": [
    {
      "severity": "CRITICAL",
      "issue": "Systemic layer violation: HTTP client in domain layer in 3 domains",
      "domains": ["users", "billing", "orders"],
      "recommendation": "Address at architecture level"
    }
  ]
}

Phase 10: Append Results Log

MANDATORY READ: Load shared/references/results_log_pattern.md

Append one row to docs/project/.audit/results_log.md with: Skill=ln-640, Metric=architecture_health_score, Scale=0-100, Score from Phase 9 output. Calculate Delta vs previous ln-640 row. Create file with header if missing. Rolling window: max 50 entries.

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
• File output only: Write results to patterns_catalog.md; no side-effect task/issue creation

Phase 11: Cleanup Worker Files

rm -rf {output_dir}

Delete the dated output directory (docs/project/.audit/ln-640/{YYYY-MM-DD}/). The consolidated report and results log already preserve all audit data.

Definition of Done

• Pattern catalog loaded or created
• Applicability verified for all detected patterns (Phase 1d); excluded patterns documented
• Best practices researched for all VERIFIED patterns needing audit
• Domain discovery completed (global or domain-aware mode selected)
• Output directory docs/project/.audit/ln-640/{YYYY-MM-DD}/ created for worker reports
• Worker output directory cleaned up after consolidation
• Layer boundaries audited via ln-642 (reports written to {output_dir}/)
• API contracts audited via ln-643 (reports written to {output_dir}/)
• Dependency graph audited via ln-644 (reports written to {output_dir}/)
• All patterns analyzed via ln-641 (reports written to {output_dir}/)
• Open-source replacement opportunities audited via ln-645 (reports written to {output_dir}/)
• Project structure audited via ln-646 (reports written to {output_dir}/)
• If domain-aware: cross-domain aggregation completed via DATA-EXTENDED from files
• Gaps identified (undocumented, missing components, layer violations, inconsistent, systemic)
• Catalog updated with scores, dates, Layer Boundary Status
• Trend analysis completed (current vs previous scores compared)
• Summary report output

Phase 12: Meta-Analysis

MANDATORY READ: Load shared/references/meta_analysis_protocol.md

Skill type: review-coordinator (workers only). Run after all phases complete. Output to chat using the review-coordinator — workers only format.

Reference Files

• Task delegation pattern: shared/references/task_delegation_pattern.md
• Domain mode pattern: shared/references/audit_coordinator_domain_mode.md
• Aggregation pattern: shared/references/audit_coordinator_aggregation.md
• Pattern catalog template: shared/templates/patterns_template.md
• Pattern library (detection + best practices + discovery): references/pattern_library.md
• Layer boundary rules (for ln-642): references/layer_rules.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
• API contract audit: ../ln-643-api-contract-auditor/SKILL.md
• Dependency graph audit: ../ln-644-dependency-graph-auditor/SKILL.md
• Open-source replacement audit: ../ln-645-open-source-replacer/SKILL.md
• Project structure audit: ../ln-646-project-structure-auditor/SKILL.md
• MANDATORY READ: shared/references/research_tool_fallback.md
• MANDATORY READ: shared/references/tools_config_guide.md
• MANDATORY READ: shared/references/storage_mode_detection.md

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Version: 2.0.0 Last Updated: 2026-02-08