ln-641-pattern-analyzer skill

---
name: ln-641-pattern-analyzer
description: L3 Worker. Analyzes single pattern implementation, calculates 4 scores (compliance, completeness, quality, implementation), identifies gaps and issues. Usually invoked by ln-640, can also analyze a specific pattern on user request.
---

> **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 Analyzer

L3 Worker that analyzes a single architectural pattern against best practices and calculates 4 scores.

## Purpose & Scope
- Analyze ONE pattern per invocation (receives pattern name, locations, best practices from coordinator)
- Find all implementations in codebase (Glob/Grep)
- Validate implementation exists and works
- Calculate 4 scores: compliance, completeness, quality, implementation
- Identify gaps and issues with severity and effort estimates
- Return structured analysis result to coordinator

**Out of Scope** (owned by ln-624-code-quality-auditor):
- Cyclomatic complexity thresholds (>10, >20)
- Method/class length thresholds (>50, >100, >500 lines)
- Quality Score focuses on pattern-specific quality (SOLID within pattern, pattern-level smells), not generic code metrics

## Input (from ln-640 coordinator)

```
- pattern: string          # Pattern name (e.g., "Job Processing")
- locations: string[]      # Known file paths/directories
- bestPractices: object    # Best practices from MCP Ref/Context7/WebSearch
- output_dir: string       # e.g., "docs/project/.audit"
```

> **Note:** All patterns arrive pre-verified (passed ln-640 Phase 1d applicability gate with >= 2 structural components confirmed).

## Workflow

### Phase 1: Find Implementations

**MANDATORY READ:** Load `../ln-640-pattern-evolution-auditor/references/pattern_library.md` — use "Pattern Detection (Grep)" table for detection keywords per pattern.

```
IF pattern.source == "adaptive":
  # Pattern discovered by coordinator Phase 1b — evidence already provided
  files = pattern.evidence.files
  SKIP detection keyword search (already done in Phase 1b)
ELSE:
  # Baseline pattern — use library detection keywords
  files = Glob(locations)
  additional = Grep("{pattern_keywords}", "**/*.{ts,js,py,rb,cs,java}")
  files = deduplicate(files + additional)
```

### Phase 2: Read and Analyze Code

```
FOR EACH file IN files (limit: 10 key files):
  Read(file)
  Extract: components, patterns, error handling, logging, tests
```

### Phase 3: Calculate 4 Scores

**MANDATORY READ:** Load `../ln-640-pattern-evolution-auditor/references/scoring_rules.md` — follow Detection column for each criterion.

| Score | Source in scoring_rules.md | Max |
|-------|---------------------------|-----|
| Compliance | "Compliance Score" section — industry standard, naming, conventions, anti-patterns | 100 |
| Completeness | "Completeness Score" section — required components table (per pattern), error handling, tests | 100 |
| Quality | "Quality Score" section — method length, complexity, code smells, SOLID | 100 |
| Implementation | "Implementation Score" section — compiles, production usage, integration, monitoring | 100 |

**Scoring process for each criterion:**
1. Run the Detection Grep/Glob from scoring_rules.md
2. If matches found → add points per criterion
3. If anti-pattern/smell detected → subtract per deduction table
4. Document evidence: file path + line for each score justification

### Phase 4: Identify Issues and Gaps

```
FOR EACH bestPractice NOT implemented:
  issues.append({
    severity: "HIGH" | "MEDIUM" | "LOW",
    category: "compliance" | "completeness" | "quality" | "implementation",
    issue: description,
    suggestion: how to fix,
    effort: "S" | "M" | "L"
  })

gaps = {
  missingComponents: required components not found in code,
  inconsistencies: conflicting or incomplete implementations
}
```

### Phase 5: Calculate Overall Score

```
overall_score = average(compliance, completeness, quality, implementation) / 10
```

### Phase 6: Write Report

**MANDATORY READ:** Load `shared/templates/audit_worker_report_template.md` for file format (ln-640 section: 4-score AUDIT-META + DATA-EXTENDED).

```
# Build pattern name slug: "Job Processing" → "job-processing"
slug = pattern.name.lower().replace(" ", "-")

# Build markdown report in memory with:
# - AUDIT-META (4-score variant: score + score_compliance/completeness/quality/implementation)
# - Checks table (compliance_check, completeness_check, quality_check, implementation_check)
# - Findings table (issues sorted by severity)
# - DATA-EXTENDED: {pattern, codeReferences, gaps, recommendations}

Write to {output_dir}/641-pattern-{slug}.md (atomic single Write call)
```

### Phase 7: Return Summary

```
Report written: docs/project/.audit/641-pattern-job-processing.md
Score: 7.9/10 (C:72 K:85 Q:68 I:90) | Issues: 3 (H:1 M:2 L:0)
```

## Critical Rules

- **One pattern only:** Analyze only the pattern passed by coordinator
- **Read before score:** Never score without reading actual code
- **Detection-based scoring:** Use Grep/Glob patterns from scoring_rules.md, not assumptions
- **Effort estimates:** Always provide S/M/L for each issue
- **Code references:** Always include file paths for findings

## Definition of Done

- All implementations found via Glob/Grep (using pattern_library.md keywords or adaptive evidence)
- Key files read and analyzed
- 4 scores calculated using scoring_rules.md Detection patterns
- Issues identified with severity, category, suggestion, effort
- Gaps documented (missing components, inconsistencies)
- Recommendations provided
- Report written to `{output_dir}/641-pattern-{slug}.md` (atomic single Write call)
- Summary returned to coordinator

## Reference Files

- **Worker report template:** `shared/templates/audit_worker_report_template.md`
- Scoring rules: `../ln-640-pattern-evolution-auditor/references/scoring_rules.md`
- Pattern library: `../ln-640-pattern-evolution-auditor/references/pattern_library.md`

---
**Version:** 2.0.0
**Last Updated:** 2026-02-08