Audits layer boundaries + cross-layer consistency: I/O violations, transaction boundaries (commit ownership), session ownership (DI vs local).
apm install @levnikolaevich/ln-642-layer-boundary-auditor[](https://apm-p1ls2dz87-atlamors-projects.vercel.app/packages/@levnikolaevich/ln-642-layer-boundary-auditor)---
name: ln-642-layer-boundary-auditor
description: "Audits layer boundaries + cross-layer consistency: I/O violations, transaction boundaries (commit ownership), session ownership (DI vs local)."
license: MIT
---
> **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.
# Layer Boundary Auditor
L3 Worker that audits architectural layer boundaries and detects violations.
## Purpose & Scope
- Read architecture.md to discover project's layer structure
- Detect layer violations (I/O code outside infrastructure layer)
- **Detect cross-layer consistency issues:**
- Transaction boundaries (commit/rollback ownership)
- Session ownership (DI vs local)
- Check pattern coverage (all HTTP calls use client abstraction)
- Detect error handling duplication
- Return violations list to coordinator
**Out of Scope** (owned by ln-628-concurrency-auditor):
- Blocking I/O in async functions (sync open/read in async def)
- Fire-and-forget tasks (create_task without error handler)
## Input (from ln-640)
```
- architecture_path: string # Path to docs/architecture.md
- codebase_root: string # Root directory to scan
- skip_violations: string[] # Files to skip (legacy)
- output_dir: string # e.g., "docs/project/.audit/ln-640/{YYYY-MM-DD}"
# Domain-aware (optional, from coordinator)
- domain_mode: "global" | "domain-aware" # Default: "global"
- current_domain: string # e.g., "users", "billing" (only if domain-aware)
- scan_path: string # e.g., "src/users/" (only if domain-aware)
```
**When domain_mode="domain-aware":** Use `scan_path` instead of `codebase_root` for all Grep/Glob operations. Tag all findings with `domain` field.
## Workflow
**MANDATORY READ:** Load `shared/references/two_layer_detection.md` for detection methodology.
### Phase 1: Discover Architecture
**MANDATORY READ:** Load `../ln-640-pattern-evolution-auditor/references/layer_rules.md` — use Architecture Presets (fallback), I/O Pattern Boundary Rules (Phase 2), Coverage Checks (Phase 4), Cross-Layer Consistency rules (Phase 3).
```
Read docs/architecture.md
Extract from Section 4.2 (Top-Level Decomposition):
- architecture_type: "Layered" | "Hexagonal" | "Clean" | "MVC" | etc.
- layers: [{name, directories[], purpose}]
Extract from Section 5.3 (Infrastructure Layer Components):
- infrastructure_components: [{name, responsibility}]
IF architecture.md not found:
Use fallback presets from layer_rules.md
Build ruleset:
FOR EACH layer:
allowed_deps = layers that can be imported
forbidden_deps = layers that cannot be imported
```
### Phase 2: Detect Layer Violations
```
scan_root = scan_path IF domain_mode == "domain-aware" ELSE codebase_root
FOR EACH violation_type IN layer_rules.md I/O Pattern Boundary Rules:
grep_pattern = violation_type.detection_grep
forbidden_dirs = violation_type.forbidden_in
matches = Grep(grep_pattern, scan_root, include="*.py,*.ts,*.js")
FOR EACH match IN matches:
IF match.path NOT IN skip_violations:
IF any(forbidden IN match.path FOR forbidden IN forbidden_dirs):
violations.append({
type: "layer_violation",
severity: "HIGH",
pattern: violation_type.name,
file: match.path,
line: match.line,
code: match.context,
allowed_in: violation_type.allowed_in,
suggestion: f"Move to {violation_type.allowed_in}"
})
```
### Phase 3: Cross-Layer Consistency Checks
#### 3.1 Transaction Boundary Violations
**What:** commit()/rollback() called at inconsistent layers (repo + service + API)
**Detection:**
```
repo_commits = Grep("\.commit\(\)|\.rollback\(\)", "**/repositories/**/*.py")
service_commits = Grep("\.commit\(\)|\.rollback\(\)", "**/services/**/*.py")
api_commits = Grep("\.commit\(\)|\.rollback\(\)", "**/api/**/*.py")
layers_with_commits = count([repo_commits, service_commits, api_commits].filter(len > 0))
```
**Safe Patterns (ignore):**
- Comment "# best-effort telemetry" in same context
- File ends with `_callbacks.py` (progress notifiers)
- Explicit `# UoW boundary` comment
**Violation Rules:**
| Condition | Severity | Issue |
|-----------|----------|-------|
| layers_with_commits >= 3 | CRITICAL | Mixed UoW ownership across all layers |
| repo + api commits | HIGH | Transaction control bypasses service layer |
| repo + service commits | HIGH | Ambiguous UoW owner (repo vs service) |
| service + api commits | MEDIUM | Transaction control spans service + API |
**Exception:** Saga pattern / distributed transactions with explicit compensating actions → downgrade CRITICAL to MEDIUM. UoW boundary documented with `// architecture decision` or ADR → skip.
**Recommendation:** Choose single UoW owner (service layer recommended), remove commit() from other layers
**Effort:** L (requires architectural decision + refactoring)
#### 3.2 Session Ownership Violations
**What:** Mixed DI-injected and locally-created sessions in same call chain
**Detection:**
```
di_session = Grep("Depends\(get_session\)|Depends\(get_db\)", "**/api/**/*.py")
local_session = Grep("AsyncSessionLocal\(\)|async_sessionmaker", "**/services/**/*.py")
local_in_repo = Grep("AsyncSessionLocal\(\)", "**/repositories/**/*.py")
```
**Violation Rules:**
| Condition | Severity | Issue |
|-----------|----------|-------|
| di_session AND local_in_repo in same module | HIGH | Repo creates own session while API injects different |
| local_session in service calling DI-based repo | MEDIUM | Session mismatch in call chain |
**Recommendation:** Use DI consistently OR use local sessions consistently. Document exceptions (e.g., telemetry)
**Effort:** M
#### 3.3 Flat Orchestration Violations
**What:** Service-layer functions calling other services that call yet other services — deep orchestration chains.
**Detection:** **MANDATORY READ:** Load `shared/references/ai_ready_architecture.md` — map service imports, find chain depth.
**Violation Rules:**
| Condition | Severity | Issue |
|-----------|----------|-------|
| Service chain >= 3 (A→B→C→D) | HIGH | Deep orchestration |
| Service chain = 2 (A→B→C) | MEDIUM | Consider flattening |
**Recommendation:** Extract orchestrator calling all services at same level. Each service becomes a sink.
**Effort:** L
---
### Phase 4: Check Pattern Coverage
```
# HTTP Client Coverage
all_http_calls = Grep("httpx\\.|aiohttp\\.|requests\\.", codebase_root)
abstracted_calls = Grep("client\\.(get|post|put|delete)", infrastructure_dirs)
IF len(all_http_calls) > 0:
coverage = len(abstracted_calls) / len(all_http_calls) * 100
IF coverage < 90%:
violations.append({
type: "low_coverage",
severity: "MEDIUM",
pattern: "HTTP Client Abstraction",
coverage: coverage,
uncovered_files: files with direct calls outside infrastructure
})
# Error Handling Duplication
http_error_handlers = Grep("except\\s+(httpx\\.|aiohttp\\.|requests\\.)", codebase_root)
unique_files = set(f.path for f in http_error_handlers)
IF len(unique_files) > 2:
violations.append({
type: "duplication",
severity: "MEDIUM",
pattern: "HTTP Error Handling",
files: list(unique_files),
suggestion: "Centralize in infrastructure layer"
})
```
### Phase 5: Calculate Score
**MANDATORY READ:** Load `shared/references/audit_worker_core_contract.md` and `shared/references/audit_scoring.md`.
### Phase 6: Write Report
**MANDATORY READ:** Load `shared/references/audit_worker_core_contract.md` and `shared/templates/audit_worker_report_template.md`.
```
# Build markdown report in memory with:
# - AUDIT-META (standard penalty-based: score, counts)
# - Checks table (io_isolation, http_abstraction, error_centralization, transaction_boundary, session_ownership)
# - Findings table (violations sorted by severity)
# - DATA-EXTENDED: {architecture, coverage}
IF domain_mode == "domain-aware":
Write to {output_dir}/642-layer-boundary-{current_domain}.md
ELSE:
Write to {output_dir}/642-layer-boundary.md
```
### Phase 7: Return Summary
```
Report written: docs/project/.audit/ln-640/{YYYY-MM-DD}/642-layer-boundary-users.md
Score: 4.5/10 | Issues: 8 (C:1 H:3 M:4 L:0)
```
## Critical Rules
**MANDATORY READ:** Load `shared/references/audit_worker_core_contract.md`.
- **Read architecture.md first** - never assume architecture type
- **Skip violations list** - respect legacy files marked for gradual fix
- **File + line + code** - always provide exact location with context
- **Actionable suggestions** - always tell WHERE to move the code
- **No false positives** - verify path contains forbidden dir, not just substring
## Definition of Done
**MANDATORY READ:** Load `shared/references/audit_worker_core_contract.md`.
- Architecture discovered from docs/architecture.md (or fallback used)
- All violation types from layer_rules.md checked
- **Cross-layer consistency checked:**
- Transaction boundaries analyzed (commit/rollback distribution)
- Session ownership analyzed (DI vs local)
- Coverage calculated for HTTP abstraction + 2 consistency metrics
- Violations list with severity, location, suggestion
- If domain-aware: all Grep scoped to scan_path, findings tagged with domain
- Report written to `{output_dir}/642-layer-boundary[-{domain}].md` (atomic single Write call)
- Summary returned to coordinator
## Reference Files
- Layer rules: `../ln-640-pattern-evolution-auditor/references/layer_rules.md`
- Scoring impact: `../ln-640-pattern-evolution-auditor/references/scoring_rules.md`
---
**Version:** 2.1.0
**Last Updated:** 2026-02-08