module-boundary-check

name	module-boundary-check
description	Enforce module boundaries, detect circular dependencies, validate layer separation and import rules
model	sonnet-4-6
token_budget	{"input":6000,"output":3000}

Module Boundary Check Skill

Validates architectural module boundaries, prevents circular dependencies, and enforces proper layer separation.

Architectural Rules

1. Layer Separation

• Valid: UI → Business Logic → Data (inward only)
• Violation: Reverse imports forbidden

2. No Circular Dependencies

• Rule: A → B → A not allowed (any cycle length)
• Detection: Build complete dependency graph
• Action: Reject and recommend refactor

3. Platform Isolation

• Separate: iOS, Android, RN code
• Shared: Common utilities only
• Violation: Platform-specific in shared forbidden

4. Shared Code Constraints

• Only: Common utilities, types, constants
• Never: Platform-specific code
• Forbidden: External imports in shared

5. Type Safety

• Require: Strict TypeScript
• Forbid: any types

Import Rule Validation

Valid Patterns

• Feature → Shared utilities
• Feature → Core services
• Screens → Components (same feature)
• Feature A → Core → Feature B (via core)

Invalid Patterns

• Component → Screen (reverse)
• Feature A → Feature B (direct cross-feature)
• Shared → Platform-specific
• Data → UI (reverse layer)

Validation Process

1. Dependency Graph Analysis: Parse imports, build graph
2. Circular Detection: Detect all cycle types
3. Layer Validation: Verify inward-only imports
4. Import Rule Check: Enforce valid patterns
5. Public API Check: Verify only public imports

Common Violations & Fixes

Violation	Fix
Circular: A ↔ B	Extract common component
Reverse layer	Move UI code to separate module
Cross-feature	Route through Core module
Shared imports external	Keep external in feature
Platform in shared	Move to platform directory

Guardrails

• Reject boundary violations (FAIL)
• Enforce layer separation (FAIL if reversed)
• No external imports in shared (FAIL)
• Proper dependency direction (FAIL if reversed)
• No circular dependencies (FAIL)
• Type safety (WARN on any)

Triggers

Use when:

• PR changes module imports
• New dependencies added
• Module structure refactored
• Cross-module refactor needed
• Architecture review required

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