feat: add architecture validation system with comprehensive pattern enforcement

Implemented automated architecture validation to enforce design decisions:

Architecture Validation System:
- Created .architecture-rules.yaml with comprehensive rule definitions
- Implemented validate_architecture.py script with AST-based validation
- Added pre-commit hook configuration for automatic validation
- Comprehensive documentation in docs/architecture/architecture-patterns.md

Key Design Rules Enforced:
- API-001 to API-004: API endpoint patterns (Pydantic models, no business logic, exception handling, auth)
- SVC-001 to SVC-004: Service layer patterns (domain exceptions, db session params, no HTTP concerns)
- MDL-001 to MDL-002: Model separation (SQLAlchemy vs Pydantic)
- EXC-001 to EXC-002: Exception handling (custom exceptions, no bare except)
- JS-001 to JS-003: JavaScript patterns (apiClient, logger, Alpine components)
- TPL-001: Template patterns (extend base.html)

Features:
- Validates separation of concerns (routes vs services vs models)
- Enforces proper exception handling (domain exceptions in services, HTTP in routes)
- Checks database session patterns and Pydantic model usage
- JavaScript and template validation
- Detailed error reporting with suggestions
- Integration with pre-commit hooks and CI/CD

UI Fix:
- Fixed icon names in content-pages.html (pencil→edit, trash→delete)

Documentation:
- Added architecture patterns guide with examples
- Created scripts/README.md for validator usage
- Updated mkdocs.yml with architecture documentation
- Built and verified documentation successfully

Usage:
  python scripts/validate_architecture.py              # Validate all
  python scripts/validate_architecture.py --verbose    # With details
  python scripts/validate_architecture.py --errors-only # Errors only

🤖 Generated with [Claude Code](https://claude.com/claude-code)

Co-Authored-By: Claude <noreply@anthropic.com>
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# Architecture Patterns & Design Decisions
This document describes the architectural patterns and design decisions that must be followed throughout the codebase.
> **Note:** These patterns are enforced automatically by `scripts/validate_architecture.py`. Run the validator before committing code.
---
## Table of Contents
1. [Core Principles](#core-principles)
2. [Layered Architecture](#layered-architecture)
3. [API Endpoint Patterns](#api-endpoint-patterns)
4. [Service Layer Patterns](#service-layer-patterns)
5. [Model Patterns](#model-patterns)
6. [Exception Handling](#exception-handling)
7. [JavaScript Patterns](#javascript-patterns)
8. [Validation](#validation)
---
## Core Principles
### 1. Separation of Concerns
**Each layer has specific responsibilities:**
- **Routes/Endpoints**: HTTP handling, validation, authentication, response formatting
- **Services**: Business logic, data processing, orchestration
- **Models**: Data structure and persistence
**❌ Bad Example - Business logic in endpoint:**
```python
@router.post("/vendors")
async def create_vendor(vendor: VendorCreate, db: Session = Depends(get_db)):
# ❌ BAD: Business logic in endpoint
if db.query(Vendor).filter(Vendor.subdomain == vendor.subdomain).first():
raise HTTPException(status_code=409, detail="Vendor exists")
db_vendor = Vendor(**vendor.dict())
db.add(db_vendor)
db.commit()
db.refresh(db_vendor)
return db_vendor
```
**✅ Good Example - Delegated to service:**
```python
@router.post("/vendors", response_model=VendorResponse)
async def create_vendor(
vendor: VendorCreate,
current_user: User = Depends(get_current_admin),
db: Session = Depends(get_db)
):
try:
# ✅ GOOD: Delegate to service
result = vendor_service.create_vendor(db, vendor)
return result
except VendorAlreadyExistsError as e:
raise HTTPException(status_code=409, detail=str(e))
except Exception as e:
logger.error(f"Failed to create vendor: {e}")
raise HTTPException(status_code=500, detail="Internal server error")
```
### 2. Type Safety
Use Pydantic for API validation, SQLAlchemy for database models.
### 3. Proper Exception Handling
Services throw domain exceptions, routes convert to HTTP responses.
---
## Layered Architecture
```
┌─────────────────────────────────────────────────────────┐
│ API Layer │
│ (app/api/v1/**/*.py, app/routes/**/*.py) │
│ │
│ Responsibilities: │
│ - HTTP request/response handling │
│ - Authentication/Authorization │
│ - Input validation (Pydantic models) │
│ - Exception handling (domain → HTTP) │
│ │
│ ❌ Should NOT: │
│ - Contain business logic │
│ - Directly access database (except via services) │
│ - Raise domain exceptions │
└─────────────────────────────────────────────────────────┘
┌─────────────────────────────────────────────────────────┐
│ Service Layer │
│ (app/services/**/*.py) │
│ │
│ Responsibilities: │
│ - Business logic │
│ - Data validation (business rules) │
│ - Database operations │
│ - Orchestration of multiple operations │
│ │
│ ❌ Should NOT: │
│ - Know about HTTP (no HTTPException) │
│ - Create database sessions (accept as parameter) │
│ - Handle HTTP-specific concerns │
└─────────────────────────────────────────────────────────┘
┌─────────────────────────────────────────────────────────┐
│ Data Layer │
│ (app/models/**/*.py) │
│ │
│ Responsibilities: │
│ - Database schema (SQLAlchemy models) │
│ - API schemas (Pydantic models) │
│ - Data structure definitions │
│ │
│ ❌ Should NOT: │
│ - Mix SQLAlchemy and Pydantic in same class │
│ - Contain business logic │
└─────────────────────────────────────────────────────────┘
```
---
## API Endpoint Patterns
### Rule API-001: Use Pydantic Models
**All endpoints MUST use Pydantic models for request/response.**
```python
# ✅ GOOD: Pydantic models for type safety
class VendorCreate(BaseModel):
name: str = Field(..., max_length=200)
subdomain: str = Field(..., max_length=100)
is_active: bool = True
class VendorResponse(BaseModel):
id: int
name: str
subdomain: str
created_at: datetime
class Config:
from_attributes = True # For SQLAlchemy compatibility
@router.post("/vendors", response_model=VendorResponse)
async def create_vendor(vendor: VendorCreate, db: Session = Depends(get_db)):
result = vendor_service.create_vendor(db, vendor)
return result
```
```python
# ❌ BAD: Raw dict, no validation
@router.post("/vendors")
async def create_vendor(data: dict):
return {"name": data["name"]} # No type safety!
```
### Rule API-002: No Business Logic in Endpoints
**Endpoints should only handle HTTP concerns.**
```python
# ✅ GOOD: Delegate to service
@router.post("/vendors")
async def create_vendor(vendor: VendorCreate, db: Session = Depends(get_db)):
result = vendor_service.create_vendor(db, vendor)
return result
```
```python
# ❌ BAD: Business logic in endpoint
@router.post("/vendors")
async def create_vendor(vendor: VendorCreate, db: Session = Depends(get_db)):
# ❌ Database operations belong in service!
db_vendor = Vendor(**vendor.dict())
db.add(db_vendor)
db.commit()
return db_vendor
```
### Rule API-003: Proper Exception Handling
**Catch service exceptions and convert to HTTPException.**
```python
# ✅ GOOD: Proper exception handling
@router.post("/vendors", response_model=VendorResponse)
async def create_vendor(vendor: VendorCreate, db: Session = Depends(get_db)):
try:
result = vendor_service.create_vendor(db, vendor)
return result
except VendorAlreadyExistsError as e:
raise HTTPException(status_code=409, detail=str(e))
except ValueError as e:
raise HTTPException(status_code=400, detail=str(e))
except Exception as e:
logger.error(f"Unexpected error creating vendor: {e}")
raise HTTPException(status_code=500, detail="Internal server error")
```
### Rule API-004: Authentication
**Protected endpoints must use dependency injection for auth.**
```python
# ✅ GOOD: Use Depends for auth
@router.post("/vendors")
async def create_vendor(
vendor: VendorCreate,
current_user: User = Depends(get_current_admin), # ✅ Auth required
db: Session = Depends(get_db)
):
result = vendor_service.create_vendor(db, vendor)
return result
```
---
## Service Layer Patterns
### Rule SVC-001: No HTTPException in Services
**Services should NOT know about HTTP. Raise domain exceptions instead.**
```python
# ✅ GOOD: Domain exception
class VendorAlreadyExistsError(Exception):
"""Raised when vendor with same subdomain already exists"""
pass
class VendorService:
def create_vendor(self, db: Session, vendor_data: VendorCreate):
if self._vendor_exists(db, vendor_data.subdomain):
raise VendorAlreadyExistsError(
f"Vendor with subdomain '{vendor_data.subdomain}' already exists"
)
# Business logic...
vendor = Vendor(**vendor_data.dict())
db.add(vendor)
db.commit()
return vendor
```
```python
# ❌ BAD: HTTPException in service
class VendorService:
def create_vendor(self, db: Session, vendor_data: VendorCreate):
if self._vendor_exists(db, vendor_data.subdomain):
# ❌ Service shouldn't know about HTTP!
raise HTTPException(status_code=409, detail="Vendor exists")
```
### Rule SVC-002: Create Custom Exception Classes
**Don't use generic `Exception`. Create specific domain exceptions.**
```python
# ✅ GOOD: Specific exceptions
class VendorError(Exception):
"""Base exception for vendor-related errors"""
pass
class VendorNotFoundError(VendorError):
"""Raised when vendor is not found"""
pass
class VendorAlreadyExistsError(VendorError):
"""Raised when vendor already exists"""
pass
class VendorService:
def get_vendor(self, db: Session, vendor_code: str):
vendor = db.query(Vendor).filter(Vendor.vendor_code == vendor_code).first()
if not vendor:
raise VendorNotFoundError(f"Vendor '{vendor_code}' not found")
return vendor
```
```python
# ❌ BAD: Generic Exception
class VendorService:
def get_vendor(self, db: Session, vendor_code: str):
vendor = db.query(Vendor).filter(Vendor.vendor_code == vendor_code).first()
if not vendor:
raise Exception("Vendor not found") # ❌ Too generic!
return vendor
```
### Rule SVC-003: Database Session as Parameter
**Services should receive database session as parameter, not create it internally.**
```python
# ✅ GOOD: db session as parameter
class VendorService:
def create_vendor(self, db: Session, vendor_data: VendorCreate):
vendor = Vendor(**vendor_data.dict())
db.add(vendor)
db.commit()
db.refresh(vendor)
return vendor
def _vendor_exists(self, db: Session, subdomain: str) -> bool:
return db.query(Vendor).filter(Vendor.subdomain == subdomain).first() is not None
```
```python
# ❌ BAD: Creating session internally
class VendorService:
def create_vendor(self, vendor_data: VendorCreate):
# ❌ Don't create session here - makes testing hard
db = SessionLocal()
vendor = Vendor(**vendor_data.dict())
db.add(vendor)
db.commit()
return vendor
```
**Benefits:**
- Testability (can inject mock session)
- Transaction control (caller controls commit/rollback)
- Resource management (caller handles session lifecycle)
### Rule SVC-004: Use Pydantic for Input Validation
**Service methods should accept Pydantic models for complex inputs.**
```python
# ✅ GOOD: Pydantic model ensures validation
class VendorService:
def create_vendor(self, db: Session, vendor_data: VendorCreate):
# vendor_data is already validated by Pydantic
vendor = Vendor(**vendor_data.dict())
db.add(vendor)
db.commit()
return vendor
```
---
## Model Patterns
### Rule MDL-001: SQLAlchemy for Database Models
```python
# ✅ GOOD: SQLAlchemy model
from sqlalchemy import Column, Integer, String, Boolean
from app.database import Base
class Vendor(Base):
__tablename__ = "vendors"
id = Column(Integer, primary_key=True, index=True)
name = Column(String(200), nullable=False)
subdomain = Column(String(100), unique=True, nullable=False)
is_active = Column(Boolean, default=True)
```
### Rule MDL-002: Separate Pydantic from SQLAlchemy
**NEVER mix SQLAlchemy and Pydantic in the same class.**
```python
# ❌ BAD: Mixing SQLAlchemy and Pydantic
class Vendor(Base, BaseModel): # ❌ Don't do this!
__tablename__ = "vendors"
name: str = Column(String(200))
```
```python
# ✅ GOOD: Separate models
# Database model (app/models/vendor.py)
class Vendor(Base):
__tablename__ = "vendors"
id = Column(Integer, primary_key=True)
name = Column(String(200), nullable=False)
# API model (app/api/v1/admin/vendors.py)
class VendorCreate(BaseModel):
name: str = Field(..., max_length=200)
class VendorResponse(BaseModel):
id: int
name: str
class Config:
from_attributes = True
```
---
## Exception Handling
### Rule EXC-001: Domain-Specific Exceptions
**Create exception hierarchy in `app/exceptions/`**
```python
# app/exceptions/vendor_exceptions.py
class VendorError(Exception):
"""Base exception for vendor domain"""
pass
class VendorNotFoundError(VendorError):
"""Vendor does not exist"""
pass
class VendorAlreadyExistsError(VendorError):
"""Vendor already exists"""
pass
class VendorValidationError(VendorError):
"""Vendor data validation failed"""
pass
```
### Rule EXC-002: Never Use Bare Except
```python
# ❌ BAD: Bare except
try:
result = do_something()
except: # ❌ Catches EVERYTHING including KeyboardInterrupt!
pass
```
```python
# ✅ GOOD: Specific exceptions
try:
result = do_something()
except ValueError as e:
logger.error(f"Validation error: {e}")
except DatabaseError as e:
logger.error(f"Database error: {e}")
except Exception as e:
logger.error(f"Unexpected error: {e}")
raise
```
---
## JavaScript Patterns
### Rule JS-001: Use apiClient Directly
```javascript
// ✅ GOOD
const vendors = await apiClient.get('/api/v1/vendors');
```
```javascript
// ❌ BAD
const vendors = await window.apiClient.get('/api/v1/vendors');
```
### Rule JS-002: Use Centralized Logger
```javascript
// ✅ GOOD: Centralized logger
const vendorLog = window.LogConfig.createLogger('vendors');
vendorLog.info('Loading vendors...');
vendorLog.error('Failed to load vendors:', error);
```
```javascript
// ❌ BAD: console
console.log('Loading vendors...'); // ❌ Use logger instead
```
### Rule JS-003: Alpine Components Pattern
```javascript
// ✅ GOOD: Proper Alpine component
function vendorsManager() {
return {
// ✅ Inherit base layout functionality
...data(),
// ✅ Set page identifier for sidebar
currentPage: 'vendors',
// Component state
vendors: [],
loading: false,
// ✅ Init with guard
async init() {
if (window._vendorsInitialized) {
return;
}
window._vendorsInitialized = true;
await this.loadVendors();
}
};
}
```
---
## Validation
### Running the Validator
```bash
# Validate entire codebase
python scripts/validate_architecture.py
# Validate specific directory
python scripts/validate_architecture.py app/api/
# Verbose output with context
python scripts/validate_architecture.py --verbose
# Errors only (suppress warnings)
python scripts/validate_architecture.py --errors-only
```
### Pre-commit Hook
Install pre-commit to validate automatically before commits:
```bash
# Install pre-commit
pip install pre-commit
# Setup hooks
pre-commit install
# Run manually
pre-commit run --all-files
```
### CI/CD Integration
Add to your CI pipeline:
```yaml
# .github/workflows/ci.yml
- name: Validate Architecture
run: |
python scripts/validate_architecture.py
```
---
## Quick Reference
| Layer | Responsibility | Can Use | Cannot Use |
|-------|---------------|---------|------------|
| **API Endpoints** | HTTP handling, auth, validation | Pydantic, HTTPException, Depends | Direct DB access, business logic |
| **Services** | Business logic, orchestration | DB session, domain exceptions | HTTPException, HTTP concepts |
| **Models** | Data structure | SQLAlchemy OR Pydantic | Mixing both in same class |
---
## Common Violations and Fixes
### Violation: Business logic in endpoint
```python
# Before
@router.post("/vendors")
async def create_vendor(vendor: VendorCreate, db: Session = Depends(get_db)):
db_vendor = Vendor(**vendor.dict())
db.add(db_vendor)
db.commit()
return db_vendor
```
```python
# After ✅
@router.post("/vendors")
async def create_vendor(vendor: VendorCreate, db: Session = Depends(get_db)):
try:
return vendor_service.create_vendor(db, vendor)
except VendorAlreadyExistsError as e:
raise HTTPException(status_code=409, detail=str(e))
```
### Violation: HTTPException in service
```python
# Before
class VendorService:
def create_vendor(self, db: Session, vendor_data):
if exists:
raise HTTPException(status_code=409, detail="Exists")
```
```python
# After ✅
class VendorService:
def create_vendor(self, db: Session, vendor_data):
if exists:
raise VendorAlreadyExistsError("Vendor already exists")
```
---
**Remember:** These patterns are enforced automatically. Run `python scripts/validate_architecture.py` before committing!