docs: add UserContext pattern documentation and architecture rules

Documentation:
- docs/architecture/user-context-pattern.md: Comprehensive guide on
  UserContext vs User model, JWT token mapping, common mistakes

Architecture Rules (auth.yaml):
- AUTH-005: Routes must use UserContext, not User model attributes
- AUTH-006: JWT token context fields must be defined in UserContext
- AUTH-007: Response models must match available UserContext data

Architecture Rules (module.yaml):
- MOD-024: Module static file mount order - specific paths first

These rules prevent issues like:
- Accessing SQLAlchemy relationships on Pydantic schemas
- Missing token fields causing fallback warnings
- Response model validation errors from missing timestamps
- 404 errors for module locale files due to mount order

Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>
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# UserContext Pattern
This document describes the `UserContext` pattern used for dependency injection in API routes, and the important distinction between `UserContext` (Pydantic schema) and `User` (SQLAlchemy model).
## Overview
The platform uses two different representations of users:
| Type | Purpose | Location | Contains |
|------|---------|----------|----------|
| `User` | Database model | `app/modules/tenancy/models/user.py` | All DB columns + relationships |
| `UserContext` | API dependency injection | `models/schema/auth.py` | Subset of fields + JWT token context |
## Why UserContext?
Routes should not import database models directly (architecture rule API-007). Instead, they receive user context through dependency injection:
```python
# CORRECT: Use UserContext from dependencies
from models.schema.auth import UserContext
@router.get("/endpoint")
def my_endpoint(current_user: UserContext = Depends(get_current_admin_api)):
# current_user is a Pydantic schema, not a SQLAlchemy model
pass
# WRONG: Don't import User model in routes
from app.modules.tenancy.models import User # noqa: API-007 violation
```
## UserContext Fields
### Core User Fields
```python
id: int # User ID
email: str # Email address
username: str # Username
role: str # "admin" or "vendor"
is_active: bool # Account status
```
### Admin-Specific Fields
```python
is_super_admin: bool # True for super admins
accessible_platform_ids: list[int] | None # Platform IDs (None = all for super admin)
token_platform_id: int | None # Selected platform from JWT
token_platform_code: str | None # Selected platform code from JWT
```
### Vendor-Specific Fields
```python
token_vendor_id: int | None # Vendor ID from JWT
token_vendor_code: str | None # Vendor code from JWT
token_vendor_role: str | None # Role in vendor (owner, manager, etc.)
```
### Profile Fields
```python
first_name: str | None
last_name: str | None
preferred_language: str | None
```
## What UserContext Does NOT Have
`UserContext` is intentionally limited. It does NOT have:
| Missing | Why | Alternative |
|---------|-----|-------------|
| `admin_platforms` | SQLAlchemy relationship | Use `accessible_platform_ids` |
| `vendors` | SQLAlchemy relationship | Use `token_vendor_id` |
| `owned_companies` | SQLAlchemy relationship | Query via service |
| `hashed_password` | Security - never expose | N/A |
| `created_at` / `updated_at` | Not needed in most routes | Query User if needed |
## Authentication Flow
### Platform Admin Login Flow
```
1. POST /api/v1/admin/auth/login
- Returns LoginResponse with user data and token
- Token includes: user_id, role, is_super_admin, accessible_platforms
2. GET /api/v1/admin/auth/accessible-platforms
- Returns list of platforms admin can access
3. POST /api/v1/admin/auth/select-platform
- Platform admin selects a platform
- Returns PlatformSelectResponse with NEW token
- New token includes: platform_id, platform_code
4. Subsequent API calls
- Token decoded → UserContext populated
- current_user.token_platform_id available
```
### JWT Token → UserContext Mapping
When a JWT token is decoded, these fields are mapped:
| JWT Claim | UserContext Field |
|-----------|-------------------|
| `sub` | `id` |
| `username` | `username` |
| `email` | `email` |
| `role` | `role` |
| `is_super_admin` | `is_super_admin` |
| `accessible_platforms` | `accessible_platform_ids` |
| `platform_id` | `token_platform_id` |
| `platform_code` | `token_platform_code` |
| `vendor_id` | `token_vendor_id` |
| `vendor_code` | `token_vendor_code` |
| `vendor_role` | `token_vendor_role` |
## Helper Methods
`UserContext` provides helper methods:
```python
# Check platform access
if current_user.can_access_platform(platform_id):
...
# Get accessible platforms
platform_ids = current_user.get_accessible_platform_ids()
# Returns None for super admins (all platforms)
# Returns list[int] for platform admins
# Check role
if current_user.is_admin:
...
if current_user.is_vendor:
...
# Full name
name = current_user.full_name # First + Last, or username
```
## Common Mistakes to Avoid
### 1. Accessing SQLAlchemy Relationships
```python
# WRONG - admin_platforms is a SQLAlchemy relationship
if current_user.admin_platforms:
platform_id = current_user.admin_platforms[0].id
# CORRECT - use accessible_platform_ids
if current_user.accessible_platform_ids:
platform_id = current_user.accessible_platform_ids[0]
```
### 2. Using User Model Attributes
```python
# WRONG - created_at exists on User, not UserContext
return {"created": current_user.created_at}
# CORRECT - if you need timestamps, query the User
user = db.query(User).filter(User.id == current_user.id).first()
return {"created": user.created_at}
```
### 3. Using getattr for Token Fields
```python
# WRONG - use getattr only for optional fallback
platform_id = getattr(current_user, "token_platform_id", None)
# CORRECT - use the field directly (it's defined on UserContext)
platform_id = current_user.token_platform_id
```
### 4. Response Models Requiring Unavailable Fields
```python
# WRONG - LoginResponse.user expects UserResponse with created_at
return LoginResponse(user=current_user) # ValidationError!
# CORRECT - use a response model that matches available data
return PlatformSelectResponse(
access_token=token,
platform_id=platform.id,
platform_code=platform.code,
)
```
## Adding New Fields to UserContext
When adding JWT token context that should be available in routes:
1. **Add field to UserContext** (`models/schema/auth.py`):
```python
token_new_field: str | None = None
```
2. **Add to JWT payload** (`middleware/auth.py` - `create_access_token`):
```python
if new_field is not None:
payload["new_field"] = new_field
```
3. **Extract from JWT** (`middleware/auth.py` - `verify_token`):
```python
if "new_field" in payload:
user_data["new_field"] = payload["new_field"]
```
4. **Attach to User object** (`middleware/auth.py` - `get_current_user`):
```python
if "new_field" in user_data:
user.token_new_field = user_data["new_field"]
```
5. **Copy in from_user()** (`models/schema/auth.py`):
```python
data["token_new_field"] = getattr(user, "token_new_field", None)
```
## Related Documentation
- [Authentication & RBAC](auth-rbac.md) - Complete auth guide
- [Middleware Reference](middleware.md) - Request processing
## Related Architecture Rules
See `.architecture-rules/auth.yaml` for:
- AUTH-005: Routes must use UserContext, not User model attributes
- AUTH-006: JWT token context fields must be defined in UserContext
- AUTH-007: Response models must match available UserContext data