fix: protect critical re-export imports from linter removal

Problem:
- Ruff removed 'from app.core.database import Base' from models/database/base.py
- Import appeared "unused" (F401) but was actually a critical re-export
- Caused ImportError: cannot import name 'Base' at runtime
- Re-export pattern: import in one file to export from package

Solution:
1. Added F401 ignore for models/database/base.py in pyproject.toml
2. Created scripts/verify_critical_imports.py verification script
3. Integrated verification into make check and CI pipeline
4. Updated documentation with explanation

New Verification Script:
- Checks all critical re-export imports exist
- Detects import variations (parentheses, 'as' clauses)
- Handles SQLAlchemy declarative_base alternatives
- Runs as part of make check automatically

Protected Files:
- models/database/base.py - Re-exports Base for all models
- models/__init__.py - Exports Base for Alembic
- models/database/__init__.py - Exports Base from package
- All __init__.py files (already protected)

Makefile Changes:
- make verify-imports - Run import verification
- make check - Now includes verify-imports
- make ci - Includes verify-imports in pipeline

Documentation Updated:
- Code quality guide explains re-export protection
- Pre-commit workflow includes verification
- Examples of why re-exports matter

This prevents future issues where linters remove seemingly
"unused" imports that are actually critical for application structure.

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

Co-Authored-By: Claude <noreply@anthropic.com>

Makefile

@@ -190,9 +190,13 @@ lint-strict:
 	@echo "Type checking with mypy..."
 	$(PYTHON) -m mypy .
 
-check: format lint
+check: format lint verify-imports
 
-ci: lint-strict test-coverage
+ci: lint-strict verify-imports test-coverage
+
+verify-imports:
+	@echo "Verifying critical imports..."
+	$(PYTHON) scripts/verify_critical_imports.py
 
 qa: format lint test-coverage docs-check
 	@echo "Quality assurance checks completed!"
@@ -333,7 +337,8 @@ help:
 	@echo "  format               - Format code with ruff"
 	@echo "  lint                 - Lint and auto-fix with ruff + mypy"
 	@echo "  lint-strict          - Lint without auto-fix + mypy"
-	@echo "  check                - Format + lint"
+	@echo "  verify-imports       - Verify critical imports haven't been removed"
+	@echo "  check                - Format + lint + verify imports"
 	@echo "  ci                   - Full CI pipeline (strict)"
 	@echo "  qa                   - Quality assurance"
 	@echo ""

app/api/deps.py

@@ -367,9 +367,7 @@ def get_current_customer_from_cookie_or_header(
 
         # Verify token hasn't expired
         exp = payload.get("exp")
-        if exp and datetime.fromtimestamp(exp, tz=UTC) < datetime.now(
-            UTC
-        ):
+        if exp and datetime.fromtimestamp(exp, tz=UTC) < datetime.now(UTC):
             logger.warning(f"Expired customer token for customer_id={customer_id}")
             raise InvalidTokenException("Token has expired")
 

app/api/v1/admin/content_pages.py

@@ -48,9 +48,7 @@ class ContentPageCreate(BaseModel):
     meta_description: str | None = Field(
         None, max_length=300, description="SEO meta description"
     )
-    meta_keywords: str | None = Field(
-        None, max_length=300, description="SEO keywords"
-    )
+    meta_keywords: str | None = Field(None, max_length=300, description="SEO keywords")
     is_published: bool = Field(default=False, description="Publish immediately")
     show_in_footer: bool = Field(default=True, description="Show in footer navigation")
     show_in_header: bool = Field(default=False, description="Show in header navigation")

app/api/v1/admin/notifications.py

@@ -88,9 +88,7 @@ def mark_all_as_read(
 @router.get("/alerts", response_model=PlatformAlertListResponse)
 def get_platform_alerts(
     severity: str | None = Query(None, description="Filter by severity"),
-    is_resolved: bool | None = Query(
-        None, description="Filter by resolution status"
-    ),
+    is_resolved: bool | None = Query(None, description="Filter by resolution status"),
     skip: int = Query(0, ge=0),
     limit: int = Query(50, ge=1, le=100),
     db: Session = Depends(get_db),

app/api/v1/shop/products.py

@@ -30,9 +30,7 @@ def get_product_catalog(
     skip: int = Query(0, ge=0),
     limit: int = Query(100, ge=1, le=1000),
     search: str | None = Query(None, description="Search products by name"),
-    is_featured: bool | None = Query(
-        None, description="Filter by featured products"
-    ),
+    is_featured: bool | None = Query(None, description="Filter by featured products"),
     db: Session = Depends(get_db),
 ):
     """

app/api/v1/vendor/content_pages.py

@@ -43,9 +43,7 @@ class VendorContentPageCreate(BaseModel):
     meta_description: str | None = Field(
         None, max_length=300, description="SEO meta description"
     )
-    meta_keywords: str | None = Field(
-        None, max_length=300, description="SEO keywords"
-    )
+    meta_keywords: str | None = Field(None, max_length=300, description="SEO keywords")
     is_published: bool = Field(default=False, description="Publish immediately")
     show_in_footer: bool = Field(default=True, description="Show in footer navigation")
     show_in_header: bool = Field(default=False, description="Show in header navigation")

app/core/config.py

@@ -13,7 +13,6 @@ Note: Environment detection is handled by app.core.environment module.
 This module focuses purely on configuration storage and validation.
 """
 
-
 from pydantic_settings import BaseSettings
 
 

app/exceptions/auth.py

@@ -3,7 +3,6 @@
 Authentication and authorization specific exceptions.
 """
 
-
 from .base import AuthenticationException, AuthorizationException, ConflictException
 
 

app/exceptions/cart.py

@@ -3,7 +3,6 @@
 Shopping cart specific exceptions.
 """
 
-
 from .base import BusinessLogicException, ResourceNotFoundException, ValidationException
 
 

app/exceptions/order.py

@@ -3,7 +3,6 @@
 Order management specific exceptions.
 """
 
-
 from .base import BusinessLogicException, ResourceNotFoundException, ValidationException
 
 

app/exceptions/product.py

@@ -3,7 +3,6 @@
 Product (vendor catalog) specific exceptions.
 """
 
-
 from .base import (
     BusinessLogicException,
     ConflictException,

app/exceptions/vendor_domain.py

@@ -3,7 +3,6 @@
 Vendor domain management specific exceptions.
 """
 
-
 from .base import (
     BusinessLogicException,
     ConflictException,

app/routes/admin_pages.py

@@ -30,7 +30,6 @@ Routes:
 - GET /code-quality/violations/{violation_id} → Violation details (auth required)
 """
 
-
 from fastapi import APIRouter, Depends, Path, Request
 from fastapi.responses import HTMLResponse, RedirectResponse
 from fastapi.templating import Jinja2Templates

app/services/product_service.py

@@ -107,9 +107,7 @@ class ProductService:
             )
 
             if existing:
-                raise ProductAlreadyExistsException(
-                    "Product already exists in catalog"
-                )
+                raise ProductAlreadyExistsException("Product already exists in catalog")
 
             # Create product
             product = Product(

app/utils/data_processing.py

@@ -108,9 +108,7 @@ class PriceProcessor:
         r"([A-Z]{3})\s*([0-9.,]+)": lambda m: (m.group(2), m.group(1)),
     }
 
-    def parse_price_currency(
-        self, price_str: any
-    ) -> tuple[str | None, str | None]:
+    def parse_price_currency(self, price_str: any) -> tuple[str | None, str | None]:
         """
         Parse a price string to extract the numeric value and currency.
 

docs/development/code-quality.md

@@ -190,7 +190,7 @@ show_missing = true
 Before committing code:
 
 ```bash
-# 1. Format and lint your code
+# 1. Format, lint, and verify critical imports
 make check
 
 # 2. Run relevant tests
@@ -201,6 +201,25 @@ git add .
 git commit -m "your message"
 ```
 
+### Critical Import Verification
+
+The `make check` command includes a critical import verification step that ensures re-export imports haven't been removed by linters.
+
+**What it checks:**
+- `models/database/base.py` - Re-exports Base from app.core.database
+- `models/__init__.py` - Exports Base for Alembic
+- `models/database/__init__.py` - Exports Base from database package
+
+**Why it matters:**
+Linters like Ruff may see these imports as "unused" (F401) because they're re-exported, not directly used. Removing them breaks the application.
+
+**Manual verification:**
+```bash
+make verify-imports
+```
+
+If this fails, imports have been removed and must be restored.
+
 ## CI/CD Integration
 
 For continuous integration:

middleware/auth.py

@@ -204,9 +204,7 @@ class AuthManager:
                 raise InvalidTokenException("Token missing expiration")
 
             # Check if token has expired (additional check beyond jwt.decode)
-            if datetime.now(UTC) > datetime.fromtimestamp(
-                exp, tz=UTC
-            ):
+            if datetime.now(UTC) > datetime.fromtimestamp(exp, tz=UTC):
                 raise TokenExpiredException()
 
             # Validate user identifier claim exists

middleware/vendor_context.py

@@ -141,9 +141,7 @@ class VendorContextManager:
                         f"[OK] Vendor found via custom domain: {domain} → {vendor.name}"
                     )
                     return vendor
-                logger.warning(
-                    f"No active vendor found for custom domain: {domain}"
-                )
+                logger.warning(f"No active vendor found for custom domain: {domain}")
                 return None
 
         # Method 2 & 3: Subdomain or path-based lookup

models/database/cart.py

@@ -1,7 +1,6 @@
 # models/database/cart.py
 """Cart item database model."""
 
-
 from sqlalchemy import (
     Column,
     Float,

models/database/customer.py

@@ -1,4 +1,3 @@
-
 from sqlalchemy import (
     JSON,
     Boolean,

models/database/marketplace_import_job.py

@@ -1,4 +1,3 @@
-
 from sqlalchemy import Column, DateTime, ForeignKey, Index, Integer, String, Text
 from sqlalchemy.orm import relationship
 

models/database/marketplace_product.py

@@ -1,4 +1,3 @@
-
 from sqlalchemy import (
     Column,
     Index,

models/database/vendor_domain.py

@@ -3,7 +3,6 @@
 Vendor Domain Model - Maps custom domains to vendors
 """
 
-
 from sqlalchemy import (
     Boolean,
     Column,

models/schema/cart.py

@@ -3,7 +3,6 @@
 Pydantic schemas for shopping cart operations.
 """
 
-
 from pydantic import BaseModel, ConfigDict, Field
 
 # ============================================================================

models/schema/product.py

@@ -11,9 +11,7 @@ class ProductCreate(BaseModel):
     marketplace_product_id: int = Field(
         ..., description="MarketplaceProduct ID to add to vendor catalog"
     )
-    product_id: str | None = Field(
-        None, description="Vendor's internal SKU/product ID"
-    )
+    product_id: str | None = Field(None, description="Vendor's internal SKU/product ID")
     price: float | None = Field(None, ge=0)
     sale_price: float | None = Field(None, ge=0)
     currency: str | None = None

models/schema/team.py

@@ -31,7 +31,6 @@ class RoleCreate(RoleBase):
     """Schema for creating a role."""
 
 
-
 class RoleUpdate(BaseModel):
     """Schema for updating a role."""
 

models/schema/vendor.py

@@ -100,9 +100,7 @@ class VendorUpdate(BaseModel):
     subdomain: str | None = Field(None, min_length=2, max_length=100)
 
     # Business Contact Information (Vendor Fields)
-    contact_email: str | None = Field(
-        None, description="Public business contact email"
-    )
+    contact_email: str | None = Field(None, description="Public business contact email")
     contact_phone: str | None = None
     website: str | None = None
 

models/schema/vendor_theme.py

@@ -3,7 +3,6 @@
 Pydantic schemas for vendor theme operations.
 """
 
-
 from pydantic import BaseModel, Field
 
 
@@ -54,14 +53,10 @@ class VendorThemeUpdate(BaseModel):
     theme_name: str | None = Field(None, description="Theme preset name")
     colors: dict[str, str] | None = Field(None, description="Color scheme")
     fonts: dict[str, str] | None = Field(None, description="Font settings")
-    branding: dict[str, str | None] | None = Field(
-        None, description="Branding assets"
-    )
+    branding: dict[str, str | None] | None = Field(None, description="Branding assets")
     layout: dict[str, str] | None = Field(None, description="Layout settings")
     custom_css: str | None = Field(None, description="Custom CSS rules")
-    social_links: dict[str, str] | None = Field(
-        None, description="Social media links"
-    )
+    social_links: dict[str, str] | None = Field(None, description="Social media links")
 
 
 class VendorThemeResponse(BaseModel):

pyproject.toml

@@ -60,8 +60,10 @@ unfixable = []
 
 # Per-file ignores
 [tool.ruff.lint.per-file-ignores]
-# Ignore import violations in __init__.py files
+# Ignore import violations in __init__.py files (re-exports)
 "__init__.py" = ["F401", "F403"]
+# Base files that re-export (re-export Base from core.database)
+"models/database/base.py" = ["F401"]
 # Ignore specific rules in test files
 "tests/**/*.py" = ["S101", "PLR2004"]
 # Alembic migrations can have longer lines and specific patterns

scripts/route_diagnostics.py

@@ -7,7 +7,6 @@ Usage: python route_diagnostics.py
 """
 
 
-
 def check_route_order():
     """Check if routes are registered in the correct order."""
     print("🔍 Checking FastAPI Route Configuration...\n")

scripts/test_auth_complete.py

@@ -20,7 +20,6 @@ Requirements:
       * Customer: username=customer, password=customer123, vendor_id=1
 """
 
-
 import requests
 
 BASE_URL = "http://localhost:8000"

scripts/test_vendor_management.py

@@ -9,7 +9,6 @@ Tests:
 - Transfer ownership
 """
 
-
 import requests
 
 BASE_URL = "http://localhost:8000"

scripts/verify_critical_imports.py

@@ -0,0 +1,156 @@
+#!/usr/bin/env python3
+"""
+Verify Critical Imports
+========================
+Checks that critical imports (re-exports) haven't been removed by linters.
+
+This script verifies that essential import statements exist in key files,
+preventing issues where tools like Ruff might remove imports that appear
+unused but are actually critical for the application structure.
+"""
+
+import sys
+from pathlib import Path
+
+# Define critical imports that must exist
+# Format: {file_path: [(import_line, description)]}
+CRITICAL_IMPORTS: dict[str, list[tuple[str, str]]] = {
+    "models/database/base.py": [
+        ("from app.core.database import Base", "Re-export Base for all models"),
+    ],
+    "models/__init__.py": [
+        ("from .database.base import Base", "Export Base for Alembic and models"),
+    ],
+    "models/database/__init__.py": [
+        ("from .base import Base", "Export Base from database package"),
+    ],
+    "app/core/database.py": [
+        (
+            "from sqlalchemy.ext.declarative import declarative_base",
+            "SQLAlchemy Base declaration",
+        ),
+        # Note: Might also use sqlalchemy.orm declarative_base in newer versions
+    ],
+}
+
+
+class ImportVerifier:
+    """Verifies critical imports exist in codebase"""
+
+    def __init__(self, project_root: Path):
+        self.project_root = project_root
+        self.issues: list[str] = []
+
+    def verify_all(self) -> bool:
+        """Verify all critical imports"""
+        print("🔍 Verifying critical imports...\n")
+
+        all_good = True
+        for file_path, imports in CRITICAL_IMPORTS.items():
+            if not self.verify_file(file_path, imports):
+                all_good = False
+
+        return all_good
+
+    def verify_file(
+        self, file_path: str, required_imports: list[tuple[str, str]]
+    ) -> bool:
+        """Verify imports in a single file"""
+        full_path = self.project_root / file_path
+
+        if not full_path.exists():
+            self.issues.append(f"❌ File not found: {file_path}")
+            print(f"❌ {file_path}: File not found")
+            return False
+
+        content = full_path.read_text()
+        file_ok = True
+
+        for import_line, description in required_imports:
+            # Check for exact import or variations
+            if import_line in content:
+                print(f"✅ {file_path}: {import_line}")
+            else:
+                # Check for alternative import formats
+                alternatives = self._get_import_alternatives(import_line)
+                found = any(alt in content for alt in alternatives)
+
+                if found:
+                    print(f"✅ {file_path}: {import_line} (alternative format)")
+                else:
+                    self.issues.append(
+                        f"❌ {file_path}: Missing critical import\n"
+                        f"   Expected: {import_line}\n"
+                        f"   Purpose: {description}"
+                    )
+                    print(f"❌ {file_path}: Missing {import_line}")
+                    file_ok = False
+
+        print()
+        return file_ok
+
+    def _get_import_alternatives(self, import_line: str) -> list[str]:
+        """Get alternative formats for an import"""
+        alternatives = [import_line]
+
+        # Handle 'from x import y' vs 'from x import (y)'
+        if "from" in import_line and "import" in import_line:
+            parts = import_line.split("import")
+            if len(parts) == 2:
+                from_part = parts[0].strip()
+                import_part = parts[1].strip()
+
+                # Add parenthesized version
+                alternatives.append(f"{from_part} import ({import_part})")
+
+                # Add version with 'as' clause
+                alternatives.append(f"{import_line} as")
+
+        # Handle declarative_base alternatives (sqlalchemy changes)
+        if "declarative_base" in import_line:
+            # Old style
+            alternatives.append(
+                "from sqlalchemy.ext.declarative import declarative_base"
+            )
+            # New style (SQLAlchemy 1.4+)
+            alternatives.append("from sqlalchemy.orm import declarative_base")
+
+        return alternatives
+
+    def print_summary(self):
+        """Print summary of verification"""
+        print("\n" + "=" * 80)
+        print("📊 CRITICAL IMPORTS VERIFICATION SUMMARY")
+        print("=" * 80)
+
+        if not self.issues:
+            print("\n✅ All critical imports verified successfully!")
+            print("\nAll re-export patterns are intact.")
+        else:
+            print(f"\n❌ Found {len(self.issues)} issue(s):\n")
+            for issue in self.issues:
+                print(issue)
+                print()
+
+            print("💡 RESOLUTION:")
+            print("   1. Check if imports were removed by linter (Ruff)")
+            print("   2. Add missing imports back to the files")
+            print("   3. Update pyproject.toml to ignore F401 for these files")
+            print("   4. Run this script again to verify")
+
+        print("=" * 80)
+
+
+def main():
+    """Main entry point"""
+    project_root = Path(__file__).parent.parent
+
+    verifier = ImportVerifier(project_root)
+    success = verifier.verify_all()
+    verifier.print_summary()
+
+    sys.exit(0 if success else 1)
+
+
+if __name__ == "__main__":
+    main()

tests/system/test_error_handling.py

@@ -6,7 +6,6 @@ Tests the complete error handling flow from FastAPI through custom exception han
 to ensure proper HTTP status codes, error structures, and client-friendly responses.
 """
 
-
 import pytest
 
 

tests/unit/middleware/test_decorators.py

@@ -12,7 +12,6 @@ Tests cover:
 - Edge cases and isolation
 """
 
-
 import pytest
 
 from app.exceptions.base import RateLimitException