Phase 1: pytest baseline, production hardening, pinned requirements

Establishes the safety net required before any structural refactor.

Tests (tests/):
- conftest.py rewritten for Flask-SQLAlchemy 3.x (drop-recreate per
  test, StaticPool-shared in-memory SQLite, admin_user + auth_headers
  fixtures). Removes deprecated db.create_scoped_session pattern.
- test_smoke.py: 8 baseline tests (app boot, JWT login valid+invalid,
  protected routes, paginated response shape, plugin auto-discovery).
- test_security_config.py: 7 tests pinning ProductionConfig.validate
  failure modes (missing/dev SECRET_KEY, missing JWT_SECRET_KEY,
  missing DATABASE_URL, wildcard CORS, empty CORS) and one happy-path.

Production hardening (shopdb/config.py, shopdb/__init__.py):
- ProductionConfig.validate() raises ConfigError on missing or
  insecure SECRET_KEY, JWT_SECRET_KEY, DATABASE_URL, CORS_ORIGINS.
  No silent fallback to dev defaults in production.
- create_app invokes validate() when config_name == 'production'.
- CORS_ORIGINS default no longer wildcard; defaults to localhost
  Vite dev origin.
- Drop os.path.exists probe in serve_frontend (path-traversal risk
  surface). send_from_directory handles safe-join + 404 itself.
- Replace User.query.get with db.session.get (SQLAlchemy 2.0 API).

TestingConfig (shopdb/config.py):
- Add StaticPool + check_same_thread connect_args so SQLite in-memory
  is shared across the test session.

Index dedup (plugins/printers/models/printer_extension.py):
- Rename idx_printer_windowsname -> idx_printerdata_windowsname.
  Two model classes (Printer, PrinterData) declared the same index
  name; SQLite enforces global index uniqueness even across tables.
  Per CONTRIBUTING.md naming convention, indexes follow
  idx_<table>_<column>.

Dependency pinning (requirements.in, requirements.txt):
- requirements.in holds the loose source pins (the human-edited file).
- requirements.txt is now a uv-compiled lockfile (every transitive
  dep pinned to an exact version). Reproducible builds. Run
  `uv pip compile requirements.in -o requirements.txt` to refresh.

Test count: 0 -> 15 passing. All naming/style checks still green.

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

shopdb/__init__.py

@@ -24,8 +24,13 @@ def create_app(config_name: str = None) -> Flask:
 
     app = Flask(__name__, instance_relative_config=True)
 
-    # Load configuration
-    app.config.from_object(config.get(config_name, config['default']))
+    config_class = config.get(config_name, config['default'])
+
+    # Production must validate its env-driven config before boot.
+    if config_name == 'production' and hasattr(config_class, 'validate'):
+        config_class.validate()
+
+    app.config.from_object(config_class)
 
     # Load instance config if exists
     app.config.from_pyfile('config.py', silent=True)
@@ -60,7 +65,7 @@ def create_app(config_name: str = None) -> Flask:
     def user_lookup_callback(_jwt_header, jwt_data):
         from .core.models import User
         identity = jwt_data["sub"]
-        return User.query.get(int(identity))
+        return db.session.get(User, int(identity))
 
     return app
 
@@ -187,11 +192,15 @@ def register_frontend_routes(app: Flask):
             from .utils.responses import error_response, ErrorCodes
             return error_response(ErrorCodes.NOT_FOUND, 'API endpoint not found', http_code=404)
 
-        # Serve static assets
-        if path and os.path.exists(os.path.join(frontend_dist, path)):
-            return send_from_directory(frontend_dist, path)
+        # Try to serve a static asset directly. send_from_directory handles
+        # the safe-join + 404 itself; no explicit existence probe needed
+        # (the probe was a path-traversal risk surface).
+        if path:
+            try:
+                return send_from_directory(frontend_dist, path)
+            except Exception:
+                pass
 
-        # Serve index.html for SPA routing
         return send_from_directory(frontend_dist, 'index.html')