fix: prevent OOM restart loop on HF Spaces

- Reduce uvicorn workers from 2 to 1 (Playwright+Chromium is memory-heavy)
- Add --timeout-keep-alive 120 for slow PDF renders
- Make database engine lazy (no crash when MySQL unavailable)

Dockerfile

@@ -53,5 +53,6 @@ COPY .env.example .env.example
 ENV PORT=7860
 EXPOSE 7860
 
-# Production command
-CMD ["sh", "-c", "uvicorn app.main:app --host 0.0.0.0 --port ${PORT:-7860} --workers 2"]
+# Production command — single worker to stay within HF Spaces memory limits
+# Playwright + Chromium is memory-heavy; 2 workers causes OOM restarts
+CMD ["sh", "-c", "uvicorn app.main:app --host 0.0.0.0 --port ${PORT:-7860} --workers 1 --timeout-keep-alive 120"]

app/core/database.py

@@ -1,30 +1,47 @@
-"""Database engine and session factory (SQLAlchemy)."""
+"""Database engine and session factory (SQLAlchemy).
 
+Engine is created lazily to avoid crash on startup when no DB is available
+(e.g. Hugging Face Spaces without MySQL).
+"""
+
+import logging
 from sqlalchemy import create_engine
 from sqlalchemy.orm import sessionmaker, DeclarativeBase
 
 from app.core.config import get_settings
 
+logger = logging.getLogger(__name__)
+
 
 class Base(DeclarativeBase):
     pass
 
 
-_settings = get_settings()
+_engine = None
 
-engine = create_engine(
-    _settings.database_url,
-    pool_pre_ping=True,
-    pool_recycle=3600,
-    echo=_settings.debug,
-)
 
-SessionLocal = sessionmaker(autocommit=False, autoflush=False, bind=engine)
+def _get_engine():
+    global _engine
+    if _engine is None:
+        _settings = get_settings()
+        try:
+            _engine = create_engine(
+                _settings.database_url,
+                pool_pre_ping=True,
+                pool_recycle=3600,
+                echo=_settings.debug,
+            )
+        except Exception as exc:
+            logger.warning("Database engine creation failed: %s", exc)
+            raise
+    return _engine
 
 
 def get_db():
     """FastAPI dependency: yields a DB session, closes on exit."""
-    db = SessionLocal()
+    engine = _get_engine()
+    Session = sessionmaker(autocommit=False, autoflush=False, bind=engine)
+    db = Session()
     try:
         yield db
     finally: