Fix backend startup: resolve relative import error and add graceful fallback for background detector

backend/Dockerfile

@@ -1,8 +1,8 @@
 FROM python:3.11-slim
 WORKDIR /app
 RUN apt-get update && apt-get install -y gcc g++ && rm -rf /var/lib/apt/lists/*
-COPY requirements.txt .
+COPY backend/requirements.txt .
 RUN pip install --no-cache-dir -r requirements.txt
 COPY . .
 ENV PORT=8080
-CMD uvicorn app.main:app --host 0.0.0.0 --port ${PORT}
+CMD uvicorn backend.app.main:app --host 0.0.0.0 --port ${PORT}

backend/app/main.py

@@ -166,20 +166,28 @@ async def startup_event():
     except Exception as e:
         logger.warning(f"GNN loading failed: {e}")
 
-    # Start Background Shock Detector if enabled
-    if settings.DEMO_MODE:
-        # In demo mode, we still run once to get any available live data to complement scenarios
-        from ..ingestion.shock_detector import run_once
-        loop = asyncio.get_event_loop()
-        loop.run_in_executor(None, run_once)
-        logger.info("Background detector triggered once (Demo Mode).")
-    else:
-        from ..ingestion.shock_detector import run_scheduler
-        import threading
-        thread = threading.Thread(target=run_scheduler, daemon=True)
-        thread.start()
-        logger.info("Background detector thread started (Live Mode).")
-        
+    # Start Background Shock Detector — optional; never crash the server if unavailable
+    try:
+        import sys, os
+        # Ensure the project root is on sys.path so 'ingestion' is importable
+        project_root = str(Path(__file__).resolve().parent.parent.parent)
+        if project_root not in sys.path:
+            sys.path.insert(0, project_root)
+
+        if settings.DEMO_MODE:
+            from ingestion.shock_detector import run_once
+            loop = asyncio.get_event_loop()
+            loop.run_in_executor(None, run_once)
+            logger.info("Background detector triggered once (Demo Mode).")
+        else:
+            from ingestion.shock_detector import run_scheduler
+            import threading
+            thread = threading.Thread(target=run_scheduler, daemon=True)
+            thread.start()
+            logger.info("Background detector thread started (Live Mode).")
+    except Exception as e:
+        logger.warning(f"Shock detector could not start (non-fatal): {e}")
+
     logger.info("PharmaShield startup sequence complete.")
 
 @app.exception_handler(Exception)

render.yaml

@@ -5,7 +5,8 @@ services:
     region: singapore
     plan: free
     healthCheckPath: /healthz
-    rootDir: backend
+    rootDir: .
+    dockerFilePath: backend/Dockerfile
     envVars:
       - key: GEMINI_API_KEY
         sync: false