fix: reliable cloud sync and connection pooling for Render live dashboard

background_tasks.py

@@ -79,3 +79,86 @@ async def retry_failed_transmissions():
             logger.error(f"Error in retry background task: {e}")
             
         await asyncio.sleep(settings.retry_interval_seconds)
+
+
+async def sync_cloud_state():
+    """
+    Periodically syncs all assigned patients and their latest non-null vitals to Render Cloud.
+    Ensures that whenever Render restarts or deploys with an empty DB, the cloud dashboard
+    is immediately populated with the same data as localhost.
+    """
+    import os
+    if os.getenv("RENDER") is not None or os.getenv("PORT") == "10000" or "render.local" in os.getenv("HOSTNAME", ""):
+        return  # Do not run sync loop if we are running inside Render
+
+    from models import Patient
+    from api_client import sync_patient_assignment_to_cloud, forward_vitals_to_api
+    from datetime import datetime, timezone
+    from sqlalchemy import or_
+
+    logger.info("Starting background task for periodic cloud state sync to Render...")
+    await asyncio.sleep(5)
+
+    while True:
+        try:
+            db = SessionLocal()
+            try:
+                patients = db.query(Patient).filter(
+                    Patient.patient_id != "UNKNOWN",
+                    Patient.mrn != "UNKNOWN"
+                ).all()
+
+                for p in patients:
+                    if not p.device_id:
+                        continue
+
+                    # 1. Sync patient demographics assignment to Render
+                    p_data = {
+                        "mrn": p.mrn or p.patient_id,
+                        "name": p.name,
+                        "gender": p.gender,
+                        "dob": p.dob,
+                        "bed_id": p.bed_id,
+                        "patient_type": getattr(p, "patient_type", None)
+                    }
+                    await sync_patient_assignment_to_cloud(p_data, p.device_id)
+
+                    # 2. Backfill and forward latest complete non-null vitals to Render
+                    patient_filters = or_(
+                        VitalReading.patient_id == p.mrn,
+                        VitalReading.patient_id == p.patient_id,
+                        VitalReading.device_id == p.device_id
+                    )
+                    recent_r = db.query(VitalReading).filter(patient_filters).order_by(VitalReading.timestamp.desc()).first()
+                    if recent_r:
+                        spo2_r = db.query(VitalReading.spo2).filter(patient_filters, VitalReading.spo2 != None).order_by(VitalReading.timestamp.desc()).first()
+                        hr_r = db.query(VitalReading.heart_rate).filter(patient_filters, VitalReading.heart_rate != None).order_by(VitalReading.timestamp.desc()).first()
+                        bp_r = db.query(VitalReading.systolic_bp, VitalReading.diastolic_bp, VitalReading.map_bp).filter(patient_filters, VitalReading.systolic_bp != None).order_by(VitalReading.timestamp.desc()).first()
+                        temp_r = db.query(VitalReading.temperature).filter(patient_filters, VitalReading.temperature != None).order_by(VitalReading.timestamp.desc()).first()
+                        rr_r = db.query(VitalReading.respiratory_rate).filter(patient_filters, VitalReading.respiratory_rate != None).order_by(VitalReading.timestamp.desc()).first()
+
+                        merged = NormalizedVitals(
+                            device_id=p.device_id,
+                            patient_id=p.mrn or p.patient_id,
+                            patient_name=p.name,
+                            patient_gender=p.gender,
+                            patient_dob=p.dob,
+                            bed_id=p.bed_id,
+                            patient_type=getattr(p, "patient_type", None),
+                            timestamp=recent_r.timestamp or datetime.now(timezone.utc),
+                            heart_rate=hr_r[0] if hr_r else None,
+                            spo2=spo2_r[0] if spo2_r else None,
+                            systolic_bp=bp_r[0] if bp_r else None,
+                            diastolic_bp=bp_r[1] if bp_r else None,
+                            map_bp=bp_r[2] if bp_r else None,
+                            temperature=temp_r[0] if temp_r else None,
+                            respiratory_rate=rr_r[0] if rr_r else None
+                        )
+                        await forward_vitals_to_api(merged)
+            finally:
+                db.close()
+        except Exception as e:
+            logger.error(f"Error in sync_cloud_state background task: {e}")
+
+        await asyncio.sleep(15)
+