Add:

- pair_devices.html template for device pairing interface
- SLMM device control lock prevents flooding nl43.
Fix:
- Polling intervals for SLMM.
- modem view now list
- device pairing much improved.
- various other tweaks through out UI.
- SLMM Scheduled downloads fixed.

backend/main.py

@@ -21,6 +21,7 @@ from backend.database import engine, Base, get_db
 from backend.routers import roster, units, photos, roster_edit, roster_rename, dashboard, dashboard_tabs, activity, slmm, slm_ui, slm_dashboard, seismo_dashboard, projects, project_locations, scheduler, modem_dashboard
 from backend.services.snapshot import emit_status_snapshot
 from backend.models import IgnoredUnit
+from backend.utils.timezone import get_user_timezone
 
 # Create database tables
 Base.metadata.create_all(bind=engine)
@@ -223,6 +224,67 @@ async def modems_page(request: Request):
     return templates.TemplateResponse("modems.html", {"request": request})
 
 
+@app.get("/pair-devices", response_class=HTMLResponse)
+async def pair_devices_page(request: Request, db: Session = Depends(get_db)):
+    """
+    Device pairing page - two-column layout for pairing recorders with modems.
+    """
+    from backend.models import RosterUnit
+
+    # Get all non-retired recorders (seismographs and SLMs)
+    recorders = db.query(RosterUnit).filter(
+        RosterUnit.retired == False,
+        RosterUnit.device_type.in_(["seismograph", "slm", None])  # None defaults to seismograph
+    ).order_by(RosterUnit.id).all()
+
+    # Get all non-retired modems
+    modems = db.query(RosterUnit).filter(
+        RosterUnit.retired == False,
+        RosterUnit.device_type == "modem"
+    ).order_by(RosterUnit.id).all()
+
+    # Build existing pairings list
+    pairings = []
+    for recorder in recorders:
+        if recorder.deployed_with_modem_id:
+            modem = next((m for m in modems if m.id == recorder.deployed_with_modem_id), None)
+            pairings.append({
+                "recorder_id": recorder.id,
+                "recorder_type": (recorder.device_type or "seismograph").upper(),
+                "modem_id": recorder.deployed_with_modem_id,
+                "modem_ip": modem.ip_address if modem else None
+            })
+
+    # Convert to dicts for template
+    recorders_data = [
+        {
+            "id": r.id,
+            "device_type": r.device_type or "seismograph",
+            "deployed": r.deployed,
+            "deployed_with_modem_id": r.deployed_with_modem_id
+        }
+        for r in recorders
+    ]
+
+    modems_data = [
+        {
+            "id": m.id,
+            "deployed": m.deployed,
+            "deployed_with_unit_id": m.deployed_with_unit_id,
+            "ip_address": m.ip_address,
+            "phone_number": m.phone_number
+        }
+        for m in modems
+    ]
+
+    return templates.TemplateResponse("pair_devices.html", {
+        "request": request,
+        "recorders": recorders_data,
+        "modems": modems_data,
+        "pairings": pairings
+    })
+
+
 @app.get("/projects", response_class=HTMLResponse)
 async def projects_page(request: Request):
     """Projects management and overview"""
@@ -587,6 +649,7 @@ async def devices_all_partial(request: Request):
             "last_calibrated": unit_data.get("last_calibrated"),
             "next_calibration_due": unit_data.get("next_calibration_due"),
             "deployed_with_modem_id": unit_data.get("deployed_with_modem_id"),
+            "deployed_with_unit_id": unit_data.get("deployed_with_unit_id"),
             "ip_address": unit_data.get("ip_address"),
             "phone_number": unit_data.get("phone_number"),
             "hardware_model": unit_data.get("hardware_model"),
@@ -610,6 +673,7 @@ async def devices_all_partial(request: Request):
             "last_calibrated": unit_data.get("last_calibrated"),
             "next_calibration_due": unit_data.get("next_calibration_due"),
             "deployed_with_modem_id": unit_data.get("deployed_with_modem_id"),
+            "deployed_with_unit_id": unit_data.get("deployed_with_unit_id"),
             "ip_address": unit_data.get("ip_address"),
             "phone_number": unit_data.get("phone_number"),
             "hardware_model": unit_data.get("hardware_model"),
@@ -633,6 +697,7 @@ async def devices_all_partial(request: Request):
             "last_calibrated": unit_data.get("last_calibrated"),
             "next_calibration_due": unit_data.get("next_calibration_due"),
             "deployed_with_modem_id": unit_data.get("deployed_with_modem_id"),
+            "deployed_with_unit_id": unit_data.get("deployed_with_unit_id"),
             "ip_address": unit_data.get("ip_address"),
             "phone_number": unit_data.get("phone_number"),
             "hardware_model": unit_data.get("hardware_model"),
@@ -656,6 +721,7 @@ async def devices_all_partial(request: Request):
             "last_calibrated": None,
             "next_calibration_due": None,
             "deployed_with_modem_id": None,
+            "deployed_with_unit_id": None,
             "ip_address": None,
             "phone_number": None,
             "hardware_model": None,
@@ -678,7 +744,8 @@ async def devices_all_partial(request: Request):
     return templates.TemplateResponse("partials/devices_table.html", {
         "request": request,
         "units": units_list,
-        "timestamp": datetime.now().strftime("%H:%M:%S")
+        "timestamp": datetime.now().strftime("%H:%M:%S"),
+        "user_timezone": get_user_timezone()
     })