Secondary SDR priority: C2 field, node command, dashboard section

Pairs with node-26 feat/secondary-sdr-priority. NodeRecord gains
secondary_sdr_priority (ordered; SDRs beyond OP25's run it top-down) and
secondary_sdr_running, both mirrored from the node's checkin.
PATCH /nodes/{id} accepts the priority, validates it, and sends it as a
'set_secondary_priority' MQTT command. A priority-only change never
re-pushes system config, because that restarts OP25. The node detail page
gets a 'Secondary SDRs' section (admin-editable) with enable, reorder,
save, and live Running / Waiting-for-SDR state from the checkin.

Verified: c2-core pytest 482 passed; frontend tsc --noEmit clean.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

drb-c2-core/app/routers/nodes.py

@@ -1,5 +1,5 @@
 import secrets
-from typing import Optional
+from typing import List, Optional
 from fastapi import APIRouter, HTTPException, Depends, Query
 from pydantic import BaseModel
 from app.models import CommandPayload
@@ -192,10 +192,15 @@ async def assign_system(
     return {"ok": True}
 
 
+SECONDARY_SDR_MODES = ("adsb", "ais")
+
+
 class NodeUpdateBody(BaseModel):
     node_type: Optional[str] = None
     enforce_override_timeout: Optional[bool] = None
-    secondary_sdr_mode: Optional[str] = None  # none | adsb | ais | op25_2
+    secondary_sdr_mode: Optional[str] = None  # legacy: none | adsb | ais
+    # Ordered, e.g. ["adsb", "ais"]: SDRs beyond op25's run these top-down.
+    secondary_sdr_priority: Optional[List[str]] = None
 
 
 @router.patch("/{node_id}")
@@ -212,8 +217,23 @@ async def update_node(
     if not updates:
         return {"ok": True}
 
+    priority = updates.get("secondary_sdr_priority")
+    if priority is not None:
+        unknown = [m for m in priority if m not in SECONDARY_SDR_MODES]
+        if unknown or len(set(priority)) != len(priority):
+            raise HTTPException(400, f"secondary_sdr_priority must be distinct values from {SECONDARY_SDR_MODES}.")
+        updates["secondary_sdr_mode"] = priority[0] if priority else "none"
+
     await fstore.doc_update("nodes", node_id, updates)
 
+    # Priority goes as its own command: a config re-push restarts OP25, and
+    # changing what the spare dongles do must never interrupt P25 recording.
+    # The node applies it, then its checkin reports back what's really running.
+    if priority is not None:
+        mqtt_handler.send_command(node_id, {"action": "set_secondary_priority", "priority": priority})
+        if set(updates) <= {"secondary_sdr_priority", "secondary_sdr_mode"}:
+            return {"ok": True}
+
     # Re-push config to apply new node settings locally
     updated_node = await fstore.doc_get("nodes", node_id)
     assigned_system_id = updated_node.get("assigned_system_id")
@@ -228,7 +248,9 @@ async def update_node(
             }
             if updated_node.get("ppm_override") is not None:
                 push_payload["ppm_override"] = updated_node["ppm_override"]
-            if updated_node.get("secondary_sdr_mode") is not None:
+            if updated_node.get("secondary_sdr_priority") is not None:
+                push_payload["secondary_sdr_priority"] = updated_node["secondary_sdr_priority"]
+            elif updated_node.get("secondary_sdr_mode") is not None:
                 push_payload["secondary_sdr_mode"] = updated_node["secondary_sdr_mode"]
             mqtt_handler.push_config(node_id, push_payload)