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/internal/mqtt_handler.py

@@ -112,6 +112,8 @@ class MQTTHandler:
                 "approval_status": "pending",
                 "node_type": payload.get("node_type", "fixed"),
                 "secondary_sdr_mode": payload.get("secondary_sdr_mode", "none"),
+                "secondary_sdr_priority": payload.get("secondary_sdr_priority", []),
+                "secondary_sdr_running": payload.get("secondary_sdr_running"),
                 "sdr_count": payload.get("sdr_count", 1),
                 "enforce_override_timeout": payload.get("enforce_override_timeout", True),
                 "is_overridden": False,
@@ -143,8 +145,9 @@ class MQTTHandler:
             updates["node_type"] = node_type
             updates["enforce_override_timeout"] = enforce_timeout
 
-            if "secondary_sdr_mode" in payload:
-                updates["secondary_sdr_mode"] = payload["secondary_sdr_mode"]
+            for key in ("secondary_sdr_mode", "secondary_sdr_priority", "secondary_sdr_running"):
+                if key in payload:
+                    updates[key] = payload[key]
             if "sdr_count" in payload:
                 updates["sdr_count"] = payload["sdr_count"]
 

drb-c2-core/app/models.py

@@ -62,7 +62,12 @@ class NodeRecord(BaseModel):
     last_seen: Optional[datetime] = None
     assigned_system_id: Optional[str] = None
     node_type: str = "fixed"  # fixed or portable
-    secondary_sdr_mode: str = "none"  # none | adsb | ais | op25_2 — requires a second physical SDR
+    secondary_sdr_mode: str = "none"  # legacy single-mode field; priority[0] on current nodes
+    # Ordered decoders for the SDRs beyond op25's (node-26#9): the node runs
+    # them top-down until it runs out of dongles. Mirrored from the node's own
+    # checkin, which is the source of truth; set via PATCH /nodes/{id}.
+    secondary_sdr_priority: List[str] = []
+    secondary_sdr_running: Optional[List[str]] = None  # what the node reports actually running
     sdr_count: int = 1  # self-reported by the node's checkin, best-effort
     enforce_override_timeout: bool = True
     is_overridden: bool = False

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)
 

drb-c2-core/tests/test_node_secondary_priority.py

@@ -0,0 +1,59 @@
+"""
+node-26#9 — PATCH /nodes/{id} secondary_sdr_priority.
+
+The priority must reach the node as its own MQTT command, never via a config
+re-push: a config push restarts OP25, and reordering what the spare dongles do
+must not interrupt P25 recording.
+"""
+from unittest.mock import AsyncMock, MagicMock, patch
+
+from fastapi.testclient import TestClient
+
+from app.main import app
+from app.internal.auth import require_admin_token, require_service_or_firebase_token
+from app.routers import nodes
+
+client = TestClient(app)
+
+NODE = {"node_id": "n1", "assigned_system_id": "sys-1", "hardware_preset": "rtl-sdr-v3"}
+
+
+def setup_function():
+    app.dependency_overrides[require_admin_token] = lambda: {"admin": True}
+    app.dependency_overrides[require_service_or_firebase_token] = lambda: {"admin": True}
+
+
+def teardown_function():
+    app.dependency_overrides.pop(require_admin_token, None)
+    app.dependency_overrides.pop(require_service_or_firebase_token, None)
+
+
+def _patch(body):
+    with patch.object(nodes.fstore, "doc_get", AsyncMock(side_effect=lambda c, i: NODE if c == "nodes" else {"system_id": "sys-1"})), \
+         patch.object(nodes.fstore, "doc_update", AsyncMock()) as update, \
+         patch.object(nodes.mqtt_handler, "send_command", MagicMock(return_value=True)) as command, \
+         patch.object(nodes.mqtt_handler, "push_config", MagicMock()) as push:
+        resp = client.patch("/nodes/n1", json=body)
+    return resp, update, command, push
+
+
+def test_priority_only_sends_command_and_never_repushes_config():
+    resp, update, command, push = _patch({"secondary_sdr_priority": ["ais", "adsb"]})
+    assert resp.status_code == 200
+    command.assert_called_once_with("n1", {"action": "set_secondary_priority", "priority": ["ais", "adsb"]})
+    push.assert_not_called()
+    (_, _, updates), _ = update.await_args
+    assert updates == {"secondary_sdr_priority": ["ais", "adsb"], "secondary_sdr_mode": "ais"}
+
+
+def test_empty_priority_turns_secondaries_off():
+    resp, update, command, push = _patch({"secondary_sdr_priority": []})
+    assert resp.status_code == 200
+    command.assert_called_once_with("n1", {"action": "set_secondary_priority", "priority": []})
+    (_, _, updates), _ = update.await_args
+    assert updates["secondary_sdr_mode"] == "none"
+
+
+def test_unknown_or_duplicate_modes_are_rejected():
+    assert _patch({"secondary_sdr_priority": ["adsb", "sonar"]})[0].status_code == 400
+    assert _patch({"secondary_sdr_priority": ["adsb", "adsb"]})[0].status_code == 400

drb-frontend/app/nodes/[id]/page.tsx

@@ -8,6 +8,7 @@ import { useSystems } from "@/lib/useSystems";
 import { useCalls } from "@/lib/useCalls";
 import { StatusBadge } from "@/components/StatusBadge";
 import { NodeConfigModal } from "@/components/NodeConfigModal";
+import { SecondarySdrPriority } from "@/components/SecondarySdrPriority";
 import { CallRow } from "@/components/CallRow";
 import { MachineOutputNotice } from "@/components/ui/MachineOutputNotice";
 import { useAuth } from "@/components/AuthProvider";
@@ -336,6 +337,8 @@ export default function NodeDetailPage() {
         )}
       </div>
 
+      <SecondarySdrPriority node={node} canEdit={isAdmin} />
+
       {/* Recent calls */}
       <section>
         <h2 className="text-sm font-semibold text-gray-400 uppercase tracking-wider mb-3">Recent Calls</h2>

drb-frontend/components/MapView.tsx

@@ -1,6 +1,7 @@
 "use client";
 
-import { useCallback, useEffect, useMemo, useState } from "react";
+import { useCallback, useEffect, useMemo, useRef, useState } from "react";
+import { createPortal } from "react-dom";
 import {
   FeatureGroup,
   LayersControl,
@@ -11,6 +12,7 @@ import {
   TileLayer,
   Tooltip,
   useMap,
+  useMapEvents,
 } from "react-leaflet";
 import L from "leaflet";
 import type { AircraftTrack, CallRecord, IncidentRecord, NodeRecord, NodeStatus } from "@/lib/types";
@@ -117,6 +119,11 @@ function altitudeColor(altFt: number | null): string {
   return `hsl(${hue.toFixed(0)}, 88%, 48%)`;
 }
 
+// Legend ticks for the altitude ramp, evenly spaced (the ramp itself isn't linear).
+const ALTITUDE_LEGEND_TICKS: [number, string][] = [
+  [1000, "1k"], [4000, "4k"], [10000, "10k"], [20000, "20k"], [40000, "40k"],
+];
+
 const AIRLINER_PATH =
   "M32 2 C34.2 2 35.2 5 35.2 8 L35.2 23 L61 37.5 L61 42 L35.2 35 L34.2 51 L42.5 57.5 L42.5 61 L32 58.5 " +
   "L21.5 61 L21.5 57.5 L29.8 51 L28.8 35 L3 42 L3 37.5 L28.8 23 L28.8 8 C28.8 5 29.8 2 32 2 Z";
@@ -158,47 +165,82 @@ function AircraftTrail({ icao, current }: { icao: string; current: AircraftTrack
   );
 }
 
+function Stat({ label, value }: { label: string; value: string }) {
+  return (
+    <div>
+      <div className="text-[10px] uppercase tracking-wide text-ink-muted">{label}</div>
+      <div className="text-ink font-medium tabular-nums">{value}</div>
+    </div>
+  );
+}
+
+// Details dock at the right edge (bottom sheet on phones, above the incident
+// drawer) instead of a popup over the plane, so the trail stays visible and
+// the map can be panned to follow it.
+function AircraftPanel({ a, onClose }: { a: AircraftTrack; onClose: () => void }) {
+  const ref = useRef<HTMLDivElement>(null);
+  useEffect(() => {
+    // The panel is portaled into the Leaflet container, whose native listeners
+    // would otherwise treat clicks/scrolls here as map clicks (deselect) or zoom.
+    if (!ref.current) return;
+    L.DomEvent.disableClickPropagation(ref.current);
+    L.DomEvent.disableScrollPropagation(ref.current);
+  }, []);
+  const fmt = (n: number | null, unit: string) => (n == null ? "—" : `${Math.round(n).toLocaleString()} ${unit}`);
+  return (
+    <div
+      ref={ref}
+      className="absolute left-3 right-3 bottom-12 md:left-auto md:bottom-auto md:top-[5.5rem] md:right-3 md:w-60 z-[1002] bg-surface/95 backdrop-blur-sm border border-line rounded-lg shadow-lg text-xs"
+    >
+      <div className="flex items-start justify-between gap-2 px-3 pt-2.5 pb-2 border-b border-line">
+        <div className="min-w-0">
+          <div className="flex items-center gap-1.5">
+            <span className="inline-block w-2.5 h-2.5 rounded-full shrink-0" style={{ background: altitudeColor(a.altitude_ft) }} />
+            <span className="text-ink font-semibold text-sm truncate">{a.callsign || a.icao}</span>
+          </div>
+          <div className="text-ink-muted mt-0.5">ICAO {a.icao}</div>
+        </div>
+        <button onClick={onClose} aria-label="Close aircraft details" className="text-ink-muted hover:text-ink px-1 leading-none text-base">
+          ×
+        </button>
+      </div>
+      <div className="grid grid-cols-2 gap-x-3 gap-y-2 px-3 py-2.5">
+        <Stat label="Altitude" value={fmt(a.altitude_ft, "ft")} />
+        <Stat label="Speed" value={fmt(a.ground_speed_kt, "kt")} />
+        <Stat label="Heading" value={a.track_deg == null ? "—" : `${Math.round(a.track_deg)}°`} />
+        <Stat label="Last heard" value={timeAgo(new Date(a.last_seen))} />
+      </div>
+    </div>
+  );
+}
+
 function AircraftLayer() {
+  const map = useMap();
   const { aircraft } = useAircraft();
   const [selected, setSelected] = useState<string | null>(null);
   const positioned = aircraft.filter((a) => a.lat != null && a.lon != null);
   const selectedTrack = positioned.find((a) => a.icao === selected);
 
+  // Clicking empty map deselects; marker clicks don't reach the map.
+  useMapEvents({ click: () => setSelected(null) });
+
   return (
     <>
       {selectedTrack && <AircraftTrail icao={selectedTrack.icao} current={selectedTrack} />}
+      {selectedTrack &&
+        createPortal(<AircraftPanel a={selectedTrack} onClose={() => setSelected(null)} />, map.getContainer())}
       {positioned.map((a) => (
         <Marker
           key={a.icao}
           position={[a.lat as number, a.lon as number]}
           icon={aircraftIcon(a.track_deg, a.altitude_ft, a.icao === selected)}
           zIndexOffset={a.icao === selected ? 1000 : 0}
-          eventHandlers={{
-            click: () => setSelected(a.icao),
-            popupclose: () => setSelected((cur) => (cur === a.icao ? null : cur)),
-          }}
+          eventHandlers={{ click: () => setSelected((cur) => (cur === a.icao ? null : a.icao)) }}
         >
           <Tooltip direction="top" offset={[0, -14]}>
             {a.callsign || a.icao}
             {a.altitude_ft != null && ` · ${Math.round(a.altitude_ft).toLocaleString()} ft`}
           </Tooltip>
-          <Popup minWidth={160}>
-            <div className="space-y-1">
-              <div className="font-semibold">{a.callsign || a.icao}</div>
-              <div className="text-xs text-ink-muted">ICAO {a.icao}</div>
-              {a.altitude_ft != null && (
-                <div className="text-xs">
-                  <span
-                    className="inline-block w-2 h-2 rounded-full mr-1 align-middle"
-                    style={{ background: altitudeColor(a.altitude_ft) }}
-                  />
-                  Altitude: {Math.round(a.altitude_ft).toLocaleString()} ft
-                </div>
-              )}
-              {a.ground_speed_kt != null && <div className="text-xs">Speed: {Math.round(a.ground_speed_kt)} kt</div>}
-              {a.track_deg != null && <div className="text-xs">Heading: {Math.round(a.track_deg)}°</div>}
-            </div>
-          </Popup>
         </Marker>
       ))}
     </>
@@ -206,12 +248,34 @@ function AircraftLayer() {
 }
 
 // ── Vessel icon — node-26#9 second-SDR AIS overlay ─────────────────────────────
+// MMSI 99xxxxxxx is an aid to navigation (buoy, beacon, light), not a vessel —
+// on the Hudson most of what a node hears is buoys (server-26#186).
+function isAidToNavigation(mmsi: string): boolean {
+  return /^99\d{7}$/.test(mmsi);
+}
+
+// AIS reports heading 511 (and course 360) for "not available".
+function aisHeading(deg: number | null): number | null {
+  return deg == null || deg >= 360 ? null : deg;
+}
+
 function vesselIcon(headingDeg: number | null): L.DivIcon {
-  const size = 14;
-  const rotation = headingDeg ?? 0;
+  const size = 22;
   return L.divIcon({
     className: "",
-    html: `<div style="width:${size}px;height:${size}px;transform:rotate(${rotation}deg)"><svg width="${size}" height="${size}" viewBox="0 0 24 24" fill="var(--accent)" stroke="var(--surface)" stroke-width="1"><path d="M12 2 L18 14 L18 20 L6 20 L6 14 Z"/></svg></div>`,
+    html:
+      `<div style="width:${size}px;height:${size}px;transform:rotate(${aisHeading(headingDeg) ?? 0}deg);filter:drop-shadow(0 1px 1px rgba(0,0,0,.45))">` +
+      `<svg width="${size}" height="${size}" viewBox="0 0 24 24"><path d="M12 2 L18 12 L18 21 L6 21 L6 12 Z" fill="hsl(190, 80%, 42%)" stroke="#000" stroke-width="1.25" stroke-linejoin="round"/></svg></div>`,
+    iconSize: [size, size],
+    iconAnchor: [size / 2, size / 2],
+  });
+}
+
+function aidToNavigationIcon(): L.DivIcon {
+  const size = 12;
+  return L.divIcon({
+    className: "",
+    html: `<svg width="${size}" height="${size}" viewBox="0 0 12 12"><rect x="2" y="2" width="8" height="8" transform="rotate(45 6 6)" fill="hsl(50, 95%, 55%)" stroke="#000" stroke-width="1"/></svg>`,
     iconSize: [size, size],
     iconAnchor: [size / 2, size / 2],
   });
@@ -223,17 +287,25 @@ function VesselLayer() {
     <>
       {vessels
         .filter((v) => v.lat != null && v.lon != null)
-        .map((v) => (
-          <Marker key={v.mmsi} position={[v.lat as number, v.lon as number]} icon={vesselIcon(v.heading_deg)}>
-            <Popup minWidth={160}>
-              <div className="space-y-1">
-                <div className="font-semibold">{v.name || v.mmsi}</div>
-                <div className="text-xs text-ink-muted">MMSI {v.mmsi}</div>
-                {v.speed_kt != null && <div className="text-xs">Speed: {Math.round(v.speed_kt)} kt</div>}
-              </div>
-            </Popup>
-          </Marker>
-        ))}
+        .map((v) => {
+          const aton = isAidToNavigation(v.mmsi);
+          return (
+            <Marker
+              key={v.mmsi}
+              position={[v.lat as number, v.lon as number]}
+              icon={aton ? aidToNavigationIcon() : vesselIcon(v.heading_deg)}
+              zIndexOffset={aton ? -100 : 0}
+            >
+              <Popup minWidth={160}>
+                <div className="space-y-1">
+                  <div className="font-semibold">{aton ? `Aid to navigation${v.name ? ` ${v.name}` : ""}` : v.name || v.mmsi}</div>
+                  <div className="text-xs text-ink-muted">MMSI {v.mmsi}</div>
+                  {!aton && v.speed_kt != null && <div className="text-xs">Speed: {Math.round(v.speed_kt)} kt</div>}
+                </div>
+              </Popup>
+            </Marker>
+          );
+        })}
     </>
   );
 }
@@ -607,6 +679,21 @@ export default function MapView({ nodes, activeCalls, incidents = [], calls = []
   const [drawerOpen, setDrawerOpen] = useState(false);
   const [agoClock, setAgoClock] = useState(0);
   const [radarEpoch, setRadarEpoch] = useState(() => Date.now());
+  const [aircraftShown, setAircraftShown] = useState(false);
+
+  // The altitude key only belongs in the legend while the opt-in Aircraft
+  // overlay is actually on (server-26#185).
+  useEffect(() => {
+    if (!mapInstance) return;
+    const on = (e: L.LayersControlEvent) => e.name === "Aircraft" && setAircraftShown(true);
+    const off = (e: L.LayersControlEvent) => e.name === "Aircraft" && setAircraftShown(false);
+    mapInstance.on("overlayadd", on);
+    mapInstance.on("overlayremove", off);
+    return () => {
+      mapInstance.off("overlayadd", on);
+      mapInstance.off("overlayremove", off);
+    };
+  }, [mapInstance]);
 
   useEffect(() => {
     const id = setInterval(() => setAgoClock((t: number) => t + 1), 10_000);
@@ -797,6 +884,18 @@ export default function MapView({ nodes, activeCalls, incidents = [], calls = []
             </div>
           ))}
         </div>
+        {aircraftShown && (
+          <div className="border-t border-line pt-1.5 space-y-1">
+            <p className="text-ink-muted font-medium text-[10px] uppercase tracking-wide">Aircraft altitude</p>
+            <div
+              className="h-2 w-32 rounded-sm border border-line"
+              style={{ background: `linear-gradient(to right, ${ALTITUDE_LEGEND_TICKS.map(([ft], i) => `${altitudeColor(ft)} ${(i / (ALTITUDE_LEGEND_TICKS.length - 1)) * 100}%`).join(", ")})` }}
+            />
+            <div className="flex justify-between w-32 text-[10px] text-ink-2 tabular-nums">
+              {ALTITUDE_LEGEND_TICKS.map(([ft, label]) => <span key={ft}>{label}</span>)}
+            </div>
+          </div>
+        )}
         <div className="border-t border-line pt-1.5 space-y-1">
           <p className="text-ink-muted font-medium text-[10px] uppercase tracking-wide">Nodes</p>
           {([

drb-frontend/components/SecondarySdrPriority.tsx

@@ -0,0 +1,139 @@
+"use client";
+
+import { useEffect, useState } from "react";
+import { c2api } from "@/lib/c2api";
+import type { NodeRecord } from "@/lib/types";
+
+// node-26#9. OP25 always keeps its own SDR; every other SDR on the node runs
+// the next enabled item here, top first — so a 3-SDR node runs both.
+const MODES: { mode: string; name: string; hint: string }[] = [
+  { mode: "adsb", name: "ADS-B", hint: "Aircraft · 1090 MHz" },
+  { mode: "ais", name: "AIS", hint: "Vessels · 162 MHz" },
+];
+
+type Row = { mode: string; enabled: boolean };
+
+function rowsFrom(priority: string[]): Row[] {
+  return [
+    ...priority.filter((m) => MODES.some((x) => x.mode === m)).map((mode) => ({ mode, enabled: true })),
+    ...MODES.filter((x) => !priority.includes(x.mode)).map((x) => ({ mode: x.mode, enabled: false })),
+  ];
+}
+
+export function SecondarySdrPriority({ node, canEdit }: { node: NodeRecord; canEdit: boolean }) {
+  const priority = node.secondary_sdr_priority ?? [];
+  const running = node.secondary_sdr_running ?? [];
+  const [rows, setRows] = useState<Row[]>(() => rowsFrom(priority));
+  const [dirty, setDirty] = useState(false);
+  const [saving, setSaving] = useState(false);
+  const [message, setMessage] = useState<string | null>(null);
+
+  // Follow the node's live checkin unless there are unsaved edits.
+  const priorityKey = priority.join(",");
+  useEffect(() => {
+    if (!dirty) setRows(rowsFrom(priorityKey ? priorityKey.split(",") : []));
+  }, [priorityKey, dirty]);
+
+  function edit(next: Row[]) {
+    setRows(next);
+    setDirty(true);
+    setMessage(null);
+  }
+
+  function move(i: number, delta: number) {
+    const next = [...rows];
+    [next[i], next[i + delta]] = [next[i + delta], next[i]];
+    edit(next);
+  }
+
+  async function save() {
+    setSaving(true);
+    setMessage(null);
+    try {
+      await c2api.updateNode(node.node_id, {
+        secondary_sdr_priority: rows.filter((r) => r.enabled).map((r) => r.mode),
+      });
+      setDirty(false);
+      setMessage("Sent to the node. Status updates when it checks in.");
+    } catch (err) {
+      setMessage(err instanceof Error ? err.message : "Save failed.");
+    } finally {
+      setSaving(false);
+    }
+  }
+
+  const sdrCount = node.sdr_count ?? 1;
+  const spare = Math.max(sdrCount - 1, 0);
+  let rank = 0;
+
+  return (
+    <section>
+      <h2 className="text-sm font-semibold text-gray-400 uppercase tracking-wider mb-1">Secondary SDRs</h2>
+      <p className="text-xs text-gray-500 font-mono mb-3">
+        OP25 always keeps its own SDR. Every other SDR runs the next enabled item, top first.
+        {" "}This node reports {sdrCount} SDR{sdrCount === 1 ? "" : "s"} ({spare} spare).
+      </p>
+      <div className="bg-gray-900 border border-gray-800 rounded-lg divide-y divide-gray-800 font-mono text-sm">
+        {rows.map((row, i) => {
+          const meta = MODES.find((x) => x.mode === row.mode)!;
+          const isRunning = running.includes(row.mode);
+          const state = !row.enabled ? "Off" : dirty ? "Unsaved" : isRunning ? "Running" : "Waiting for SDR";
+          return (
+            <div key={row.mode} className="flex items-center gap-3 px-4 py-2.5">
+              <span className="w-4 text-right text-gray-600 text-xs">{row.enabled ? ++rank : ""}</span>
+              <input
+                type="checkbox"
+                checked={row.enabled}
+                disabled={!canEdit}
+                aria-label={`Enable ${meta.name}`}
+                onChange={(e) => edit(rows.map((r, j) => (j === i ? { ...r, enabled: e.target.checked } : r)))}
+                className="rounded bg-gray-800 border-gray-700 text-indigo-600 focus:ring-indigo-500 focus:ring-offset-gray-900"
+              />
+              <div className="flex-1 min-w-0">
+                <div className="text-gray-200">{meta.name}</div>
+                <div className="text-xs text-gray-500">{meta.hint}</div>
+              </div>
+              {canEdit && (
+                <div className="flex gap-1">
+                  <button
+                    type="button"
+                    onClick={() => move(i, -1)}
+                    disabled={i === 0}
+                    aria-label={`Move ${meta.name} up`}
+                    className="w-7 h-7 rounded bg-gray-800 hover:bg-gray-700 text-gray-300 disabled:opacity-30"
+                  >
+                    ▲
+                  </button>
+                  <button
+                    type="button"
+                    onClick={() => move(i, 1)}
+                    disabled={i === rows.length - 1}
+                    aria-label={`Move ${meta.name} down`}
+                    className="w-7 h-7 rounded bg-gray-800 hover:bg-gray-700 text-gray-300 disabled:opacity-30"
+                  >
+                    ▼
+                  </button>
+                </div>
+              )}
+              <span className={`w-28 text-right text-xs ${state === "Running" ? "text-green-400" : "text-gray-500"}`}>
+                {state}
+              </span>
+            </div>
+          );
+        })}
+      </div>
+      {canEdit && (
+        <div className="flex items-center gap-3 mt-3">
+          <button
+            onClick={save}
+            disabled={!dirty || saving}
+            className="px-4 py-2 bg-indigo-700 hover:bg-indigo-600 disabled:opacity-50 text-white rounded-lg text-sm font-mono transition-colors"
+          >
+            {saving ? "Saving…" : "Save priority"}
+          </button>
+          {message && <span className="text-xs text-gray-500 font-mono">{message}</span>}
+        </div>
+      )}
+    </section>
+  );
+}

drb-frontend/lib/c2api.ts

@@ -35,7 +35,10 @@ export const c2api = {
     request(`/nodes/${nodeId}/override/ack`, { method: "POST", body: JSON.stringify({ timeout_minutes: timeoutMinutes }) }),
   resetOverride: (nodeId: string) =>
     request(`/nodes/${nodeId}/override/reset`, { method: "POST" }),
-  updateNode: (id: string, body: { node_type?: string; enforce_override_timeout?: boolean }) =>
+  updateNode: (
+    id: string,
+    body: { node_type?: string; enforce_override_timeout?: boolean; secondary_sdr_priority?: string[] },
+  ) =>
     request(`/nodes/${id}`, { method: "PATCH", body: JSON.stringify(body) }),
 
   // Systems

drb-frontend/lib/types.ts

@@ -53,7 +53,11 @@ export interface NodeRecord {
   hardware_preset?: string;
   ppm_override?: number | null;
   node_type?: string;
-  secondary_sdr_mode?: string;
+  secondary_sdr_mode?: string; // legacy; priority[0] on current nodes
+  /** Ordered decoders for the SDRs beyond OP25's, run top-down (node-26#9). */
+  secondary_sdr_priority?: string[];
+  /** What the node's last checkin reported actually running. */
+  secondary_sdr_running?: string[] | null;
   sdr_count?: number;
   enforce_override_timeout?: boolean;
   is_overridden?: boolean;