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-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/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;