feat: Add local system override with 24h timeout support

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

@@ -192,6 +192,54 @@ export default function NodeDetailPage() {
         <StatusBadge status={node.status} />
       </div>
 
+      {/* Override Warning */}
+      {node.is_overridden && (
+        <div className="bg-yellow-950/40 border border-yellow-800/60 rounded-lg p-4 font-mono text-sm space-y-3">
+          <div className="flex items-center gap-2 text-yellow-400 font-semibold">
+            <span className="text-base">⚠</span>
+            <span>Local System Override Active</span>
+          </div>
+          <p className="text-gray-400 text-xs leading-relaxed">
+            This node is operating on a local system override. 
+            {node.override_timeout_at ? (
+              <> Resets automatically on: <span className="text-white font-bold">{new Date(node.override_timeout_at).toLocaleString()}</span>.</>
+            ) : (
+              <> No timeout is currently enforced (permanent override).</>
+            )}
+          </p>
+          <div className="flex gap-2">
+            {node.override_timeout_at && (
+              <button
+                onClick={async () => {
+                  try {
+                    await c2api.ackOverride(id, 1440);
+                  } catch (e) {
+                    alert("Failed to extend timer.");
+                  }
+                }}
+                className="px-3 py-1 bg-yellow-800 hover:bg-yellow-700 text-white rounded text-xs transition-colors"
+              >
+                Ack (Reset 24h Timer)
+              </button>
+            )}
+            <button
+              onClick={async () => {
+                if (confirm("Force this node to revert back to its assigned system config?")) {
+                  try {
+                    await c2api.resetOverride(id);
+                  } catch (e) {
+                    alert("Failed to reset override.");
+                  }
+                }
+              }}
+              className="px-3 py-1 bg-red-900 hover:bg-red-800 text-red-200 rounded text-xs transition-colors"
+            >
+              Force Revert Config
+            </button>
+          </div>
+        </div>
+      )}
+
       {/* Info */}
       <div className="bg-gray-900 border border-gray-800 rounded-lg divide-y divide-gray-800 font-mono text-sm">
         {[
@@ -199,6 +247,8 @@ export default function NodeDetailPage() {
           ["Location",  `${node.lat}, ${node.lon}`],
           ["Last Seen", node.last_seen ? new Date(node.last_seen).toLocaleString() : "never"],
           ["Configured", node.configured ? "Yes" : "No"],
+          ["Node Type", node.node_type ?? "fixed"],
+          ...(node.node_type !== "portable" ? [["Enforce Timeout", node.enforce_override_timeout ? "Yes" : "No"]] : []),
         ].map(([label, value]) => (
           <div key={label} className="flex justify-between px-4 py-2.5">
             <span className="text-gray-500">{label}</span>

drb-frontend/components/NodeCard.tsx

@@ -45,6 +45,18 @@ export function NodeCard({ node, system }: Props) {
             ⚠ Needs configuration
           </div>
         )}
+        {node.is_overridden && (
+          <div className="mt-3 text-xs text-yellow-500 font-mono border-t border-gray-800 pt-2 flex justify-between">
+            <span>⚠ Local Override</span>
+            {node.override_timeout_at ? (
+              <span className="text-gray-500">
+                Resets: {new Date(node.override_timeout_at).toLocaleTimeString()}
+              </span>
+            ) : (
+              <span className="text-gray-500">Permanent</span>
+            )}
+          </div>
+        )}
       </div>
     </Link>
   );

drb-frontend/components/NodeConfigModal.tsx

@@ -17,9 +17,11 @@ const PRESETS = [
 ];
 
 export function NodeConfigModal({ node, systems, onClose }: Props) {
-  const [systemId, setSystemId] = useState("");
-  const [preset, setPreset] = useState("rtl-sdr-v3");
-  const [ppm, setPpm] = useState("0");
+  const [systemId, setSystemId] = useState(node.assigned_system_id ?? "");
+  const [preset, setPreset] = useState(node.hardware_preset ?? "rtl-sdr-v3");
+  const [ppm, setPpm] = useState(node.ppm_override ? String(node.ppm_override) : "0");
+  const [nodeType, setNodeType] = useState(node.node_type ?? "fixed");
+  const [enforceTimeout, setEnforceTimeout] = useState(node.enforce_override_timeout ?? true);
   const [saving, setSaving] = useState(false);
   const [error, setError] = useState<string | null>(null);
 
@@ -32,6 +34,10 @@ export function NodeConfigModal({ node, systems, onClose }: Props) {
     setSaving(true);
     setError(null);
     try {
+      await c2api.updateNode(node.node_id, {
+        node_type: nodeType,
+        enforce_override_timeout: enforceTimeout,
+      });
       await c2api.assignSystem(node.node_id, systemId, preset, ppmOverride);
       onClose();
     } catch (err) {
@@ -100,6 +106,33 @@ export function NodeConfigModal({ node, systems, onClose }: Props) {
             />
           </div>
 
+          <div>
+            <label className="block text-xs text-gray-400 mb-1">Node Type</label>
+            <select
+              value={nodeType}
+              onChange={(e) => setNodeType(e.target.value)}
+              className="w-full bg-gray-800 border border-gray-700 rounded-lg px-3 py-2 text-white text-sm focus:outline-none focus:border-indigo-500"
+            >
+              <option value="fixed">Fixed Node (Standard)</option>
+              <option value="portable">Portable Node (Handheld)</option>
+            </select>
+          </div>
+
+          {nodeType === "fixed" && (
+            <div className="flex items-center gap-2 py-1">
+              <input
+                type="checkbox"
+                id="enforceTimeout"
+                checked={enforceTimeout}
+                onChange={(e) => setEnforceTimeout(e.target.checked)}
+                className="rounded bg-gray-800 border-gray-700 text-indigo-600 focus:ring-indigo-500 focus:ring-offset-gray-900"
+              />
+              <label htmlFor="enforceTimeout" className="text-xs text-gray-400 cursor-pointer select-none">
+                Enforce Local Override Timeout (24 hours)
+              </label>
+            </div>
+          )}
+
           {error && <p className="text-red-400 text-xs">{error}</p>}
 
           <div className="flex gap-3 pt-1">

drb-frontend/lib/c2api.ts

@@ -30,6 +30,12 @@ export const c2api = {
     if (ppmOverride !== undefined) params.set("ppm_override", String(ppmOverride));
     return request(`/nodes/${nodeId}/config/${systemId}?${params}`, { method: "POST" });
   },
+  ackOverride: (nodeId: string, timeoutMinutes: number = 1440) =>
+    request(`/nodes/${nodeId}/override/ack`, { method: "POST", body: JSON.stringify({ timeout_minutes: timeoutMinutes }) }),
+  resetOverride: (nodeId: string) =>
+    request(`/nodes/${nodeId}/override/reset`, { method: "POST" }),
+  updateNode: (id: string, body: { node_type?: string; enforce_override_timeout?: boolean }) =>
+    request(`/nodes/${id}`, { method: "PATCH", body: JSON.stringify(body) }),
 
   // Systems
   getSystems: () => request<unknown[]>("/systems"),

drb-frontend/lib/types.ts

@@ -52,6 +52,11 @@ export interface NodeRecord {
   approval_status: ApprovalStatus | null;
   hardware_preset?: string;
   ppm_override?: number | null;
+  node_type?: string;
+  enforce_override_timeout?: boolean;
+  is_overridden?: boolean;
+  override_system_id?: string | null;
+  override_timeout_at?: string | null;
 }
 
 export interface VocabularyPendingTerm {