diff --git a/webui/src/lib/nanobot-client.ts b/webui/src/lib/nanobot-client.ts
index 4b4d9d079..29afba534 100644
--- a/webui/src/lib/nanobot-client.ts
+++ b/webui/src/lib/nanobot-client.ts
@@ -109,10 +109,8 @@ interface PendingRequest<T> {
   timer: ReturnType<typeof setTimeout>;
 }
 
-type WebUIRequestFrame = Extract<Outbound, { type: "webui_request" }>;
-
 interface PendingWebUIRequest extends PendingRequest<unknown> {
-  frame: WebUIRequestFrame;
+  serializedFrame: string;
 }
 
 export class WebUIMutationError extends Error {
@@ -868,6 +866,13 @@ export class NanobotClient {
     }
 
     return new Promise<T>((resolve, reject) => {
+      let serializedFrame: string;
+      try {
+        serializedFrame = JSON.stringify(frame);
+      } catch {
+        reject(new WebUIMutationError(503, "Could not encode WebUI request"));
+        return;
+      }
       const timer = setTimeout(() => {
         this.pendingWebUIRequests.delete(requestId);
         reject(
@@ -881,10 +886,10 @@ export class NanobotClient {
         resolve: (value) => resolve(value as T),
         reject,
         timer,
-        frame,
+        serializedFrame,
       });
       try {
-        socket.send(JSON.stringify(frame));
+        socket.send(serializedFrame);
       } catch {
         clearTimeout(timer);
         this.pendingWebUIRequests.delete(requestId);
@@ -1028,7 +1033,7 @@ export class NanobotClient {
       this.rawSend({ type: "attach", chat_id: chatId });
     }
     for (const pending of this.pendingWebUIRequests.values()) {
-      this.rawSend(pending.frame);
+      this.rawSendSerialized(pending.serializedFrame);
     }
     // Flush anything queued during reconnect.
     const queued = this.sendQueue.splice(0);
@@ -1476,4 +1481,13 @@ export class NanobotClient {
       this.sendQueue.push(frame);
     }
   }
+
+  private rawSendSerialized(serializedFrame: string): void {
+    if (!this.socket) return;
+    try {
+      this.socket.send(serializedFrame);
+    } catch {
+      // The pending request remains available for the next successful reconnect.
+    }
+  }
 }
diff --git a/webui/src/tests/nanobot-client.test.ts b/webui/src/tests/nanobot-client.test.ts
index 6256e904a..3d15965bc 100644
--- a/webui/src/tests/nanobot-client.test.ts
+++ b/webui/src/tests/nanobot-client.test.ts
@@ -183,12 +183,12 @@ describe("NanobotClient", () => {
     const firstSocket = lastSocket();
     firstSocket.fakeOpen();
 
-    const pending = client.requestMutation<{ ran: boolean }>(
-      "automation.run",
-      { id: "daily-summary" },
-    );
+    const payload = { id: "daily-summary", options: { force: false } };
+    const pending = client.requestMutation<{ ran: boolean }>("automation.run", payload);
     const frame = firstSocket.sent.at(-1) as string;
     const requestId = JSON.parse(frame).request_id;
+    payload.id = "weekly-summary";
+    payload.options.force = true;
     const settled = expect(pending).resolves.toEqual({ ran: true });
     firstSocket.fakeCloseWithCode(1006);