fix(webchat): support image-only sends

src/gateway/protocol/schema/logs-chat.ts

@@ -35,7 +35,7 @@ export const ChatHistoryParamsSchema = Type.Object(
 export const ChatSendParamsSchema = Type.Object(
   {
     sessionKey: NonEmptyString,
-    message: NonEmptyString,
+    message: Type.String(),
     thinking: Type.Optional(Type.String()),
     deliver: Type.Optional(Type.Boolean()),
     attachments: Type.Optional(Type.Array(Type.Unknown())),

src/gateway/server-methods/chat.ts

@@ -338,6 +338,15 @@ export const chatHandlers: GatewayRequestHandlers = {
                 : undefined,
         }))
         .filter((a) => a.content) ?? [];
+    const rawMessage = p.message.trim();
+    if (!rawMessage && normalizedAttachments.length === 0) {
+      respond(
+        false,
+        undefined,
+        errorShape(ErrorCodes.INVALID_REQUEST, "message or attachment required"),
+      );
+      return;
+    }
     let parsedMessage = p.message;
     let parsedImages: ChatImageContent[] = [];
     if (normalizedAttachments.length > 0) {

src/gateway/server.chat.gateway-server-chat.e2e.test.ts

@@ -208,6 +208,39 @@ describe("gateway server chat", () => {
         | undefined;
       expect(imgOpts?.images).toEqual([{ type: "image", data: pngB64, mimeType: "image/png" }]);
 
+      const callsBeforeImageOnly = spy.mock.calls.length;
+      const reqIdOnly = "chat-img-only";
+      ws.send(
+        JSON.stringify({
+          type: "req",
+          id: reqIdOnly,
+          method: "chat.send",
+          params: {
+            sessionKey: "main",
+            message: "",
+            idempotencyKey: "idem-img-only",
+            attachments: [
+              {
+                type: "image",
+                mimeType: "image/png",
+                fileName: "dot.png",
+                content: `data:image/png;base64,${pngB64}`,
+              },
+            ],
+          },
+        }),
+      );
+
+      const imgOnlyRes = await onceMessage(ws, (o) => o.type === "res" && o.id === reqIdOnly, 8000);
+      expect(imgOnlyRes.ok).toBe(true);
+      expect(imgOnlyRes.payload?.runId).toBeDefined();
+
+      await waitFor(() => spy.mock.calls.length > callsBeforeImageOnly, 8000);
+      const imgOnlyOpts = spy.mock.calls.at(-1)?.[1] as
+        | { images?: Array<{ type: string; data: string; mimeType: string }> }
+        | undefined;
+      expect(imgOnlyOpts?.images).toEqual([{ type: "image", data: pngB64, mimeType: "image/png" }]);
+
       const historyDir = await fs.mkdtemp(path.join(os.tmpdir(), "clawdbot-gw-"));
       tempDirs.push(historyDir);
       testState.sessionStorePath = path.join(historyDir, "sessions.json");