fix(whatsapp): allow media-only sends and normalize leading blank payloads (#14408)

Co-authored-by: Tak Hoffman <781889+Takhoffman@users.noreply.github.com>

src/gateway/server-methods/send.test.ts

@@ -1,4 +1,4 @@
-import { describe, expect, it, vi } from "vitest";
+import { beforeEach, describe, expect, it, vi } from "vitest";
 import type { GatewayRequestContext } from "./types.js";
 import { sendHandlers } from "./send.js";
 
@@ -47,6 +47,67 @@ const makeContext = (): GatewayRequestContext =>
   }) as unknown as GatewayRequestContext;
 
 describe("gateway send mirroring", () => {
+  beforeEach(() => {
+    vi.clearAllMocks();
+  });
+
+  it("accepts media-only sends without message", async () => {
+    mocks.deliverOutboundPayloads.mockResolvedValue([{ messageId: "m-media", channel: "slack" }]);
+
+    const respond = vi.fn();
+    await sendHandlers.send({
+      params: {
+        to: "channel:C1",
+        mediaUrl: "https://example.com/a.png",
+        channel: "slack",
+        idempotencyKey: "idem-media-only",
+      },
+      respond,
+      context: makeContext(),
+      req: { type: "req", id: "1", method: "send" },
+      client: null,
+      isWebchatConnect: () => false,
+    });
+
+    expect(mocks.deliverOutboundPayloads).toHaveBeenCalledWith(
+      expect.objectContaining({
+        payloads: [{ text: "", mediaUrl: "https://example.com/a.png", mediaUrls: undefined }],
+      }),
+    );
+    expect(respond).toHaveBeenCalledWith(
+      true,
+      expect.objectContaining({ messageId: "m-media" }),
+      undefined,
+      expect.objectContaining({ channel: "slack" }),
+    );
+  });
+
+  it("rejects empty sends when neither text nor media is present", async () => {
+    const respond = vi.fn();
+    await sendHandlers.send({
+      params: {
+        to: "channel:C1",
+        message: "   ",
+        channel: "slack",
+        idempotencyKey: "idem-empty",
+      },
+      respond,
+      context: makeContext(),
+      req: { type: "req", id: "1", method: "send" },
+      client: null,
+      isWebchatConnect: () => false,
+    });
+
+    expect(mocks.deliverOutboundPayloads).not.toHaveBeenCalled();
+    expect(respond).toHaveBeenCalledWith(
+      false,
+      undefined,
+      expect.objectContaining({
+        message: expect.stringContaining("text or media is required"),
+      }),
+    );
+  });
+
   it("does not mirror when delivery returns no results", async () => {
     mocks.deliverOutboundPayloads.mockResolvedValue([]);