fix(whatsapp): preserve outbound document filenames (#15594)

Merged via /review-pr -> /prepare-pr -> /merge-pr.

Prepared head SHA: 8e0d765d1d
Co-authored-by: TsekaLuk <79151285+TsekaLuk@users.noreply.github.com>
Co-authored-by: steipete <58493+steipete@users.noreply.github.com>
Reviewed-by: @steipete

src/web/inbound/send-api.test.ts

@@ -0,0 +1,54 @@
+import { beforeEach, describe, expect, it, vi } from "vitest";
+
+const recordChannelActivity = vi.fn();
+vi.mock("../../infra/channel-activity.js", () => ({
+  recordChannelActivity: (...args: unknown[]) => recordChannelActivity(...args),
+}));
+
+import { createWebSendApi } from "./send-api.js";
+
+describe("createWebSendApi", () => {
+  const sendMessage = vi.fn(async () => ({ key: { id: "msg-1" } }));
+  const sendPresenceUpdate = vi.fn(async () => {});
+  const api = createWebSendApi({
+    sock: { sendMessage, sendPresenceUpdate },
+    defaultAccountId: "main",
+  });
+
+  beforeEach(() => {
+    vi.clearAllMocks();
+  });
+
+  it("uses sendOptions fileName for outbound documents", async () => {
+    const payload = Buffer.from("pdf");
+    await api.sendMessage("+1555", "doc", payload, "application/pdf", { fileName: "invoice.pdf" });
+    expect(sendMessage).toHaveBeenCalledWith(
+      "1555@s.whatsapp.net",
+      expect.objectContaining({
+        document: payload,
+        fileName: "invoice.pdf",
+        caption: "doc",
+        mimetype: "application/pdf",
+      }),
+    );
+    expect(recordChannelActivity).toHaveBeenCalledWith({
+      channel: "whatsapp",
+      accountId: "main",
+      direction: "outbound",
+    });
+  });
+
+  it("falls back to default document filename when fileName is absent", async () => {
+    const payload = Buffer.from("pdf");
+    await api.sendMessage("+1555", "doc", payload, "application/pdf");
+    expect(sendMessage).toHaveBeenCalledWith(
+      "1555@s.whatsapp.net",
+      expect.objectContaining({
+        document: payload,
+        fileName: "file",
+        caption: "doc",
+        mimetype: "application/pdf",
+      }),
+    );
+  });
+});

src/web/inbound/send-api.ts

@@ -38,9 +38,10 @@ export function createWebSendApi(params: {
             ...(gifPlayback ? { gifPlayback: true } : {}),
           };
         } else {
+          const fileName = sendOptions?.fileName?.trim() || "file";
           payload = {
             document: mediaBuffer,
-            fileName: "file",
+            fileName,
             caption: text || undefined,
             mimetype: mediaType,
           };