fix: guard mediaType fallback, add missing MIME + send-api tests, changelog

CHANGELOG.md

@@ -1030,6 +1030,7 @@ Docs: https://docs.openclaw.ai
 - Exec: harden host env override handling across gateway and node (#51207) Thanks @gladiator9797 and @joshavant.
 - Voice Call: enforce spoken-output contract and fix stream TTS silence regression (#51500) Thanks @joshavant.
 - xAI/models: rename the bundled Grok 4.20 catalog entries to the GA IDs and normalize saved deprecated beta IDs at runtime so existing configs and sessions keep resolving. (#50772) thanks @Jaaneek
+- WhatsApp/outbound media: fix HTML, XML, and CSS files being silently dropped on outbound send by adding missing MIME entries and falling back to `application/octet-stream` for unknown media types. (#51562) Thanks @bobbyt74
 - Agents/bootstrap warnings: move bootstrap truncation warnings out of the system prompt and into the per-turn prompt body so prompt-cache reuse stays stable when truncation warnings appear or disappear. (#48753) Thanks @scoootscooob and @obviyus.
 - Telegram/DM topic session keys: route named-account DM topics through the same per-account base session key across inbound messages, native commands, and session-state lookups so `/status` and thread recovery stop creating phantom `agent:main:main:thread:...` sessions. (#48204) Thanks @vincentkoc.
 - ACP/configured bindings: reinitialize configured ACP sessions that are stuck in `error` state instead of reusing the failed runtime.

extensions/whatsapp/src/inbound/send-api.test.ts

@@ -162,4 +162,24 @@ describe("createWebSendApi", () => {
     await api.sendComposingTo("+1555");
     expect(sendPresenceUpdate).toHaveBeenCalledWith("composing", "1555@s.whatsapp.net");
   });
+
+  it("sends media as document when mediaType is undefined", async () => {
+    const mediaBuffer = Buffer.from("test");
+
+    await api.sendMessage("123", "hello", mediaBuffer, undefined);
+
+    expect(sendMessage).toHaveBeenCalledWith(
+      "123@s.whatsapp.net",
+      expect.objectContaining({
+        document: mediaBuffer,
+        mimetype: "application/octet-stream",
+      }),
+    );
+  });
+
+  it("does not set mediaType when mediaBuffer is absent", async () => {
+    await api.sendMessage("123", "hello");
+
+    expect(sendMessage).toHaveBeenCalledWith("123@s.whatsapp.net", { text: "hello" });
+  });
 });

extensions/whatsapp/src/inbound/send-api.ts

@@ -34,7 +34,9 @@ export function createWebSendApi(params: {
     ): Promise<{ messageId: string }> => {
       const jid = toWhatsappJid(to);
       let payload: AnyMessageContent;
-      mediaType ??= "application/octet-stream";
+      if (mediaBuffer) {
+        mediaType ??= "application/octet-stream";
+      }
       if (mediaBuffer && mediaType) {
         if (mediaType.startsWith("image/")) {
           payload = {

src/media/mime.test.ts

@@ -138,6 +138,7 @@ describe("extensionForMime", () => {
     { mime: "text/html", expected: ".html" },
     { mime: "text/xml", expected: ".xml" },
     { mime: "text/css", expected: ".css" },
+    { mime: "application/xml", expected: ".xml" },
     { mime: "IMAGE/JPEG", expected: ".jpg" },
     { mime: "Audio/X-M4A", expected: ".m4a" },
     { mime: "Video/QuickTime", expected: ".mov" },