Outbound: avoid empty multi-media fallback sends

src/infra/outbound/deliver.test.ts

@@ -918,9 +918,59 @@ describe("deliverOutboundPayloads", () => {
         text: "caption",
       }),
     );
+    expect(logMocks.warn).toHaveBeenCalledWith(
+      "Plugin outbound adapter does not implement sendMedia; media URLs will be dropped and text fallback will be used",
+      expect.objectContaining({
+        channel: "matrix",
+        mediaCount: 1,
+      }),
+    );
     expect(results).toEqual([{ channel: "matrix", messageId: "mx-1" }]);
   });
 
+  it("falls back to one sendText call for multi-media payloads when sendMedia is omitted", async () => {
+    const sendText = vi.fn().mockResolvedValue({ channel: "matrix", messageId: "mx-2" });
+    setActivePluginRegistry(
+      createTestRegistry([
+        {
+          pluginId: "matrix",
+          source: "test",
+          plugin: createOutboundTestPlugin({
+            id: "matrix",
+            outbound: { deliveryMode: "direct", sendText },
+          }),
+        },
+      ]),
+    );
+
+    const results = await deliverOutboundPayloads({
+      cfg: {},
+      channel: "matrix",
+      to: "!room:1",
+      payloads: [
+        {
+          text: "caption",
+          mediaUrls: ["https://example.com/a.png", "https://example.com/b.png"],
+        },
+      ],
+    });
+
+    expect(sendText).toHaveBeenCalledTimes(1);
+    expect(sendText).toHaveBeenCalledWith(
+      expect.objectContaining({
+        text: "caption",
+      }),
+    );
+    expect(logMocks.warn).toHaveBeenCalledWith(
+      "Plugin outbound adapter does not implement sendMedia; media URLs will be dropped and text fallback will be used",
+      expect.objectContaining({
+        channel: "matrix",
+        mediaCount: 2,
+      }),
+    );
+    expect(results).toEqual([{ channel: "matrix", messageId: "mx-2" }]);
+  });
+
   it("emits message_sent failure when delivery errors", async () => {
     hookMocks.runner.hasHooks.mockReturnValue(true);
     const sendWhatsApp = vi.fn().mockRejectedValue(new Error("downstream failed"));

src/infra/outbound/deliver.ts

@@ -97,6 +97,7 @@ type ChannelHandler = {
   chunker: Chunker | null;
   chunkerMode?: "text" | "markdown";
   textChunkLimit?: number;
+  supportsMedia: boolean;
   sendPayload?: (
     payload: ReplyPayload,
     overrides?: {
@@ -169,6 +170,7 @@ function createPluginHandler(
     chunker,
     chunkerMode,
     textChunkLimit: outbound.textChunkLimit,
+    supportsMedia: Boolean(sendMedia),
     sendPayload: outbound.sendPayload
       ? async (payload, overrides) =>
           outbound.sendPayload!({
@@ -737,6 +739,30 @@ async function deliverOutboundPayloadsCore(
         continue;
       }
 
+      if (!handler.supportsMedia) {
+        log.warn(
+          "Plugin outbound adapter does not implement sendMedia; media URLs will be dropped and text fallback will be used",
+          {
+            channel,
+            to,
+            mediaCount: payloadSummary.mediaUrls.length,
+          },
+        );
+        const fallbackText = payloadSummary.text.trim();
+        if (!fallbackText) {
+          continue;
+        }
+        const beforeCount = results.length;
+        await sendTextChunks(fallbackText, sendOverrides);
+        const messageId = results.at(-1)?.messageId;
+        emitMessageSent({
+          success: results.length > beforeCount,
+          content: payloadSummary.text,
+          messageId,
+        });
+        continue;
+      }
+
       let first = true;
       let lastMessageId: string | undefined;
       for (const url of payloadSummary.mediaUrls) {