fix(feishu): skip empty-text messages with no media to prevent blank session turns (#74634) (#74661)

Feishu delivers empty-text events (e.g. {"text":""}) when users send
blank messages or when a media-only message produces no text content.
Writing a blank user turn to the session file causes downstream LLM
providers such as MiniMax to reject requests with:

  invalid params, messages must not be empty (2013)

Guard at the point after media resolution: if ctx.content.trim() is
empty AND mediaList is empty, log the skip and return without queuing
a reply. This preserves all existing behaviour for text, media, and
mixed messages.

Regression test: dispatch a DM with {"text":""} (no media), assert
mockDispatchReplyFromConfig is not called.

Closes #74634. Thanks @xdengli.

extensions/feishu/src/bot.test.ts

@@ -2999,4 +2999,42 @@ describe("handleFeishuMessage command authorization", () => {
     await Promise.all([dispatchMessage({ cfg, event }), dispatchMessage({ cfg, event })]);
     expect(mockDispatchReplyFromConfig).toHaveBeenCalledTimes(1);
   });
+
+  it("skips empty-text messages with no media to prevent blank user turns in session (#74634)", async () => {
+    // Feishu can deliver { "text": "" } events (empty-text or media-stripped
+    // messages). Writing blank user content to the session causes downstream
+    // LLM providers such as MiniMax to reject requests with "messages must not
+    // be empty". The handler should drop such events before queuing a reply.
+    mockShouldComputeCommandAuthorized.mockReturnValue(false);
+
+    const cfg: ClawdbotConfig = {
+      channels: {
+        feishu: {
+          dmPolicy: "open",
+          allowFrom: ["*"],
+        },
+      },
+    } as ClawdbotConfig;
+
+    const event: FeishuMessageEvent = {
+      sender: {
+        sender_id: {
+          open_id: "ou-empty-text-sender",
+        },
+      },
+      message: {
+        message_id: "msg-empty-text-74634",
+        chat_id: "oc-dm",
+        chat_type: "p2p",
+        message_type: "text",
+        // Feishu encodes empty text as {"text":""}
+        content: JSON.stringify({ text: "" }),
+      },
+    };
+
+    await dispatchMessage({ cfg, event });
+
+    // No reply should be dispatched: empty message is silently skipped
+    expect(mockDispatchReplyFromConfig).not.toHaveBeenCalled();
+  });
 });

extensions/feishu/src/bot.ts

@@ -859,6 +859,19 @@ export async function handleFeishuMessage(params: {
       log,
       accountId: account.accountId,
     });
+    // Skip messages with no text content and no media attachments. Feishu can
+    // deliver empty-text events (e.g. `{"text":""}`) when a user sends a blank
+    // message or when media parsing produces an empty string. Writing a blank
+    // user turn to the session causes downstream LLM providers (e.g. MiniMax)
+    // to reject the request with "messages must not be empty" errors. Logging
+    // the skip avoids silent loss without polluting the agent session.
+    if (!ctx.content.trim() && mediaList.length === 0) {
+      log(
+        `feishu[${account.accountId}]: skipping empty message (no text, no media) from ${ctx.senderOpenId}`,
+      );
+      return;
+    }
+
     const mediaPayload = buildAgentMediaPayload(mediaList);
     const audioTranscript = await resolveFeishuAudioPreflightTranscript({
       cfg: effectiveCfg,