fix(slack): extract attachment text for bot messages with empty text (#27616) (#27642)

Verified:
- pnpm install --frozen-lockfile
- pnpm build
- pnpm check
- pnpm test:macmini

src/slack/monitor/message-handler/prepare.test.ts

@@ -255,6 +255,36 @@ describe("slack prepareSlackMessage inbound contract", () => {
     expect(prepared!.ctxPayload.RawBody).toContain("[Slack file: file]");
   });
 
+  it("extracts attachment text for bot messages with empty text when allowBots is true (#27616)", async () => {
+    const slackCtx = createInboundSlackCtx({
+      cfg: {
+        channels: {
+          slack: { enabled: true },
+        },
+      } as OpenClawConfig,
+      defaultRequireMention: false,
+    });
+    // oxlint-disable-next-line typescript/no-explicit-any
+    slackCtx.resolveUserName = async () => ({ name: "Bot" }) as any;
+
+    const account = createSlackAccount({ allowBots: true });
+    const message = createSlackMessage({
+      text: "",
+      bot_id: "B0AGV8EQYA3",
+      subtype: "bot_message",
+      attachments: [
+        {
+          text: "Readiness probe failed: Get http://10.42.13.132:8000/status: context deadline exceeded",
+        },
+      ],
+    });
+
+    const prepared = await prepareMessageWith(slackCtx, account, message);
+
+    expect(prepared).toBeTruthy();
+    expect(prepared!.ctxPayload.RawBody).toContain("Readiness probe failed");
+  });
+
   it("keeps channel metadata out of GroupSystemPrompt", async () => {
     const slackCtx = createInboundSlackCtx({
       cfg: {

src/slack/monitor/message-handler/prepare.ts

@@ -357,8 +357,25 @@ export async function prepareSlackMessage(params: {
       : undefined;
   const fileOnlyPlaceholder = fileOnlyFallback ? `[Slack file: ${fileOnlyFallback}]` : undefined;
 
+  // Bot messages (e.g. Prometheus, Gatus webhooks) often carry content only in
+  // non-forwarded attachments (is_share !== true).  Extract their text/fallback
+  // so the message isn't silently dropped when `allowBots: true` (#27616).
+  const botAttachmentText =
+    isBotMessage && !attachmentContent?.text
+      ? (message.attachments ?? [])
+          .map((a) => a.text?.trim() || a.fallback?.trim())
+          .filter(Boolean)
+          .join("\n")
+      : undefined;
+
   const rawBody =
-    [(message.text ?? "").trim(), attachmentContent?.text, mediaPlaceholder, fileOnlyPlaceholder]
+    [
+      (message.text ?? "").trim(),
+      attachmentContent?.text,
+      botAttachmentText,
+      mediaPlaceholder,
+      fileOnlyPlaceholder,
+    ]
       .filter(Boolean)
       .join("\n") || "";
   if (!rawBody) {