fix: harden Slack file-only fallback placeholder (#25181) (thanks @justinhuangcode)

CHANGELOG.md

@@ -22,6 +22,7 @@ Docs: https://docs.openclaw.ai
 - Telegram/Markdown spoilers: keep valid `||spoiler||` pairs while leaving unmatched trailing `||` delimiters as literal text, avoiding false all-or-nothing spoiler suppression. (#26105) Thanks @Sid-Qin.
 - Hooks/Inbound metadata: include `guildId` and `channelName` in `message_received` metadata for both plugin and internal hook paths. (#26115) Thanks @davidrudduck.
 - Discord/Component auth: evaluate guild component interactions with command-gating authorizers so unauthorized users no longer get `CommandAuthorized: true` on modal/button events. (#26119) Thanks @bmendonca3.
+- Slack/Inbound media fallback: deliver file-only messages even when Slack media downloads fail by adding a filename placeholder fallback, capping fallback names to the shared media-file limit, and normalizing empty filenames to `file` so attachment-only messages are not silently dropped. (#25181) Thanks @justinhuangcode.
 
 ## 2026.2.24
 

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

@@ -239,6 +239,18 @@ describe("slack prepareSlackMessage inbound contract", () => {
     expect(prepared!.ctxPayload.RawBody).toContain("photo.jpg");
   });
 
+  it("falls back to generic file label when a Slack file name is empty", async () => {
+    const prepared = await prepareWithDefaultCtx(
+      createSlackMessage({
+        text: "",
+        files: [{ name: "" }],
+      }),
+    );
+
+    expect(prepared).toBeTruthy();
+    expect(prepared!.ctxPayload.RawBody).toContain("[Slack file: file]");
+  });
+
   it("keeps channel metadata out of GroupSystemPrompt", async () => {
     const slackCtx = createInboundSlackCtx({
       cfg: {

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

@@ -371,7 +371,7 @@ export async function prepareSlackMessage(params: {
     !mediaPlaceholder && (message.files?.length ?? 0) > 0
       ? message
           .files!.slice(0, MAX_SLACK_MEDIA_FILES)
-          .map((f) => f.name ?? "file")
+          .map((f) => f.name?.trim() || "file")
           .join(", ")
       : undefined;
   const fileOnlyPlaceholder = fileOnlyFallback ? `[Slack file: ${fileOnlyFallback}]` : undefined;