slack: promote legacy-attachment content to message body text

src/slack/conversation-view.ts

@@ -10,6 +10,7 @@ import {
   collectEarlierThreadFiles,
   decodeSlackEntities,
   isOversize,
+  messageBodyText,
   recentWindow,
 } from "./lib.ts";
 import type { BotIdentity, Directory } from "./directory.ts";
@@ -157,7 +158,7 @@ export function createConversationSerializer(deps: {
       ts: m.ts as string,
       name: messageAuthorName(m, nameById, botNameById),
       ...(m.user || m.bot_id ? { authorId: String(m.user || m.bot_id) } : {}),
-      text: decodeSlackEntities(String(m.text ?? "").trim()),
+      text: decodeSlackEntities(messageBodyText(m).trim()),
       ...(m.ts === triggerTs ? { isTrigger: true } : {}),
       ...(m.bot_id ? { isBot: true } : {}),
       ...(isSelfMessage(m) ? { isSelf: true } : {}),
@@ -234,7 +235,7 @@ export function createConversationSerializer(deps: {
         kind: "thread",
         youOpenedIt,
         ...(starterName ? { starterName } : {}),
-        ...(youOpenedIt && root?.text ? { openerText: decodeSlackEntities(String(root.text).trim()) } : {}),
+        ...(youOpenedIt && root && messageBodyText(root).trim() ? { openerText: decodeSlackEntities(messageBodyText(root).trim()) } : {}),
       };
     } else {
       here = { kind: "top-level" };

src/slack/events.ts

@@ -6,6 +6,7 @@ import {
   isGroupMembershipMessage,
   isThreadReply,
   mentionsBot,
+  messageBodyText,
   onBotJoinedChannel,
   type SurfaceHeaderClient,
   shouldProcessMessage,
@@ -114,7 +115,7 @@ export function registerSlackEvents(
           channel: m.channel,
           userId: m.user,
           ...(m.bot_profile?.name || m.username ? { authorName: String(m.bot_profile?.name || m.username) } : {}),
-          rawText: m.text ?? "",
+          rawText: messageBodyText(m),
           files: (m.files as SlackFile[]) ?? [],
           threadTs: m.thread_ts,
           ts: m.ts,
@@ -152,7 +153,7 @@ export function registerSlackEvents(
           channel: m.channel,
           userId: m.user,
           ...(m.bot_profile?.name || m.username ? { authorName: String(m.bot_profile?.name || m.username) } : {}),
-          rawText: m.text ?? "",
+          rawText: messageBodyText(m),
           files: (m.files as SlackFile[]) ?? [],
           threadTs: m.thread_ts,
           ts: m.ts,

src/slack/lib.ts

@@ -37,6 +37,8 @@ export {
   channelPrivacyChange,
   createRefreshCoalescer,
   hasContent,
+  messageBodyText,
+  type LegacyAttachment,
   isThreadReply,
   createThreadTracker,
   dmThreadRef,

src/slack/message-gating.ts

@@ -75,6 +75,27 @@ export function hasContent(text: string, files: readonly unknown[]): boolean {
   return text.trim().length > 0 || files.length > 0;
 }
 
+export interface LegacyAttachment {
+  fallback?: string;
+  pretext?: string;
+  title?: string;
+  text?: string;
+}
+
+export function messageBodyText(m: { text?: string; attachments?: LegacyAttachment[] }): string {
+  if (m.text?.trim()) return m.text;
+  return (m.attachments ?? [])
+    .map((a) => {
+      const composed = [a.pretext, a.title, a.text]
+        .map((s) => s?.trim())
+        .filter(Boolean)
+        .join("\n");
+      return composed || a.fallback?.trim() || "";
+    })
+    .filter(Boolean)
+    .join("\n");
+}
+
 export function isThreadReply(m: { thread_ts?: string; ts?: string }): boolean {
   return Boolean(m.thread_ts) && m.thread_ts !== m.ts;
 }

src/slack/mirror.ts

@@ -1,5 +1,5 @@
 import { swallow } from "../util/errors.ts";
-import { decodeSlackEntities, mentionsBot, resolveMentionsInText } from "./lib.ts";
+import { decodeSlackEntities, mentionsBot, messageBodyText, resolveMentionsInText } from "./lib.ts";
 import type { SlackCoreClient } from "../api/slack-core-client.ts";
 import type { IngestEvent } from "../surface-cache/surface-cache.ts";
 import type { BotIdentity, Directory } from "./directory.ts";
@@ -104,7 +104,7 @@ export function createMirror(deps: {
       }
       if (!gate.allowed) return;
     }
-    const raw = String(m.text ?? "");
+    const raw = messageBodyText(m);
     const { text, mentions } = await resolveTextMentions(client, decodeSlackEntities(raw));
     await pushSurfaceEvents([
       {

test/slack-message-gating.test.ts

@@ -7,6 +7,7 @@ import {
   channelPrivacyChange,
   createRefreshCoalescer,
   hasContent,
+  messageBodyText,
   dmThreadRef,
   mentionsBot,
   threadHasBotStake,
@@ -288,3 +289,29 @@ test("createInFlightThreadMap: clear is runId-guarded so a finished run can't un
   runs.clear("dm:C1", "run-2");
   assert.equal(runs.get("dm:C1"), undefined);
 });
+
+test("messageBodyText returns text verbatim when present", () => {
+  assert.equal(messageBodyText({ text: "hello" }), "hello");
+  assert.equal(messageBodyText({ text: "hello", attachments: [{ fallback: "ignored" }] }), "hello");
+});
+
+test("messageBodyText falls back to attachment content for empty-text bot notifications", () => {
+  assert.equal(messageBodyText({ text: "" }), "");
+  assert.equal(messageBodyText({}), "");
+  assert.equal(
+    messageBodyText({ text: "", attachments: [{ fallback: "[org/repo] Pull request opened by someone" }] }),
+    "[org/repo] Pull request opened by someone",
+  );
+  assert.equal(
+    messageBodyText({ text: " ", attachments: [{ pretext: "pre", title: "PR #1", text: "body" }] }),
+    "pre\nPR #1\nbody",
+  );
+  assert.equal(
+    messageBodyText({ text: "", attachments: [{ fallback: "first" }, { title: "second" }, {}] }),
+    "first\nsecond",
+  );
+  assert.equal(
+    messageBodyText({ text: "", attachments: [{ fallback: "fb", title: "title only" }] }),
+    "title only",
+  );
+});