feat(config): add broadcastReplies option

README.md

@@ -42,6 +42,7 @@ Add to your `~/.openacp/config.json`:
 | `autoCreateSession` | Create a startup session on boot. Default: `true` |
 | `outputMode` | Default verbosity: `"low"`, `"medium"`, or `"high"`. Default: `"medium"` |
 | `subscribedChannels` | Optional. Channels to watch: `[{ "channelId": "C...", "trigger": "mention" \| "all" }]`. Invite the bot to each. Default: `[]` |
+| `broadcastReplies` | Optional. Also mirror the bot's threaded replies into the channel's main timeline (Slack `reply_broadcast`), so important answers are visible without opening the thread. Default: `false` |
 
 ### Output Mode
 

src/__tests__/config-schema.test.ts

@@ -11,4 +11,14 @@ describe("SlackChannelConfigSchema", () => {
     const cfg = SlackChannelConfigSchema.parse({ respondToDms: false });
     expect(cfg.respondToDms).toBe(false);
   });
+
+  it("defaults broadcastReplies to false", () => {
+    const cfg = SlackChannelConfigSchema.parse({});
+    expect(cfg.broadcastReplies).toBe(false);
+  });
+
+  it("allows broadcastReplies to be enabled", () => {
+    const cfg = SlackChannelConfigSchema.parse({ broadcastReplies: true });
+    expect(cfg.broadcastReplies).toBe(true);
+  });
 });

src/__tests__/text-buffer.test.ts

@@ -137,4 +137,34 @@ describe("SlackTextBuffer", () => {
       expect.objectContaining({ channel: "C_SUB", thread_ts: "169.1" }),
     );
   });
+
+  it("does not set reply_broadcast by default", async () => {
+    const enqueue = vi.fn().mockResolvedValue({ ts: "1.1" });
+    const queue = { enqueue } as any;
+    const buf = new SlackTextBuffer("C_SUB", "169.1", "sess-1", queue);
+    buf.append("hello world");
+    await buf.flush();
+    expect(enqueue.mock.calls[0][1]).not.toHaveProperty("reply_broadcast");
+  });
+
+  it("sets reply_broadcast on threaded replies when broadcast is enabled", async () => {
+    const enqueue = vi.fn().mockResolvedValue({ ts: "1.1" });
+    const queue = { enqueue } as any;
+    const buf = new SlackTextBuffer("C_SUB", "169.1", "sess-1", queue, undefined, true);
+    buf.append("important answer");
+    await buf.flush();
+    expect(enqueue).toHaveBeenCalledWith(
+      "chat.postMessage",
+      expect.objectContaining({ thread_ts: "169.1", reply_broadcast: true }),
+    );
+  });
+
+  it("omits reply_broadcast when broadcast is enabled but there is no thread", async () => {
+    const enqueue = vi.fn().mockResolvedValue({ ts: "1.1" });
+    const queue = { enqueue } as any;
+    const buf = new SlackTextBuffer("C_SUB", undefined, "sess-1", queue, undefined, true);
+    buf.append("dm answer");
+    await buf.flush();
+    expect(enqueue.mock.calls[0][1]).not.toHaveProperty("reply_broadcast");
+  });
 });

src/adapter.ts

@@ -1053,7 +1053,7 @@ export class SlackAdapter extends MessagingAdapter {
   private getTextBuffer(sessionId: string, channelId: string, threadTs?: string): SlackTextBuffer {
     let buf = this.textBuffers.get(sessionId);
     if (!buf) {
-      buf = new SlackTextBuffer(channelId, threadTs, sessionId, this.queue, this.log);
+      buf = new SlackTextBuffer(channelId, threadTs, sessionId, this.queue, this.log, this.slackConfig.broadcastReplies);
       this.textBuffers.set(sessionId, buf);
     }
     return buf;

src/text-buffer.ts

@@ -23,6 +23,7 @@ export class SlackTextBuffer {
     private sessionId: string,
     private queue: ISlackSendQueue,
     logger?: Logger,
+    private broadcast: boolean = false,
   ) {
     this.log = logger ?? { info() {}, warn() {}, error() {}, debug() {} };
   }
@@ -57,6 +58,9 @@ export class SlackTextBuffer {
           const result = await this.queue.enqueue("chat.postMessage", {
             channel: this.channelId,
             ...(this.threadTs ? { thread_ts: this.threadTs } : {}),
+            // reply_broadcast only has meaning on a threaded reply; Slack
+            // ignores it on top-level posts.
+            ...(this.threadTs && this.broadcast ? { reply_broadcast: true } : {}),
             text: chunk,
             blocks: [{ type: "section", text: { type: "mrkdwn", text: chunk } }],
           });

src/types.ts

@@ -48,6 +48,13 @@ export const SlackChannelConfigSchema = z.object({
    * gates who may start a DM session. Set false to ignore DMs entirely.
    */
   respondToDms: z.boolean().default(true),
+  /**
+   * When true, the bot's reply text in subscribed-channel threads is also
+   * mirrored into the channel's main timeline via Slack's `reply_broadcast`,
+   * so important answers are visible without opening the thread. Only affects
+   * threaded replies; DM and non-threaded output are unchanged. Default false.
+   */
+  broadcastReplies: z.boolean().default(false),
 });
 
 export type SlackChannelConfig = z.infer<typeof SlackChannelConfigSchema>;