fix: read Slack thread replies for message reads (#1450) (#1450)

Co-authored-by: Peter Steinberger <steipete@gmail.com>
Co-authored-by: Rodrigo Uroz <rodrigouroz@users.noreply.github.com>

src/slack/actions.ts

@@ -186,9 +186,29 @@ export async function readSlackMessages(
     limit?: number;
     before?: string;
     after?: string;
+    threadId?: string;
   } = {},
 ): Promise<{ messages: SlackMessageSummary[]; hasMore: boolean }> {
   const client = await getClient(opts);
+
+  // Use conversations.replies for thread messages, conversations.history for channel messages.
+  if (opts.threadId) {
+    const result = await client.conversations.replies({
+      channel: channelId,
+      ts: opts.threadId,
+      limit: opts.limit,
+      latest: opts.before,
+      oldest: opts.after,
+    });
+    return {
+      // conversations.replies includes the parent message; drop it for replies-only reads.
+      messages: (result.messages ?? []).filter(
+        (message) => (message as SlackMessageSummary)?.ts !== opts.threadId,
+      ) as SlackMessageSummary[],
+      hasMore: Boolean(result.has_more),
+    };
+  }
+
   const result = await client.conversations.history({
     channel: channelId,
     limit: opts.limit,