Carry conversations into new sessions with a visible summary

- Bots get continue_in_new_session: the bot writes a title and summary,
  the session closes for good (read-only) and the new one opens with the
  summary as a "Carried over from the last session" message that links
  back to the old session.
- Continue in new session (conversation menu, sessions modal) and the
  automatic rollover at the session length do the same; New session now
  starts a fresh, unlinked session.
- Session length is an app setting in Settings > General.
- ?session_id= opens a session; a carried-over one shows a bar linking to
  where the conversation went on instead of the composer.
- The thread can open the previous session above the current one (shown
  only, never in the prompt), and replies get search_past_sessions and
  read_past_session.
- Sessions are named from their opening messages, not their latest, and
  a carried summary is labelled as the earlier session's.

Co-Authored-By: Claude Opus 5.5 <[email protected]>

src/functions/backend/db/bot-sessions/grab-conversation-history.ts

@@ -3,6 +3,9 @@ import type { ConversationHistory } from "@/src/types";
 import grabActiveBotTask from "../bots/grab-active-bot-task";
 import grabBotMessages from "../bots/grab-bot-messages";
 import ensureBotSession from "./ensure-bot-session";
+import grabCarriedToSessionId from "./grab-carried-to-session-id";
+import reopenBotSession from "./reopen-bot-session";
+import grabUserBotSession from "./grab-user-bot-session";
 import grabUserConversation from "./grab-user-conversation";
 import markBotSessionRead from "./mark-bot-session-read";
 
@@ -13,12 +16,20 @@ type Params = {
      * The workspace the conversation is in; none for the bot's own chat.
      */
     workspace_id?: number | string | null;
+    /**
+     * A session of the conversation to show instead of the active one
+     * (the page's `?session_id=`). One that isn't the user's, or is in
+     * another conversation, is ignored.
+     */
+    session_id?: number | string | null;
 };
 
 /**
  * A conversation's history, which the conversation pages load on the
  * client once they render (`api/admin/bots/conversation-history`): the
- * bot's active session there (marked read), its latest
+ * bot's active session there, or the one asked for (marked read; a closed
+ * one is reopened, unless it was carried over, which only shows, with
+ * where the conversation went on), its latest
  * `AppData.ConversationFirstMessages` messages (the thread loads older
  * ones as it scrolls) and the bot's active task in it. Everything else on
  * the page comes with it from the server (`grabConversationProps`).
@@ -28,6 +39,7 @@ export default async function grabConversationHistory({
     user_id,
     bot_id,
     workspace_id,
+    session_id,
 }: Params): Promise<ConversationHistory | null> {
     const conversation = await grabUserConversation({ user_id, bot_id, workspace_id }).catch(
         () => null,
@@ -36,11 +48,37 @@ export default async function grabConversationHistory({
     if (!conversation?.bot?.id) return null;
 
     const open_bot_id = conversation.bot.id;
-    const session = await ensureBotSession({
-        user_id,
-        bot_id: open_bot_id,
-        workspace_id: conversation.workspace_id,
-    });
+    const conversation_workspace_id = conversation.workspace_id || null;
+
+    const asked = session_id
+        ? await grabUserBotSession({ session_id, user_id })
+        : null;
+
+    const in_conversation =
+        asked?.id &&
+        Number(asked.bot_id) == Number(open_bot_id) &&
+        (asked.workspace_id ? Number(asked.workspace_id) : null) ==
+            (conversation_workspace_id ? Number(conversation_workspace_id) : null);
+
+    /**
+     * A closed session asked for is reopened, as clicking it in a list
+     * does, unless it was carried over into a newer one: that one only
+     * shows, with the way to where the conversation went on.
+     */
+    const carried_to =
+        in_conversation && asked.status != "active"
+            ? await grabCarriedToSessionId({ session_id: asked.id!, user_id })
+            : null;
+
+    const session = !in_conversation
+        ? await ensureBotSession({
+              user_id,
+              bot_id: open_bot_id,
+              workspace_id: conversation.workspace_id,
+          })
+        : asked.status == "active" || carried_to
+          ? asked
+          : await reopenBotSession({ session_id: asked.id!, user_id });
 
     if (session.unread) {
         await markBotSessionRead({ session_id: session.id!, user_id });
@@ -63,5 +101,6 @@ export default async function grabConversationHistory({
         messages: has_more ? messages.slice(1) : messages,
         has_more,
         task,
+        moved_to_session_id: carried_to,
     };
 }