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/carry-over-bot-session.ts

@@ -0,0 +1,123 @@
+import type { BUN_SQLITE_COBBLE_BOT_MESSAGES } from "@/db/types/db";
+import BunSQLite from "@moduletrace/bun-sqlite";
+import { AppData } from "@/src/data/app-data";
+import AppError from "@/src/utils/app-error";
+import insertBotMessage from "../bots/insert-bot-message";
+import createBotSession from "./create-bot-session";
+import grabActiveBotSession from "./grab-active-bot-session";
+
+type Params = {
+    /**
+     * The session the bot is answering in: it must be the conversation's
+     * active one.
+     */
+    session_id: number | string;
+    user_id: number | string;
+    bot_id: number;
+    workspace_id?: number | null;
+    /**
+     * What the next session needs to carry on (markdown), written by the
+     * bot.
+     */
+    summary: string;
+    /**
+     * The new session's title, written by the bot. Left out: the closed
+     * session's.
+     */
+    title?: string | null;
+    /**
+     * The reply moving it: its answer goes in the new session, under the
+     * summary.
+     */
+    job_id?: number | null;
+};
+
+/**
+ * Moves a conversation into a fresh session when the bot asks to
+ * (`continue_in_new_session`): the bot's summary is kept on the session it
+ * closes (covering all its messages, so `grabSessionCarryOver` hands it to
+ * the next prompt as written) and opens the new one as a bot message
+ * (`carried_from_session_id`), and the reply's own answer follows it
+ * there. The new session is titled by the bot (else after the old one).
+ * Returns that first message, for the caller to push.
+ */
+export default async function carryOverBotSession({
+    session_id,
+    user_id,
+    bot_id,
+    workspace_id,
+    summary,
+    title,
+    job_id,
+}: Params): Promise<BUN_SQLITE_COBBLE_BOT_MESSAGES> {
+    const text = summary.trim().slice(0, AppData.BotSessionSummaryMaxChars);
+
+    if (!text) throw new AppError(`The summary is empty.`);
+
+    const active = await grabActiveBotSession({ user_id, bot_id, workspace_id });
+
+    if (!active?.id || active.id != Number(session_id)) {
+        throw new AppError(`This session isn't the conversation's current one, so it can't be moved on from.`);
+    }
+
+    const message_count =
+        Number(
+            (
+                await BunSQLite.sql<{ n: number }>({
+                    sql: `SELECT COUNT(*) AS n FROM bot_messages WHERE session_id = ?`,
+                    values: [active.id],
+                })
+            ).payload?.[0]?.n,
+        ) || 0;
+
+    if (!message_count) {
+        throw new AppError(`This session has no messages yet: it's already fresh.`);
+    }
+
+    const now = Date.now();
+
+    await BunSQLite.sql({
+        sql: `UPDATE bot_sessions SET status = 'closed', unread = 0, summary = ?, summary_message_count = ?, updated_at = ?
+            WHERE id = ?`,
+        values: [text, message_count, now, active.id],
+    });
+
+    /**
+     * A session is named after its first exchange (`nameBotSession`), and
+     * this one opens with the bot's messages alone: it's named now, and
+     * previewed with the summary it opens with. The summary covers none
+     * of its own messages, so it's written again before it's carried on.
+     */
+    const next = await createBotSession({
+        user_id,
+        bot_id,
+        workspace_id,
+        previous_session_id: active.id,
+        title:
+            title?.replace(/\s+/g, " ").trim().slice(0, AppData.BotSessionTitleMaxChars) ||
+            active.title ||
+            null,
+    });
+
+    await BunSQLite.sql({
+        sql: `UPDATE bot_sessions SET summary = ?, summary_message_count = 0 WHERE id = ?`,
+        values: [text, next.id!],
+    });
+
+    const message = await insertBotMessage({
+        bot_id,
+        session_id: Number(next.id),
+        workspace_id,
+        text,
+        carried_from_session_id: active.id,
+    });
+
+    if (job_id) {
+        await BunSQLite.sql({
+            sql: `UPDATE bots_queue SET session_id = ? WHERE id = ?`,
+            values: [next.id!, job_id],
+        });
+    }
+
+    return message;
+}