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/app-settings/grab-bot-session-max-messages.ts

@@ -0,0 +1,31 @@
+import { AppData } from "@/src/data/app-data";
+import { BotSessionMaxMessagesSettingKey } from "@/src/dict/bot-dict";
+import type { SessionLengthOverview } from "@/src/types";
+import readStepLimit from "@/src/utils/read-step-limit";
+import grabAppSetting from "./grab-app-setting";
+
+/**
+ * How many messages a session takes before the user's next message starts
+ * a new one: the install's own number (`bot_session_max_messages`,
+ * Settings > General), else `AppData.BotSessionMaxMessages`.
+ */
+export async function grabBotSessionMaxMessages() {
+    return readStepLimit({
+        saved: await grabAppSetting({ key: BotSessionMaxMessagesSettingKey }),
+        fallback: AppData.BotSessionMaxMessages,
+        max: AppData.BotSessionMaxMessagesMax,
+    });
+}
+
+/**
+ * The number with its default and ceiling, for the settings page.
+ */
+export default async function grabSessionLengthOverview() {
+    const overview: SessionLengthOverview = {
+        max_messages: await grabBotSessionMaxMessages(),
+        default_messages: AppData.BotSessionMaxMessages,
+        max: AppData.BotSessionMaxMessagesMax,
+    };
+
+    return overview;
+}

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;
+}

src/functions/backend/db/bot-sessions/continue-bot-session.ts

@@ -0,0 +1,84 @@
+import type { BUN_SQLITE_COBBLE_BOT_MESSAGES } from "@/db/types/db";
+import { AppData } from "@/src/data/app-data";
+import { SessionContinuePrompt } from "@/src/data/harness-prompts";
+import parseSessionName from "@/src/bots-queue/parse-session-name";
+import sessionNameTranscript from "@/src/bots-queue/session-name-transcript";
+import generateText from "@/src/harness/text/generate-text";
+import { runWithHarnessUsageScope } from "@/src/harness/usage/harness-usage-scope";
+import AppError from "@/src/utils/app-error";
+import grabBotMessages from "../bots/grab-bot-messages";
+import carryOverBotSession from "./carry-over-bot-session";
+import grabActiveBotSession from "./grab-active-bot-session";
+import hasOpenSessionJob from "./has-open-session-job";
+
+type Params = {
+    user_id: number | string;
+    bot_id: number;
+    workspace_id?: number | null;
+};
+
+/**
+ * Continue in new session, asked by the user from the conversation's
+ * menu (and the automatic rollover, `rollOverBotSession`): does what the
+ * bot does with `continue_in_new_session`. The bot's
+ * text model writes the new session's title and the summary from the
+ * session's latest messages, then `carryOverBotSession` closes this
+ * session for good and opens the new one with the summary. Refused while
+ * the bot is still working in the session, since its answer would land in
+ * the closed one. Returns the summary's message, for the caller to push.
+ */
+export default async function continueBotSession({
+    user_id,
+    bot_id,
+    workspace_id,
+}: Params): Promise<BUN_SQLITE_COBBLE_BOT_MESSAGES> {
+    const active = await grabActiveBotSession({ user_id, bot_id, workspace_id });
+
+    if (!active?.id) throw new AppError(`This conversation has no session to continue from yet.`);
+
+    if (await hasOpenSessionJob({ session_id: active.id })) {
+        throw new AppError(`The bot is still working in this session. Wait for it to finish, or stop it, then continue.`);
+    }
+
+    const messages = await grabBotMessages({
+        session_id: active.id,
+        limit: AppData.BotSessionSummaryMessages,
+    });
+
+    if (!messages.length) throw new AppError(`This session has no messages yet: it's already fresh.`);
+
+    const result = await runWithHarnessUsageScope({
+        scope: {
+            user_id,
+            bot_id,
+            workspace_id: workspace_id || null,
+            session_id: active.id,
+            job_id: null,
+            message_id: null,
+        },
+        task: () =>
+            generateText({
+                messages: [
+                    { role: "system", content: SessionContinuePrompt },
+                    { role: "user", content: sessionNameTranscript({ messages }) },
+                ],
+                bot_id,
+                workspace_id,
+            }),
+    });
+
+    const written = parseSessionName({ text: result.text });
+
+    if (!written?.summary) {
+        throw new AppError(`Couldn't write the summary to carry over. Try again.`);
+    }
+
+    return await carryOverBotSession({
+        session_id: active.id,
+        user_id,
+        bot_id,
+        workspace_id,
+        summary: written.summary,
+        title: written.title,
+    });
+}

src/functions/backend/db/bot-sessions/ensure-bot-session.ts

@@ -1,9 +1,9 @@
 import type { BUN_SQLITE_COBBLE_BOT_SESSIONS } from "@/db/types/db";
 import BunSQLite from "@moduletrace/bun-sqlite";
-import { AppData } from "@/src/data/app-data";
+import { grabBotSessionMaxMessages } from "../app-settings/grab-bot-session-max-messages";
 import createBotSession from "./create-bot-session";
 import grabActiveBotSession from "./grab-active-bot-session";
-import startBotSession from "./start-bot-session";
+import rollOverBotSession from "./roll-over-bot-session";
 
 type Params = {
     /**
@@ -13,8 +13,8 @@ type Params = {
     bot_id: number | string;
     workspace_id?: number | string | null;
     /**
-     * Start the next session when the active one is full
-     * (`AppData.BotSessionMaxMessages`). Set when the user writes, so a
+     * Carry the conversation into a new session when the active one is
+     * full (`grabBotSessionMaxMessages`, `rollOverBotSession`). Set when the user writes, so a
      * message never lands in a session that's about to be cut.
      */
     rollover?: boolean;
@@ -22,8 +22,8 @@ type Params = {
 
 /**
  * The user's conversation's active session, started first when there is none
- * (carrying on from its latest closed one) or, with `rollover`, when the
- * active one is full.
+ * (fresh) or, with `rollover`, carried into a new one when the active one
+ * is full.
  */
 export default async function ensureBotSession({
     user_id,
@@ -46,23 +46,15 @@ export default async function ensureBotSession({
                 ).payload?.[0]?.n,
             ) || 0;
 
-        return count < AppData.BotSessionMaxMessages
+        return count < (await grabBotSessionMaxMessages())
             ? active
-            : await startBotSession({ user_id, bot_id, workspace_id });
+            : await rollOverBotSession({
+                  user_id,
+                  bot_id: Number(bot_id),
+                  workspace_id: workspace_id ? Number(workspace_id) : null,
+                  active,
+              });
     }
 
-    const latest = (
-        await BunSQLite.sql<BUN_SQLITE_COBBLE_BOT_SESSIONS>({
-            sql: `SELECT id FROM bot_sessions WHERE user_id = ? AND bot_id = ? AND workspace_id IS ?
-                ORDER BY last_activity_at DESC, id DESC LIMIT 1`,
-            values: [user_id, bot_id, workspace_id ? Number(workspace_id) : null],
-        })
-    ).payload?.[0];
-
-    return await createBotSession({
-        user_id,
-        bot_id,
-        workspace_id,
-        previous_session_id: latest?.id || null,
-    });
+    return await createBotSession({ user_id, bot_id, workspace_id });
 }

src/functions/backend/db/bot-sessions/grab-carried-to-session-id.ts

@@ -0,0 +1,22 @@
+import BunSQLite from "@moduletrace/bun-sqlite";
+
+type Params = {
+    session_id: number | string;
+    user_id: number | string;
+};
+
+/**
+ * The session a closed session of the user's was carried into
+ * (`carryOverBotSession`), or null when it wasn't carried over.
+ */
+export default async function grabCarriedToSessionId({ session_id, user_id }: Params): Promise<number | null> {
+    const carried = (
+        await BunSQLite.sql<{ session_id: number }>({
+            sql: `SELECT m.session_id FROM bot_messages m JOIN bot_sessions s ON s.id = m.session_id
+                WHERE m.carried_from_session_id = ? AND s.user_id = ? ORDER BY m.id DESC LIMIT 1`,
+            values: [session_id, user_id],
+        })
+    ).payload?.[0];
+
+    return carried?.session_id ? Number(carried.session_id) : null;
+}

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,
     };
 }

src/functions/backend/db/bot-sessions/grab-past-session-messages.ts

@@ -0,0 +1,127 @@
+import type { BUN_SQLITE_COBBLE_BOT_MESSAGES, BUN_SQLITE_COBBLE_BOT_SESSIONS } from "@/db/types/db";
+import BunSQLite from "@moduletrace/bun-sqlite";
+import AppError from "@/src/utils/app-error";
+import type { PastSessionScope } from "./past-session-messages-sql";
+
+type Params = PastSessionScope & {
+    /**
+     * Read around this message (and in its session).
+     */
+    message_id?: number | null;
+    /**
+     * Read this session from its start, or from after `after_id`. Left
+     * out (with no `message_id`): the session the current one carries on
+     * from.
+     */
+    session_id?: number | null;
+    after_id?: number | null;
+    /**
+     * Messages to return (around a message: about half before it).
+     */
+    limit: number;
+};
+
+export type PastSessionRead = {
+    session: Pick<BUN_SQLITE_COBBLE_BOT_SESSIONS, "id" | "title" | "previous_session_id">;
+    messages: Pick<BUN_SQLITE_COBBLE_BOT_MESSAGES, "id" | "author" | "text" | "created_at">[];
+    /**
+     * More of the session comes after the last message returned.
+     */
+    has_more: boolean;
+};
+
+/**
+ * Reads messages of one of the conversation's earlier sessions, oldest
+ * first: around a message, or a session in order. A session outside the
+ * conversation (another user's, another bot's, another place's) or the
+ * one being answered is never read.
+ */
+export default async function grabPastSessionMessages({
+    user_id,
+    bot_id,
+    workspace_id,
+    current_session_id,
+    message_id,
+    session_id,
+    after_id,
+    limit,
+}: Params): Promise<PastSessionRead> {
+    const target_session_id = message_id
+        ? (
+              await BunSQLite.sql<{ session_id: number }>({
+                  sql: `SELECT session_id FROM bot_messages WHERE id = ? LIMIT 1`,
+                  values: [message_id],
+              })
+          ).payload?.[0]?.session_id
+        : session_id ||
+          (
+              await BunSQLite.sql<{ previous_session_id: number }>({
+                  sql: `SELECT previous_session_id FROM bot_sessions WHERE id = ? LIMIT 1`,
+                  values: [current_session_id],
+              })
+          ).payload?.[0]?.previous_session_id;
+
+    if (!target_session_id) {
+        throw new AppError(
+            message_id
+                ? `Message #${message_id} wasn't found.`
+                : `This session doesn't carry on from an earlier one. Name a session, or search with search_past_sessions.`,
+        );
+    }
+
+    const session = (
+        await BunSQLite.sql<BUN_SQLITE_COBBLE_BOT_SESSIONS>({
+            sql: `SELECT id, title, previous_session_id FROM bot_sessions
+                WHERE id = ? AND user_id = ? AND bot_id = ? AND workspace_id IS ? AND id != ? LIMIT 1`,
+            values: [
+                target_session_id,
+                user_id,
+                bot_id,
+                workspace_id ? Number(workspace_id) : null,
+                current_session_id,
+            ],
+        })
+    ).payload?.[0];
+
+    if (!session?.id) {
+        throw new AppError(`That isn't an earlier session of this conversation.`);
+    }
+
+    const columns = `id, author, text, created_at`;
+    let messages: PastSessionRead["messages"];
+    let has_more: boolean;
+
+    if (message_id) {
+        const before = Math.floor(limit / 2);
+        const earlier =
+            (
+                await BunSQLite.sql<PastSessionRead["messages"][number]>({
+                    sql: `SELECT ${columns} FROM bot_messages WHERE session_id = ? AND id < ? ORDER BY id DESC LIMIT ?`,
+                    values: [session.id, message_id, before],
+                })
+            ).payload || [];
+        const later =
+            (
+                await BunSQLite.sql<PastSessionRead["messages"][number]>({
+                    sql: `SELECT ${columns} FROM bot_messages WHERE session_id = ? AND id >= ? ORDER BY id ASC LIMIT ?`,
+                    values: [session.id, message_id, limit - before + 1],
+                })
+            ).payload || [];
+
+        has_more = later.length > limit - before;
+        messages = [...earlier.reverse(), ...later.slice(0, limit - before)];
+    } else {
+        const rows =
+            (
+                await BunSQLite.sql<PastSessionRead["messages"][number]>({
+                    sql: `SELECT ${columns} FROM bot_messages WHERE session_id = ? AND id > ? ORDER BY id ASC LIMIT ?`,
+                    values: [session.id, after_id || 0, limit + 1],
+                })
+            ).payload || [];
+
+        has_more = rows.length > limit;
+        messages = rows.slice(0, limit);
+    }
+
+    return { session, messages, has_more };
+}

src/functions/backend/db/bot-sessions/grab-session-opening.ts

@@ -0,0 +1,28 @@
+import type { BUN_SQLITE_COBBLE_BOT_MESSAGES } from "@/db/types/db";
+import BunSQLite from "@moduletrace/bun-sqlite";
+
+type Params = {
+    session_id: number | string;
+    limit: number;
+};
+
+export type SessionOpeningMessage = Pick<
+    BUN_SQLITE_COBBLE_BOT_MESSAGES,
+    "id" | "author" | "text" | "carried_from_session_id"
+>;
+
+/**
+ * A session's first messages, oldest first: what it was started for,
+ * however long it has gone on since. (`grabBotMessages` reads the latest.)
+ */
+export default async function grabSessionOpening({ session_id, limit }: Params): Promise<SessionOpeningMessage[]> {
+    return (
+        (
+            await BunSQLite.sql<SessionOpeningMessage>({
+                sql: `SELECT id, author, text, carried_from_session_id FROM bot_messages
+                    WHERE session_id = ? ORDER BY created_at ASC, id ASC LIMIT ?`,
+                values: [session_id, limit],
+            })
+        ).payload || []
+    );
+}

src/functions/backend/db/bot-sessions/has-open-session-job.ts

@@ -0,0 +1,20 @@
+import BunSQLite from "@moduletrace/bun-sqlite";
+
+type Params = {
+    session_id: number | string;
+};
+
+/**
+ * Whether the bot still has work queued or running in a session, whose
+ * answer lands there: a session isn't carried over meanwhile.
+ */
+export default async function hasOpenSessionJob({ session_id }: Params) {
+    return Boolean(
+        (
+            await BunSQLite.sql({
+                sql: `SELECT id FROM bots_queue WHERE session_id = ? AND status IN ('pending', 'processing') LIMIT 1`,
+                values: [session_id],
+            })
+        ).payload?.[0],
+    );
+}

src/functions/backend/db/bot-sessions/past-session-messages-sql.test.ts

@@ -0,0 +1,77 @@
+import { Database } from "bun:sqlite";
+import { describe, expect, test } from "bun:test";
+import searchPastSessionsSql, { type SearchPastSessionsParams } from "./past-session-messages-sql";
+
+/**
+ * A bot's search of its earlier sessions reads only that user's
+ * conversation with it (in the same place), never the session it's
+ * answering. Run against real SQLite.
+ */
+const db = new Database(":memory:");
+
+db.run(`CREATE TABLE bot_sessions (id INTEGER PRIMARY KEY, user_id INTEGER, bot_id INTEGER, workspace_id INTEGER, title TEXT)`);
+db.run(`CREATE TABLE bot_messages (id INTEGER PRIMARY KEY, session_id INTEGER, author TEXT, text TEXT, created_at INTEGER)`);
+db.run(`INSERT INTO bot_sessions VALUES
+    (1, 1, 10, NULL, 'Invoices'),
+    (2, 1, 10, NULL, 'Current'),
+    (3, 2, 10, NULL, 'Another user'),
+    (4, 1, 11, NULL, 'Another bot'),
+    (5, 1, 10, 7, 'In a workspace')`);
+db.run(`INSERT INTO bot_messages (id, session_id, author, text) VALUES
+    (1, 1, 'user', 'Send the Acme invoice to [email protected]'),
+    (2, 1, 'bot', 'Done: invoice INV-42 sent to Acme.'),
+    (3, 2, 'user', 'What happened with the Acme invoice?'),
+    (4, 3, 'user', 'Acme invoice for someone else'),
+    (5, 4, 'user', 'Acme invoice to another bot'),
+    (6, 5, 'user', 'Acme invoice in the workspace'),
+    (7, 1, 'user', 'Discount of 100% off'),
+    (8, 1, 'user', 'Discount of 10 off')`);
+
+function ids(params: Partial<SearchPastSessionsParams>) {
+    const { sql, values } = searchPastSessionsSql({
+        user_id: 1,
+        bot_id: 10,
+        current_session_id: 2,
+        query: "",
+        ...params,
+    });
+
+    return (db.query(sql).all(...values) as { id: number }[]).map((row) => row.id);
+}
+
+describe("searchPastSessionsSql", () => {
+    test("finds only this conversation's earlier sessions, newest first", () => {
+        expect(ids({ query: "acme invoice" })).toEqual([2, 1]);
+    });
+
+    test("keeps the workspace's conversation apart from the bot's own chat", () => {
+        expect(ids({ query: "acme", workspace_id: 7, current_session_id: 99 })).toEqual([6]);
+    });
+
+    test("every word must match", () => {
+        expect(ids({ query: "invoice INV-42" })).toEqual([2]);
+    });
+
+    test("% matches only itself", () => {
+        expect(ids({ query: "100%" })).toEqual([7]);
+    });
+
+    test("pages with before_id", () => {
+        expect(ids({ query: "acme", before_id: 2 })).toEqual([1]);
+    });
+
+    test("cuts the text around the match", () => {
+        const { sql, values } = searchPastSessionsSql({
+            user_id: 1,
+            bot_id: 10,
+            current_session_id: 2,
+            query: "billing",
+            snippet_chars: 12,
+        });
+        const row = db.query(sql).get(...values) as { snippet: string; session_title: string };
+
+        expect(row.snippet).toContain("billing");
+        expect(row.snippet.length).toBeLessThanOrEqual(12);
+        expect(row.session_title).toBe("Invoices");
+    });
+});

src/functions/backend/db/bot-sessions/past-session-messages-sql.ts

@@ -0,0 +1,88 @@
+import { AppData } from "@/src/data/app-data";
+
+/**
+ * Which earlier sessions are read: one user's conversation with one bot,
+ * in its own chat or one workspace, without the session being answered.
+ */
+export type PastSessionScope = {
+    user_id: number | string;
+    bot_id: number | string;
+    workspace_id?: number | string | null;
+    /**
+     * The session the bot is answering in: its messages are already in
+     * the prompt.
+     */
+    current_session_id: number | string;
+};
+
+export type SearchPastSessionsParams = PastSessionScope & {
+    /**
+     * Words to find in the messages; every one must be there.
+     */
+    query: string;
+    /**
+     * Only messages older than this one (paging).
+     */
+    before_id?: number | string | null;
+    limit?: number;
+    snippet_chars?: number;
+};
+
+/**
+ * Finds messages of the conversation's earlier sessions, newest first,
+ * with their session's title and the text around the first word's match
+ * (cut in SQL). Every word must match, in any case; `%` and `_` match
+ * only themselves.
+ */
+export default function searchPastSessionsSql({
+    user_id,
+    bot_id,
+    workspace_id,
+    current_session_id,
+    query,
+    before_id,
+    limit = AppData.PastSessionSearchLimit,
+    snippet_chars = AppData.PastSessionSnippetChars,
+}: SearchPastSessionsParams) {
+    const words = query.trim().split(/\s+/).filter(Boolean).slice(0, 8);
+    const first = words[0] || "";
+    const lead = Math.floor(snippet_chars / 3);
+
+    const values: (string | number | null)[] = [
+        first,
+        lead,
+        snippet_chars,
+        Number(user_id),
+        Number(bot_id),
+        workspace_id ? Number(workspace_id) : null,
+        Number(current_session_id),
+    ];
+    const where = [
+        `s.user_id = ?`,
+        `s.bot_id = ?`,
+        `s.workspace_id IS ?`,
+        `s.id != ?`,
+    ];
+
+    for (const word of words) {
+        where.push(`m.text LIKE ? ESCAPE '\\'`);
+        values.push(`%${word.replace(/[\\%_]/g, (c) => `\\${c}`)}%`);
+    }
+
+    if (before_id) {
+        where.push(`m.id < ?`);
+        values.push(Number(before_id));
+    }
+
+    values.push(Math.min(Math.max(Math.floor(limit) || 1, 1), 100));
+
+    return {
+        sql: `SELECT m.id, m.session_id, m.author, m.created_at, s.title AS session_title,
+                substr(m.text, max(1, instr(lower(m.text), lower(?)) - ?), ?) AS snippet
+            FROM bot_messages m JOIN bot_sessions s ON s.id = m.session_id
+            WHERE ${where.join(" AND ")}
+            ORDER BY m.id DESC
+            LIMIT ?`,
+        values,
+    };
+}

src/functions/backend/db/bot-sessions/reopen-bot-session.ts

@@ -11,7 +11,8 @@ type Params = {
 /**
  * Makes a closed session of one of the user's conversations the active
  * one again, so the bot carries on from where it left off. The session
- * that was active is closed (an empty one is deleted).
+ * that was active is closed (an empty one is deleted). A session the bot
+ * moved the conversation on from is never reopened.
  */
 export default async function reopenBotSession({
     session_id,
@@ -25,6 +26,22 @@ export default async function reopenBotSession({
 
     if (session.status == "active") return session;
 
+    /**
+     * The bot moved the conversation on from it (`continue_in_new_session`):
+     * reopened, the conversation would go on without what was said since,
+     * and the user's last word there was already answered in the new one.
+     */
+    const carried_on = (
+        await BunSQLite.sql({
+            sql: `SELECT id FROM bot_messages WHERE carried_from_session_id = ? LIMIT 1`,
+            values: [session.id],
+        })
+    ).payload?.[0];
+
+    if (carried_on) {
+        throw new AppError(`This conversation moved on to a newer session, so this one stays closed. You can still read it.`);
+    }
+
     const now = Date.now();
     const workspace_id = session.workspace_id || null;
 

src/functions/backend/db/bot-sessions/roll-over-bot-session.ts

@@ -0,0 +1,57 @@
+import type { BUN_SQLITE_COBBLE_BOT_SESSIONS } from "@/db/types/db";
+import pushBotNotice from "@/src/bots-queue/push-bot-notice";
+import { logError } from "@/src/functions/backend/logger";
+import carryOverBotSession from "./carry-over-bot-session";
+import continueBotSession from "./continue-bot-session";
+import grabActiveBotSession from "./grab-active-bot-session";
+import hasOpenSessionJob from "./has-open-session-job";
+
+type Params = {
+    user_id: number | string;
+    bot_id: number;
+    workspace_id?: number | null;
+    /**
+     * The conversation's active session, now full.
+     */
+    active: BUN_SQLITE_COBBLE_BOT_SESSIONS;
+};
+
+/**
+ * The automatic rollover at the session length, when the user writes: the
+ * conversation is carried into a new session the same way the bot or
+ * Continue in new session carry it (`continueBotSession`: a written title
+ * and summary, the full session closed for good). A model that can't
+ * write the summary now falls back to the summary the session already
+ * has. The full session is kept (and the rollover tried again on the
+ * next message) while the bot still works in it, or when there's nothing
+ * to carry. Returns the session the user's message goes in.
+ */
+export default async function rollOverBotSession({
+    user_id,
+    bot_id,
+    workspace_id,
+    active,
+}: Params): Promise<BUN_SQLITE_COBBLE_BOT_SESSIONS> {
+    if (await hasOpenSessionJob({ session_id: active.id! })) return active;
+
+    const message = await continueBotSession({ user_id, bot_id, workspace_id }).catch(async (error: unknown) => {
+        await logError({ title: `Session #${active.id} rollover summary not written`, error }).catch(() => {});
+
+        if (!active.summary?.trim()) return null;
+
+        return await carryOverBotSession({
+            session_id: active.id!,
+            user_id,
+            bot_id,
+            workspace_id,
+            summary: active.summary,
+            title: active.title,
+        }).catch(() => null);
+    });
+
+    if (!message) return active;
+
+    await pushBotNotice({ bot_id, message, quiet_push: true });
+
+    return (await grabActiveBotSession({ user_id, bot_id, workspace_id })) || active;
+}

src/functions/backend/db/bot-sessions/start-bot-session.ts

@@ -13,10 +13,11 @@ type Params = {
 };
 
 /**
- * Closes the conversation's active session and starts the next one, which
- * carries on from it (its summary goes into the next reply's prompt,
- * rewritten first when it covers fewer messages than the session ended
- * with). An active session with no messages yet is kept as it is.
+ * New session: closes the conversation's active session and starts a
+ * fresh one, linked to nothing and carrying nothing over. Carrying a
+ * conversation on is `carryOverBotSession` (the bot, Continue in new
+ * session, the rollover). An active session with no messages yet is kept
+ * as it is.
  */
 export default async function startBotSession({
     user_id,
@@ -41,10 +42,5 @@ export default async function startBotSession({
         });
     }
 
-    return await createBotSession({
-        user_id,
-        bot_id,
-        workspace_id,
-        previous_session_id: active?.id || null,
-    });
+    return await createBotSession({ user_id, bot_id, workspace_id });
 }

src/functions/backend/db/bots/insert-bot-message.ts

@@ -28,6 +28,11 @@ type Params = {
      * message in later turns (`botMessagesToHarness`).
      */
     tool_log?: HarnessToolUse[];
+    /**
+     * Opens a session the conversation moved into
+     * (`carryOverBotSession`): the session it carries on from.
+     */
+    carried_from_session_id?: number;
 };
 
 /**
@@ -43,6 +48,7 @@ export default async function insertBotMessage({
     interim,
     media_ids = [],
     tool_log,
+    carried_from_session_id,
 }: Params): Promise<BUN_SQLITE_COBBLE_BOT_MESSAGES> {
     const now = Date.now();
     const needs_you_flag = needs_you ? 1 : 0;
@@ -64,6 +70,7 @@ export default async function insertBotMessage({
                 needs_you: needs_you_flag,
                 interim: interim_flag,
                 tool_log: tool_log_json,
+                carried_from_session_id,
             },
         ],
     });
@@ -96,6 +103,7 @@ export default async function insertBotMessage({
         needs_you: needs_you_flag,
         interim: interim_flag,
         tool_log: tool_log_json,
+        carried_from_session_id,
         created_at: now,
         updated_at: now,
     };

src/functions/frontend/post-session-api.ts

@@ -7,6 +7,7 @@ type Params = {
      */
     path: | "list-sessions"
         | "new-session"
+        | "continue-session"
         | "reopen-session"
         | "session-messages"
         | "older-messages";