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]>

AGENTS.md

@@ -88,9 +88,9 @@ Enables SQLite foreign keys (`enableForeignKeys`), `bunextInit()`, `ensureDocker
 ### Bots, sessions, chat
 
 - **Tables:** `bots` (`kind`, `color` `#rrggbb`, `stone`, `role`, `system_prompt`; `hue` is a legacy fallback), `bot_user_faces`, `bot_sessions`, `bot_messages`, `bot_tasks`, `bot_task_steps` (unused yet). Enums in `src/dict/bot-dict.ts`.
-- **Sessions:** one thread per user per bot in its own chat plus one per workspace; split into `bot_sessions` (rollover at `AppData.BotSessionMaxMessages`, titled and summarised by `name-bot-session.ts`, summary carried into the next session). Helpers in `src/functions/backend/db/bot-sessions/`. Job results land in the job's own session, even after it closes.
+- **Sessions:** one thread per user per bot in its own chat plus one per workspace; split into `bot_sessions` (rollover at the app setting `bot_session_max_messages`, default `AppData.BotSessionMaxMessages`, via `grabBotSessionMaxMessages`; titled and summarised by `name-bot-session.ts` from the session's opening (`grabSessionOpening`; `grabBotMessages` reads the latest), summary carried into the next session only when they're linked by `previous_session_id`, which only a carry-over sets; older implicit links were cleared on 2026-10-26). New session (`startBotSession`) and a conversation with no active session always start fresh. The rollover carries over like the bot does (`rollOverBotSession` -> `continueBotSession`, falling back to the stored summary; kept for the next message while a job is open in the full session or there's nothing to carry), inside send-message, so the user's message lands under the summary. Helpers in `src/functions/backend/db/bot-sessions/`. Job results land in the job's own session, even after it closes, except a reply that called `continue_in_new_session` (`carryOverBotSession`; the menu's and sessions modal's Continue in new session does the same through `continueBotSession`, the model writing title and summary, refused while a job is open in the session): its summary is kept on the closed session and opens the new one as a bot message (`carried_from_session_id`), the job's `session_id` moves so the answer follows, the new session is titled by the bot then (it has no first exchange to be named from), and the old one can never be reopened (`reopenBotSession` refuses; a thread showing it swaps its composer for a link to the new one). Session lists (rail, sessions modal) reopen a session on click, as before; a carried-over one can't be, so it opens to read (`?session_id=`, `conversationHref`). From half the session length the reply prompt suggests moving on (`longSessionNote`). Earlier sessions never enter the prompt (only the last one's summary): the thread can open them above a session (`useOlderMessages.loadPrevious`, a divider per session, quote and reply as usual), and replies get `search_past_sessions`/`read_past_session` (scoped to that user, bot and place, never the current session) when the conversation has any.
 - **Coordinator:** exactly one, the super admin's alone, created idempotently by `ensureCoordinatorBot`. Default prompt `src/data/coordinator-system-prompt.ts`, backfilled only when empty.
-- **Routes:** `/admin/bots` reopens the last visited bot (cookie `cobble_last_visited_bot_id`, never a workspace conversation) if still reachable, else coordinator (super admin) / latest bot / first workspace / empty. `/admin/bots/[bot_id]` conversation (header, thread and composer at 760px, no right panel); `/admin/bots/[bot_id]/models`; `/admin/workspaces/[id]` dashboard; `/admin/workspaces/[id]/bots/[bot_id]` same conversation scoped to the workspace.
+- **Routes:** `/admin/bots` reopens the last visited bot (cookie `cobble_last_visited_bot_id`, never a workspace conversation) if still reachable, else coordinator (super admin) / latest bot / first workspace / empty. `/admin/bots/[bot_id]` conversation (header, thread and composer at 760px, no right panel; `?session_id=` opens another of the user's sessions there: a closed one is reopened, except a carried-over one, which shows with `SessionMovedBar` instead of the composer, pointing where the conversation went on); `/admin/bots/[bot_id]/models`; `/admin/workspaces/[id]` dashboard; `/admin/workspaces/[id]/bots/[bot_id]` same conversation scoped to the workspace.
 - **Conversation loading:** pages render everything server-side (`grabConversationProps`) **except the history**, which the client loads (`api/admin/bots/conversation-history`, merged with what's already shown, refetched on bfcache restore) and pages older messages on scroll. Rail lists go through `railBots`/`railWorkspaces` (no prompts/memory, previews cut). While a reply is due the page polls `session-messages` (`use-reply-catch-up`) in case a push was missed.
 - **Sending:** `api/admin/bots/send-message.ts` -> `enqueueBotReply` -> `wakeBotsQueue`. **Never import `src/bots-queue/index.ts` from a page or API route** (pulls the bunext runtime into page bundles). Optimistic bubble in `pending_messages` until the saved message replaces it.
 - **Composer:** Tiptap editor reading/writing markdown, drafts in `localStorage`, `@` bots / `#` workspaces written as `[bot:ID]`/`[workspace:ID]`. Enter sends (Mod+Enter in lists/code). `@tiptap/react` needs `use-sync-external-store`; the app ships an ESM stand-in in `packages/use-sync-external-store-esm` (file dependency + override; the Dockerfile copies `packages/` before `bun install`).