Trim page props and page the conversation's messages

Bot and workspace lists in page props leave out instructions, memory and
workspace context, and carry the last message as a short preview. The
header avatar's edit form loads the bot's instructions when it opens.
The conversation renders its latest 30 messages and loads older ones as
the thread scrolls to its top.

Also: the composer shows a placeholder until its editor loads, and
`bun start` no longer builds first.

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

src/functions/backend/db/bots/grab-bot-messages.ts

@@ -9,6 +9,10 @@ import mediaToAttachment from "./media-to-attachment";
 type Params = {
     session_id: number | string;
     limit?: number;
+    /**
+     * Only messages older than this one, for loading further back.
+     */
+    before_id?: number | null;
     /**
      * Whose conversation it is, so a reaction can show as the user's own.
      * Left out for the bot's own history reads, which don't need it.
@@ -17,12 +21,14 @@ type Params = {
 };
 
 /**
- * The latest messages of a session, oldest first, with their attachments,
+ * The latest messages of a session (or the latest before `before_id`),
+ * oldest first, with their attachments,
  * what each replies to, and (when `user_id` is given) its reactions.
  */
 export default async function grabBotMessages({
     session_id,
     limit = 100,
+    before_id,
     user_id,
 }: Params): Promise<BotMessageWithAttachments[]> {
     let sql = ``;
@@ -30,13 +36,18 @@ export default async function grabBotMessages({
     sql += `SELECT * FROM (\n`;
     sql += `    SELECT * FROM bot_messages\n`;
     sql += `    WHERE session_id = ?\n`;
+
+    if (before_id) {
+        sql += `    AND (created_at, id) < (SELECT created_at, id FROM bot_messages WHERE id = ?)\n`;
+    }
+
     sql += `    ORDER BY created_at DESC, id DESC\n`;
     sql += `    LIMIT ?\n`;
     sql += `) ORDER BY created_at ASC, id ASC\n`;
 
     const res = await BunSQLite.sql<BUN_SQLITE_COBBLE_BOT_MESSAGES>({
         sql,
-        values: [session_id, limit],
+        values: before_id ? [session_id, before_id, limit] : [session_id, limit],
     });
 
     const messages = res.payload || [];