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/pages/admin/bots/[bot_id]/(partials)/message-thread.tsx

@@ -8,6 +8,7 @@ import useMessageSelection from "../(hooks)/use-message-selection";
 import groupMessages from "../(utils)/group-messages";
 import BotThinkingRow from "./bot-thinking-row";
 import MessageGroupBlock from "./message-group-block";
+import OlderMessagesLoader from "./older-messages-loader";
 import QuoteSelectionButton from "./quote-selection-button";
 
 type Props = {
@@ -33,6 +34,15 @@ type Props = {
      * Quotes text selected in a message in the composer.
      */
     onQuote?: (params: { text: string }) => void;
+    /**
+     * The session's older messages, loaded at the top of the thread.
+     */
+    older?: {
+        has_more: boolean;
+        loading: boolean;
+        error?: string;
+        loadOlder: () => void;
+    };
 };
 
 /**
@@ -40,6 +50,8 @@ type Props = {
  * upward. Empty space belongs at the top. New messages announce politely.
  * While the bot works on a reply or a task, a status row sits under the
  * last one. Text selected in a message can be quoted in the composer.
+ * Older messages load as it scrolls to the top; the reversed column keeps
+ * the view where it was as they land above it.
  */
 export default function MessageThread({
     bot,
@@ -49,6 +61,7 @@ export default function MessageThread({
     receiving,
     has_task,
     onQuote,
+    older,
 }: Props) {
     const groups = useMemo(() => groupMessages({ messages }), [messages]);
     const ref = useRef<HTMLDivElement>(null);
@@ -64,6 +77,13 @@ export default function MessageThread({
                 aria-label={`Conversation with ${bot.name}`}
                 className="w-full max-w-container mx-auto gap-4! items-stretch px-3 md:px-6 pt-6 pb-6"
             >
+                {older?.has_more ? (
+                    <OlderMessagesLoader
+                        loading={older.loading}
+                        error={older.error}
+                        onLoad={older.loadOlder}
+                    />
+                ) : null}
                 {groups.map((group) => (
                     <MessageGroupBlock
                         key={group.key}