Mark the session on screen as Current in the session lists

- The conversation page tells the rail and the sessions modal which
  session it shows (announceShownSession, useShownSession); they reload,
  so a session reopened by ?session_id= shows at once.
- Only that session is Current and greyed out (the active one without
  ?session_id=); the active row then leads back to it.
- The rail lists the session on screen even when it's older than its
  latest sessions.

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

src/hooks/use-bot-sessions.ts

@@ -15,6 +15,11 @@ type Params = {
      * How many to load, latest first; the modal leaves it out for a page.
      */
     limit?: number;
+    /**
+     * Reloads the list whenever it changes (the session the page shows,
+     * which loading it may have reopened).
+     */
+    refresh_key?: string | number | null;
 };
 
 type ChangedSession = {
@@ -51,7 +56,7 @@ function belongsToConversation({
  * session started in the conversation (or named once its first reply is
  * in) shows without a reload.
  */
-export default function useBotSessions({ bot_id, workspace_id, open, limit }: Params) {
+export default function useBotSessions({ bot_id, workspace_id, open, limit, refresh_key }: Params) {
     const [query, setQuery] = useState("");
     const [sessions, setSessions] = useState<BotSessionListItem[]>([]);
     const [loading, setLoading] = useState(false);
@@ -111,7 +116,7 @@ export default function useBotSessions({ bot_id, workspace_id, open, limit }: Pa
             stale = true;
             clearTimeout(timer);
         };
-    }, [open, query, bot_id, workspace_id, limit, revision]);
+    }, [open, query, bot_id, workspace_id, limit, revision, refresh_key]);
 
     const act = async ({ id, path, body }: { id: number | "new"; path: "new-session" | "reopen-session"; body: Record<string, unknown> }) => {
         if (busy_id) return;

src/hooks/use-shown-session.ts

@@ -0,0 +1,38 @@
+import { useEffect, useState } from "react";
+import { lastShownSession, ShownSessionEvent } from "@/src/functions/frontend/announce-shown-session";
+import type { ShownSession } from "@/src/types";
+
+type Params = {
+    bot_id: number;
+    workspace_id?: number | null;
+};
+
+function isFor({ shown, bot_id, workspace_id }: Params & { shown: ShownSession | null }) {
+    return Boolean(
+        shown && shown.bot_id == bot_id && (shown.workspace_id || null) == (workspace_id || null),
+    );
+}
+
+/**
+ * The session the conversation page shows, when it's this conversation's
+ * (`announceShownSession`): a session opened by `?session_id=`, a
+ * reopened one or the active one.
+ */
+export default function useShownSession({ bot_id, workspace_id }: Params) {
+    const [shown, setShown] = useState<ShownSession | null>(() =>
+        isFor({ shown: lastShownSession, bot_id, workspace_id }) ? lastShownSession : null,
+    );
+
+    useEffect(() => {
+        const listener = (e: Event) => {
+            const detail = (e as CustomEvent<ShownSession>).detail;
+
+            if (isFor({ shown: detail, bot_id, workspace_id })) setShown(detail);
+        };
+
+        window.addEventListener(ShownSessionEvent, listener);
+        return () => window.removeEventListener(ShownSessionEvent, listener);
+    }, [bot_id, workspace_id]);
+
+    return shown?.session || null;
+}