Auto-reindex channel on page visit if stale

GET /channels/{id} now fires a background _index_channel_task if the
channel hasn't been crawled in the last hour. The frontend refetches
channel + videos 8s after page load to pick up the updated data.

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

backend/routers/channels.py

@@ -546,6 +546,7 @@ def bulk_channel_action(
 @router.get("/{channel_id}", response_model=ChannelOut)
 def get_channel(
     channel_id: int,
+    background_tasks: BackgroundTasks,
     db: Session = Depends(get_db),
     current_user: User = Depends(get_current_user),
 ):
@@ -576,6 +577,16 @@ def get_channel(
     ).mappings().first()
     if not row:
         raise HTTPException(status_code=404, detail="Channel not found")
+
+    # Re-index in the background if stale (not crawled in the last hour)
+    crawled_at = row.get("crawled_at")
+    stale = (
+        crawled_at is None
+        or (datetime.utcnow() - crawled_at).total_seconds() > 3600
+    )
+    if stale:
+        background_tasks.add_task(_index_channel_task, channel_id, current_user.id)
+
     return ChannelOut(**dict(row))
 
 

frontend/src/pages/Channel.jsx

@@ -1,4 +1,4 @@
-import { useState, useMemo } from "react";
+import { useState, useMemo, useEffect, useRef } from "react";
 import { useParams } from "react-router-dom";
 import { useQuery, useMutation, useQueryClient } from "@tanstack/react-query";
 import { getChannel, getChannelVideos, followChannel, unfollowChannel, indexChannel, downloadChannel } from "../api";
@@ -41,6 +41,18 @@ export default function ChannelPage() {
     queryFn: () => getChannelVideos(id).then((r) => r.data),
   });
 
+  // Refetch after the background re-index has had time to run
+  const refetchedRef = useRef(false);
+  useEffect(() => {
+    if (!id || refetchedRef.current) return;
+    refetchedRef.current = true;
+    const t = setTimeout(() => {
+      qc.invalidateQueries({ queryKey: ["channel", id] });
+      qc.invalidateQueries({ queryKey: ["channel-videos", id] });
+    }, 8000);
+    return () => clearTimeout(t);
+  }, [id, qc]);
+
   const followMut = useMutation({
     mutationFn: () =>
       channel?.status === "followed" ? unfollowChannel(id) : followChannel(id),