fix: address reader-UI feedback (shorts, search, tags, login, UX)

- Shorts: confirm via youtube.com/shorts/<id> probe (SOCS cookie bypasses the
  consent redirect) instead of a 60s heuristic; concurrent probing, shorts_probed
  flag, scheduled refinement (migration 0005)
- Search: match title + channel name only (descriptions caused noisy results)
- Faceted tag filtering: AND across categories (language AND topic narrows),
  OR within a category; any/all toggle applies to topics
- Language detection: majority vote over individual titles (fixes misdetections
  like multipoleguy -> English; drops bogus Polish/Romanian)
- Login: drop forced consent so returning sign-in is quick (select_account)
- Feed cards: clickable channel name (opens channel), persistent saved badge,
  undo toast on hide, Hidden view to restore; tag chips show counts in tooltip

backend/app/routes/feed.py

@@ -6,7 +6,7 @@ from sqlalchemy.orm import Session, aliased
 
 from app.auth import current_user
 from app.db import get_db
-from app.models import Channel, ChannelTag, User, Video, VideoState
+from app.models import Channel, ChannelTag, Tag, User, Video, VideoState
 
 router = APIRouter(prefix="/api", tags=["feed"])
 
@@ -14,6 +14,12 @@ VALID_STATES = {"new", "watched", "saved", "hidden"}
 HIDDEN_LIVE = ("live", "upcoming")
 
 
+def _channel_url(channel_id: str, handle: str | None) -> str:
+    if handle and handle.startswith("@"):
+        return f"https://www.youtube.com/{handle}"
+    return f"https://www.youtube.com/channel/{channel_id}"
+
+
 def _serialize(row) -> dict:
     return {
         "id": row.id,
@@ -21,6 +27,7 @@ def _serialize(row) -> dict:
         "channel_id": row.channel_id,
         "channel_title": row.channel_title,
         "channel_thumbnail": row.channel_thumbnail,
+        "channel_url": _channel_url(row.channel_id, row.channel_handle),
         "published_at": row.published_at.isoformat() if row.published_at else None,
         "thumbnail_url": row.thumbnail_url,
         "duration_seconds": row.duration_seconds,
@@ -61,6 +68,7 @@ def get_feed(
             Video.channel_id,
             Channel.title.label("channel_title"),
             Channel.thumbnail_url.label("channel_thumbnail"),
+            Channel.handle.label("channel_handle"),
             Video.published_at,
             Video.thumbnail_url,
             Video.duration_seconds,
@@ -91,23 +99,35 @@ def get_feed(
             Video.published_at >= datetime.fromtimestamp(cutoff, tz=timezone.utc)
         )
     if q:
+        # Title (and channel name) only — searching descriptions produced noisy matches.
         like = f"%{q}%"
-        query = query.where(or_(Video.title.ilike(like), Video.description.ilike(like)))
+        query = query.where(or_(Video.title.ilike(like), Channel.title.ilike(like)))
 
     if tags:
+        # Group selected tags by category: AND across categories (e.g. language AND
+        # topic narrows results), OR within a category. The any/all toggle controls
+        # whether multiple topic tags are OR'd (any) or AND'd (all).
+        cat_rows = db.execute(
+            select(Tag.id, Tag.category).where(Tag.id.in_(tags))
+        ).all()
+        by_category: dict[str, list[int]] = {}
+        for tag_id, category in cat_rows:
+            by_category.setdefault(category, []).append(tag_id)
+
         visible = or_(ChannelTag.user_id.is_(None), ChannelTag.user_id == user.id)
-        if tag_mode == "and":
-            sub = (
-                select(ChannelTag.channel_id)
-                .where(ChannelTag.tag_id.in_(tags), visible)
-                .group_by(ChannelTag.channel_id)
-                .having(func.count(func.distinct(ChannelTag.tag_id)) == len(set(tags)))
-            )
-        else:
-            sub = select(ChannelTag.channel_id).where(
-                ChannelTag.tag_id.in_(tags), visible
-            )
-        query = query.where(Video.channel_id.in_(sub))
+        for category, ids in by_category.items():
+            if category == "topic" and tag_mode == "and" and len(ids) > 1:
+                sub = (
+                    select(ChannelTag.channel_id)
+                    .where(ChannelTag.tag_id.in_(ids), visible)
+                    .group_by(ChannelTag.channel_id)
+                    .having(func.count(func.distinct(ChannelTag.tag_id)) == len(set(ids)))
+                )
+            else:
+                sub = select(ChannelTag.channel_id).where(
+                    ChannelTag.tag_id.in_(ids), visible
+                )
+            query = query.where(Video.channel_id.in_(sub))
 
     # Watch-state visibility.
     if show == "unwatched":