fix: feedback round 2 — language, subscriptions, feed scope, UX

- Language detection: classify one cleaned+concatenated blob (strip emoji,
  @mentions, #tags, numbers, punctuation); fixes caps/emoji-heavy channels
  (e.g. Nessaj -> Hungarian, no more bogus Chinese/Korean)
- Feed now joins the user's subscriptions, so unsubscribing on YouTube removes a
  channel from the feed; periodic subscription re-sync job picks up changes
- Watched/Saved/Hidden views ignore the Shorts/live default-hiding so the full
  set is visible (fixes hidden videos missing from the Hidden view)
- Persist feed filters + search across reloads (localStorage)
- 3D polish: cards lift with shadow on hover; chips/buttons get depth and a
  press effect; undo toast lasts longer

backend/app/sync/autotag.py

@@ -5,7 +5,7 @@ detection over a sample of recent video titles. Topics are mapped from YouTube's
 topicDetails categories and the channel's dominant video category. System tags are
 regenerated freely; user tags are never touched here.
 """
-from collections import Counter
+import re
 
 from sqlalchemy import and_, exists, func, select
 from sqlalchemy.orm import Session
@@ -145,9 +145,18 @@ def map_topic_slug(slug: str) -> str | None:
     return _TOPIC_SLUGS.get(slug)
 
 
+def _clean_title(title: str | None) -> str:
+    """Strip emojis, @mentions, #tags, URLs, numbers and punctuation so the language
+    detector sees actual words, not caps/emoji-heavy noise."""
+    text = title or ""
+    text = re.sub(r"http\S+", " ", text)
+    text = re.sub(r"[@#]\w+", " ", text)
+    text = re.sub(r"\d+", " ", text)
+    text = re.sub(r"[^\w\s]", " ", text, flags=re.UNICODE).replace("_", " ")
+    return " ".join(w for w in text.split() if len(w) > 1)
+
+
 def detect_channel_language(db: Session, channel: Channel) -> tuple[str | None, float]:
-    if channel.default_language:
-        return channel.default_language.split("-")[0].lower(), 0.99
     titles = (
         db.execute(
             select(Video.title)
@@ -158,20 +167,16 @@ def detect_channel_language(db: Session, channel: Channel) -> tuple[str | None,
         .scalars()
         .all()
     )
-    # Majority vote over individual titles is more robust than one concatenated blob
-    # (short/technical titles otherwise skew the detector).
-    votes: Counter[str] = Counter()
-    for title in titles:
-        cleaned = (title or "").strip()
-        if len(cleaned) < 8:
-            continue
-        lang, _conf = _classify(cleaned)
-        votes[lang] += 1
-    if not votes:
-        return None, 0.0
-    lang, count = votes.most_common(1)[0]
-    total = sum(votes.values())
-    return lang, count / total
+    # Detect over one cleaned, concatenated blob — more context and far less skew from
+    # short, emoji/caps-heavy titles than per-title voting.
+    blob = " ".join(_clean_title(t) for t in titles).strip()
+    if len(blob) >= 15:
+        lang, confidence = _classify(blob)
+        return lang, float(confidence)
+    # Sparse text: fall back to the channel's declared language if any.
+    if channel.default_language:
+        return channel.default_language.split("-")[0].lower(), 0.6
+    return None, 0.0
 
 
 def compute_channel_topics(db: Session, channel: Channel) -> set[str]:

backend/app/sync/runner.py

@@ -10,6 +10,7 @@ from sqlalchemy.orm import Session
 from app import quota
 from app.config import settings
 from app.models import Channel, OAuthToken, User
+from app.sync.subscriptions import import_subscriptions
 from app.sync.videos import (
     backfill_channel_deep,
     backfill_channel_recent,
@@ -65,6 +66,26 @@ def run_shorts(db: Session) -> dict:
     return run_shorts_classification(db)
 
 
+def run_subscription_resync(db: Session) -> dict:
+    """Re-import every user's subscriptions so unsubscribes and new subscriptions on
+    YouTube are reflected automatically."""
+    users = (
+        db.execute(
+            select(User)
+            .join(OAuthToken)
+            .where(OAuthToken.refresh_token_enc.is_not(None))
+        )
+        .scalars()
+        .all()
+    )
+    for user in users:
+        try:
+            import_subscriptions(db, user)
+        except Exception:
+            db.rollback()
+    return {"users": len(users)}
+
+
 def run_recent_backfill(
     db: Session, channels: list[Channel] | None = None, max_channels: int | None = None
 ) -> dict: