diff --git a/VERSION b/VERSION
index d2e2400..23b64a4 100644
--- a/VERSION
+++ b/VERSION
@@ -1 +1 @@
-0.39.1
+0.40.0
\ No newline at end of file
diff --git a/backend/app/downloads/gc.py b/backend/app/downloads/gc.py
index 570d130..35536d7 100644
--- a/backend/app/downloads/gc.py
+++ b/backend/app/downloads/gc.py
@@ -1,12 +1,14 @@
 """Download retention garbage collector (a scheduler job).
 
-Three passes each run:
+Four passes each run:
   1. Pre-expiry warning — for ready assets expiring within the grace window, notify each holder
      once (gc_notified flag) so a download isn't silently deleted.
   2. Expiry deletion — delete assets past their TTL (files + row). The FK SET NULL nulls the
      holders' jobs' asset_id, so those jobs surface as "expired" (re-downloadable) in the UI.
   3. LRU eviction — if a total cache cap is set and exceeded, delete least-recently-accessed
      ready assets until back under it.
+  4. Orphan reap — delete errored, fileless, unreferenced asset rows (they carry no TTL, so
+     passes 1-3 skip them; benign row-count hygiene).
 
 Runs in the API process (which mounts DOWNLOAD_ROOT). Pure disk/DB work — no YouTube quota.
 """
@@ -58,7 +60,7 @@ def _delete_asset(db: Session, asset: MediaAsset, ntype: str) -> None:
 def run_download_gc(db: Session) -> dict:
     now = datetime.now(timezone.utc)
     grace_days = sysconfig.get_int(db, "download_gc_grace_days")
-    warned = expired = evicted = 0
+    warned = expired = evicted = reaped = 0
 
     # 1. Pre-expiry warnings.
     warn_before = now + timedelta(days=grace_days)
@@ -114,6 +116,22 @@ def run_download_gc(db: Session) -> dict:
                 evicted += 1
             db.commit()
 
-    result = {"warned": warned, "expired": expired, "evicted": evicted}
+    # 4. Reap orphaned errored rows (no file, no holder). get_or_create_asset resets a still-
+    #    referenced errored row to pending on re-enqueue, so these only accumulate once every
+    #    holder is gone; they carry no expires_at, so passes 1-3 never touch them.
+    orphans = db.execute(
+        select(MediaAsset).where(
+            MediaAsset.status == "error",
+            MediaAsset.ref_count == 0,
+            MediaAsset.rel_path.is_(None),
+        )
+    ).scalars().all()
+    for asset in orphans:
+        db.delete(asset)  # no file to unlink; FK SET NULL clears any stray job.asset_id
+        reaped += 1
+    if orphans:
+        db.commit()
+
+    result = {"warned": warned, "expired": expired, "evicted": evicted, "reaped": reaped}
     log.info("download_gc %s", result)
     return result
diff --git a/backend/app/routes/channels.py b/backend/app/routes/channels.py
index bdb5230..38b5dff 100644
--- a/backend/app/routes/channels.py
+++ b/backend/app/routes/channels.py
@@ -175,15 +175,21 @@ def discover_channels(
 
     rows = _discovery_rows(db, user)
 
-    # Enrich stub channels' metadata (uses the API key — no write scope needed). Re-read
-    # the rows afterwards so the response carries the fresh subscriber counts/thumbnails.
+    # Enrich stub channels' metadata (uses the API key — no write scope needed). The Channel
+    # objects are identity-mapped, so apply_channel_details mutates the very rows we already hold
+    # (fresh subscriber counts/thumbnails carry through without a re-query). Only the title can
+    # change, which affects the tie-break order → re-sort in Python instead of re-hitting the DB.
     need = [ch.id for ch, _, _ in rows if ch.details_synced_at is None][:DISCOVERY_ENRICH_CAP]
     if need:
         try:
             with quota.attribute(user.id, quota.QuotaAction.CHANNELS_DISCOVER), YouTubeClient(db, user) as yt:
                 apply_channel_details(db, yt.get_channels(need))
             db.commit()
-            rows = _discovery_rows(db, user)
+            # Match _discovery_rows' ORDER BY exactly: video-count DESC, then title (NULLs LAST,
+            # as Postgres orders them — coercing NULL→"" would wrongly float untitled channels up).
+            rows = sorted(
+                rows, key=lambda r: (-int(r[1]), r[0].title is None, (r[0].title or "").lower())
+            )
         except YouTubeError as exc:
             log.warning("discovery: channel enrich failed (user %s): %s", user.id, exc)
             db.rollback()
@@ -418,11 +424,18 @@ def reset_backfill(
     channel = db.get(Channel, channel_id)
     if channel is None:
         raise HTTPException(status_code=404, detail="Unknown channel")
-    sub = _user_subscription(db, user, channel_id)
     channel.backfill_done = False
     channel.backfill_cursor = None
     channel.recent_synced_at = None
-    sub.deep_requested = True
+    # Re-arm the demand-driven deep scheduler for this channel. run_deep_backfill gates on an
+    # EXISTS over subscriptions with deep_requested=True, so flip it on EVERY subscriber rather
+    # than requiring the admin to be personally subscribed (they reset from the manager, not
+    # their own feed). No-op row count if the channel has no subscribers.
+    db.execute(
+        update(Subscription)
+        .where(Subscription.channel_id == channel_id)
+        .values(deep_requested=True)
+    )
     db.commit()
     with quota.attribute(user.id, quota.QuotaAction.VIDEOS_BACKFILL_RECENT):
         run_recent_backfill(db, [channel], max_channels=1)
@@ -455,25 +468,30 @@ def subscribe(
     ).scalar_one_or_none()
     if existing is not None:
         raise HTTPException(status_code=409, detail="Already subscribed to this channel.")
-    try:
-        with quota.attribute(user.id, quota.QuotaAction.CHANNELS_SUBSCRIBE), YouTubeClient(db, user) as yt:
+    with quota.attribute(user.id, quota.QuotaAction.CHANNELS_SUBSCRIBE), YouTubeClient(db, user) as yt:
+        try:
             yt_sub_id = yt.insert_subscription(channel_id)
-            # Enrich a stub channel (title/thumbnail/subscriber count) so it shows up
-            # properly right away; no video pull here.
-            if channel.details_synced_at is None:
+        except YouTubeError as exc:
+            # Already following on YouTube but not recorded here (a desync — e.g. a stale import
+            # dropped the local row, so it resurfaced in discovery). That's not a failure: the end
+            # state the user wanted already holds, so record it locally and move on. The next
+            # subscription resync fills in the resource id. Any other YouTube error is a real
+            # problem — surface it with a clear message (422, not a 502 that the client would
+            # mistake for a transient "connection lost").
+            msg = str(exc).lower()
+            if "already exists" in msg or "duplicate" in msg:
+                yt_sub_id = ""
+            else:
+                raise HTTPException(status_code=422, detail=f"YouTube couldn't subscribe you: {exc}")
+        # Enrich a stub channel (title/thumbnail/subscriber count) so it shows up properly right
+        # away, on BOTH the normal and the desync path — a resurfaced stub still needs metadata to
+        # render. Keep the client open (we're still inside the `with`); a metadata failure here
+        # must not block recording the subscription the user asked for.
+        if channel.details_synced_at is None:
+            try:
                 apply_channel_details(db, yt.get_channels([channel_id]))
-    except YouTubeError as exc:
-        # Already following on YouTube but not recorded here (a desync — e.g. a stale import
-        # dropped the local row, so it resurfaced in discovery). That's not a failure: the end
-        # state the user wanted already holds, so record it locally and move on. The next
-        # subscription resync fills in the resource id. Any other YouTube error is a real
-        # problem — surface it with a clear message (422, not a 502 that the client would
-        # mistake for a transient "connection lost").
-        msg = str(exc).lower()
-        if "already exists" in msg or "duplicate" in msg:
-            yt_sub_id = ""
-        else:
-            raise HTTPException(status_code=422, detail=f"YouTube couldn't subscribe you: {exc}")
+            except YouTubeError as exc:
+                log.warning("subscribe: stub enrich failed (%s): %s", channel_id, exc)
     db.add(
         Subscription(
             user_id=user.id,
diff --git a/backend/app/routes/downloads.py b/backend/app/routes/downloads.py
index 71153d5..3317130 100644
--- a/backend/app/routes/downloads.py
+++ b/backend/app/routes/downloads.py
@@ -265,7 +265,7 @@ def enqueue_download(
             db, user.id, source_kind, source_ref, spec, profile_id, display_name
         )
     except quota.QuotaExceeded as e:
-        raise HTTPException(status_code=422, detail=_quota_message(e))
+        raise HTTPException(status_code=422, detail=_quota_detail(e))
     return _serialize_job(db, job)
 
 
@@ -288,27 +288,16 @@ def enqueue_edit(
     try:
         job = service.enqueue_edit(db, user.id, source_job, spec, display_name)
     except quota.QuotaExceeded as e:
-        raise HTTPException(status_code=422, detail=_quota_message(e))
+        raise HTTPException(status_code=422, detail=_quota_detail(e))
     except service.EditError as e:
-        raise HTTPException(status_code=400, detail=_edit_message(e))
+        raise HTTPException(status_code=400, detail={"code": "edit", "reason": e.reason})
     return _serialize_job(db, job)
 
 
-def _edit_message(e: service.EditError) -> str:
-    if e.reason == "empty_edit":
-        return "Choose a trim range or crop area first."
-    if e.reason == "source_not_ready":
-        return "The source download isn't ready to edit."
-    return "That edit couldn't be created."
-
-
-def _quota_message(e: quota.QuotaExceeded) -> str:
-    if e.reason == "max_jobs":
-        return f"You've reached your download limit ({e.limit} items). Remove some first."
-    if e.reason == "max_bytes":
-        gb = e.limit / 1_073_741_824
-        return f"You've used your download storage quota ({gb:.1f} GB). Free up space first."
-    return "Download quota exceeded."
+def _quota_detail(e: quota.QuotaExceeded) -> dict:
+    """Structured error the trilingual client localizes (reason key + numbers), instead of a
+    pre-baked English string with a dot-decimal GB value. See lib/api.ts localizeDetail()."""
+    return {"code": "quota", "reason": e.reason, "limit": e.limit, "current": e.current}
 
 
 @router.get("")
diff --git a/backend/app/routes/messages.py b/backend/app/routes/messages.py
index 6089550..de41d13 100644
--- a/backend/app/routes/messages.py
+++ b/backend/app/routes/messages.py
@@ -17,7 +17,7 @@ from datetime import datetime, timezone
 
 from fastapi import APIRouter, Depends, HTTPException, WebSocket, WebSocketDisconnect
 from pydantic import BaseModel
-from sqlalchemy import and_, func, or_, select
+from sqlalchemy import and_, case, func, or_, select
 from sqlalchemy.orm import Session
 
 from app.auth import require_human, resolved_user_id
@@ -220,25 +220,40 @@ def list_conversations(
     with the latest message + my unread count, newest first. Lazily creates the welcome on the
     first open. User-message previews are ciphertext — the client decrypts them."""
     ensure_welcome(db, user)
-    msgs = (
+    # The conversation partner for a message, from this user's perspective (system → 0).
+    partner_expr = case(
+        (Message.kind == "system", SYSTEM_PARTNER_ID),
+        (Message.sender_id == user.id, Message.recipient_id),
+        else_=Message.sender_id,
+    )
+    mine = or_(Message.sender_id == user.id, Message.recipient_id == user.id)
+    # Latest message per conversation in ONE query (DISTINCT ON, Postgres) instead of loading the
+    # user's whole message history into Python — bounded by the number of conversations.
+    latest = (
         db.execute(
             select(Message)
-            .where(or_(Message.sender_id == user.id, Message.recipient_id == user.id))
-            .order_by(Message.created_at.desc())
+            .where(mine)
+            .distinct(partner_expr)
+            .order_by(partner_expr, Message.created_at.desc())
         )
         .scalars()
         .all()
     )
-    convs: dict[int, dict] = {}
-    for m in msgs:
+    # Unread incoming, grouped per conversation.
+    unread = dict(
+        db.execute(
+            select(partner_expr, func.count())
+            .where(mine, Message.recipient_id == user.id, Message.read_at.is_(None))
+            .group_by(partner_expr)
+        ).all()
+    )
+
+    def _pid(m: Message) -> int:
         if m.kind == "system":
-            pid = SYSTEM_PARTNER_ID
-        else:
-            pid = m.recipient_id if m.sender_id == user.id else m.sender_id
-        c = convs.setdefault(pid, {"last": m, "unread": 0})
-        if m.recipient_id == user.id and m.read_at is None:
-            c["unread"] += 1
-    user_ids = [pid for pid in convs if pid != SYSTEM_PARTNER_ID]
+            return SYSTEM_PARTNER_ID
+        return m.recipient_id if m.sender_id == user.id else m.sender_id
+
+    user_ids = [_pid(m) for m in latest if m.kind != "system"]
     partners = {}
     if user_ids:
         partners = {
@@ -246,7 +261,8 @@ def list_conversations(
             for u in db.execute(select(User).where(User.id.in_(user_ids))).scalars().all()
         }
     items = []
-    for pid, c in convs.items():
+    for m in latest:
+        pid = _pid(m)
         if pid == SYSTEM_PARTNER_ID:
             partner = _system_partner()
         elif pid in partners:
@@ -254,7 +270,7 @@ def list_conversations(
         else:
             continue
         items.append(
-            {"partner": partner, "last_message": _serialize_msg(c["last"]), "unread": c["unread"]}
+            {"partner": partner, "last_message": _serialize_msg(m), "unread": int(unread.get(pid, 0))}
         )
     items.sort(key=lambda x: x["last_message"]["created_at"] or "", reverse=True)
     return {"items": items}
@@ -275,9 +291,6 @@ def get_thread(
         cond = and_(Message.recipient_id == user.id, Message.kind == "system")
     else:
         p = db.get(User, partner_id)
-        if p is None:
-            raise HTTPException(status_code=404, detail="User not found")
-        partner = _serialize_user(p)
         cond = and_(
             Message.kind == "user",
             or_(
@@ -285,6 +298,13 @@ def get_thread(
                 and_(Message.sender_id == partner_id, Message.recipient_id == user.id),
             ),
         )
+        # MB2: don't leak arbitrary user identities. Resolve a partner only if they're messageable
+        # OR we already share a thread (so a conversation with a since-suspended/deactivated user
+        # still opens). Otherwise the same 404 as a non-existent id → no enumeration oracle.
+        has_history = db.scalar(select(Message.id).where(cond).limit(1))
+        if p is None or (not is_messageable_user(p) and not has_history):
+            raise HTTPException(status_code=404, detail="User not found")
+        partner = _serialize_user(p)
     msgs = (
         db.execute(select(Message).where(cond).order_by(Message.created_at.asc()))
         .scalars()
@@ -299,6 +319,10 @@ def get_thread(
                 changed = True
         if changed:
             db.commit()
+            # MB3: ping this user's OTHER tabs/devices that their unread dropped so the badge
+            # refreshes live instead of waiting for the next 20s poll. The client re-fetches the
+            # count on this signal, so no number is carried here.
+            manager.push(user.id, {"type": "unread"})
     return {"partner": partner, "items": [_serialize_msg(m) for m in msgs]}
 
 
diff --git a/backend/app/routes/playlists.py b/backend/app/routes/playlists.py
index e81a2c9..e37d625 100644
--- a/backend/app/routes/playlists.py
+++ b/backend/app/routes/playlists.py
@@ -92,19 +92,12 @@ def _remove_item(db: Session, pl: Playlist, video_id: str, *, mark_dirty: bool)
 
 
 def _summary(
-    db: Session,
     pl: Playlist,
     count: int,
     total_duration: int = 0,
     has_video: bool | None = None,
+    cover: str | None = None,
 ) -> dict:
-    cover = db.scalar(
-        select(Video.thumbnail_url)
-        .join(PlaylistItem, PlaylistItem.video_id == Video.id)
-        .where(PlaylistItem.playlist_id == pl.id)
-        .order_by(PlaylistItem.position)
-        .limit(1)
-    )
     out = {
         "id": pl.id,
         "name": pl.name,
@@ -121,18 +114,6 @@ def _summary(
     return out
 
 
-def _total_duration(db: Session, playlist_id: int) -> int:
-    return (
-        db.scalar(
-            select(func.coalesce(func.sum(Video.duration_seconds), 0))
-            .select_from(PlaylistItem)
-            .join(Video, Video.id == PlaylistItem.video_id)
-            .where(PlaylistItem.playlist_id == playlist_id)
-        )
-        or 0
-    )
-
-
 @router.get("")
 def list_playlists(
     contains: str | None = None,
@@ -183,13 +164,34 @@ def list_playlists(
             .scalars()
             .all()
         )
+    # Batch the cover thumbnails (first item per playlist by position) in ONE window query
+    # instead of a per-playlist SELECT inside _summary (the old N+1).
+    rn = func.row_number().over(
+        partition_by=PlaylistItem.playlist_id,
+        order_by=PlaylistItem.position,
+    ).label("rn")
+    first_items = (
+        select(
+            PlaylistItem.playlist_id.label("pid"),
+            Video.thumbnail_url.label("thumb"),
+            rn,
+        )
+        .join(Video, Video.id == PlaylistItem.video_id)
+        .where(PlaylistItem.playlist_id.in_(ids))
+        .subquery()
+    )
+    covers = dict(
+        db.execute(
+            select(first_items.c.pid, first_items.c.thumb).where(first_items.c.rn == 1)
+        ).all()
+    )
     return [
         _summary(
-            db,
             p,
             counts.get(p.id, 0),
             durations.get(p.id, 0),
             (p.id in member) if contains else None,
+            covers.get(p.id),
         )
         for p in pls
     ]
@@ -207,7 +209,7 @@ def create_playlist(
     pl = Playlist(user_id=user.id, name=name, position=_next_playlist_position(db, user.id))
     db.add(pl)
     db.commit()
-    return _summary(db, pl, 0)
+    return _summary(pl, 0)
 
 
 def _watch_later(db: Session, user: User) -> Playlist:
@@ -350,13 +352,23 @@ def push(
         )
     try:
         with quota.attribute(user.id, quota.QuotaAction.PLAYLISTS_PUSH):
-            plan = plan_push(db, user, pl)
+            # Read the live playlist ONCE (linked playlists only) and share it with both the
+            # plan and the push, halving read-quota and closing the second read→write TOCTOU
+            # window. A fresh export (no yt_playlist_id) reads nothing.
+            live = None
+            if pl.yt_playlist_id:
+                with YouTubeClient(db, user) as yt:
+                    live = (
+                        list(yt.iter_playlist_items_with_ids(pl.yt_playlist_id)),
+                        yt.get_playlist_snippet(pl.yt_playlist_id),
+                    )
+            plan = plan_push(db, user, pl, live=live)
             if plan["units_estimate"] > quota.remaining_today(db):
                 raise HTTPException(
                     status_code=429,
                     detail="Not enough YouTube quota left today for this sync.",
                 )
-            return push_playlist(db, user, pl)
+            return push_playlist(db, user, pl, live=live)
     except YouTubeError:
         db.rollback()
         raise HTTPException(status_code=422, detail="YouTube playlist sync failed.")
@@ -405,10 +417,25 @@ def rename_playlist(
             pl.name = name
             recompute_dirty(db, pl)
     db.commit()
-    count = db.scalar(
-        select(func.count()).where(PlaylistItem.playlist_id == pl.id)
+    # One aggregate for count + duration (outer join so an empty playlist still returns 0),
+    # plus a single cover lookup — was 3 separate round-trips.
+    count, total = db.execute(
+        select(
+            func.count(PlaylistItem.id),
+            func.coalesce(func.sum(Video.duration_seconds), 0),
+        )
+        .select_from(PlaylistItem)
+        .outerjoin(Video, Video.id == PlaylistItem.video_id)
+        .where(PlaylistItem.playlist_id == pl.id)
+    ).one()
+    cover = db.scalar(
+        select(Video.thumbnail_url)
+        .join(PlaylistItem, PlaylistItem.video_id == Video.id)
+        .where(PlaylistItem.playlist_id == pl.id)
+        .order_by(PlaylistItem.position)
+        .limit(1)
     )
-    return _summary(db, pl, count or 0, _total_duration(db, pl.id))
+    return _summary(pl, count or 0, total or 0, cover=cover)
 
 
 @router.delete("/{playlist_id}")
diff --git a/backend/app/routes/search.py b/backend/app/routes/search.py
index d744714..b5489dd 100644
--- a/backend/app/routes/search.py
+++ b/backend/app/routes/search.py
@@ -60,6 +60,11 @@ def _classify_shorts(db: Session, videos: list[Video]) -> None:
     for v in videos:
         if v.shorts_probed:
             continue
+        if v.enriched_at is None:
+            # Enrichment failed (proxy blip) or YouTube omitted the row — duration is unknown,
+            # so DON'T finalise shorts_probed off a null duration; leave it for the scheduler
+            # (which only classifies enriched rows) to retry. Otherwise a real Short would leak.
+            continue
         if (
             v.live_status != "none"
             or v.duration_seconds is None
@@ -164,7 +169,13 @@ def _ingest_candidates(
     # 4) Confirm/deny Shorts (no quota) so none enter via search.
     _classify_shorts(db, videos)
 
-    keep = {v.id for v in videos if not v.is_short and v.live_status not in LIVE_OR_UPCOMING}
+    keep = {
+        v.id
+        for v in videos
+        if v.enriched_at is not None
+        and not v.is_short
+        and v.live_status not in LIVE_OR_UPCOMING
+    }
     return [vid for vid in ids if vid in keep]
 
 
diff --git a/backend/app/sync/playlists.py b/backend/app/sync/playlists.py
index 9634a99..59dbdc0 100644
--- a/backend/app/sync/playlists.py
+++ b/backend/app/sync/playlists.py
@@ -217,11 +217,12 @@ def _reorder_moves(current: list[str], desired: list[str]) -> int:
     return moves
 
 
-def plan_push(db: Session, user: User, pl: Playlist) -> dict:
+def plan_push(db: Session, user: User, pl: Playlist, *, live=None) -> dict:
     """Compute (without writing) what pushing this local playlist to YouTube would do:
     create vs update, how many inserts/deletes/reorders, the quota estimate, and whether
     YouTube has diverged (items present there that local will remove). Costs read units
-    (1/page) for a linked playlist; nothing for a fresh export."""
+    (1/page) for a linked playlist; nothing for a fresh export. `live` = a pre-fetched
+    (current_items, snippet) tuple so the caller can share one read with push_playlist."""
     desired = _local_video_ids(db, pl)
     if not pl.yt_playlist_id:
         ops = 1 + len(desired)  # create the playlist + one insert per video
@@ -234,9 +235,12 @@ def plan_push(db: Session, user: User, pl: Playlist) -> dict:
             "yt_extra": 0,
             "units_estimate": ops * WRITE_UNIT_COST,
         }
-    with YouTubeClient(db, user) as yt:
-        current = list(yt.iter_playlist_items_with_ids(pl.yt_playlist_id))
-        snippet = yt.get_playlist_snippet(pl.yt_playlist_id)
+    if live is not None:
+        current, snippet = live
+    else:
+        with YouTubeClient(db, user) as yt:
+            current = list(yt.iter_playlist_items_with_ids(pl.yt_playlist_id))
+            snippet = yt.get_playlist_snippet(pl.yt_playlist_id)
     rename = bool(snippet) and (snippet.get("title") or "") != pl.name
     cur_vids = [it["video_id"] for it in current]
     cur_set = set(cur_vids)
@@ -259,10 +263,11 @@ def plan_push(db: Session, user: User, pl: Playlist) -> dict:
     }
 
 
-def push_playlist(db: Session, user: User, pl: Playlist) -> dict:
+def push_playlist(db: Session, user: User, pl: Playlist, *, live=None) -> dict:
     """Push a local playlist to YouTube: create it if needed, then reconcile membership
     and order so YouTube matches local (local wins). Marks the playlist clean on success.
-    Caller must have checked the write scope and the quota budget."""
+    Caller must have checked the write scope and the quota budget. `live` = a pre-fetched
+    (current_items, snippet) tuple (from plan_push's read) to avoid a second live page-through."""
     desired = _local_video_ids(db, pl)
     inserted = deleted = reordered = created = 0
     failures: list[str] = []
@@ -291,14 +296,17 @@ def push_playlist(db: Session, user: User, pl: Playlist) -> dict:
                 "yt_playlist_id": pl.yt_playlist_id,
             }
 
-        # Existing link: diff against the live YouTube state.
-        snippet = yt.get_playlist_snippet(pl.yt_playlist_id)
+        # Existing link: diff against the live YouTube state (reuse plan_push's read if given).
+        if live is not None:
+            current, snippet = live
+        else:
+            snippet = yt.get_playlist_snippet(pl.yt_playlist_id)
+            current = list(yt.iter_playlist_items_with_ids(pl.yt_playlist_id))
         if snippet is not None and (snippet.get("title") or "") != pl.name:
             try:
                 yt.update_playlist_title(pl.yt_playlist_id, pl.name)
             except YouTubeError:
                 failures.append("title")
-        current = list(yt.iter_playlist_items_with_ids(pl.yt_playlist_id))
         item_id_by_vid = {it["video_id"]: it["item_id"] for it in current}
         cur_vids = [it["video_id"] for it in current]
         desired_set = set(desired)
diff --git a/backend/app/sysconfig.py b/backend/app/sysconfig.py
index 6a6742a..8264fb5 100644
--- a/backend/app/sysconfig.py
+++ b/backend/app/sysconfig.py
@@ -25,6 +25,7 @@ class ConfigSpec:
     secret: bool = False
     min: int | None = None
     max: int | None = None
+    allow_empty: bool = False  # str keys: a stored "" is an explicit empty value, not "unset"
 
 
 # Registry of DB-overridable keys. Add a key here + wire its read through get_*() to move it
@@ -33,7 +34,7 @@ SPECS: tuple[ConfigSpec, ...] = (
     # --- Email / SMTP (one logical group; the password is the only secret) ---
     ConfigSpec("smtp_host", "str", "email", "smtp_host"),
     ConfigSpec("smtp_port", "int", "email", "smtp_port", min=1, max=65535),
-    ConfigSpec("smtp_user", "str", "email", "smtp_user"),
+    ConfigSpec("smtp_user", "str", "email", "smtp_user", allow_empty=True),
     ConfigSpec("smtp_from", "str", "email", "smtp_from"),
     ConfigSpec("smtp_password", "str", "email", "smtp_password", secret=True),
     # --- Quota (shared YouTube Data API daily budget) ---
@@ -59,7 +60,7 @@ SPECS: tuple[ConfigSpec, ...] = (
     # --- YouTube Data API key (secret; optional — public reads prefer it over OAuth) ---
     ConfigSpec("youtube_api_key", "str", "youtube", "youtube_api_key", secret=True),
     # Optional egress proxy for YouTube API calls (fixed-IP host for an IP-restricted key).
-    ConfigSpec("youtube_api_proxy", "str", "youtube", "youtube_api_proxy"),
+    ConfigSpec("youtube_api_proxy", "str", "youtube", "youtube_api_proxy", allow_empty=True),
     # --- Google OAuth client (Sign in with Google; both encrypted, env fallback). Set from the
     #     install wizard / Configuration page so no restart is needed when the creds change. ---
     ConfigSpec("google_client_id", "str", "google", "google_client_id", secret=True),
@@ -124,7 +125,12 @@ def get(db: Session, key: str):
     """Effective value: the DB override (typed) if set, else the env/config default."""
     s = _BY_KEY[key]
     raw = _raw_override(db, key)
-    if raw is None or raw == "":
+    if raw is None:
+        return _default(s)
+    if raw == "" and not s.allow_empty:
+        # For most keys an empty override means "fall back to the env default". Keys that opt
+        # into allow_empty (e.g. smtp_user, youtube_api_proxy) treat "" as a real value — so an
+        # admin can blank one to DISABLE it rather than being stuck with the env default.
         return _default(s)
     try:
         return _coerce(s, raw)
@@ -197,6 +203,7 @@ def describe(db: Session) -> dict:
             "min": s.min,
             "max": s.max,
             "is_set": is_set,  # an override row exists
+            "allow_empty": s.allow_empty,  # if true, the UI stores "" rather than deleting the row
         }
         if s.secret:
             item["default_is_set"] = bool(_default(s))
diff --git a/frontend/src/App.tsx b/frontend/src/App.tsx
index 68d1339..a498575 100644
--- a/frontend/src/App.tsx
+++ b/frontend/src/App.tsx
@@ -275,8 +275,10 @@ export default function App() {
   // "Focus this channel in the manager": jump to the Channels page and seed its name filter
   // so the channel is isolated. Cleared when leaving the page so it doesn't re-apply later.
   const [focusChannelName, setFocusChannelName] = useState<string | null>(null);
+  const [focusChannelToken, setFocusChannelToken] = useState(0);
   const focusChannel = (name: string) => {
     setFocusChannelName(name);
+    setFocusChannelToken((n) => n + 1); // re-seed even when the same channel is re-focused
     setChannelsView("subscribed"); // the name filter applies to the subscriptions table
     setPage("channels");
   };
@@ -803,6 +805,7 @@ export default function App() {
               canWrite={meQuery.data!.can_write}
               isAdmin={meQuery.data!.role === "admin"}
               focusChannelName={focusChannelName}
+              focusChannelToken={focusChannelToken}
               onFocusChannel={focusChannel}
               statusFilter={channelFilter}
               setStatusFilter={setChannelFilter}
diff --git a/frontend/src/components/AdminUsers.tsx b/frontend/src/components/AdminUsers.tsx
index 20b69af..9c56ba2 100644
--- a/frontend/src/components/AdminUsers.tsx
+++ b/frontend/src/components/AdminUsers.tsx
@@ -52,19 +52,32 @@ function UsersRoles({ me }: { me: Me }) {
   const qc = useQueryClient();
   const confirm = useConfirm();
   const q = useQuery({ queryKey: ["admin-users"], queryFn: api.adminUsers });
+  // Which rows have an action in flight, so we disable ONLY those rows' buttons (SC1) — a Set, since
+  // with per-row disabling the admin can now start actions on several rows concurrently.
+  const [pendingIds, setPendingIds] = useState<Set<number>>(new Set());
+  const startPending = (id: number) => setPendingIds((s) => new Set(s).add(id));
+  const endPending = (id: number) =>
+    setPendingIds((s) => {
+      const n = new Set(s);
+      n.delete(id);
+      return n;
+    });
   const setRole = useMutation({
     mutationFn: ({ id, role }: { id: number; role: "user" | "admin"; email: string }) =>
       api.setUserRole(id, role),
+    onMutate: (vars) => startPending(vars.id),
     onSuccess: (_d, vars) => {
       qc.invalidateQueries({ queryKey: ["admin-users"] });
       notify({ level: "success", message: t("users.roles.updated", { email: vars.email }) });
     },
+    onSettled: (_d, _e, vars) => endPending(vars.id),
     // Errors (e.g. last-admin / self) surface via the global error dialog with the server's detail.
   });
 
   const suspend = useMutation({
     mutationFn: ({ id, suspended }: { id: number; suspended: boolean; email: string }) =>
       api.setUserSuspended(id, suspended),
+    onMutate: (vars) => startPending(vars.id),
     onSuccess: (_d, vars) => {
       qc.invalidateQueries({ queryKey: ["admin-users"] });
       notify({
@@ -74,14 +87,17 @@ function UsersRoles({ me }: { me: Me }) {
         }),
       });
     },
+    onSettled: (_d, _e, vars) => endPending(vars.id),
     // Guards (demo / self / last admin) surface via the global error dialog.
   });
   const del = useMutation({
     mutationFn: ({ id }: { id: number; email: string }) => api.adminDeleteUser(id),
+    onMutate: (vars) => startPending(vars.id),
     onSuccess: (_d, vars) => {
       qc.invalidateQueries({ queryKey: ["admin-users"] });
       notify({ level: "success", message: t("users.delete.done", { email: vars.email }) });
     },
+    onSettled: (_d, _e, vars) => endPending(vars.id),
   });
 
   const onToggle = async (u: AdminUserRow) => {
@@ -162,7 +178,7 @@ function UsersRoles({ me }: { me: Me }) {
                 >
                   <button
                     onClick={() => onToggle(u)}
-                    disabled={u.is_demo || self || setRole.isPending}
+                    disabled={u.is_demo || self || pendingIds.has(u.id)}
                     className="shrink-0 glass-card glass-hover inline-flex items-center gap-1 px-2.5 py-1.5 rounded-lg text-xs disabled:opacity-40 transition"
                   >
                     <Shield className="w-3.5 h-3.5" />
@@ -182,7 +198,7 @@ function UsersRoles({ me }: { me: Me }) {
                 >
                   <button
                     onClick={() => onSuspend(u)}
-                    disabled={u.is_demo || self || suspend.isPending}
+                    disabled={u.is_demo || self || pendingIds.has(u.id)}
                     aria-label={u.is_suspended ? t("users.suspend.undoAction") : t("users.suspend.action")}
                     className={`shrink-0 p-1.5 rounded-lg border disabled:opacity-40 transition ${
                       u.is_suspended
@@ -196,7 +212,7 @@ function UsersRoles({ me }: { me: Me }) {
                 <Tooltip hint={u.is_demo || self ? t("users.delete.locked") : t("users.delete.action")}>
                   <button
                     onClick={() => onDelete(u)}
-                    disabled={u.is_demo || self || del.isPending}
+                    disabled={u.is_demo || self || pendingIds.has(u.id)}
                     aria-label={t("users.delete.action")}
                     className="shrink-0 p-1.5 rounded-lg border border-border text-muted hover:text-red-400 disabled:opacity-40 transition"
                   >
@@ -217,6 +233,7 @@ function UsersRoles({ me }: { me: Me }) {
 function AdminInvites() {
   const { t } = useTranslation();
   const qc = useQueryClient();
+  const confirm = useConfirm();
   const invites = useQuery({ queryKey: ["admin-invites"], queryFn: () => api.adminInvites() });
   const [newEmail, setNewEmail] = useState("");
   const refresh = () => {
@@ -233,9 +250,21 @@ function AdminInvites() {
   });
   const deny = useMutation({
     mutationFn: (id: number) => api.denyInvite(id),
-    onSuccess: refresh,
+    onSuccess: (_d, _id) => {
+      refresh();
+      notify({ level: "success", message: t("settings.invites.denied") });
+    },
     onError: () => notify({ level: "error", message: t("settings.invites.denyFailed") }),
   });
+  const onDeny = async (i: { id: number; email: string }) => {
+    const ok = await confirm({
+      title: t("settings.invites.denyTitle"),
+      message: t("settings.invites.denyConfirm", { email: i.email }),
+      confirmLabel: t("settings.invites.deny"),
+      danger: true,
+    });
+    if (ok) deny.mutate(i.id);
+  };
   const add = useMutation({
     mutationFn: (email: string) => api.addInvite(email),
     onSuccess: (_d, email) => {
@@ -261,7 +290,7 @@ function AdminInvites() {
               key={i.id}
               inv={i}
               onApprove={() => approve.mutate({ id: i.id, email: i.email })}
-              onDeny={() => deny.mutate(i.id)}
+              onDeny={() => onDeny(i)}
               busy={approve.isPending || deny.isPending}
             />
           ))}
@@ -329,9 +358,21 @@ function AdminDemo() {
   });
   const remove = useMutation({
     mutationFn: (id: number) => api.removeDemoWhitelist(id),
-    onSuccess: () => qc.invalidateQueries({ queryKey: ["demo-whitelist"] }),
+    onSuccess: () => {
+      qc.invalidateQueries({ queryKey: ["demo-whitelist"] });
+      notify({ level: "success", message: t("settings.demo.removed") });
+    },
     onError: () => notify({ level: "error", message: t("settings.demo.removeFailed") }),
   });
+  const onRemove = async (r: { id: number; email: string }) => {
+    const ok = await confirm({
+      title: t("settings.demo.removeTitle"),
+      message: t("settings.demo.removeConfirm", { email: r.email }),
+      confirmLabel: t("settings.demo.remove"),
+      danger: true,
+    });
+    if (ok) remove.mutate(r.id);
+  };
   const reset = useMutation({
     mutationFn: () => api.resetDemo(),
     onSuccess: (r: { playlists_seeded: number }) =>
@@ -362,7 +403,7 @@ function AdminDemo() {
               </div>
               <Tooltip hint={t("settings.demo.removeHint")}>
                 <button
-                  onClick={() => remove.mutate(r.id)}
+                  onClick={() => onRemove(r)}
                   disabled={remove.isPending}
                   className="shrink-0 p-1.5 rounded-lg border border-border text-muted hover:text-red-400 disabled:opacity-50 transition"
                   aria-label={t("settings.demo.remove")}
diff --git a/frontend/src/components/Channels.tsx b/frontend/src/components/Channels.tsx
index 85b7f93..b4e2043 100644
--- a/frontend/src/components/Channels.tsx
+++ b/frontend/src/components/Channels.tsx
@@ -48,6 +48,7 @@ export default function Channels({
   onFilterByTag,
   onFocusChannel,
   focusChannelName,
+  focusChannelToken,
   statusFilter,
   setStatusFilter,
   view,
@@ -61,6 +62,9 @@ export default function Channels({
   onFilterByTag: (tagId: number, name: string) => void;
   onFocusChannel: (name: string) => void;
   focusChannelName: string | null;
+  // Bumped every time a focus-channel intent is (re-)issued, so re-clicking the same channel
+  // re-seeds the search box even when the name is unchanged.
+  focusChannelToken: number;
   statusFilter: ChannelStatusFilter;
   setStatusFilter: (f: ChannelStatusFilter) => void;
   // The active tab lives in App so navigation intents that target the subscriptions table
@@ -92,6 +96,10 @@ export default function Channels({
     qc.invalidateQueries({ queryKey: ["channels"] });
     qc.invalidateQueries({ queryKey: ["tags"] });
     qc.invalidateQueries({ queryKey: ["my-status"] });
+    // FB2: syncing subscriptions can change the feed immediately — newly-followed channels may
+    // already have videos in the shared catalog, so refresh the feed too (not just the manager).
+    qc.invalidateQueries({ queryKey: ["feed"] });
+    qc.invalidateQueries({ queryKey: ["feed-count"] });
   };
 
   const userTags = (tagsQuery.data ?? []).filter((t) => !t.system);
@@ -189,7 +197,8 @@ export default function Channels({
   // A focus-channel intent (header "without full history" / tag manager) seeds the search box.
   useEffect(() => {
     if (focusChannelName) setSearch(focusChannelName);
-  }, [focusChannelName]);
+    // eslint-disable-next-line react-hooks/exhaustive-deps
+  }, [focusChannelToken]);
   // The header's reset intent clears the search + tag chips (skip the initial mount).
   const resetRef = useRef(filtersResetToken);
   useEffect(() => {
diff --git a/frontend/src/components/ChatDock.tsx b/frontend/src/components/ChatDock.tsx
index 87dbb0d..6304563 100644
--- a/frontend/src/components/ChatDock.tsx
+++ b/frontend/src/components/ChatDock.tsx
@@ -3,7 +3,7 @@ import { useTranslation } from "react-i18next";
 import { useQueryClient } from "@tanstack/react-query";
 import { ChevronDown, ChevronUp, X } from "lucide-react";
 import { closeChat, initDock, notifyIncoming, toggleMinimize, useDockChats, type DockChat } from "../lib/chatDock";
-import { onMessage } from "../lib/messagesSocket";
+import { onMessage, onUnread } from "../lib/messagesSocket";
 import * as e2ee from "../lib/e2ee";
 import Avatar from "./Avatar";
 import ChatThread from "./ChatThread";
@@ -39,6 +39,16 @@ export default function ChatDock({ meId }: { meId: number }) {
     [qc, meId]
   );
 
+  // Live badge sync: another tab/device read a thread → refresh this tab's unread count + list.
+  useEffect(
+    () =>
+      onUnread(() => {
+        qc.invalidateQueries({ queryKey: ["message-unread"] });
+        qc.invalidateQueries({ queryKey: ["conversations"] });
+      }),
+    [qc]
+  );
+
   if (chats.length === 0) return null;
   return (
     <div className="fixed bottom-0 right-0 z-40 flex flex-row-reverse items-end gap-3 p-4 pointer-events-none">
diff --git a/frontend/src/components/ChatThread.tsx b/frontend/src/components/ChatThread.tsx
index 58b6816..c577740 100644
--- a/frontend/src/components/ChatThread.tsx
+++ b/frontend/src/components/ChatThread.tsx
@@ -6,12 +6,10 @@ import { api, HttpError, type Message, type MessageUser } from "../lib/api";
 import { useLiveQuery } from "../lib/useLiveQuery";
 import { relativeTime } from "../lib/format";
 import { notify } from "../lib/notifications";
-import { partnerPub, useKeyState } from "../lib/messaging";
+import { partnerPub, POLL_MS, useKeyState } from "../lib/messaging";
 import * as e2ee from "../lib/e2ee";
 import KeyGate from "./KeyGate";
 
-const POLL_MS = 20000; // safety net; live updates arrive over the WebSocket
-
 // The message list + composer for one conversation, shared by the full Messages page and the
 // floating dock window. Handles client-side decryption and encrypt-on-send; the surrounding
 // chrome (back button / minimize / close) is the caller's. Self-contained key gating: prompts
@@ -66,13 +64,28 @@ export default function ChatThread({
     // eslint-disable-next-line react-hooks/exhaustive-deps
   }, [q.dataUpdatedAt, ready, isSystem, partnerId, t]);
 
-  // Opening / refreshing the thread marks incoming messages read, so clear the badges.
+  // Opening the thread (or a new incoming message arriving) marks messages read server-side, so
+  // refresh the badges — but ONLY when the incoming-message count actually changed, not on every
+  // 20s poll (which would needlessly refetch /conversations + /unread_count each tick).
+  const lastIncoming = useRef(-1);
+  const lastPartner = useRef(partnerId);
   useEffect(() => {
-    if (q.dataUpdatedAt) {
+    if (!q.dataUpdatedAt) return;
+    // The Messages page reuses one ChatThread instance across conversation switches (not keyed by
+    // partnerId), so reset the counter when the partner changes — otherwise switching to a thread
+    // with the same incoming-count would skip the open-marks-read refresh.
+    if (lastPartner.current !== partnerId) {
+      lastPartner.current = partnerId;
+      lastIncoming.current = -1;
+    }
+    const incoming = (q.data?.items ?? []).filter((m) => m.recipient_id === meId).length;
+    if (incoming !== lastIncoming.current) {
+      lastIncoming.current = incoming;
       qc.invalidateQueries({ queryKey: ["conversations"] });
       qc.invalidateQueries({ queryKey: ["message-unread"] });
     }
-  }, [q.dataUpdatedAt, qc]);
+    // eslint-disable-next-line react-hooks/exhaustive-deps
+  }, [q.dataUpdatedAt, partnerId, meId, qc]);
 
   // Scroll to the newest message when the count changes (open / new message) — NOT on `plain`,
   // which gets a fresh object on every poll's decrypt pass and would yank a scrolled-up reader
diff --git a/frontend/src/components/ConfigPanel.tsx b/frontend/src/components/ConfigPanel.tsx
index 680586a..730dd0d 100644
--- a/frontend/src/components/ConfigPanel.tsx
+++ b/frontend/src/components/ConfigPanel.tsx
@@ -38,15 +38,23 @@ export default function ConfigPanel() {
   // clearing the field, since an empty secret field means "leave unchanged").
   const [secretReset, setSecretReset] = useState<Record<string, boolean>>({});
   const [saveState, setSaveState] = useState<SaveState>("idle");
+  // Bumped after our own save so the draft re-seeds from fresh server values; a plain mid-edit
+  // refetch does NOT (see the effect below).
+  const [reseedToken, setReseedToken] = useState(0);
   // One tab per config group (persisted). Called before the loading guard so hook order is
   // stable; the active id is clamped to a real group at render time once data has loaded.
   const [tab, setTab] = usePersistedTab(LS.configTab);
 
-  // Re-seed the draft whenever the server data changes (initial load + after a save/reset).
+  // A stable signature of the config SHAPE — changes only when keys are added/removed, not when an
+  // unchanged refetch produces a new baseline object. Re-seed the draft on a shape change (initial
+  // load, registry change) or an explicit post-save bump — so a refetch that resolves mid-edit
+  // (e.g. an invalidation) can no longer clobber the admin's in-progress draft (CB2).
+  const dataVersion = useMemo(() => items.map((i) => i.key).join("|"), [items]);
   useEffect(() => {
     setDraft(baseline);
     setSecretReset({});
-  }, [baseline]);
+    // eslint-disable-next-line react-hooks/exhaustive-deps
+  }, [dataVersion, reseedToken]);
 
   const isDirty = (it: ConfigItem): boolean => {
     if (it.secret) return (draft[it.key] ?? "").trim() !== "" || !!secretReset[it.key];
@@ -67,12 +75,16 @@ export default function ConfigPanel() {
         } else if (it.type === "bool") {
           await api.setConfig(key, raw === "true");
         } else if (raw === "") {
-          if (it.is_set) await api.resetConfig(key); // cleared → fall back to default
+          // allow_empty keys treat a blank as an explicit empty value (e.g. disable smtp_user /
+          // youtube_api_proxy) rather than resetting to the env default (AB3).
+          if (it.allow_empty) await api.setConfig(key, "");
+          else if (it.is_set) await api.resetConfig(key); // cleared → fall back to default
         } else {
           await api.setConfig(key, it.type === "int" ? Number(raw) : raw);
         }
       }
       await qc.invalidateQueries({ queryKey: ["admin-config"] });
+      setReseedToken((n) => n + 1); // re-seed the draft from the saved server state
       setSaveState("saved");
       setTimeout(() => setSaveState((s) => (s === "saved" ? "idle" : s)), 2500);
     } catch {
diff --git a/frontend/src/components/Messages.tsx b/frontend/src/components/Messages.tsx
index 769256e..86b20f7 100644
--- a/frontend/src/components/Messages.tsx
+++ b/frontend/src/components/Messages.tsx
@@ -5,7 +5,7 @@ import { ArrowLeft, ShieldCheck, SquarePen, ExternalLink } from "lucide-react";
 import { api, type Conversation, type MessageUser } from "../lib/api";
 import { useLiveQuery } from "../lib/useLiveQuery";
 import { relativeTime } from "../lib/format";
-import { partnerPub, SYSTEM_ID, useKeyState } from "../lib/messaging";
+import { partnerPub, POLL_MS, SYSTEM_ID, useKeyState } from "../lib/messaging";
 import { useHistorySubview } from "../lib/history";
 import { openChat } from "../lib/chatDock";
 import * as e2ee from "../lib/e2ee";
@@ -13,8 +13,6 @@ import Avatar from "./Avatar";
 import KeyGate from "./KeyGate";
 import ChatThread from "./ChatThread";
 
-const POLL_MS = 20000;
-
 type View = "list" | "new" | { partnerId: number; name?: string; avatar?: string | null; system?: boolean };
 
 export default function Messages({ meId }: { meId: number }) {
diff --git a/frontend/src/components/PlayerModal.tsx b/frontend/src/components/PlayerModal.tsx
index 1f663ae..ad173dd 100644
--- a/frontend/src/components/PlayerModal.tsx
+++ b/frontend/src/components/PlayerModal.tsx
@@ -107,6 +107,10 @@ export default function PlayerModal({
   const mountRef = useRef<HTMLDivElement | null>(null);
   const playerRef = useRef<any>(null);
   const autoMarkedRef = useRef(false);
+  // Bound consecutive unplayable items so an auto-advancing queue (esp. loop=all) can't spin over a
+  // run of dead videos — after the cap we stop on the error overlay instead of skipping forever.
+  const MAX_CONSECUTIVE_ERRORS = 3;
+  const errorStreakRef = useRef(0);
   // Keyboard/wheel controls. We keep focus on the modal card (not the cross-origin player
   // iframe) so F / Space / Esc keep working until the user clicks into YouTube's native
   // controls; the interaction overlay below also stops the iframe stealing focus on a video
@@ -502,6 +506,7 @@ export default function PlayerModal({
           onStateChange: (e: any) => {
             // 1 === playing → sync the navigated-to video's title/author for display.
             if (e?.data === 1) {
+              errorStreakRef.current = 0; // a successful play breaks any unplayable run
               const p = playerRef.current;
               const d = p && typeof p.getVideoData === "function" ? p.getVideoData() : null;
               if (d) setLiveData({ title: d.title, author: d.author });
@@ -517,17 +522,47 @@ export default function PlayerModal({
           },
           // The embed couldn't play this video (embedding disabled, removed, private…).
           // Surface our own message + an "Open on YouTube" escape hatch.
-          onError: (e: any) => setPlayerError(typeof e?.data === "number" ? e.data : -1),
+          onError: (e: any) => {
+            setPlayerError(typeof e?.data === "number" ? e.data : -1);
+            // The IFrame API fires onError (not 'ended') for an unplayable item, so advanceOnEnd()
+            // never runs and an auto-advancing queue would freeze here. Skip forward instead — but
+            // bounded, so a run of dead items (or loop=all over a broken queue) can't spin. We do
+            // NOT mark the broken video watched (only the ended-handler does that).
+            if (currentIdRef.current !== id) return; // a navigated description-link error: leave the queue alone
+            const { autoMode: a } = modeRef.current;
+            const { queue: q } = navRef.current;
+            if (a === "off" || !q || q.length <= 1) return;
+            errorStreakRef.current += 1;
+            if (errorStreakRef.current >= MAX_CONSECUTIVE_ERRORS) return; // give up; leave the overlay
+            advanceOnEnd();
+          },
         },
       });
     });
 
     // Periodic checkpoint so progress (and auto-watch) survive a crash/refresh.
     const timer = window.setInterval(persist, 5000);
+    // Save on page unload too (F5/close/navigate): effect cleanup doesn't run on a full reload, so
+    // without this the resume point lags up to 5s (a seek right before F5 would be lost). A keepalive
+    // beacon so the POST survives the unload. Only for the library item we opened with — a navigated
+    // description-link video may not be in this user's library (the server would 404).
+    const onHide = () => {
+      const p = playerRef.current;
+      if (!p || typeof p.getCurrentTime !== "function" || currentIdRef.current !== id) return;
+      try {
+        const cur = p.getCurrentTime();
+        const dur = typeof p.getDuration === "function" ? p.getDuration() : 0;
+        if (cur > 0 && dur > 0) api.saveProgressBeacon(id, cur, dur);
+      } catch {
+        /* player tearing down */
+      }
+    };
+    window.addEventListener("pagehide", onHide);
 
     return () => {
       cancelled = true;
       window.clearInterval(timer);
+      window.removeEventListener("pagehide", onHide);
       // Final flush, then refresh the feed + playlists so resume bars reflect this session.
       Promise.resolve(persist()).finally(() => {
         qc.invalidateQueries({ queryKey: ["feed"] });
diff --git a/frontend/src/components/Scheduler.tsx b/frontend/src/components/Scheduler.tsx
index e399ccd..8a227f2 100644
--- a/frontend/src/components/Scheduler.tsx
+++ b/frontend/src/components/Scheduler.tsx
@@ -318,11 +318,33 @@ export default function Scheduler() {
   });
   const data = q.data;
 
-  // Tick once a second so the per-job countdowns move between polls.
+  // Tick once a second so the per-job countdowns move between polls — but only while the tab is
+  // visible; a hidden tab doesn't need to re-render the whole page every second (SB3).
   const [, setTick] = useState(0);
   useEffect(() => {
-    const id = setInterval(() => setTick((n) => n + 1), 1000);
-    return () => clearInterval(id);
+    let id: ReturnType<typeof setInterval> | undefined;
+    const start = () => {
+      if (id == null) id = setInterval(() => setTick((n) => n + 1), 1000);
+    };
+    const stop = () => {
+      if (id != null) {
+        clearInterval(id);
+        id = undefined;
+      }
+    };
+    const onVisibility = () => {
+      if (document.hidden) stop();
+      else {
+        setTick((n) => n + 1); // snap the countdown to the correct value on return
+        start();
+      }
+    };
+    onVisibility(); // honor the current visibility on mount
+    document.addEventListener("visibilitychange", onVisibility);
+    return () => {
+      stop();
+      document.removeEventListener("visibilitychange", onVisibility);
+    };
   }, []);
 
   const pauseResume = useMutation({
diff --git a/frontend/src/i18n/locales/de/downloads.json b/frontend/src/i18n/locales/de/downloads.json
index fd7b4c8..001f96e 100644
--- a/frontend/src/i18n/locales/de/downloads.json
+++ b/frontend/src/i18n/locales/de/downloads.json
@@ -185,5 +185,17 @@
     "added": "Hinzugefügt",
     "user": "Nutzer"
   },
-  "clipBadge": "Clip"
+  "clipBadge": "Clip",
+  "errors": {
+    "quota": {
+      "max_bytes": "Dein Download-Speicherkontingent ist aufgebraucht ({{size}} GB). Gib zuerst Speicher frei.",
+      "max_jobs": "Du hast dein Download-Limit erreicht ({{limit}} Objekte). Entferne zuerst einige.",
+      "generic": "Download-Kontingent überschritten."
+    },
+    "edit": {
+      "empty_edit": "Wähle zuerst einen Zuschneidebereich oder Ausschnitt.",
+      "source_not_ready": "Der Quell-Download ist noch nicht bearbeitbar.",
+      "generic": "Dieser Schnitt konnte nicht erstellt werden."
+    }
+  }
 }
diff --git a/frontend/src/i18n/locales/de/settings.json b/frontend/src/i18n/locales/de/settings.json
index 3425b9f..77b9755 100644
--- a/frontend/src/i18n/locales/de/settings.json
+++ b/frontend/src/i18n/locales/de/settings.json
@@ -124,7 +124,10 @@
     "resetTitle": "Demo-Zustand zurücksetzen?",
     "resetConfirm": "Dies löscht alles, was das Demo-Konto angesammelt hat — Playlists, ausgeblendete/angesehene/gespeicherte Videos und Einstellungen — und legt ein paar Beispiel-Playlists neu an. Es kann nicht rückgängig gemacht werden.",
     "resetDone": "Demo zurückgesetzt — {{count}} Beispiel-Playlist(s) angelegt",
-    "resetFailed": "Das Demo-Konto konnte nicht zurückgesetzt werden"
+    "resetFailed": "Das Demo-Konto konnte nicht zurückgesetzt werden",
+    "removed": "Von der Demo-Whitelist entfernt",
+    "removeTitle": "Demo-Zugang entfernen?",
+    "removeConfirm": "{{email}} von der Demo-Whitelist entfernen? Der Zugang zum Demo-Konto ist dann nicht mehr möglich."
   },
   "invites": {
     "title": "Zugriffsanfragen",
@@ -141,6 +144,9 @@
     "approveHint": "Genehmigen — setzt diese E-Mail auf die Whitelist und benachrichtigt sie per E-Mail, dass sie dabei sind.",
     "approve": "Genehmigen",
     "denyHint": "Diese Anfrage ablehnen.",
-    "deny": "Ablehnen"
+    "deny": "Ablehnen",
+    "denied": "Anfrage abgelehnt",
+    "denyTitle": "Zugriffsanfrage ablehnen?",
+    "denyConfirm": "Die Zugriffsanfrage von {{email}} ablehnen?"
   }
 }
diff --git a/frontend/src/i18n/locales/en/downloads.json b/frontend/src/i18n/locales/en/downloads.json
index 0b404dc..896007f 100644
--- a/frontend/src/i18n/locales/en/downloads.json
+++ b/frontend/src/i18n/locales/en/downloads.json
@@ -185,5 +185,17 @@
     "added": "Added",
     "user": "User"
   },
-  "clipBadge": "Clip"
+  "clipBadge": "Clip",
+  "errors": {
+    "quota": {
+      "max_bytes": "You've used your download storage quota ({{size}} GB). Free up space first.",
+      "max_jobs": "You've reached your download limit ({{limit}} items). Remove some first.",
+      "generic": "Download quota exceeded."
+    },
+    "edit": {
+      "empty_edit": "Choose a trim range or crop area first.",
+      "source_not_ready": "The source download isn't ready to edit.",
+      "generic": "That edit couldn't be created."
+    }
+  }
 }
diff --git a/frontend/src/i18n/locales/en/settings.json b/frontend/src/i18n/locales/en/settings.json
index c6c4ac0..6b97891 100644
--- a/frontend/src/i18n/locales/en/settings.json
+++ b/frontend/src/i18n/locales/en/settings.json
@@ -124,7 +124,10 @@
     "resetTitle": "Reset demo state?",
     "resetConfirm": "This clears everything the demo account has accumulated — playlists, hidden/watched/saved videos and settings — and re-seeds a few sample playlists. It can't be undone.",
     "resetDone": "Demo reset — {{count}} sample playlist(s) seeded",
-    "resetFailed": "Couldn't reset the demo account"
+    "resetFailed": "Couldn't reset the demo account",
+    "removed": "Removed from the demo whitelist",
+    "removeTitle": "Remove demo access?",
+    "removeConfirm": "Remove {{email}} from the demo whitelist? They'll no longer be able to enter the demo account."
   },
   "invites": {
     "title": "Access requests",
@@ -141,6 +144,9 @@
     "approveHint": "Approve — whitelist this email and email them they're in.",
     "approve": "Approve",
     "denyHint": "Deny this request.",
-    "deny": "Deny"
+    "deny": "Deny",
+    "denied": "Request denied",
+    "denyTitle": "Deny access request?",
+    "denyConfirm": "Deny the access request from {{email}}?"
   }
 }
diff --git a/frontend/src/i18n/locales/hu/downloads.json b/frontend/src/i18n/locales/hu/downloads.json
index b7e61de..61cf56b 100644
--- a/frontend/src/i18n/locales/hu/downloads.json
+++ b/frontend/src/i18n/locales/hu/downloads.json
@@ -185,5 +185,17 @@
     "added": "Hozzáadva",
     "user": "Felhasználó"
   },
-  "clipBadge": "Klip"
+  "clipBadge": "Klip",
+  "errors": {
+    "quota": {
+      "max_bytes": "Elfogyott a letöltési tárhelykereted ({{size}} GB). Előbb szabadíts fel helyet.",
+      "max_jobs": "Elérted a letöltési korlátodat ({{limit}} elem). Előbb távolíts el néhányat.",
+      "generic": "Túllépted a letöltési kvótát."
+    },
+    "edit": {
+      "empty_edit": "Előbb válassz vágási tartományt vagy körbevágási területet.",
+      "source_not_ready": "A forrásletöltés még nem szerkeszthető.",
+      "generic": "Ezt a vágást nem sikerült létrehozni."
+    }
+  }
 }
diff --git a/frontend/src/i18n/locales/hu/settings.json b/frontend/src/i18n/locales/hu/settings.json
index 1048ae0..99bd459 100644
--- a/frontend/src/i18n/locales/hu/settings.json
+++ b/frontend/src/i18n/locales/hu/settings.json
@@ -124,7 +124,10 @@
     "resetTitle": "Visszaállítod a demo állapotot?",
     "resetConfirm": "Ez törli mindazt, amit a demo fiók összegyűjtött — lejátszási listák, elrejtett/megnézett/mentett videók és beállítások —, és újra létrehoz pár minta lejátszási listát. Nem vonható vissza.",
     "resetDone": "Demo visszaállítva — {{count}} minta lejátszási lista létrehozva",
-    "resetFailed": "Nem sikerült visszaállítani a demo fiókot"
+    "resetFailed": "Nem sikerült visszaállítani a demo fiókot",
+    "removed": "Eltávolítva a demo fehérlistáról",
+    "removeTitle": "Visszavonod a demo hozzáférést?",
+    "removeConfirm": "Eltávolítod {{email}} címet a demo fehérlistáról? Többé nem tud belépni a demo fiókba."
   },
   "invites": {
     "title": "Hozzáférési kérelmek",
@@ -141,6 +144,9 @@
     "approveHint": "Jóváhagyás — fehérlistára teszi ezt az e-mailt és e-mailben értesíti őket, hogy bekerültek.",
     "approve": "Jóváhagyás",
     "denyHint": "Kérelem elutasítása.",
-    "deny": "Elutasítás"
+    "deny": "Elutasítás",
+    "denied": "Kérelem elutasítva",
+    "denyTitle": "Elutasítod a hozzáférési kérelmet?",
+    "denyConfirm": "Elutasítod {{email}} hozzáférési kérelmét?"
   }
 }
diff --git a/frontend/src/lib/api.ts b/frontend/src/lib/api.ts
index 53e0de2..470c954 100644
--- a/frontend/src/lib/api.ts
+++ b/frontend/src/lib/api.ts
@@ -209,13 +209,35 @@ export interface VersionInfo {
 class HttpError extends Error {
   status: number;
   detail?: string; // server-provided reason (FastAPI's `detail`), when present
-  constructor(status: number, detail?: string) {
+  detailData?: any; // structured detail ({ code, reason, ... }) when the server sent an object
+  constructor(status: number, detail?: string, detailData?: any) {
     super(detail || `HTTP ${status}`);
     this.status = status;
     this.detail = detail;
+    this.detailData = detailData;
   }
 }
 
+// Localize a STRUCTURED server error ({ code, reason, ... }) into the user's language. FastAPI
+// usually returns a plain string `detail`, but some routes (e.g. download quota/edit) return a
+// structured object with an i18n reason key + numbers so HU/DE users don't get hardcoded English
+// with a dot-decimal separator. Falls back to a generic message for unknown shapes.
+function localizeDetail(d: any): string {
+  const t = i18n.t.bind(i18n);
+  if (d?.code === "quota") {
+    if (d.reason === "max_bytes") {
+      const gb = new Intl.NumberFormat(i18n.language, { maximumFractionDigits: 1 }).format(
+        (d.limit || 0) / 1_073_741_824,
+      );
+      return t("downloads.errors.quota.max_bytes", { size: gb });
+    }
+    if (d.reason === "max_jobs") return t("downloads.errors.quota.max_jobs", { limit: d.limit });
+    return t("downloads.errors.quota.generic");
+  }
+  if (d?.code === "edit") return t(`downloads.errors.edit.${d.reason}`, t("downloads.errors.edit.generic"));
+  return t("errors.generic");
+}
+
 // A single, self-resolving "connection lost" status: while the server is unreachable we
 // show one sticky, transient (non-persisted) notice; the moment any request reaches the
 // server again we remove it. This makes good on its "clears once it's back" copy and keeps
@@ -277,6 +299,29 @@ const setupHeaders = (token: string) => ({
 const ACTIVE_ACCOUNT_HEADER = "X-Siftlode-Account";
 
 export const getActiveAccount = activeAccountId;
+
+// Fire-and-forget POST that survives page unload (keepalive) — shared by the resume-position
+// beacons (YT + Plex players). A normal fetch is cancelled on unload and React effect cleanup
+// doesn't run on a full reload, so without keepalive the last position (esp. right after a seek)
+// would be lost.
+function beacon(url: string, body: Record<string, unknown>): void {
+  const active = getActiveAccount();
+  try {
+    void fetch(url, {
+      method: "POST",
+      keepalive: true,
+      credentials: "include",
+      headers: {
+        "Content-Type": "application/json",
+        ...(active != null ? { [ACTIVE_ACCOUNT_HEADER]: String(active) } : {}),
+      },
+      body: JSON.stringify(body),
+    }).catch(() => {});
+  } catch {
+    /* ignore */
+  }
+}
+
 export function setActiveAccount(id: number): void {
   try {
     sessionStorage.setItem(ACTIVE_ACCOUNT_KEY, String(id));
@@ -337,9 +382,14 @@ async function req(url: string, opts: RequestInit = {}, cfg: ReqConfig = {}): Pr
     if (!r.ok) {
       // Capture the server's reason (FastAPI returns `{ detail }`) so callers can react.
       let detail: string | undefined;
+      let detailData: any;
       try {
         const body = await r.json();
         if (body && typeof body.detail === "string") detail = body.detail;
+        else if (body && body.detail && typeof body.detail === "object") {
+          detailData = body.detail;
+          detail = localizeDetail(body.detail); // structured error → localized message
+        }
       } catch {
         /* no JSON body */
       }
@@ -361,7 +411,7 @@ async function req(url: string, opts: RequestInit = {}, cfg: ReqConfig = {}): Pr
       } else if (r.status === 400 || r.status === 409 || r.status === 422) {
         reportError(detail);
       }
-      throw new HttpError(r.status, detail);
+      throw new HttpError(r.status, detail, detailData);
     }
     return r.status === 204 ? null : r.json();
   }
@@ -601,6 +651,7 @@ export interface ConfigItem {
   min: number | null;
   max: number | null;
   is_set: boolean; // a DB override row exists (else using the env/config default)
+  allow_empty?: boolean; // if true, a blank field stores "" (explicit empty) rather than resetting
   value?: string | number | boolean; // non-secret: effective value
   default?: string | number | boolean; // non-secret: env/config default
   default_is_set?: boolean; // secret: whether an env default exists
@@ -1074,6 +1125,12 @@ export const api = {
       },
       { idempotent: true }
     ),
+  // Fire-and-forget YT progress save that survives page unload (F5/close/navigate).
+  saveProgressBeacon: (id: string, positionSeconds: number, durationSeconds: number): void =>
+    beacon(`/api/videos/${encodeURIComponent(id)}/progress`, {
+      position_seconds: Math.floor(positionSeconds),
+      duration_seconds: Math.floor(durationSeconds),
+    }),
   videoDetail: (id: string): Promise<VideoDetail> => req(`/api/videos/${id}`),
   pauseSync: () => req("/api/sync/pause", { method: "POST" }),
   resumeSync: () => req("/api/sync/resume", { method: "POST" }),
@@ -1306,23 +1363,12 @@ export const api = {
     position_seconds: number,
     duration_seconds: number,
     final = false,
-  ): void => {
-    const active = getActiveAccount();
-    try {
-      void fetch(`/api/plex/item/${encodeURIComponent(id)}/progress`, {
-        method: "POST",
-        keepalive: true,
-        credentials: "include",
-        headers: {
-          "Content-Type": "application/json",
-          ...(active != null ? { [ACTIVE_ACCOUNT_HEADER]: String(active) } : {}),
-        },
-        body: JSON.stringify({ position_seconds, duration_seconds, final }),
-      }).catch(() => {});
-    } catch {
-      /* ignore */
-    }
-  },
+  ): void =>
+    beacon(`/api/plex/item/${encodeURIComponent(id)}/progress`, {
+      position_seconds,
+      duration_seconds,
+      final,
+    }),
   plexSetState: (id: string, status: "new" | "watched" | "hidden"): Promise<unknown> =>
     req(`/api/plex/item/${encodeURIComponent(id)}/state`, {
       method: "POST",
diff --git a/frontend/src/lib/e2ee.ts b/frontend/src/lib/e2ee.ts
index f0d5c0f..003d552 100644
--- a/frontend/src/lib/e2ee.ts
+++ b/frontend/src/lib/e2ee.ts
@@ -112,6 +112,15 @@ export async function loadFromDevice(userId: number): Promise<boolean> {
   return false;
 }
 
+// Install a freshly-imported private key as the current identity: drop any derived conversation
+// keys, persist it to this device, and notify unlock subscribers. Shared by setup() and unlock().
+async function installKey(userId: number, key: CryptoKey): Promise<void> {
+  privKey = key;
+  convKeys.clear();
+  await idbPut(userId, key);
+  emitUnlock();
+}
+
 // First-run setup: generate a keypair, wrap the private key with the passphrase, persist a
 // non-extractable copy locally, and return the bundle to upload to the server.
 export async function setup(userId: number, passphrase: string): Promise<KeySetup> {
@@ -128,10 +137,7 @@ export async function setup(userId: number, passphrase: string): Promise<KeySetu
   const keyCheck = await subtle.encrypt({ name: "AES-GCM", iv: bsrc(checkIv) }, wrapKey, bsrc(enc.encode("ok")));
   const spki = await subtle.exportKey("spki", kp.publicKey);
 
-  privKey = await importPrivate(pkcs8);
-  convKeys.clear();
-  await idbPut(userId, privKey);
-  emitUnlock();
+  await installKey(userId, await importPrivate(pkcs8));
   return {
     public_key: b64(spki),
     wrapped_private_key: b64(wrapped),
@@ -154,10 +160,7 @@ export async function unlock(userId: number, passphrase: string, bundle: MyKeyBu
     wrapKey,
     bsrc(ub64(bundle.wrapped_private_key))
   );
-  privKey = await importPrivate(pkcs8);
-  convKeys.clear();
-  await idbPut(userId, privKey);
-  emitUnlock();
+  await installKey(userId, await importPrivate(pkcs8));
 }
 
 // --- per-conversation encryption ---
diff --git a/frontend/src/lib/messagesSocket.ts b/frontend/src/lib/messagesSocket.ts
index 7a03148..37bb431 100644
--- a/frontend/src/lib/messagesSocket.ts
+++ b/frontend/src/lib/messagesSocket.ts
@@ -11,8 +11,10 @@ interface IncomingMessage {
   to?: MessageUser;
 }
 type Handler = (e: IncomingMessage) => void;
+type UnreadHandler = () => void;
 
 const handlers = new Set<Handler>();
+const unreadHandlers = new Set<UnreadHandler>();
 let ws: WebSocket | null = null;
 let started = false;
 let backoff = 1000;
@@ -21,7 +23,9 @@ let reconnectTimer: ReturnType<typeof setTimeout> | null = null;
 function url(): string {
   const proto = location.protocol === "https:" ? "wss" : "ws";
   // A WebSocket can't carry the X-Siftlode-Account header, so the per-tab account rides in the
-  // query string (validated against the browser wallet server-side).
+  // query string (validated against the browser wallet server-side). The account is read once
+  // here: switching accounts always goes through location.reload() (NavSidebar), which rebuilds
+  // this module and reopens the socket, so it's intentionally fixed for the socket's lifetime.
   const account = getActiveAccount();
   const qs = account != null ? `?account=${account}` : "";
   return `${proto}://${location.host}/api/messages/ws${qs}`;
@@ -43,6 +47,9 @@ function open() {
       if (data?.type === "message" && data.message) {
         const e: IncomingMessage = { message: data.message as Message, from: data.from, to: data.to };
         for (const h of handlers) h(e);
+      } else if (data?.type === "unread") {
+        // Sent to a user's OTHER tabs when they read a thread elsewhere, so the badge updates live.
+        for (const h of unreadHandlers) h();
       }
     } catch {
       /* ignore malformed frames */
@@ -87,3 +94,13 @@ export function onMessage(h: Handler): () => void {
     }
   };
 }
+
+// Subscribe to "your unread changed elsewhere" pings (a read on another tab/device). The socket is
+// already opened/closed by onMessage subscribers (the app-wide ChatDock keeps one), so this only
+// registers a callback — it does not open the socket on its own.
+export function onUnread(h: UnreadHandler): () => void {
+  unreadHandlers.add(h);
+  return () => {
+    unreadHandlers.delete(h);
+  };
+}
diff --git a/frontend/src/lib/messaging.ts b/frontend/src/lib/messaging.ts
index ee4e1bd..a532db2 100644
--- a/frontend/src/lib/messaging.ts
+++ b/frontend/src/lib/messaging.ts
@@ -6,6 +6,9 @@ import { isUnlocked, subscribeUnlock } from "./e2ee";
 
 export const SYSTEM_ID = 0; // synthetic "Siftlode" system conversation partner id
 
+// Safety-net poll interval for message queries; live updates arrive over the WebSocket.
+export const POLL_MS = 20000;
+
 // Set-once cache of partner public keys (the server is the directory; keys never change).
 const pubCache = new Map<number, string>();
 export async function partnerPub(partnerId: number): Promise<string> {
diff --git a/frontend/src/lib/releaseNotes.ts b/frontend/src/lib/releaseNotes.ts
index daba6f9..b7787b9 100644
--- a/frontend/src/lib/releaseNotes.ts
+++ b/frontend/src/lib/releaseNotes.ts
@@ -14,6 +14,22 @@ export interface ReleaseEntry {
 }
 
 export const RELEASE_NOTES: ReleaseEntry[] = [
+  {
+    version: "0.40.0",
+    date: "2026-07-12",
+    summary: "A wave of polish and reliability fixes closing out the internal cleanup pass.",
+    fixes: [
+      "Your place in a video is now saved even if you refresh or close the tab right after skipping around.",
+      "Auto-advance no longer gets stuck on a video that can't be played — it moves on to the next one.",
+      "The unread badge on your messages now updates live across your other open tabs.",
+      "Download storage/limit messages now appear in your language, with the right number format.",
+      "Removing a demo email or denying an access request now asks for confirmation first.",
+      "After syncing your subscriptions, the feed refreshes right away to reflect the change.",
+    ],
+    chores: [
+      "Many internal correctness and efficiency fixes across search, playlists, channels, messages, and downloads; admin-panel polish. No feature changes.",
+    ],
+  },
   {
     version: "0.39.1",
     date: "2026-07-12",