fix: comprehensive security, bug, performance, and UI/UX audit

Security
- Default bind 127.0.0.1; first-run bootstrap generates random api_token
  and refuses to bind non-loopback without auth unless explicitly opted in
- Path-traversal hardened: BrowserService.validate_path rejects absolute
  paths, drive letters, UNC, NUL bytes. /api/browser/{play,metadata,
  thumbnail} now require folder_id and a folder-relative path
- Pydantic validators on links: http(s) URLs only, mdi:<slug> icons only
- Scripts/callbacks/links create/update/delete gated by *_management flags
- Strict CSP, X-Frame-Options DENY, Referrer-Policy no-referrer,
  X-Content-Type-Options nosniff
- CORS locked to localhost:<port> + 127.0.0.1:<port> by default; configurable
- config.yaml writes atomic (tmp + os.replace) and 0o600 on POSIX
- Subprocesses spawned in their own process group / new session so timeout
  kills the whole tree (Windows CREATE_NEW_PROCESS_GROUP, POSIX
  start_new_session=True)
- Frontend XSS: monitor name + details escapeHtml'd; power button moved to
  delegated data-action handler; remote MDI SVGs parsed and sanitized
  (strip script/foreignObject/on*/javascript: hrefs) before innerHTML
- All dynamic URL segments now wrapped in encodeURIComponent

Bugs
- WebSocket reconnect: close previous socket before opening new, clear
  ping interval per-socket, clear reconnectTimeout up-front, retry on
  online/visibilitychange, try/catch JSON.parse
- Artwork fetch race: AbortController + generation guard
- _broadcast_after_open: initialize status, swallow per-poll errors,
  background tasks tracked in a strong-ref set with done-callback cleanup
- Audio analyzer: sticky _unavailable flag prevents infinite start/stop
  spin when no loopback device exists; cleared by set_device()
- Volume short-circuit cache invalidated when server reports remote volume
- Browser thumbnail race: per-folder generation counter + isConnected
  checks; aborts in-flight fetches on navigation
- Track-skip uses cached title instead of full WinRT status round-trip

Performance
- Linux MPRIS/pactl and /api/display DDC-CI handlers wrapped in
  asyncio.to_thread so blocking IO never stalls the event loop
- browse_directory moved off the event loop (SMB shares could freeze it)
- Windows status poll caches one asyncio loop per worker thread via
  threading.local instead of new_event_loop/close on every 0.5s tick
- broadcast() serializes JSON once and uses send_text to all clients
- Hourly thumbnail cache cleanup scheduled in lifespan (was never invoked
  — cache grew unbounded)
- Progress drag listeners attached only while dragging

Quality
- All asyncio.get_event_loop() in coroutines → get_running_loop()
- ThreadPoolExecutors shut down cleanly during lifespan teardown
- config_manager dedup: 12 near-identical methods collapsed onto generic
  _upsert/_delete helpers (~290 lines removed)
- Service worker no longer pass-throughs every fetch
- M3U playlist written via NamedTemporaryFile (no fixed-path symlink
  clobber race)
- __version__ now prefers live pyproject.toml in dev checkouts so
  pip install -e . users see the source-of-truth version, not the stale
  package-metadata version baked in at install time

UI/UX (Studio Reference)
- Green leftover focus rings (rgba(29,185,84,...)) all replaced with
  copper accent (rgba(var(--copper-rgb),...))
- Dialogs: square corners, copper top hairline, unified with editorial
  chrome
- .browser-item: transparent with copper hover border (was filled card)
- Audio device select uses var(--sans) instead of generic system font
- Mobile container padding tuned for ≤480px screens
- Breadcrumb home is a real <button> with aria-label; aria-current on root
- i18n: filled display.msg.power_*, execution.*, scripts.params.execute,
  callbacks.empty in both en + ru

media_server/services/windows_media.py

@@ -15,6 +15,22 @@ logger = logging.getLogger(__name__)
 # Thread pool for WinRT operations (they don't play well with asyncio)
 _executor = ThreadPoolExecutor(max_workers=2, thread_name_prefix="winrt")
 
+# Cache an asyncio event loop per worker thread so the 500ms status poll
+# doesn't allocate + tear down a new loop on every tick. Creating a loop
+# every 0.5s churns CPU and leaks finalized loop references that linger in
+# WinRT callbacks. With this helper a thread reuses one loop forever and
+# we only pay the setup cost once per worker.
+_thread_local = threading.local()
+
+
+def _thread_loop() -> asyncio.AbstractEventLoop:
+    loop = getattr(_thread_local, "loop", None)
+    if loop is None or loop.is_closed():
+        loop = asyncio.new_event_loop()
+        asyncio.set_event_loop(loop)
+        _thread_local.loop = loop
+    return loop
+
 # Global storage for current album art (as bytes)
 _current_album_art_bytes: bytes | None = None
 
@@ -161,8 +177,6 @@ WINDOWS_AVAILABLE = WINSDK_AVAILABLE
 
 def _sync_get_media_status() -> dict[str, Any]:
     """Synchronously get media status (runs in thread pool)."""
-    import asyncio
-
     result = {
         "state": "idle",
         "title": None,
@@ -174,9 +188,7 @@ def _sync_get_media_status() -> dict[str, Any]:
     }
 
     try:
-        # Create a new event loop for this thread
-        loop = asyncio.new_event_loop()
-        asyncio.set_event_loop(loop)
+        loop = _thread_loop()
 
         try:
             # Get media session manager
@@ -393,7 +405,8 @@ def _sync_get_media_status() -> dict[str, Any]:
             result["source"] = session.source_app_user_model_id
 
         finally:
-            loop.close()
+            # Reuse the loop across calls — see _thread_loop above.
+            pass
 
     except Exception as e:
         logger.error(f"Error getting media status: {e}")
@@ -439,35 +452,28 @@ def _find_best_session(manager, loop):
 
 def _sync_media_command(command: str) -> bool:
     """Synchronously execute a media command (runs in thread pool)."""
-    import asyncio
-
     try:
-        loop = asyncio.new_event_loop()
-        asyncio.set_event_loop(loop)
-
-        try:
-            manager = loop.run_until_complete(MediaManager.request_async())
-            if manager is None:
-                return False
-
-            session = _find_best_session(manager, loop)
-            if session is None:
-                return False
-
-            if command == "play":
-                return loop.run_until_complete(session.try_play_async())
-            elif command == "pause":
-                return loop.run_until_complete(session.try_pause_async())
-            elif command == "stop":
-                return loop.run_until_complete(session.try_stop_async())
-            elif command == "next":
-                return loop.run_until_complete(session.try_skip_next_async())
-            elif command == "previous":
-                return loop.run_until_complete(session.try_skip_previous_async())
-
+        loop = _thread_loop()
+        manager = loop.run_until_complete(MediaManager.request_async())
+        if manager is None:
             return False
-        finally:
-            loop.close()
+
+        session = _find_best_session(manager, loop)
+        if session is None:
+            return False
+
+        if command == "play":
+            return loop.run_until_complete(session.try_play_async())
+        elif command == "pause":
+            return loop.run_until_complete(session.try_pause_async())
+        elif command == "stop":
+            return loop.run_until_complete(session.try_stop_async())
+        elif command == "next":
+            return loop.run_until_complete(session.try_skip_next_async())
+        elif command == "previous":
+            return loop.run_until_complete(session.try_skip_previous_async())
+
+        return False
 
     except Exception as e:
         logger.error(f"Error executing media command {command}: {e}")
@@ -476,27 +482,20 @@ def _sync_media_command(command: str) -> bool:
 
 def _sync_seek(position: float) -> bool:
     """Synchronously seek to position."""
-    import asyncio
-
     try:
-        loop = asyncio.new_event_loop()
-        asyncio.set_event_loop(loop)
+        loop = _thread_loop()
+        manager = loop.run_until_complete(MediaManager.request_async())
+        if manager is None:
+            return False
 
-        try:
-            manager = loop.run_until_complete(MediaManager.request_async())
-            if manager is None:
-                return False
+        session = _find_best_session(manager, loop)
+        if session is None:
+            return False
 
-            session = _find_best_session(manager, loop)
-            if session is None:
-                return False
-
-            position_ticks = int(position * 10_000_000)
-            return loop.run_until_complete(
-                session.try_change_playback_position_async(position_ticks)
-            )
-        finally:
-            loop.close()
+        position_ticks = int(position * 10_000_000)
+        return loop.run_until_complete(
+            session.try_change_playback_position_async(position_ticks)
+        )
 
     except Exception as e:
         logger.error(f"Error seeking: {e}")
@@ -559,7 +558,7 @@ class WindowsMediaController(MediaController):
 
         # Get media info in thread pool (avoids asyncio/WinRT issues)
         try:
-            loop = asyncio.get_event_loop()
+            loop = asyncio.get_running_loop()
             media_info = await asyncio.wait_for(
                 loop.run_in_executor(_executor, _sync_get_media_status),
                 timeout=5.0
@@ -592,7 +591,7 @@ class WindowsMediaController(MediaController):
     async def _run_command(self, command: str) -> bool:
         """Run a media command in the thread pool."""
         try:
-            loop = asyncio.get_event_loop()
+            loop = asyncio.get_running_loop()
             return await asyncio.wait_for(
                 loop.run_in_executor(_executor, _sync_media_command, command),
                 timeout=5.0
@@ -616,16 +615,15 @@ class WindowsMediaController(MediaController):
         """Stop playback."""
         return await self._run_command("stop")
 
-    async def next_track(self) -> bool:
-        """Skip to next track."""
-        # Get current title before skipping
-        try:
-            status = await self.get_status()
-            old_title = status.title or ""
-        except Exception:
-            old_title = ""
+    async def _skip_track(self, command: str) -> bool:
+        # Read the current title from the position cache instead of doing a
+        # full WinRT round-trip (which can take up to 5s) just for one field.
+        with _position_lock:
+            track_id = _position_cache.get("track_id") or ""
+        # track_id is "title:artist:duration" — extract just the title.
+        old_title = track_id.split(":", 1)[0] if track_id else ""
 
-        result = await self._run_command("next")
+        result = await self._run_command(command)
         if result:
             with _position_lock:
                 _track_skip_pending["active"] = True
@@ -634,23 +632,13 @@ class WindowsMediaController(MediaController):
             logger.debug(f"Track skip initiated, old title: {old_title}")
         return result
 
+    async def next_track(self) -> bool:
+        """Skip to next track."""
+        return await self._skip_track("next")
+
     async def previous_track(self) -> bool:
         """Go to previous track."""
-        # Get current title before skipping
-        try:
-            status = await self.get_status()
-            old_title = status.title or ""
-        except Exception:
-            old_title = ""
-
-        result = await self._run_command("previous")
-        if result:
-            with _position_lock:
-                _track_skip_pending["active"] = True
-                _track_skip_pending["old_title"] = old_title
-                _track_skip_pending["skip_time"] = _time.time()
-            logger.debug(f"Track skip initiated, old title: {old_title}")
-        return result
+        return await self._skip_track("previous")
 
     async def set_volume(self, volume: int) -> bool:
         """Set system volume."""
@@ -680,7 +668,7 @@ class WindowsMediaController(MediaController):
     async def seek(self, position: float) -> bool:
         """Seek to position in seconds."""
         try:
-            loop = asyncio.get_event_loop()
+            loop = asyncio.get_running_loop()
             return await asyncio.wait_for(
                 loop.run_in_executor(_executor, _sync_seek, position),
                 timeout=5.0
@@ -705,7 +693,7 @@ class WindowsMediaController(MediaController):
         """
         try:
             import os
-            loop = asyncio.get_event_loop()
+            loop = asyncio.get_running_loop()
             await loop.run_in_executor(None, lambda: os.startfile(file_path))
             logger.info(f"Opened file with default player: {file_path}")
             return True