music-assistant-server

1"""
2Protocol Linking Mixin for the Player Controller.
3
4Handles all logic for linking protocol players (AirPlay, Chromecast, DLNA) to
5native players or wrapping them in Universal Players.
6
7This module provides the ProtocolLinkingMixin class which is inherited by
8PlayerController to add protocol linking capabilities.
9"""
10
11from __future__ import annotations
12
13import asyncio
14import logging
15from contextlib import suppress
16from copy import deepcopy
17from typing import TYPE_CHECKING, cast
18
19from music_assistant_models.enums import (
20    EventType,
21    IdentifierType,
22    PlaybackState,
23    PlayerFeature,
24    PlayerType,
25    ProviderType,
26)
27from music_assistant_models.errors import PlayerCommandFailed, PlayerUnavailableError
28
29from music_assistant.constants import (
30    CONF_CACHED_ARP_MAC,
31    CONF_GROUP_MEMBERS,
32    CONF_LINKED_PROTOCOL_IDS,
33    CONF_PLAYER_DSP,
34    CONF_PLAYER_QUEUES,
35    CONF_PLAYERS,
36    CONF_PREFERRED_OUTPUT_PROTOCOL,
37    CONF_PROTOCOL_KEY_SPLITTER,
38    CONF_PROTOCOL_PARENT_ID,
39    CONF_REPORTED_MAC,
40    CONF_UNDERLYING_PLAYER_ID,
41    PROTOCOL_PRIORITY,
42    VERBOSE_LOG_LEVEL,
43)
44from music_assistant.helpers.util import (
45    is_locally_administered_mac,
46    is_valid_mac_address,
47    normalize_mac_for_matching,
48)
49from music_assistant.models.player import LinkedOutputProtocol, Player
50from music_assistant.providers.sync_group.constants import CONF_ALLOWED_MEMBERS
51from music_assistant.providers.universal_player import UniversalPlayer, UniversalPlayerProvider
52from music_assistant.providers.universal_player.constants import (
53    CONF_CREATED_AT,
54    CONF_DEVICE_IDENTIFIERS,
55    CONF_DEVICE_INFO,
56)
57
58if TYPE_CHECKING:
59    from collections.abc import Coroutine
60    from typing import Any
61
62    from music_assistant_models.player import OutputProtocol
63
64    from music_assistant import MusicAssistant
65
66# Config value keys that are bookkeeping of the universal player wrapper itself
67# (protocol links, device-identity caches and its creation moment) and must never
68# be carried over when a native player replaces a universal player, or when one
69# universal player absorbs another.
70UNIVERSAL_PLAYER_INTERNAL_CONF_KEYS = (
71    CONF_LINKED_PROTOCOL_IDS,
72    CONF_PROTOCOL_PARENT_ID,
73    CONF_UNDERLYING_PLAYER_ID,
74    CONF_DEVICE_IDENTIFIERS,
75    CONF_DEVICE_INFO,
76    CONF_CACHED_ARP_MAC,
77    CONF_REPORTED_MAC,
78    CONF_CREATED_AT,
79)
80
81
82class ProtocolLinkingMixin:
83    """
84    Mixin class providing protocol linking functionality for PlayerController.
85
86    Handles the complex logic of:
87    - Matching protocol players to native players via device identifiers
88    - Creating Universal Players for devices without native support
89    - Managing protocol links and their lifecycle
90    - Selecting the best output protocol for playback
91
92    This mixin expects to be mixed with a class that provides:
93    - mass: MusicAssistant instance
94    - _players: dict of registered players
95    - _pending_protocol_evaluations: dict of pending protocol evaluations
96    - logger: logging.Logger instance
97    - all(): method to get all players
98    - get(): method to get a player by ID
99    - unregister(): method to unregister a player
100    """
101
102    # Type hints for attributes provided by the class this mixin is used with
103    if TYPE_CHECKING:
104        mass: MusicAssistant
105        _players: dict[str, Player]
106        _pending_protocol_evaluations: dict[str, asyncio.TimerHandle]
107        _delayed_evaluation_lock: asyncio.Lock
108        logger: logging.Logger
109
110        def all_players(  # noqa: D102
111            self,
112            return_unavailable: bool = True,
113            return_disabled: bool = False,
114            provider_filter: str | None = None,
115            return_protocol_players: bool = False,
116        ) -> list[Player]: ...
117
118        def get_player(self, player_id: str) -> Player | None: ...  # noqa: D102
119
120        def unregister(  # noqa: D102
121            self, player_id: str, permanent: bool = False
122        ) -> Coroutine[Any, Any, None]: ...
123
124    def _is_protocol_player(self, player: Player) -> bool:
125        """
126        Check if a player is a generic protocol player without native support.
127
128        Protocol players have PlayerType.PROTOCOL set by their provider, indicating
129        they are generic streaming endpoints (e.g., AirPlay receiver, Chromecast device)
130        without vendor-specific native support in Music Assistant.
131        """
132        return player.state.type == PlayerType.PROTOCOL
133
134    def _evaluate_protocol_links(self, player: Player) -> None:
135        """
136        Evaluate and establish protocol links for a player.
137
138        Called when a player is registered to:
139        1. If it's from a protocol provider - try to link to a native player.
140        2. If it's a native player - try to link any existing protocol players.
141        """
142        if player.state.type == PlayerType.PROTOCOL:
143            # Protocol player: try to find a native parent
144            self._try_link_protocol_to_native(player)
145        elif player.state.type == PlayerType.GROUP:
146            return
147        else:
148            # A player that registers with a non-protocol type can no longer be a
149            # protocol child: drop a leftover persisted parent link (e.g. from a
150            # bridge client that turned web player) so the startup repair pass
151            # doesn't heal its player type back to protocol.
152            if self._get_cached_protocol_parent_id(player.player_id):
153                self._clear_protocol_parent_id(player.player_id)
154            # Native player (including STEREO_PAIR): try to find protocol players to link
155            self._try_link_protocols_to_native(player)
156
157    def _try_link_protocol_to_native(self, protocol_player: Player) -> None:
158        """Try to link a protocol player to a native player."""
159        protocol_domain = protocol_player.provider.domain
160
161        # Derived protocol players (e.g. Sendspin bridges riding on another
162        # protocol) resolve strictly via their underlying player - no identifier
163        # matching or delayed evaluation. If the underlying player has no parent
164        # yet, the link is established by _link_derived_protocols_of as soon as
165        # the underlying player gets linked.
166        if protocol_player.underlying_player_id:
167            self._try_link_derived_protocol(protocol_player)
168            return
169
170        # Check for cached parent_id from previous session and restore link immediately
171        cached_parent_id = self._get_cached_protocol_parent_id(protocol_player.player_id)
172        if cached_parent_id:
173            result = self._try_restore_cached_parent(
174                protocol_player, cached_parent_id, protocol_domain
175            )
176            if result:
177                return
178            # Link was refused or parent has active domain - fall through to search
179
180        # Look for a matching native player
181        if self._try_link_to_existing_player(protocol_player, protocol_domain):
182            return
183
184        # No native player found - schedule delayed evaluation to allow other protocols to register
185        if not protocol_player.protocol_parent_id:
186            self._schedule_protocol_evaluation(protocol_player)
187
188    def _try_restore_cached_parent(
189        self, protocol_player: Player, cached_parent_id: str, protocol_domain: str
190    ) -> bool:
191        """
192        Try to restore a cached parent link from a previous session.
193
194        :param protocol_player: The protocol player to link.
195        :param cached_parent_id: The cached parent player ID.
196        :param protocol_domain: The protocol domain (e.g., "airplay").
197        :return: True if handled (linked or waiting), False if should fall through.
198        """
199        if parent_player := self.get_player(cached_parent_id):
200            if parent_player.state.type == PlayerType.GROUP:
201                self._clear_protocol_parent_id(protocol_player.player_id)
202                return False
203            already_linked = any(
204                link.output_protocol_id == protocol_player.player_id
205                for link in parent_player.linked_output_protocols
206            )
207            if already_linked:
208                # Already linked from a previous call - just restore parent and identifiers
209                protocol_player.set_protocol_parent_id(cached_parent_id)
210            else:
211                # Try to add the link (may be refused if domain already has active link)
212                self._add_protocol_link(parent_player, protocol_player, protocol_domain)
213            if protocol_player.protocol_parent_id:
214                protocol_player.refresh_state()
215                parent_player.refresh_state()
216                # Merge the protocol player's identifiers into the universal player
217                # so identifiers discovered since the last persist (e.g. an
218                # ARP-resolved MAC) are included and new protocol players
219                # (like Sendspin bridges) can match via identifiers.
220                if parent_player.provider.domain == "universal_player" and isinstance(
221                    parent_player, UniversalPlayer
222                ):
223                    for conn_type, value in protocol_player.device_info.identifiers.items():
224                        parent_player.device_info.add_identifier(conn_type, value)
225                    self._update_universal_device_info(parent_player, protocol_player)
226                    # Check if this universal player should now be merged with another
227                    # (e.g., DLNA brought a MAC via ARP that matches an AirPlay universal)
228                    self._check_merge_universal_players(parent_player)
229                return True
230            # Link was refused (domain already active on parent) - fall through
231            return False
232
233        # Parent is not registered yet. Leave the protocol player unparented
234        # so the caller schedules delayed evaluation, which can wait for the
235        # cached parent without stranding the protocol player on a dangling id.
236        return False
237
238    def _try_link_to_existing_player(self, protocol_player: Player, protocol_domain: str) -> bool:
239        """
240        Try to link a protocol player to an existing native or universal player.
241
242        :param protocol_player: The protocol player to link.
243        :param protocol_domain: The protocol domain (e.g., "airplay").
244        :return: True if linked successfully, False if no match found.
245        """
246        # Protocol players should only link to:
247        # 1. True native players (Sonos, etc.)
248        # 2. Universal players
249        # NOT to other protocol players (they get merged via universal_player)
250        for native_player in self.all_players(return_protocol_players=False):
251            if native_player.player_id == protocol_player.player_id:
252                continue
253            if native_player.state.type in (PlayerType.PROTOCOL, PlayerType.GROUP):
254                continue
255
256            # For universal players, check if this protocol player is in its stored list
257            # or if identifiers match (for new protocol players like Sendspin bridges
258            # that weren't previously known to the Universal Player)
259            if native_player.provider.domain == "universal_player":
260                if isinstance(native_player, UniversalPlayer):
261                    is_known = protocol_player.player_id in native_player._protocol_player_ids
262                    is_match = not is_known and self._identifiers_match(
263                        native_player, protocol_player, protocol_domain
264                    )
265                    if is_known or is_match:
266                        self._add_protocol_link(native_player, protocol_player, protocol_domain)
267                        # Check if linking actually succeeded (may be refused for
268                        # duplicate domain)
269                        if not protocol_player.protocol_parent_id:
270                            continue
271                        # Merge the protocol player's identifiers into the universal
272                        # player so newly discovered identifiers are included as well
273                        for conn_type, value in protocol_player.device_info.identifiers.items():
274                            native_player.device_info.add_identifier(conn_type, value)
275                        # Update model/manufacturer if universal player has generic values
276                        self._update_universal_device_info(native_player, protocol_player)
277                        # Register newly matched protocol player with the universal player
278                        if is_match:
279                            native_player.add_protocol_player(protocol_player.player_id)
280                        # Persist updated data to config (async via task)
281                        self._save_universal_player_data(native_player)
282                        # Check if this universal player should now be merged with another
283                        self._check_merge_universal_players(native_player)
284                        protocol_player.refresh_state()
285                        native_player.refresh_state()
286                        return True
287                continue
288
289            # Check cached protocol IDs first for fast matching on restart
290            cached_ids = self._get_cached_protocol_ids(native_player.player_id)
291            if protocol_player.player_id in cached_ids:
292                self._add_protocol_link(native_player, protocol_player, protocol_domain)
293                if protocol_player.protocol_parent_id:
294                    protocol_player.refresh_state()
295                    native_player.refresh_state()
296                    return True
297                # Link refused (domain duplicate) - try next native player
298                continue
299
300            # Fallback to identifier matching
301            if self._identifiers_match(native_player, protocol_player, protocol_domain):
302                self._add_protocol_link(native_player, protocol_player, protocol_domain)
303                if protocol_player.protocol_parent_id:
304                    protocol_player.refresh_state()
305                    native_player.refresh_state()
306                    return True
307                # Link refused (domain duplicate) - try next native player
308                continue
309
310            # Final fallback: check if any already-linked protocol player on this native
311            # player shares identifiers with the new protocol player ("sibling matching").
312            # This handles native players (e.g., HEOS) that don't have their own MAC/serial
313            # identifiers but have protocol players (e.g., AirPlay) from the same device
314            # that do share identifiers with the new protocol player (e.g., Sendspin bridge).
315            if self._match_via_linked_protocols(native_player, protocol_player, protocol_domain):
316                return True
317
318        return False
319
320    def _match_via_linked_protocols(
321        self,
322        native_player: Player,
323        protocol_player: Player,
324        protocol_domain: str,
325    ) -> bool:
326        """
327        Try to match a protocol player to a native player via sibling protocol identifiers.
328
329        Check if any of the native player's already-linked protocol players share
330        identifiers with the new protocol player. This handles native players that lack
331        their own device identifiers but have sibling protocols from the same physical device.
332
333        :param native_player: The native player to potentially link to.
334        :param protocol_player: The new protocol player to link.
335        :param protocol_domain: The protocol domain of the new player.
336        :return: True if linked successfully, False if no match found.
337        """
338        for linked in native_player.linked_output_protocols:
339            linked_player = self.get_player(linked.output_protocol_id)
340            if not linked_player:
341                continue
342            if self._identifiers_match(linked_player, protocol_player, protocol_domain):
343                self._add_protocol_link(native_player, protocol_player, protocol_domain)
344                if protocol_player.protocol_parent_id:
345                    protocol_player.refresh_state()
346                    native_player.refresh_state()
347                    return True
348                # Link refused (domain duplicate) - stop checking siblings
349                break
350        return False
351
352    def _try_link_derived_protocol(self, protocol_player: Player) -> bool:
353        """
354        Link a derived protocol player to the parent of its underlying player.
355
356        Derived protocol players carry an underlying_player_id declared by their
357        bridge, which makes the parent resolution deterministic: they always join
358        the parent of the player they ride on (or that player itself when it is
359        not a protocol player). Callers must ensure the player is not linked yet.
360
361        :param protocol_player: The derived protocol player to link.
362        :return: True if the player got linked, False if the underlying player
363            (or its parent) is not available yet or the link was refused.
364        """
365        underlying = self.get_player(protocol_player.underlying_player_id or "")
366        if underlying is None:
367            return False
368        if underlying.state.type == PlayerType.PROTOCOL:
369            parent = (
370                self.get_player(underlying.protocol_parent_id)
371                if underlying.protocol_parent_id
372                else None
373            )
374        else:
375            parent = underlying
376        if parent is None or parent.state.type == PlayerType.GROUP:
377            return False
378
379        self._add_protocol_link(parent, protocol_player, protocol_player.provider.domain)
380        if not protocol_player.protocol_parent_id:
381            # Link refused (e.g. parent already has an active link from this domain)
382            return False
383
384        if parent.provider.domain == "universal_player" and isinstance(parent, UniversalPlayer):
385            # Track membership and identifiers on the universal player so the
386            # derived protocol restores quickly on the next start.
387            parent.add_protocol_player(protocol_player.player_id)
388            for conn_type, value in protocol_player.device_info.identifiers.items():
389                parent.device_info.add_identifier(conn_type, value)
390            self._save_universal_player_data(parent)
391
392        protocol_player.refresh_state()
393        parent.refresh_state()
394        self.logger.debug(
395            "Linked derived protocol %s to %s (via underlying %s)",
396            protocol_player.player_id,
397            parent.player_id,
398            underlying.player_id,
399        )
400        return True
401
402    def _link_derived_protocols_of(self, underlying_player: Player) -> None:
403        """
404        Link any waiting derived protocol players that ride on the given player.
405
406        Called after a player is linked to a parent (or registered as a native
407        player), so derived protocol players that registered earlier can join
408        the same parent.
409        """
410        for candidate in self.all_players(return_protocol_players=True):
411            if candidate.underlying_player_id != underlying_player.player_id:
412                continue
413            if candidate.protocol_parent_id:
414                continue
415            self._try_link_derived_protocol(candidate)
416
417    def _schedule_protocol_evaluation(self, protocol_player: Player) -> None:
418        """
419        Schedule a delayed protocol evaluation.
420
421        Delays evaluation to allow other protocol players and native players to register.
422        Uses a longer delay (30s) if this protocol player was previously linked to a native
423        player that hasn't registered yet, giving native providers time to start up.
424        """
425        player_id = protocol_player.player_id
426
427        # Cancel any existing pending evaluation for this player
428        if player_id in self._pending_protocol_evaluations:
429            self._pending_protocol_evaluations[player_id].cancel()
430
431        # Check if this protocol player has a cached parent (was previously linked)
432        cached_parent_id = self._get_cached_protocol_parent_id(player_id)
433        if cached_parent_id and not self.get_player(cached_parent_id):
434            # Previously linked to a native player that hasn't registered yet
435            # Use longer delay to give native providers time to start up
436            delay = 45.0
437            self.logger.debug(
438                "Protocol player %s waiting for cached parent %s (45s delay)",
439                player_id,
440                cached_parent_id,
441            )
442        else:
443            # Standard delay for protocol player discovery
444            # Allows time for other protocols and native players to register
445            delay = 15.0
446
447        # Schedule evaluation after the delay
448        handle = self.mass.loop.call_later(
449            delay,
450            lambda: self.mass.create_task(self._delayed_protocol_evaluation(player_id)),
451        )
452        self._pending_protocol_evaluations[player_id] = handle
453
454    async def _delayed_protocol_evaluation(self, player_id: str) -> None:
455        """
456        Perform delayed protocol evaluation.
457
458        Called after a delay to allow all protocol players for a device to register.
459        Decides whether to create a universal player, join an existing one, or
460        promote a single protocol player directly.
461
462        Uses a shared lock to serialize evaluations - multiple protocol players from the
463        same device may trigger concurrent evaluations that would otherwise race each other.
464        """
465        self._pending_protocol_evaluations.pop(player_id, None)
466
467        async with self._delayed_evaluation_lock:
468            protocol_player = self.get_player(player_id)
469            if not protocol_player or protocol_player.protocol_parent_id:
470                return
471            if protocol_player.state.type != PlayerType.PROTOCOL:
472                # The player changed type while the evaluation was pending
473                # (e.g. re-registered as a regular player); it must never be
474                # linked as a protocol or wrapped in a universal player.
475                return
476
477            # Derived protocol players resolve strictly via their underlying
478            # player and never match by identifiers or wrap into universal
479            # players; they wait for _link_derived_protocols_of otherwise.
480            if protocol_player.underlying_player_id:
481                self._try_link_derived_protocol(protocol_player)
482                return
483
484            protocol_domain = protocol_player.provider.domain
485
486            # Re-try linking to an existing native/universal player
487            if self._try_link_to_existing_player(protocol_player, protocol_domain):
488                return
489
490            # Check if there's an existing universal player we should join
491            if existing_universal := self._find_matching_universal_player(protocol_player):
492                await self._add_protocol_to_existing_universal(
493                    existing_universal, protocol_player, protocol_domain
494                )
495                if protocol_player.protocol_parent_id is not None:
496                    return
497                # Link refused (domain duplicate) - fall through to create separate UP
498
499            # Refuse to create a universal player wrapper when the cached parent
500            # config exists but is disabled. The user explicitly turned the
501            # parent device off; surfacing its protocols as a separate player
502            # would defeat that intent.
503            cached_parent_id = self._get_cached_protocol_parent_id(player_id)
504            if cached_parent_id:
505                parent_raw = self.mass.config.get(f"{CONF_PLAYERS}/{cached_parent_id}")
506                if parent_raw and not parent_raw.get("enabled", True):
507                    self.logger.debug(
508                        "Skipping universal player creation for %s: cached parent %s is disabled",
509                        player_id,
510                        cached_parent_id,
511                    )
512                    return
513
514            # Find all protocol players that match this device's identifiers
515            matching_protocols = self._find_matching_protocol_players(protocol_player)
516
517            # Create or update UniversalPlayer for all protocol players
518            await self._create_or_update_universal_player(matching_protocols)
519
520    def _find_matching_protocol_players(self, protocol_player: Player) -> list[Player]:
521        """
522        Find all protocol players that match the same device as the given player.
523
524        Searches through all registered protocol players to find ones that share
525        identifiers (MAC, IP, UUID) with the given player, indicating they represent
526        the same physical device.
527        """
528        matching = [protocol_player]
529        protocol_domain = protocol_player.provider.domain
530
531        for other_player in self.all_players(return_protocol_players=True):
532            if other_player.player_id == protocol_player.player_id:
533                continue
534            if other_player.state.type != PlayerType.PROTOCOL:
535                continue
536            if other_player.protocol_parent_id:
537                continue
538            if other_player.underlying_player_id:
539                # Derived protocol players follow their underlying player
540                # once it is linked; they never seed a universal player.
541                continue
542            # Skip players from the same protocol domain
543            # Multiple instances of the same protocol on one host are separate players
544            if other_player.provider.domain == protocol_domain:
545                continue
546            if self._identifiers_match(protocol_player, other_player):
547                matching.append(other_player)
548
549        return matching
550
551    def _find_matching_universal_player(self, protocol_player: Player) -> Player | None:
552        """Find an existing universal player that matches this protocol player."""
553        for player in self._players.values():
554            if not isinstance(player, UniversalPlayer):
555                continue
556            if self._identifiers_match(protocol_player, player, ""):
557                return player
558        return None
559
560    async def _add_protocol_to_existing_universal(
561        self, universal_player: Player, protocol_player: Player, protocol_domain: str
562    ) -> None:
563        """Add a protocol player to an existing universal player."""
564        # Refuse if the universal player already has a registered player from this domain.
565        # This prevents a second instance (e.g., two snapcast players on the same host)
566        # from replacing the first. The caller falls through to create a separate UP.
567        for link in universal_player.linked_output_protocols:
568            if link.protocol_domain == protocol_domain and self.get_player(link.output_protocol_id):
569                return
570
571        self._add_protocol_link(universal_player, protocol_player, protocol_domain)
572
573        # Check if linking actually succeeded (may be refused for duplicate domain)
574        if not protocol_player.protocol_parent_id:
575            return
576
577        if isinstance(universal_player, UniversalPlayer):
578            universal_player.add_protocol_player(protocol_player.player_id)
579            for conn_type, value in protocol_player.device_info.identifiers.items():
580                universal_player.device_info.add_identifier(conn_type, value)
581            # Update model/manufacturer if universal player has generic values
582            self._update_universal_device_info(universal_player, protocol_player)
583
584            # Persist all player data (protocol IDs, identifiers, device info) to config
585            for provider in self.mass.get_providers(ProviderType.PLAYER):
586                if provider.domain == "universal_player":
587                    await cast("UniversalPlayerProvider", provider)._save_player_data(
588                        universal_player.player_id, universal_player
589                    )
590                    break
591
592            # Check if this universal player should now be merged with another
593            self._check_merge_universal_players(universal_player)
594
595        protocol_player.refresh_state()
596        universal_player.refresh_state()
597
598    def _update_universal_device_info(
599        self, universal_player: UniversalPlayer, protocol_player: Player
600    ) -> None:
601        """
602        Update universal player's device info from protocol player if needed.
603
604        A universal player carries generic placeholder device info
605        (model="Universal Player", manufacturer="Music Assistant") when no real
606        values are known for it (yet). This method updates those values from a
607        protocol player that has real device info.
608        """
609        # Check if universal player has generic placeholder device info
610        device_info = universal_player.device_info
611        protocol_info = protocol_player.device_info
612
613        # Update model if universal player has generic value
614        if device_info.model in (None, "Universal Player") and protocol_info.model:
615            device_info.model = protocol_info.model
616
617        # Update manufacturer if universal player has generic value
618        if device_info.manufacturer in (None, "Music Assistant") and protocol_info.manufacturer:
619            device_info.manufacturer = protocol_info.manufacturer
620
621    def _save_universal_player_data(self, universal_player: UniversalPlayer) -> None:
622        """
623        Save universal player data to config via background task.
624
625        This is a helper to persist player data from synchronous code.
626        """
627
628        async def _do_save() -> None:
629            for provider in self.mass.get_providers(ProviderType.PLAYER):
630                if provider.domain == "universal_player":
631                    await cast("UniversalPlayerProvider", provider)._save_player_data(
632                        universal_player.player_id, universal_player
633                    )
634                    break
635
636        self.mass.create_task(_do_save())
637
638    def _get_known_protocol_ids(self, parent: Player) -> list[str]:
639        """
640        Get all protocol IDs tracked for a parent player.
641
642        Includes both active links and cached/inactive protocol IDs so callers can
643        safely migrate or clean up the full parent/protocol relationship.
644        """
645        result: list[str] = []
646        seen: set[str] = set()
647
648        for linked in parent.linked_output_protocols:
649            if linked.output_protocol_id not in seen:
650                result.append(linked.output_protocol_id)
651                seen.add(linked.output_protocol_id)
652
653        if parent.provider.domain == "universal_player" and isinstance(parent, UniversalPlayer):
654            cached_ids = parent._protocol_player_ids
655        else:
656            cached_ids = self._get_cached_protocol_ids(parent.player_id)
657
658        for protocol_id in cached_ids:
659            if protocol_id not in seen:
660                result.append(protocol_id)
661                seen.add(protocol_id)
662
663        return result
664
665    def _migrate_protocol_ids_to_parent(self, parent: Player, protocol_ids: set[str]) -> None:
666        """
667        Persist protocol ownership on a new parent without requiring active links.
668
669        This is used when protocol ownership moves from one parent to another during
670        promotion/merge flows. Active protocols are already linked in memory, but
671        disabled or temporarily unavailable protocols still need their cached parent
672        relationship moved as well.
673        """
674        if not protocol_ids:
675            return
676
677        if parent.provider.domain == "universal_player" and isinstance(parent, UniversalPlayer):
678            for protocol_id in protocol_ids:
679                parent.add_protocol_player(protocol_id)
680            self._save_universal_player_data(parent)
681        else:
682            conf_key = f"{CONF_PLAYERS}/{parent.player_id}/values/{CONF_LINKED_PROTOCOL_IDS}"
683            cached_ids = self._get_cached_protocol_ids(parent.player_id)
684            changed = False
685            for protocol_id in protocol_ids:
686                if protocol_id not in cached_ids:
687                    cached_ids.append(protocol_id)
688                    changed = True
689            if changed:
690                self.mass.config.set(conf_key, cached_ids)
691
692        for protocol_id in protocol_ids:
693            if self.mass.config.get(f"{CONF_PLAYERS}/{protocol_id}"):
694                self._save_protocol_parent_id(protocol_id, parent.player_id)
695
696    def _remove_protocol_ids_from_parent(self, parent: Player, protocol_ids: set[str]) -> None:
697        """
698        Remove protocol ownership from a parent before it is permanently cleaned up.
699
700        This prevents `_cleanup_protocol_links` from treating already-migrated
701        protocols as orphaned when the obsolete parent is unregistered.
702        """
703        if not protocol_ids:
704            return
705
706        remaining_links = [
707            link
708            for link in parent.linked_output_protocols
709            if link.output_protocol_id not in protocol_ids
710        ]
711        if len(remaining_links) != len(parent.linked_output_protocols):
712            parent.set_linked_output_protocols(remaining_links)
713
714        if parent.provider.domain == "universal_player" and isinstance(parent, UniversalPlayer):
715            for protocol_id in protocol_ids:
716                parent.remove_protocol_player(protocol_id)
717            if self.mass.config.get(f"{CONF_PLAYERS}/{parent.player_id}"):
718                self.mass.config.set(
719                    f"{CONF_PLAYERS}/{parent.player_id}/values/{CONF_LINKED_PROTOCOL_IDS}",
720                    parent._protocol_player_ids,
721                )
722        else:
723            for protocol_id in protocol_ids:
724                self._remove_protocol_id_from_cache(parent.player_id, protocol_id)
725
726    def _check_merge_universal_players(self, universal_player: UniversalPlayer) -> None:
727        """
728        Check if another universal player should be merged into this one.
729
730        Called after identifiers are copied from a protocol player to a universal player.
731        When a protocol player brings new identifiers (e.g., MAC from ARP enrichment),
732        the universal player may now match another universal player that was created
733        from a different protocol (e.g., DLNA-based universal player now matches
734        AirPlay-based universal player because they share the same MAC address).
735
736        The oldest universal player absorbs the other one. Only one merge is performed
737        per call; re-evaluation will catch cascading merges.
738        """
739        if not (match := self._find_mergeable_universal_player(universal_player)):
740            return
741        keep, remove = self._select_merge_winner(universal_player, match)
742        self.logger.info(
743            "Merging universal player %s into %s (shared identifiers)",
744            remove.player_id,
745            keep.player_id,
746        )
747        self._merge_universal_players(keep, remove)
748
749    def _find_mergeable_universal_player(
750        self, universal_player: UniversalPlayer
751    ) -> UniversalPlayer | None:
752        """
753        Return the first other universal player that represents the same device, if any.
754
755        Players that share a protocol domain are not returned: they are separate devices
756        that merely share an identifier, so merging them would orphan a protocol.
757
758        :param universal_player: The universal player to find a merge candidate for.
759        """
760        for player in list(self._players.values()):
761            if player.provider.domain != "universal_player":
762                continue
763            if player.player_id == universal_player.player_id:
764                continue
765            if not isinstance(player, UniversalPlayer):
766                continue
767
768            if not self._identifiers_match(universal_player, player, ""):
769                continue
770
771            # Do not merge if both UPs have protocols from the same domain.
772            # Multiple instances of the same protocol on one host (e.g., several
773            # squeezelite players on the same VM) are separate devices that happen
774            # to share an IP. Merging them would orphan one instance's protocol.
775            domains_a = {
776                link.protocol_domain
777                for link in universal_player.linked_output_protocols
778                if link.protocol_domain
779            }
780            domains_b = {
781                link.protocol_domain
782                for link in player.linked_output_protocols
783                if link.protocol_domain
784            }
785            if domains_a & domains_b:
786                self.logger.debug(
787                    "Skipping merge of %s and %s: shared protocol domain(s) %s",
788                    universal_player.player_id,
789                    player.player_id,
790                    domains_a & domains_b,
791                )
792                continue
793
794            return player
795
796        return None
797
798    def _select_merge_winner(
799        self, universal_player: UniversalPlayer, other_player: UniversalPlayer
800    ) -> tuple[UniversalPlayer, UniversalPlayer]:
801        """
802        Return which of the two universal players absorbs the other, as (keeper, absorbed).
803
804        The oldest player wins, on a tie the one with the most protocol links.
805
806        :param universal_player: The universal player the merge was triggered for.
807        :param other_player: The universal player it matched with.
808        """
809        # The outcome must be stable across server restarts. Without that, which
810        # UniversalPlayer "wins" depends on iteration order of self._players.values(),
811        # which can shift between runs and causes downstream player_id reshuffling
812        # (and broken entity bindings in consumers like the Home Assistant MA integration).
813        if self._merge_rank(universal_player) <= self._merge_rank(other_player):
814            return universal_player, other_player
815        return other_player, universal_player
816
817    def _merge_rank(self, universal_player: Player) -> tuple[int, int, str]:
818        """
819        Return the sort key of a universal player in a merge, lowest wins.
820
821        Age comes first because the keeper's player id is the one that survives, and the
822        oldest player is the one API consumers have been bound to the longest. The links
823        of the absorbed player move over either way, so nothing is lost by keeping the
824        smaller one. A player from before player ids were minted has no stored moment and
825        counts as the oldest, which is exactly what it is.
826        """
827        created_at = self.mass.config.get(
828            f"{CONF_PLAYERS}/{universal_player.player_id}/values/{CONF_CREATED_AT}", 0
829        )
830        return (
831            created_at if isinstance(created_at, int) else 0,
832            -len(universal_player.linked_output_protocols),
833            universal_player.player_id,
834        )
835
836    def _merge_universal_players(self, keep: UniversalPlayer, remove: UniversalPlayer) -> None:
837        """
838        Absorb one universal player into another and schedule the absorbed one's removal.
839
840        :param keep: The universal player that stays.
841        :param remove: The universal player that is absorbed.
842        """
843        known_protocol_ids = set(self._get_known_protocol_ids(remove))
844        active_protocol_ids = {link.output_protocol_id for link in remove.linked_output_protocols}
845        moved_protocol_ids: set[str] = set()
846
847        # Transfer protocol links from the removed player to the keeper
848        for linked in list(remove.linked_output_protocols):
849            if protocol_player := self.get_player(linked.output_protocol_id):
850                protocol_player.set_protocol_parent_id(None)
851                domain = linked.protocol_domain or protocol_player.provider.domain
852
853                # Check if keeper already has an active link from this domain
854                if self._parent_has_active_protocol_from_domain(keep, domain):
855                    self.logger.debug(
856                        "Skipping duplicate %s link during merge: %s",
857                        domain,
858                        linked.output_protocol_id,
859                    )
860                    continue
861
862                self._add_protocol_link(keep, protocol_player, domain)
863                if protocol_player.protocol_parent_id == keep.player_id:
864                    moved_protocol_ids.add(protocol_player.player_id)
865                    protocol_player.refresh_state()
866
867        # Move cached-only protocol ownership as well so old-parent cleanup
868        # does not wipe protocols that were intentionally preserved.
869        cached_only_ids = known_protocol_ids - active_protocol_ids
870        preserved_protocol_ids = moved_protocol_ids | cached_only_ids
871        self._migrate_protocol_ids_to_parent(keep, preserved_protocol_ids)
872        self._remove_protocol_ids_from_parent(remove, preserved_protocol_ids)
873
874        # Merge identifiers
875        for conn_type, value in remove.device_info.identifiers.items():
876            keep.device_info.add_identifier(conn_type, value)
877        keep.refresh_state()
878
879        # Persist updated data before the obsolete player is removed
880        self._save_universal_player_data(keep)
881
882        # Carry over the user's configuration and re-point group memberships
883        # before the permanent removal below deletes the losing wrapper's config
884        self._migrate_universal_player_config(remove.player_id, keep.player_id)
885        self._repoint_group_memberships(remove.player_id, keep.player_id)
886
887        # Stop playback and remove the obsolete player
888        self.mass.create_task(self._stop_and_unregister(remove))
889
890    def _link_protocols_to_universal(
891        self, universal_player: Player, protocol_players: list[Player]
892    ) -> None:
893        """Link protocol players to a universal player, cleaning up existing links."""
894        for player in protocol_players:
895            # Clean up if linked to another player
896            if player.protocol_parent_id:
897                if parent := self.get_player(player.protocol_parent_id):
898                    self._remove_protocol_link(parent, player.player_id)
899                player.set_protocol_parent_id(None)
900            # Link to universal player
901            self._add_protocol_link(universal_player, player, player.provider.domain)
902            player.refresh_state()
903
904        # Update availability from protocol players
905        universal_player.refresh_state()
906
907    async def _create_or_update_universal_player(self, protocol_players: list[Player]) -> None:
908        """
909        Create or update a UniversalPlayer for a set of protocol players.
910
911        Delegates to the universal player provider which handles orchestration,
912        locking, and player creation. The controller then links the protocols
913        to the universal player.
914        """
915        # Filter out players that got linked during the async delay
916        protocol_players = [p for p in protocol_players if not p.protocol_parent_id]
917        if not protocol_players:
918            return
919
920        # Get the universal_player provider
921        universal_provider: UniversalPlayerProvider | None = None
922        for provider in self.mass.get_providers(ProviderType.PLAYER):
923            if provider.domain == "universal_player":
924                universal_provider = cast("UniversalPlayerProvider", provider)
925                break
926
927        if not universal_provider:
928            return
929
930        # Delegate to provider - it handles locking, create/update decision, etc.
931        # It reports which universal player each protocol player belongs to, as a
932        # device with several instances of one protocol domain gets more than one.
933        assignments = await universal_provider.ensure_universal_players_for_protocols(
934            protocol_players
935        )
936
937        # Link the protocols to their universal player (the controller manages
938        # cross-provider state), skipping players that were linked in the meantime.
939        by_universal_player: dict[str, list[Player]] = {}
940        for player in protocol_players:
941            if player.protocol_parent_id:
942                continue
943            if universal_player := assignments.get(player.player_id):
944                by_universal_player.setdefault(universal_player.player_id, []).append(player)
945
946        for universal_player_id, players in by_universal_player.items():
947            if universal_player := self.get_player(universal_player_id):
948                self._link_protocols_to_universal(universal_player, players)
949
950    def _try_link_protocols_to_native(self, native_player: Player) -> None:
951        """Try to link protocol players to a native player."""
952        # First, check if there's a universal player for this device that should be replaced
953        self._check_replace_universal_player(native_player)
954
955        # Look for protocol players that should be linked
956        for protocol_player in self.all_players(return_protocol_players=True):
957            if protocol_player.state.type != PlayerType.PROTOCOL:
958                continue
959            if protocol_player.protocol_parent_id:
960                # Already linked to a parent (could be this native player after replacement)
961                continue
962            if protocol_player.underlying_player_id:
963                # Derived protocol players link via their underlying player instead
964                continue
965
966            protocol_domain = protocol_player.provider.domain
967
968            # Skip if this native player already has an active link from this domain
969            # (prevents a second instance of the same protocol from trying to link)
970            if self._parent_has_active_protocol_from_domain(native_player, protocol_domain):
971                continue
972
973            if self._identifiers_match(native_player, protocol_player, protocol_domain):
974                self._add_protocol_link(native_player, protocol_player, protocol_domain)
975                # Check if linking succeeded (may be refused for duplicate domain)
976                if protocol_player.protocol_parent_id is not None:
977                    protocol_player.refresh_state()
978                    native_player.refresh_state()
979
980        # Proactively recover disabled/missing protocols from config
981        # This ensures disabled protocols show up in the UI so they can be re-enabled
982        self._recover_cached_protocol_links(native_player)
983
984        # Second pass: match remaining unlinked protocol players via sibling identifiers.
985        # After cache recovery, the native player has linked protocols (e.g., AirPlay)
986        # whose identifiers can be used to match new protocol players (e.g., Sendspin bridge)
987        # that share the same device identifiers but couldn't match the native player directly.
988        for protocol_player in self.all_players(return_protocol_players=True):
989            if protocol_player.state.type != PlayerType.PROTOCOL:
990                continue
991            if protocol_player.protocol_parent_id:
992                continue
993            if protocol_player.underlying_player_id:
994                continue
995            protocol_domain = protocol_player.provider.domain
996            if self._parent_has_active_protocol_from_domain(native_player, protocol_domain):
997                continue
998            if self._match_via_linked_protocols(native_player, protocol_player, protocol_domain):
999                self.logger.debug(
1000                    "Linked %s to %s via sibling protocol identifiers",
1001                    protocol_player.player_id,
1002                    native_player.player_id,
1003                )
1004
1005        # Finally, link derived protocol players that ride directly on this
1006        # native player (derived players riding on the protocol players linked
1007        # above are handled by _add_protocol_link itself).
1008        self._link_derived_protocols_of(native_player)
1009
1010    def _check_replace_universal_player(self, native_player: Player) -> None:
1011        """Check if a universal player should be replaced by this native player."""
1012        # Skip if native_player is itself a universal player (prevent self-replacement)
1013        if native_player.provider.domain == "universal_player":
1014            return
1015
1016        # Look for universal players that match this native player
1017        for player in list(self._players.values()):
1018            if player.provider.domain != "universal_player":
1019                continue
1020
1021            # Check by identifiers first
1022            identifiers_match = self._identifiers_match(native_player, player, "")
1023
1024            # Also check if native player's ID is in the universal player's stored protocol list
1025            # This handles players that changed type (e.g., sendspin web players changed from
1026            # PROTOCOL to PLAYER type) and have no identifiers to match against
1027            player_id_in_protocols = (
1028                isinstance(player, UniversalPlayer)
1029                and native_player.player_id in player._protocol_player_ids
1030            )
1031
1032            if not identifiers_match and not player_id_in_protocols:
1033                continue
1034
1035            known_protocol_ids = set(self._get_known_protocol_ids(player))
1036            active_protocol_ids = {
1037                link.output_protocol_id for link in player.linked_output_protocols
1038            }
1039            moved_protocol_ids: set[str] = set()
1040
1041            # Transfer all protocol links from universal player to native player
1042            for linked in list(player.linked_output_protocols):
1043                if protocol_player := self.get_player(linked.output_protocol_id):
1044                    protocol_player.set_protocol_parent_id(None)
1045                    domain = linked.protocol_domain or protocol_player.provider.domain
1046                    self._add_protocol_link(native_player, protocol_player, domain)
1047                    if protocol_player.protocol_parent_id == native_player.player_id:
1048                        moved_protocol_ids.add(protocol_player.player_id)
1049                        protocol_player.refresh_state()
1050                    else:
1051                        # Link refused, keep the protocol owned by the universal player.
1052                        protocol_player.set_protocol_parent_id(player.player_id)
1053
1054            if active_protocol_ids - moved_protocol_ids:
1055                # A link was refused, keep the universal player and hand over only
1056                # what moved so the refused protocols are not orphaned.
1057                self._migrate_protocol_ids_to_parent(native_player, moved_protocol_ids)
1058                self._remove_protocol_ids_from_parent(player, moved_protocol_ids)
1059                native_player.refresh_state()
1060                continue
1061
1062            cached_only_ids = known_protocol_ids - active_protocol_ids
1063            preserved_protocol_ids = moved_protocol_ids | cached_only_ids
1064            # A device that kept its id across a type change lists itself here.
1065            # It must never become its own protocol, and it must also be dropped
1066            # from the obsolete universal player so the permanent cleanup below
1067            # doesn't treat it as an orphaned protocol (which would re-wrap the
1068            # native player in a fresh universal player).
1069            preserved_protocol_ids.discard(native_player.player_id)
1070            self._migrate_protocol_ids_to_parent(native_player, preserved_protocol_ids)
1071            self._remove_protocol_ids_from_parent(
1072                player, preserved_protocol_ids | {native_player.player_id}
1073            )
1074            native_player.refresh_state()
1075
1076            # Carry over the user's configuration and re-point group memberships
1077            # before the permanent removal below deletes the universal player's config
1078            self._migrate_universal_player_config(player.player_id, native_player.player_id)
1079            self._repoint_group_memberships(player.player_id, native_player.player_id)
1080
1081            # Stop playback and remove the now-obsolete universal player
1082            self.mass.create_task(self._stop_and_unregister(player))
1083
1084    def _migrate_universal_player_config(self, universal_id: str, native_id: str) -> None:
1085        """
1086        Carry over user-set configuration from a replaced universal player.
1087
1088        Copies the custom display name, player config values, DSP settings and
1089        per-queue settings of the (obsolete) universal player onto the native
1090        player that replaces it, without overwriting values explicitly set on
1091        the native player itself. Must be called while the universal player's
1092        config still exists, as the permanent removal deletes it.
1093
1094        :param universal_id: Player id of the obsolete universal player being replaced.
1095        :param native_id: Player id of the native player that replaces it.
1096        """
1097        source_raw = self.mass.config.get(f"{CONF_PLAYERS}/{universal_id}")
1098        source_raw = source_raw if isinstance(source_raw, dict) else {}
1099        target_key = f"{CONF_PLAYERS}/{native_id}"
1100        target_raw = self.mass.config.get(target_key)
1101        target_raw = target_raw if isinstance(target_raw, dict) else {}
1102        player_config_changed = False
1103
1104        # only carry an actual user rename, not the auto-generated default name;
1105        # likewise a name on the native player only counts as a user override when
1106        # it differs from the default name
1107        custom_name = source_raw.get("name")
1108        target_name = target_raw.get("name")
1109        target_has_custom_name = bool(target_name) and target_name != target_raw.get("default_name")
1110        if (
1111            custom_name
1112            and custom_name != source_raw.get("default_name")
1113            and not target_has_custom_name
1114        ):
1115            self.mass.config.set(f"{target_key}/name", custom_name)
1116            player_config_changed = True
1117
1118        source_values = source_raw.get("values")
1119        source_values = source_values if isinstance(source_values, dict) else {}
1120        target_values = target_raw.get("values")
1121        target_values = target_values if isinstance(target_values, dict) else {}
1122        for key, value in source_values.items():
1123            if key in UNIVERSAL_PLAYER_INTERNAL_CONF_KEYS:
1124                continue
1125            if CONF_PROTOCOL_KEY_SPLITTER in key:
1126                # stale virtual mirror of a protocol player's own config
1127                continue
1128            if key in target_values:
1129                continue
1130            self.mass.config.set(f"{target_key}/values/{key}", deepcopy(value))
1131            player_config_changed = True
1132
1133        # DSP settings follow wholesale, unless the native player has its own
1134        dsp_changed = False
1135        source_dsp = self.mass.config.get(f"{CONF_PLAYER_DSP}/{universal_id}")
1136        if source_dsp and not self.mass.config.get(f"{CONF_PLAYER_DSP}/{native_id}"):
1137            self.mass.config.set(f"{CONF_PLAYER_DSP}/{native_id}", deepcopy(source_dsp))
1138            dsp_changed = True
1139
1140        queue_changed = self._migrate_universal_queue_config(universal_id, native_id)
1141
1142        if not (player_config_changed or dsp_changed or queue_changed):
1143            return
1144        self.logger.info(
1145            "Carried over configuration of universal player %s to %s", universal_id, native_id
1146        )
1147        if player_config_changed:
1148            # the native player's in-place config was loaded before the carry-over,
1149            # so reload it to make the migrated values (e.g. custom name) effective
1150            self.mass.create_task(self._reapply_player_config(native_id))
1151
1152    def _migrate_universal_queue_config(self, universal_id: str, native_id: str) -> bool:
1153        """
1154        Move the per-queue settings of a replaced universal player to its replacement.
1155
1156        Queue ids equal player ids, so the source entry is removed once it is carried over.
1157
1158        :param universal_id: Player id of the obsolete universal player.
1159        :param native_id: Player id of the native player that replaces it.
1160        :return: True if any queue setting was carried over.
1161        """
1162        queue_changed = False
1163        source_queue_raw = self.mass.config.get(f"{CONF_PLAYER_QUEUES}/{universal_id}")
1164        source_queue_raw = source_queue_raw if isinstance(source_queue_raw, dict) else None
1165        if source_queue_values := (source_queue_raw or {}).get("values"):
1166            target_queue_key = f"{CONF_PLAYER_QUEUES}/{native_id}"
1167            target_queue_raw = self.mass.config.get(target_queue_key)
1168            target_queue_raw = (
1169                deepcopy(target_queue_raw) if isinstance(target_queue_raw, dict) else {}
1170            )
1171            target_queue_values = target_queue_raw.setdefault("values", {})
1172            for key, value in source_queue_values.items():
1173                if key in target_queue_values:
1174                    continue
1175                target_queue_values[key] = deepcopy(value)
1176                queue_changed = True
1177            if queue_changed:
1178                target_queue_raw["queue_id"] = native_id
1179                self.mass.config.set(target_queue_key, target_queue_raw)
1180        if source_queue_raw is not None:
1181            self.mass.config.remove(f"{CONF_PLAYER_QUEUES}/{universal_id}")
1182        return queue_changed
1183
1184    async def _reapply_player_config(self, player_id: str) -> None:
1185        """Reload the stored config onto a registered player and refresh its state."""
1186        if not (player := self.get_player(player_id)):
1187            return
1188        config = await self.mass.config.get_player_config(player_id)
1189        player.set_config(config)
1190        player.update_state()
1191        self.mass.signal_event(EventType.PLAYER_CONFIG_UPDATED, object_id=player_id, data=config)
1192
1193    def _repoint_group_memberships(self, old_player_id: str, new_player_id: str) -> None:
1194        """
1195        Re-point group memberships from a removed player to its successor.
1196
1197        When a universal player is replaced by a native player or merged into
1198        another universal player, other players that list the removed player as
1199        a group member (or allowed member) must follow its successor so those
1200        memberships are not silently lost. Updates the persisted config and keeps
1201        any registered player whose membership changed in sync.
1202
1203        :param old_player_id: Player id that is being removed.
1204        :param new_player_id: Player id that replaces it.
1205        """
1206        all_player_configs = self.mass.config.get(CONF_PLAYERS, {})
1207        if not isinstance(all_player_configs, dict):
1208            return
1209        for other_id, other_cfg in all_player_configs.items():
1210            if not isinstance(other_cfg, dict):
1211                continue
1212            other_values = other_cfg.get("values")
1213            if not isinstance(other_values, dict):
1214                continue
1215            for key in (CONF_GROUP_MEMBERS, CONF_ALLOWED_MEMBERS):
1216                members = other_values.get(key)
1217                if not isinstance(members, list) or old_player_id not in members:
1218                    continue
1219                new_members: list[str] = []
1220                for member_id in members:
1221                    resolved = new_player_id if member_id == old_player_id else member_id
1222                    if resolved not in new_members:
1223                        new_members.append(resolved)
1224                self.mass.config.set(f"{CONF_PLAYERS}/{other_id}/values/{key}", new_members)
1225                # keep a registered player's in-place config copy and state in sync
1226                if other_player := self.get_player(other_id):
1227                    if entry := other_player.config.values.get(key):
1228                        entry.value = new_members
1229                    other_player.refresh_state()
1230
1231    async def _stop_and_unregister(self, player: Player) -> None:
1232        """
1233        Stop active playback on a player and then permanently unregister it.
1234
1235        Used when an obsolete universal player is replaced or merged away: while
1236        it is not idle its protocol child keeps playing the dead queue's stream
1237        until the buffer drains, so playback is stopped first. Queue ownership is
1238        intentionally not transferred.
1239
1240        :param player: The obsolete player to stop and permanently remove.
1241        """
1242        if player.playback_state != PlaybackState.IDLE:
1243            with suppress(PlayerCommandFailed, PlayerUnavailableError):
1244                await self.mass.player_queues.stop(player.player_id)
1245        await self.unregister(player.player_id, permanent=True)
1246
1247    def _parent_has_active_protocol_from_domain(
1248        self, parent: Player, domain: str, exclude_player_id: str | None = None
1249    ) -> bool:
1250        """
1251        Check if a parent already has an active (registered) protocol player from a given domain.
1252
1253        This prevents a second protocol player of the same domain (e.g., a second AirPlay
1254        instance on the same host) from replacing the first one's link on the same parent.
1255
1256        :param parent: The parent player to check.
1257        :param domain: The protocol domain to check for (e.g., "airplay", "dlna").
1258        :param exclude_player_id: Optional player ID to exclude from the check
1259            (used when checking if a player's own domain is already linked).
1260        """
1261        for link in parent.linked_output_protocols:
1262            if link.protocol_domain != domain:
1263                continue
1264            if exclude_player_id and link.output_protocol_id == exclude_player_id:
1265                continue
1266            # A registered player from this domain blocks the link, even if unavailable.
1267            # Being offline doesn't make it a different device — it's still occupying
1268            # this domain slot. The provider should remove stale players explicitly.
1269            if self.get_player(link.output_protocol_id):
1270                return True
1271        return False
1272
1273    def _add_protocol_link(
1274        self, native_player: Player, protocol_player: Player, protocol_domain: str
1275    ) -> None:
1276        """Add a protocol link from native player to protocol player."""
1277        # Never link a player to itself (hides it as its own protocol child).
1278        if native_player.player_id == protocol_player.player_id:
1279            return
1280        # Guard: refuse to replace an existing active link from the same domain.
1281        # This prevents a second instance of the same protocol (e.g., two AirPlay
1282        # instances on the same host) from silently replacing the first one.
1283        if self._parent_has_active_protocol_from_domain(
1284            native_player, protocol_domain, exclude_player_id=protocol_player.player_id
1285        ):
1286            self.logger.debug(
1287                "Refusing to link %s to %s: parent already has an active %s link",
1288                protocol_player.player_id,
1289                native_player.player_id,
1290                protocol_domain,
1291            )
1292            return
1293
1294        # Remove any existing link for the same protocol domain
1295        updated_protocols = [
1296            link
1297            for link in native_player.linked_output_protocols
1298            if link.protocol_domain != protocol_domain
1299        ]
1300
1301        # Get priority for this protocol
1302        priority = PROTOCOL_PRIORITY.get(protocol_domain, 100)
1303
1304        # Derived transports (e.g. a Sendspin bridge riding on an AirPlay player)
1305        # reference the base output they run on top of; "native" when they ride
1306        # on the parent player itself
1307        derived_from = protocol_player.underlying_player_id
1308        if derived_from == native_player.player_id:
1309            derived_from = "native"
1310
1311        # Add the new link
1312        updated_protocols.append(
1313            LinkedOutputProtocol(
1314                output_protocol_id=protocol_player.player_id,
1315                protocol_domain=protocol_domain,
1316                priority=priority,
1317                derived_from=derived_from,
1318            )
1319        )
1320        native_player.set_linked_output_protocols(updated_protocols)
1321
1322        # Set protocol player's parent
1323        protocol_player.set_protocol_parent_id(native_player.player_id)
1324
1325        # Persist linked protocol IDs to config for fast restart
1326        # (only for non-universal players, as universal players handle this themselves)
1327        if native_player.provider.domain != "universal_player":
1328            self._save_linked_protocol_ids(native_player)
1329        # Always save the parent ID on the protocol player for reverse lookup on restart
1330        # (needed for both native and universal parents to enable fast restore)
1331        self._save_protocol_parent_id(protocol_player.player_id, native_player.player_id)
1332
1333        # The freshly linked player may have derived protocol players (e.g. a
1334        # Sendspin bridge riding on it) waiting to join the same parent.
1335        self._link_derived_protocols_of(protocol_player)
1336
1337    def _remove_protocol_link(
1338        self, native_player: Player, protocol_player_id: str, permanent: bool = False
1339    ) -> None:
1340        """
1341        Remove a protocol link.
1342
1343        :param native_player: The parent player to remove the link from.
1344        :param protocol_player_id: The protocol player ID to unlink.
1345        :param permanent: If True, also removes the protocol ID from the cached list.
1346            Use this when the protocol player config is being deleted. If False,
1347            the protocol ID remains in the cache so it can be shown as disabled
1348            and re-enabled later.
1349        """
1350        updated_protocols = [
1351            link
1352            for link in native_player.linked_output_protocols
1353            if link.output_protocol_id != protocol_player_id
1354        ]
1355        native_player.set_linked_output_protocols(updated_protocols)
1356
1357        # Clear parent reference on protocol player if it still exists
1358        if protocol_player := self.get_player(protocol_player_id):
1359            if protocol_player.protocol_parent_id == native_player.player_id:
1360                protocol_player.set_protocol_parent_id(None)
1361
1362        # Update persisted linked protocol IDs
1363        if native_player.provider.domain != "universal_player":
1364            if permanent:
1365                # Permanently remove from cache (player config is being deleted)
1366                self._remove_protocol_id_from_cache(native_player.player_id, protocol_player_id)
1367            # Note: we don't call _save_linked_protocol_ids here anymore for non-permanent
1368            # removals because the merge approach will preserve the ID in the cache
1369        # Always clear the cached parent ID (for both native and universal parents)
1370        self._clear_protocol_parent_id(protocol_player_id)
1371
1372    def _save_linked_protocol_ids(self, native_player: Player) -> None:
1373        """
1374        Save linked protocol IDs to config for persistence across restarts.
1375
1376        This method merges active protocol IDs with existing cached IDs to preserve
1377        disabled protocol players in the cache. This allows disabled protocols to be
1378        shown in the UI so they can be re-enabled.
1379        """
1380        conf_key = f"{CONF_PLAYERS}/{native_player.player_id}/values/{CONF_LINKED_PROTOCOL_IDS}"
1381        # Get existing cached IDs to preserve disabled protocols
1382        existing_ids: list[str] = self.mass.config.get(conf_key, [])
1383        # Get currently active protocol IDs
1384        active_ids = {link.output_protocol_id for link in native_player.linked_output_protocols}
1385        # Merge: keep existing IDs and add any new active ones
1386        merged_ids = list(existing_ids)
1387        for protocol_id in active_ids:
1388            if protocol_id not in merged_ids:
1389                merged_ids.append(protocol_id)
1390        self.mass.config.set(conf_key, merged_ids)
1391
1392    def _get_cached_protocol_ids(self, player_id: str) -> list[str]:
1393        """Get cached linked protocol IDs from config."""
1394        conf_key = f"{CONF_PLAYERS}/{player_id}/values/{CONF_LINKED_PROTOCOL_IDS}"
1395        result = self.mass.config.get(conf_key, [])
1396        return list(result) if result else []
1397
1398    def _remove_protocol_id_from_cache(
1399        self, parent_player_id: str, protocol_player_id: str
1400    ) -> None:
1401        """
1402        Permanently remove a protocol player ID from the cached linked protocol IDs.
1403
1404        Use this when a protocol player config is being deleted, not just disabled.
1405        """
1406        conf_key = f"{CONF_PLAYERS}/{parent_player_id}/values/{CONF_LINKED_PROTOCOL_IDS}"
1407        cached_ids: list[str] = self.mass.config.get(conf_key, [])
1408        if protocol_player_id in cached_ids:
1409            cached_ids.remove(protocol_player_id)
1410            self.mass.config.set(conf_key, cached_ids)
1411
1412    def _save_protocol_parent_id(self, protocol_player_id: str, parent_id: str) -> None:
1413        """Save the parent ID for a protocol player for persistence across restarts."""
1414        # Only save if the player config still exists to avoid creating partial entries
1415        if not self.mass.config.get(f"{CONF_PLAYERS}/{protocol_player_id}"):
1416            return
1417        conf_key = f"{CONF_PLAYERS}/{protocol_player_id}/values/{CONF_PROTOCOL_PARENT_ID}"
1418        self.mass.config.set(conf_key, parent_id)
1419
1420    def _save_underlying_player_id(self, player: Player) -> None:
1421        """
1422        Persist the derived-transport edge of a player to config.
1423
1424        Allows the edge to be resolved (e.g. by the config UI) even while the
1425        player is not registered. Clears a previously persisted edge when the
1426        player is no longer derived (e.g. a bridge client turned web player).
1427        """
1428        # Only save if the player config still exists to avoid creating partial entries
1429        if not self.mass.config.get(f"{CONF_PLAYERS}/{player.player_id}"):
1430            return
1431        conf_key = f"{CONF_PLAYERS}/{player.player_id}/values/{CONF_UNDERLYING_PLAYER_ID}"
1432        if player.underlying_player_id:
1433            self.mass.config.set(conf_key, player.underlying_player_id)
1434        elif self.mass.config.get(conf_key) is not None:
1435            self.mass.config.set(conf_key, None)
1436
1437    def _get_cached_protocol_parent_id(self, protocol_player_id: str) -> str | None:
1438        """Get cached parent ID for a protocol player from config."""
1439        conf_key = f"{CONF_PLAYERS}/{protocol_player_id}/values/{CONF_PROTOCOL_PARENT_ID}"
1440        result = self.mass.config.get(conf_key, None)
1441        return str(result) if result else None
1442
1443    def _clear_protocol_parent_id(self, protocol_player_id: str) -> None:
1444        """Clear the cached parent ID for a protocol player."""
1445        # Only clear if the player config still exists to avoid creating partial entries
1446        if not self.mass.config.get(f"{CONF_PLAYERS}/{protocol_player_id}"):
1447            return
1448        conf_key = f"{CONF_PLAYERS}/{protocol_player_id}/values/{CONF_PROTOCOL_PARENT_ID}"
1449        self.mass.config.set(conf_key, None)
1450
1451    def _recover_cached_protocol_links(self, native_player: Player) -> None:
1452        """
1453        Recover protocol links from config for disabled/missing protocols.
1454
1455        This ensures that disabled protocols show up in the output_protocols list
1456        so they can be re-enabled by the user. It also handles the case where
1457        protocol players haven't registered yet during startup.
1458        """
1459        # Get currently linked protocol IDs
1460        linked_protocol_ids = {
1461            link.output_protocol_id for link in native_player.linked_output_protocols
1462        }
1463
1464        # Get cached protocol IDs from config (includes protocols that were explicitly linked)
1465        cached_protocol_ids = self._get_cached_protocol_ids(native_player.player_id)
1466
1467        # Also check all protocol players that have protocol_parent_id pointing to this player
1468        # (this handles disabled protocols that may not be in linked_protocol_ids)
1469        all_player_configs = self.mass.config.get(CONF_PLAYERS, {})
1470        for protocol_id, protocol_config in all_player_configs.items():
1471            # Skip if not a protocol player
1472            if protocol_config.get("player_type") != "protocol":
1473                continue
1474            # Check if this protocol has a parent_id pointing to this native player
1475            protocol_values = protocol_config.get("values", {})
1476            protocol_parent_id = protocol_values.get(CONF_PROTOCOL_PARENT_ID)
1477            if protocol_parent_id == native_player.player_id:
1478                if protocol_id not in cached_protocol_ids:
1479                    cached_protocol_ids.append(protocol_id)
1480
1481        if not cached_protocol_ids:
1482            return
1483
1484        # Add link entries for any cached protocols that aren't currently linked
1485        updated_protocols = list(native_player.linked_output_protocols)
1486        for protocol_id in cached_protocol_ids:
1487            if protocol_id in linked_protocol_ids:
1488                continue  # Already linked
1489
1490            # Get protocol player config to determine the protocol domain
1491            protocol_config = self.mass.config.get(f"{CONF_PLAYERS}/{protocol_id}")
1492            if not protocol_config:
1493                continue
1494
1495            # Determine protocol domain from provider
1496            protocol_provider: str = protocol_config.get("provider")
1497            if not protocol_provider:
1498                continue
1499
1500            # Extract domain from provider instance_id (e.g., "airplay--uuid" -> "airplay")
1501            protocol_domain = protocol_provider.split("--", maxsplit=1)[0]
1502
1503            # Skip if parent already has a link from this domain
1504            existing_domains = {link.protocol_domain for link in updated_protocols}
1505            if protocol_domain in existing_domains:
1506                continue
1507
1508            # Get priority for this protocol
1509            priority = PROTOCOL_PRIORITY.get(protocol_domain, 100)
1510
1511            # Resolve the derived-transport edge from the live player when
1512            # registered, else from the persisted edge in config
1513            protocol_player = self.get_player(protocol_id)
1514            derived_from = (
1515                protocol_player.underlying_player_id
1516                if protocol_player
1517                else protocol_config.get("values", {}).get(CONF_UNDERLYING_PLAYER_ID)
1518            )
1519            if derived_from == native_player.player_id:
1520                derived_from = "native"
1521
1522            updated_protocols.append(
1523                LinkedOutputProtocol(
1524                    output_protocol_id=protocol_id,
1525                    protocol_domain=protocol_domain,
1526                    priority=priority,
1527                    derived_from=derived_from,
1528                )
1529            )
1530            self.logger.debug(
1531                "Recovered cached protocol link %s -> %s",
1532                native_player.player_id,
1533                protocol_id,
1534            )
1535
1536        if len(updated_protocols) != len(native_player.linked_output_protocols):
1537            native_player.set_linked_output_protocols(updated_protocols)
1538
1539    def _cleanup_protocol_links(self, player: Player) -> None:
1540        """Clean up protocol links when a player is permanently removed."""
1541        if player.state.type == PlayerType.PROTOCOL:
1542            # Protocol player being removed: remove link from parent
1543            if parent_id := player.protocol_parent_id:
1544                if parent_player := self.get_player(parent_id):
1545                    # Use permanent=True to also remove from cached protocol IDs
1546                    self._remove_protocol_link(parent_player, player.player_id, permanent=True)
1547                    if (
1548                        parent_player.provider.domain == "universal_player"
1549                        and len(parent_player.linked_output_protocols) == 0
1550                    ):
1551                        # No protocols left - the universal player has nothing to play
1552                        # on. Its config is deliberately kept: the player id is opaque
1553                        # and cannot be recreated, so deleting it here would orphan the
1554                        # entities API consumers bound to it. Only an explicit removal
1555                        # by the user deletes a universal player for good.
1556                        self.logger.info(
1557                            "Universal player %s has no protocols left",
1558                            parent_id,
1559                        )
1560                        self.mass.create_task(
1561                            self.mass.players.unregister(parent_id, permanent=False)
1562                        )
1563                    else:
1564                        parent_player.refresh_state()
1565                else:
1566                    # Parent not registered yet — still purge the cached id
1567                    self._remove_protocol_id_from_cache(parent_id, player.player_id)
1568        else:
1569            # Native/universal player being removed: handle all linked protocol players.
1570            # Collect all known protocol IDs from both active links and cached state,
1571            # since disabled/inactive protocols may only exist in the cached parent data.
1572            all_protocol_ids = set(self._get_known_protocol_ids(player))
1573            for protocol_id in all_protocol_ids:
1574                if protocol_player := self.get_player(protocol_id):
1575                    # Protocol player is available: clear parent and schedule re-evaluation
1576                    # so it can be matched to a new parent or a new universal player
1577                    self.logger.debug(
1578                        "Player %s removed - scheduling evaluation for protocol %s",
1579                        player.player_id,
1580                        protocol_id,
1581                    )
1582                    self._detach_protocol_child(protocol_player)
1583                else:
1584                    # Clear cached parent ID in config so protocol won't try to
1585                    # restore a link to the deleted player on next restart
1586                    self._clear_protocol_parent_id(protocol_id)
1587                    # Protocol player is not registered yet — it may still be
1588                    # mid-discovery (e.g., DLNA connecting via SSDP). Don't delete
1589                    # its config as that would cause a KeyError when it finishes
1590                    # registering. Stale configs are harmless and get cleaned up
1591                    # naturally on subsequent restarts.
1592                    self.logger.debug(
1593                        "Player %s removed - protocol %s not registered, skipping cleanup",
1594                        player.player_id,
1595                        protocol_id,
1596                    )
1597
1598    def _detach_protocol_children(self, parent_id: str) -> None:
1599        """
1600        Detach the registered protocol players of a parent player that is going away.
1601
1602        Covers the removal paths that don't unregister the parent first (e.g. its
1603        provider is unloaded), where the parent is not around anymore to enumerate
1604        its protocol players.
1605
1606        :param parent_id: Player id of the parent that is being removed.
1607        """
1608        for protocol_player in list(self._players.values()):
1609            if protocol_player.state.type != PlayerType.PROTOCOL:
1610                continue
1611            # a protocol player waiting for a parent that never registered only has
1612            # the link in its config, so fall back to the cached parent
1613            linked_parent_id = protocol_player.protocol_parent_id or (
1614                self._get_cached_protocol_parent_id(protocol_player.player_id)
1615            )
1616            if linked_parent_id != parent_id:
1617                continue
1618            self.logger.debug(
1619                "Player %s removed - scheduling evaluation for protocol %s",
1620                parent_id,
1621                protocol_player.player_id,
1622            )
1623            self._detach_protocol_child(protocol_player)
1624
1625    def _detach_protocol_child(self, protocol_player: Player) -> None:
1626        """Clear a protocol player's parent link and schedule a fresh evaluation."""
1627        self._clear_protocol_parent_id(protocol_player.player_id)
1628        protocol_player.set_protocol_parent_id(None)
1629        protocol_player.refresh_state()
1630        self._schedule_protocol_evaluation(protocol_player)
1631
1632    def _identifiers_match(
1633        self, player_a: Player, player_b: Player, protocol_domain: str = ""
1634    ) -> bool:
1635        """
1636        Check if identifiers match between two players.
1637
1638        Matching is done by comparing connection identifiers (MAC, serial, UUID).
1639        As a last resort, IP address is used when at least one player has a
1640        locally-administered MAC, indicating the device uses MAC randomization
1641        and ARP could not resolve the real hardware address.
1642
1643        Invalid identifiers (e.g., 00:00:00:00:00:00 MAC addresses) are filtered out
1644        to prevent false matches between unrelated devices.
1645        """
1646        identifiers_a = player_a.device_info.identifiers
1647        identifiers_b = player_b.device_info.identifiers
1648
1649        # Check identifiers in order of reliability
1650        # MAC_ADDRESS > SERIAL_NUMBER > UUID > CAST_UUID > AIRPLAY_ID
1651        for conn_type in (
1652            IdentifierType.MAC_ADDRESS,
1653            IdentifierType.SERIAL_NUMBER,
1654            IdentifierType.UUID,
1655            IdentifierType.CAST_UUID,
1656            IdentifierType.AIRPLAY_ID,
1657        ):
1658            val_a = identifiers_a.get(conn_type)
1659            val_b = identifiers_b.get(conn_type)
1660
1661            if not val_a or not val_b:
1662                continue
1663
1664            # Filter out invalid MAC addresses (00:00:00:00:00:00, ff:ff:ff:ff:ff:ff)
1665            if conn_type == IdentifierType.MAC_ADDRESS:
1666                if not is_valid_mac_address(val_a) or not is_valid_mac_address(val_b):
1667                    self.logger.log(
1668                        VERBOSE_LOG_LEVEL,
1669                        "Skipping invalid MAC address for matching: %s=%s, %s=%s",
1670                        player_a.display_name,
1671                        val_a,
1672                        player_b.display_name,
1673                        val_b,
1674                    )
1675                    continue
1676
1677            # Normalize values for comparison
1678            if conn_type == IdentifierType.MAC_ADDRESS:
1679                # Use MAC normalization that handles locally-administered bit differences
1680                # Some protocols (like AirPlay) report a locally-administered MAC variant
1681                # where bit 1 of the first octet is set (e.g., 54:78:... vs 56:78:...)
1682                val_a_norm = normalize_mac_for_matching(val_a)
1683                val_b_norm = normalize_mac_for_matching(val_b)
1684
1685                # Direct match on current MAC
1686                if val_a_norm == val_b_norm:
1687                    return True
1688
1689                # Multi-MAC matching: also check original reported MACs.
1690                # Devices with multiple interfaces (WiFi + Ethernet) may have ARP
1691                # resolve one MAC while the protocol reports a different one.
1692                macs_a = {val_a_norm}
1693                macs_b = {val_b_norm}
1694                reported_a = player_a.extra_data.get("reported_mac")
1695                reported_b = player_b.extra_data.get("reported_mac")
1696                if reported_a and is_valid_mac_address(reported_a):
1697                    macs_a.add(normalize_mac_for_matching(reported_a))
1698                if reported_b and is_valid_mac_address(reported_b):
1699                    macs_b.add(normalize_mac_for_matching(reported_b))
1700                if macs_a & macs_b:
1701                    return True
1702
1703                # No MAC match - continue to next identifier type
1704                continue
1705
1706            val_a_norm = val_a.lower().replace(":", "").replace("-", "")
1707            val_b_norm = val_b.lower().replace(":", "").replace("-", "")
1708
1709            # Direct match
1710            if val_a_norm == val_b_norm:
1711                return True
1712
1713            # Special case: Sonos UUID matching with DLNA _MR suffix
1714            # Sonos uses RINCON_xxx, DLNA uses RINCON_xxx_MR for Media Renderer
1715            if conn_type == IdentifierType.UUID:
1716                if val_b_norm.endswith("_mr") and val_b_norm[:-3] == val_a_norm:
1717                    return True
1718                if val_a_norm.endswith("_mr") and val_a_norm[:-3] == val_b_norm:
1719                    return True
1720
1721        # Last resort: IP-based matching.
1722        # Two players on the same IP are very likely the same physical device.
1723        # This handles two cases:
1724        # 1. MAC randomization: at least one player has no real MAC (LA or missing),
1725        #    so ARP couldn't resolve a usable address.
1726        # 2. Different MACs per protocol: some devices (e.g., Yamaha MusicCast) report
1727        #    different valid globally-unique MACs per protocol (DLNA vs AirPlay differ
1728        #    by 1 in the last octet). IP matching is safe here because two different
1729        #    devices on a LAN cannot share the same IP simultaneously.
1730        #    To avoid false positives between unrelated native players, this path
1731        #    requires at least one player to be a protocol or universal player.
1732        ip_a = identifiers_a.get(IdentifierType.IP_ADDRESS)
1733        ip_b = identifiers_b.get(IdentifierType.IP_ADDRESS)
1734        if ip_a and ip_b and ip_a == ip_b:
1735            mac_a = identifiers_a.get(IdentifierType.MAC_ADDRESS)
1736            mac_b = identifiers_b.get(IdentifierType.MAC_ADDRESS)
1737            a_is_real = (
1738                mac_a is not None
1739                and is_valid_mac_address(mac_a)
1740                and not is_locally_administered_mac(mac_a)
1741            )
1742            b_is_real = (
1743                mac_b is not None
1744                and is_valid_mac_address(mac_b)
1745                and not is_locally_administered_mac(mac_b)
1746            )
1747            # Case 1: at least one player has no real hardware MAC
1748            if not (a_is_real and b_is_real):
1749                return True
1750            # Case 2: both have real MACs but at least one is a protocol/universal player
1751            a_is_protocol = (
1752                player_a.type == PlayerType.PROTOCOL
1753                or player_a.provider.domain == "universal_player"
1754            )
1755            b_is_protocol = (
1756                player_b.type == PlayerType.PROTOCOL
1757                or player_b.provider.domain == "universal_player"
1758            )
1759            if a_is_protocol or b_is_protocol:
1760                return True
1761
1762        return False
1763
1764    def _select_best_output_protocol(self, player: Player) -> tuple[Player, OutputProtocol | None]:
1765        """
1766        Select the best available output protocol for a player.
1767
1768        Selection priority:
1769        1. Output protocol that is currently grouped/synced with other players.
1770        2. User's preferred output protocol (from player settings).
1771        3. Native playback (if player supports PLAY_MEDIA).
1772        4. The player's declared default output protocol domain, if available.
1773        5. Best available protocol by priority.
1774
1775        Returns tuple of (target_player, output_protocol).
1776        output_protocol is None when using native playback.
1777        """
1778        self.logger.log(
1779            VERBOSE_LOG_LEVEL,
1780            "Selecting output protocol for %s",
1781            player.state.name,
1782        )
1783
1784        # 1. Check if any output protocol is currently grouped
1785        for linked in player.linked_output_protocols:
1786            if protocol_player := self.get_player(linked.output_protocol_id):
1787                if protocol_player.available_for_playback and self._is_protocol_grouped(
1788                    protocol_player
1789                ):
1790                    self.logger.log(
1791                        VERBOSE_LOG_LEVEL,
1792                        "Selected protocol for %s: %s (grouped)",
1793                        player.state.name,
1794                        protocol_player.state.name,
1795                    )
1796                    return protocol_player, player.get_linked_protocol(linked.output_protocol_id)
1797
1798        # 2. Check for user's preferred output protocol.
1799        # The value is only stored while it differs from the entry's default: "native" when a
1800        # native output is available, otherwise "auto". A player without a native output (e.g. a
1801        # LinkPlay shell) therefore has no stored preference by default and gets its default
1802        # output domain applied in step 4.
1803        preferred = self.mass.config.get_raw_player_config_value(
1804            player.player_id, CONF_PREFERRED_OUTPUT_PROTOCOL
1805        )
1806        if preferred and preferred != "auto":
1807            if preferred == "native":
1808                if PlayerFeature.PLAY_MEDIA in player.supported_features:
1809                    self.logger.log(
1810                        VERBOSE_LOG_LEVEL,
1811                        "Selected protocol for %s: native (user preference)",
1812                        player.state.name,
1813                    )
1814                    return player, None
1815            else:
1816                for linked in player.linked_output_protocols:
1817                    if linked.output_protocol_id == preferred:
1818                        if protocol_player := self.get_player(linked.output_protocol_id):
1819                            if protocol_player.available_for_playback:
1820                                self.logger.log(
1821                                    VERBOSE_LOG_LEVEL,
1822                                    "Selected protocol for %s: %s (user preference)",
1823                                    player.state.name,
1824                                    protocol_player.state.name,
1825                                )
1826                                return protocol_player, player.get_linked_protocol(
1827                                    linked.output_protocol_id
1828                                )
1829                        break
1830
1831        # 3. Use native playback if available
1832        if PlayerFeature.PLAY_MEDIA in player.supported_features:
1833            self.logger.log(
1834                VERBOSE_LOG_LEVEL, "Selected protocol for %s: native", player.state.name
1835            )
1836            return player, None
1837
1838        # 4. Use the player's preferred default protocol domain, if it declares one and a
1839        # matching linked protocol is available (e.g. a LinkPlay shell prefers DLNA). This
1840        # never influences grouping; it only steers the default output for playback. "Auto"
1841        # is the entry default here, so it consistently resolves to this domain default.
1842        if default_domain := player.default_output_protocol_domain:
1843            for linked in sorted(player.linked_output_protocols, key=lambda x: x.priority):
1844                if linked.protocol_domain != default_domain:
1845                    continue
1846                if (protocol_player := self.get_player(linked.output_protocol_id)) and (
1847                    protocol_player.available_for_playback
1848                ):
1849                    self.logger.log(
1850                        VERBOSE_LOG_LEVEL,
1851                        "Selected protocol for %s: %s (default domain %s)",
1852                        player.state.name,
1853                        protocol_player.state.name,
1854                        default_domain,
1855                    )
1856                    return protocol_player, player.get_linked_protocol(linked.output_protocol_id)
1857
1858        # 5. Fall back to best protocol by priority
1859        for linked in sorted(player.linked_output_protocols, key=lambda x: x.priority):
1860            if protocol_player := self.get_player(linked.output_protocol_id):
1861                if protocol_player.available_for_playback:
1862                    self.logger.log(
1863                        VERBOSE_LOG_LEVEL,
1864                        "Selected protocol for %s: %s (priority-based)",
1865                        player.state.name,
1866                        protocol_player.state.name,
1867                    )
1868                    return protocol_player, player.get_linked_protocol(linked.output_protocol_id)
1869
1870        raise PlayerCommandFailed(f"Player {player.state.name} has no available output protocols")
1871
1872    def _get_control_target(
1873        self,
1874        player: Player,
1875        required_feature: PlayerFeature,
1876        require_active: bool = False,
1877    ) -> Player | None:
1878        """
1879        Get the best player(protocol) to send audio-path commands to.
1880
1881        Resolves commands that travel with the audio (enqueue, pause, announcements),
1882        so the output that renders the audio outranks the native player. Volume and
1883        mute are control-plane instead and resolve through
1884        :meth:`Player._get_protocol_player_for_feature`, which orders differently.
1885
1886        :param player: The player the command was issued on.
1887        :param required_feature: The feature the resolved target has to support.
1888        :param require_active: Only accept the output that is already rendering,
1889            instead of falling back to an idle one.
1890        """
1891        # If we have an active protocol, use that
1892        if (
1893            player.active_output_protocol
1894            and player.active_output_protocol != "native"
1895            and (protocol_player := self.mass.players.get_player(player.active_output_protocol))
1896            and required_feature in protocol_player.supported_features
1897        ):
1898            return protocol_player
1899
1900        # if the player natively supports the required feature, use that
1901        if (
1902            player.active_output_protocol == "native"
1903            and required_feature in player.supported_features
1904        ):
1905            return player
1906
1907        # If require_active is set, and no active protocol found, return None
1908        if require_active:
1909            return None
1910
1911        # if the player natively supports the required feature, use that
1912        if required_feature in player.supported_features:
1913            return player
1914
1915        # An output the user explicitly picked owns the audio, so a command that has to
1916        # start playback on an idle player follows it rather than the priority below.
1917        # The stored value survives a relink, so it only counts while it still names one
1918        # of this player's own outputs.
1919        preferred = self.mass.config.get_raw_player_config_value(
1920            player.player_id, CONF_PREFERRED_OUTPUT_PROTOCOL
1921        )
1922        if preferred and preferred not in ("auto", "native"):
1923            for linked in player.linked_output_protocols:
1924                if linked.output_protocol_id != preferred:
1925                    continue
1926                if (
1927                    (preferred_player := self.mass.players.get_player(str(preferred)))
1928                    and preferred_player.available_for_playback
1929                    and required_feature in preferred_player.supported_features
1930                ):
1931                    return preferred_player
1932                break
1933
1934        # Otherwise, use the best available linked protocol, ordered by the same
1935        # priority that regular playback selection applies.
1936        for linked in sorted(player.linked_output_protocols, key=lambda x: x.priority):
1937            if (
1938                (protocol_player := self.mass.players.get_player(linked.output_protocol_id))
1939                and protocol_player.available_for_playback
1940                and required_feature in protocol_player.supported_features
1941            ):
1942                return protocol_player
1943
1944        return None
1945
1946    def _is_protocol_grouped(self, protocol_player: Player) -> bool:
1947        """
1948        Check if a protocol player is currently grouped/synced with other players.
1949
1950        Used to prefer protocols that are actively participating in a group,
1951        ensuring consistent playback across grouped players.
1952        """
1953        is_grouped = bool(
1954            protocol_player.state.synced_to
1955            or (
1956                protocol_player.state.group_members and len(protocol_player.state.group_members) > 1
1957            )
1958            or protocol_player.state.active_group
1959        )
1960        if is_grouped:
1961            self.logger.log(
1962                VERBOSE_LOG_LEVEL,
1963                "Protocol player %s is grouped",
1964                protocol_player.state.name,
1965            )
1966        return is_grouped
1967
1968    def _translate_members_to_remove_for_protocols(
1969        self,
1970        parent_player: Player,
1971        player_ids: list[str],
1972        parent_protocol_player: Player | None,
1973        parent_protocol_domain: str | None,
1974    ) -> tuple[list[str], list[str]]:
1975        """
1976        Translate member IDs to remove into protocol and native lists.
1977
1978        :param parent_player: The parent player to remove members from.
1979        :param player_ids: List of visible player IDs to remove.
1980        :param parent_protocol_player: The parent's protocol player if available.
1981        :param parent_protocol_domain: The parent's protocol domain if available.
1982        """
1983        self.logger.debug(
1984            "Translating members to remove for %s: player_ids=%s, parent_protocol_domain=%s",
1985            parent_player.state.name,
1986            player_ids,
1987            parent_protocol_domain,
1988        )
1989        protocol_members: list[str] = []
1990        native_members: list[str] = []
1991
1992        for child_player_id in player_ids:
1993            child_player = self.get_player(child_player_id)
1994            if not child_player:
1995                continue
1996
1997            # Check if this member is in the parent's group via protocol
1998            if parent_protocol_domain and parent_protocol_player:
1999                child_protocol = child_player.get_output_protocol_by_domain(parent_protocol_domain)
2000                if child_protocol and child_protocol.available:
2001                    # For native protocol players, use the child's player_id directly
2002                    child_protocol_id = (
2003                        child_player.player_id
2004                        if child_protocol.is_native
2005                        else child_protocol.output_protocol_id
2006                    )
2007                    if child_protocol_id in parent_protocol_player.group_members:
2008                        self.logger.debug(
2009                            "Translating removal: %s -> protocol %s",
2010                            child_player_id,
2011                            child_protocol_id,
2012                        )
2013                        protocol_members.append(child_protocol_id)
2014                        continue
2015
2016            # Check if child's protocol player is in parent's native group_members
2017            # This handles native protocol players (e.g., native AirPlay player like Apple TV)
2018            # where the parent itself contains protocol player IDs in its group_members
2019            translated = False
2020            for linked in child_player.linked_output_protocols:
2021                if linked.output_protocol_id in parent_player.group_members:
2022                    self.logger.debug(
2023                        "Translating removal (native parent): %s -> protocol %s",
2024                        child_player_id,
2025                        linked.output_protocol_id,
2026                    )
2027                    native_members.append(linked.output_protocol_id)
2028                    translated = True
2029                    break
2030
2031            if not translated:
2032                native_members.append(child_player_id)
2033
2034        return protocol_members, native_members
2035
2036    def _filter_protocol_members(self, member_ids: list[str], protocol_player: Player) -> list[str]:
2037        """Filter member IDs to only include players from the same protocol domain."""
2038        return [
2039            pid
2040            for pid in member_ids
2041            if (p := self.get_player(pid)) and p.provider.domain == protocol_player.provider.domain
2042        ]
2043
2044    def _filter_native_members(self, member_ids: list[str], parent_player: Player) -> list[str]:
2045        """Filter member IDs to only include players compatible with the parent."""
2046        return [
2047            pid
2048            for pid in member_ids
2049            if (p := self.get_player(pid))
2050            and (
2051                p.provider.instance_id == parent_player.provider.instance_id
2052                or pid in parent_player._attr_can_group_with
2053                or p.provider.instance_id in parent_player._attr_can_group_with
2054            )
2055        ]
2056
2057    def _try_child_preferred_protocol(
2058        self,
2059        child_player: Player,
2060        parent_player: Player,
2061    ) -> tuple[str | None, str | None]:
2062        """
2063        Try to use child's preferred output protocol for grouping.
2064
2065        Returns tuple of (child_protocol_id, protocol_domain) or (None, None).
2066        """
2067        child_preferred = self.mass.config.get_raw_player_config_value(
2068            child_player.player_id, CONF_PREFERRED_OUTPUT_PROTOCOL
2069        )
2070        if not child_preferred or child_preferred in {"auto", "native"}:
2071            return None, None
2072
2073        # Find child's preferred protocol, with its current availability
2074        child_protocol = None
2075        for output_protocol in child_player.output_protocols:
2076            if output_protocol.output_protocol_id == child_preferred:
2077                child_protocol = output_protocol
2078                break
2079
2080        if not child_protocol or not child_protocol.available:
2081            return None, None
2082
2083        # Check if parent supports this protocol (including native protocol)
2084        parent_protocol = parent_player.get_output_protocol_by_domain(
2085            child_protocol.protocol_domain
2086        )
2087        if not parent_protocol or not parent_protocol.available:
2088            return None, None
2089
2090        # Check if this protocol supports set_members
2091        protocol_player = parent_player.get_protocol_player(parent_protocol.output_protocol_id)
2092        if (
2093            not protocol_player
2094            or PlayerFeature.SET_MEMBERS not in protocol_player.state.supported_features
2095        ):
2096            return None, None
2097
2098        return child_protocol.output_protocol_id, child_protocol.protocol_domain
2099
2100    def _can_use_native_grouping(
2101        self,
2102        child_player: Player,
2103        parent_player: Player,
2104        parent_supports_native: bool,
2105    ) -> bool:
2106        """Check if child can be grouped with parent using native grouping."""
2107        if not parent_supports_native:
2108            return False
2109        return (
2110            parent_player.is_native_group_compatible(child_player)
2111            or child_player.player_id in parent_player._attr_can_group_with
2112            or child_player.provider.instance_id in parent_player._attr_can_group_with
2113        )
2114
2115    def _try_find_common_protocol(
2116        self, child_player: Player, parent_player: Player
2117    ) -> tuple[OutputProtocol | None, OutputProtocol | None]:
2118        """
2119        Find common protocol that supports set_members.
2120
2121        Returns tuple of (parent_protocol, child_protocol) or (None, None).
2122        """
2123        for parent_output_protocol in parent_player.output_protocols:
2124            if not parent_output_protocol.available:
2125                continue
2126            child_protocol = child_player.get_output_protocol_by_domain(
2127                parent_output_protocol.protocol_domain
2128            )
2129            if not child_protocol or not child_protocol.available:
2130                continue
2131            protocol_player = parent_player.get_protocol_player(
2132                parent_output_protocol.output_protocol_id
2133            )
2134            if protocol_player and PlayerFeature.SET_MEMBERS in protocol_player.supported_features:
2135                return parent_output_protocol, child_protocol
2136        return None, None
2137
2138    def _parent_has_live_native_session(self, parent_player: Player) -> bool:
2139        """
2140        Return True when the parent currently holds a live native playback session.
2141
2142        The active output protocol lingers for a few seconds after stop, so a non-idle
2143        playback state is required to distinguish a real session from a just-stopped one.
2144        """
2145        return parent_player.active_output_protocol == "native" and (
2146            parent_player.state.playback_state in (PlaybackState.PLAYING, PlaybackState.PAUSED)
2147        )
2148
2149    def _order_members_for_native_join(
2150        self,
2151        player_ids: list[str],
2152        parent_player: Player,
2153        parent_supports_native_grouping: bool,
2154    ) -> list[str]:
2155        """
2156        Order members so a live native session can be joined without splitting the group.
2157
2158        When the parent already holds a live native session, children that cannot group
2159        natively are evaluated first: they may force a shared protocol for the whole group,
2160        and processing them before the native-capable children lets those join that same
2161        protocol instead of being stranded in a separate native sub-group. The order is left
2162        untouched when the parent is not playing natively, so fresh-group selection is unchanged.
2163
2164        :param player_ids: The member IDs to be added, in their original order.
2165        :param parent_player: The parent player being joined.
2166        :param parent_supports_native_grouping: Whether the parent can group natively.
2167        """
2168        if not self._parent_has_live_native_session(parent_player):
2169            return player_ids
2170        return sorted(
2171            player_ids,
2172            key=lambda pid: bool(
2173                (child := self.get_player(pid))
2174                and self._can_use_native_grouping(
2175                    child, parent_player, parent_supports_native_grouping
2176                )
2177            ),
2178        )
2179
2180    def _try_join_active_native_session(
2181        self,
2182        child_player: Player,
2183        parent_player: Player,
2184        parent_protocol_domain: str | None,
2185        parent_supports_native_grouping: bool,
2186        native_members: list[str],
2187    ) -> bool:
2188        """
2189        Add the child to native_members if it can join the parent's active native session.
2190
2191        A child's preferred output protocol must only steer protocol selection when the child
2192        initiates its own playback; when it joins a parent that is already playing natively it
2193        should adopt native grouping if compatible, rather than forcing the whole group onto
2194        the child's preferred protocol. Skipped once a protocol has been selected for the group,
2195        so mixed batches stay cohesive on a single protocol.
2196
2197        :param child_player: The player being added to the group.
2198        :param parent_player: The parent player being joined.
2199        :param parent_protocol_domain: The protocol domain already selected for the group, if any.
2200        :param parent_supports_native_grouping: Whether the parent can group natively.
2201        :param native_members: The native members list to append to when the child joins.
2202        """
2203        if not (
2204            self._parent_has_live_native_session(parent_player)
2205            and not parent_protocol_domain
2206            and self._can_use_native_grouping(
2207                child_player, parent_player, parent_supports_native_grouping
2208            )
2209        ):
2210            return False
2211        native_members.append(child_player.player_id)
2212        self.logger.log(
2213            VERBOSE_LOG_LEVEL,
2214            "Joining parent's active native session for %s",
2215            child_player.state.name,
2216        )
2217        return True
2218
2219    def _translate_native_members_to_protocol(
2220        self, parent_player: Player, protocol_domain: str, member_ids: list[str]
2221    ) -> list[str]:
2222        """
2223        Translate natively grouped members onto the protocol domain the parent plays through.
2224
2225        Members that do not have that protocol cannot follow the parent at all and are
2226        dropped with a warning instead.
2227
2228        :param parent_player: The parent player the members are grouped with.
2229        :param protocol_domain: The protocol domain selected for the group.
2230        :param member_ids: The member IDs that were selected for native grouping.
2231        """
2232        translated: list[str] = []
2233        for member_id in member_ids:
2234            member_player = self.get_player(member_id)
2235            if not member_player:
2236                continue
2237            # a native group's members may be listed by their protocol player id
2238            if member_player.protocol_parent_id:
2239                member_player = self.get_player(member_player.protocol_parent_id) or member_player
2240            member_protocol = member_player.get_output_protocol_by_domain(protocol_domain)
2241            if not member_protocol or not member_protocol.available:
2242                self.logger.warning(
2243                    "Cannot group %s with %s: the group plays through the %s protocol, "
2244                    "which %s does not support",
2245                    member_player.state.name,
2246                    parent_player.state.name,
2247                    protocol_domain,
2248                    member_player.state.name,
2249                )
2250                continue
2251            # For native protocol players, use the member's player_id directly
2252            translated.append(
2253                member_player.player_id
2254                if member_protocol.is_native
2255                else member_protocol.output_protocol_id
2256            )
2257            self.logger.log(
2258                VERBOSE_LOG_LEVEL,
2259                "Moving %s from native grouping to the %s protocol",
2260                member_player.state.name,
2261                protocol_domain,
2262            )
2263        return translated
2264
2265    def _move_native_members_to_group_protocol(
2266        self,
2267        parent_player: Player,
2268        parent_protocol_player: Player | None,
2269        parent_protocol_domain: str | None,
2270        protocol_members: list[str],
2271        native_members: list[str],
2272    ) -> None:
2273        """
2274        Move the members selected for native grouping onto the protocol the group ended up on.
2275
2276        Does nothing unless the group ends up on one of the parent's protocols while the
2277        parent's native grouping needs the parent's own stream: only then do those members
2278        have no session left to attach to.
2279
2280        :param parent_player: The parent player being joined.
2281        :param parent_protocol_player: The protocol player selected for the group, if any.
2282        :param parent_protocol_domain: The protocol domain selected for the group, if any.
2283        :param protocol_members: The protocol member list the translated IDs are added to.
2284        :param native_members: The native member IDs, emptied when they are moved over.
2285        """
2286        if not (
2287            native_members
2288            and parent_protocol_domain
2289            and parent_protocol_player
2290            and parent_protocol_player.player_id != parent_player.player_id
2291            and parent_player.native_grouping_requires_own_stream
2292        ):
2293            return
2294        protocol_members.extend(
2295            self._translate_native_members_to_protocol(
2296                parent_player, parent_protocol_domain, native_members
2297            )
2298        )
2299        native_members.clear()
2300
2301    def _migrate_stranded_native_members(
2302        self,
2303        parent_player: Player,
2304        parent_protocol_player: Player,
2305        protocol_members: list[str],
2306    ) -> list[str]:
2307        """
2308        Move the native members that a switch to the given protocol strands onto that protocol.
2309
2310        Returns the member IDs that are still attached to the parent's own stream, so the
2311        caller can release them from it. Empty unless the parent renders that stream itself
2312        while its native grouping attaches the members to exactly that stream: only then are
2313        they left without anything to play.
2314
2315        :param parent_player: The parent player that is about to switch protocol.
2316        :param parent_protocol_player: The protocol player the parent will render through.
2317        :param protocol_members: The protocol member list the translated IDs are added to.
2318        """
2319        if parent_protocol_player.player_id == parent_player.player_id:
2320            return []
2321        if not parent_player.native_grouping_requires_own_stream:
2322            return []
2323        if parent_player.active_output_protocol not in (None, "native"):
2324            return []
2325        if parent_player.state.playback_state not in (PlaybackState.PLAYING, PlaybackState.PAUSED):
2326            return []
2327        stranded = [
2328            member_id
2329            for member_id in parent_player.group_members
2330            if member_id != parent_player.player_id
2331        ]
2332        for protocol_id in self._translate_native_members_to_protocol(
2333            parent_player, parent_protocol_player.provider.domain, stranded
2334        ):
2335            if protocol_id not in protocol_members:
2336                protocol_members.append(protocol_id)
2337        return stranded
2338
2339    async def _stop_native_session(
2340        self,
2341        parent_player: Player,
2342        parent_protocol_player: Player,
2343        stranded_native_members: list[str],
2344    ) -> None:
2345        """
2346        Release the given members from the parent's own stream and stop it.
2347
2348        :param parent_player: The parent player whose native session is handed over.
2349        :param parent_protocol_player: The protocol player taking the output over.
2350        :param stranded_native_members: The members to release, already migrated.
2351        """
2352        self.logger.debug(
2353            "Stopping the native session of %s before switching to %s, migrated members: %s",
2354            parent_player.state.name,
2355            parent_protocol_player.state.name,
2356            stranded_native_members,
2357        )
2358        # The members already joined the protocol group, so the native session only has to
2359        # release them and stop. Releasing them first also clears the native group, which
2360        # keeps a later native playback command from resurrecting it. Both calls take the
2361        # provider's own lock, so they must run one after the other.
2362        await parent_player.set_members(player_ids_to_remove=stranded_native_members)
2363        await parent_player.stop()
2364
2365    def _translate_members_for_protocols(
2366        self,
2367        parent_player: Player,
2368        player_ids: list[str],
2369        parent_protocol_player: Player | None,
2370        parent_protocol_domain: str | None,
2371    ) -> tuple[list[str], list[str], Player | None, str | None]:
2372        """
2373        Translate member IDs to protocol or native IDs.
2374
2375        The grouping method is picked per member, see _select_grouping_for_member.
2376
2377        Returns tuple of (protocol_members, native_members, protocol_player, protocol_domain).
2378        """
2379        protocol_members: list[str] = []
2380        native_members: list[str] = []
2381        parent_supports_native_grouping = (
2382            PlayerFeature.SET_MEMBERS in parent_player.supported_features
2383        )
2384        player_ids = self._order_members_for_native_join(
2385            player_ids, parent_player, parent_supports_native_grouping
2386        )
2387
2388        self.logger.log(
2389            VERBOSE_LOG_LEVEL,
2390            "Translating members for %s: parent_supports_native=%s, parent_protocol=%s (%s)",
2391            parent_player.state.name,
2392            parent_supports_native_grouping,
2393            parent_protocol_player.state.name if parent_protocol_player else "none",
2394            parent_protocol_domain or "none",
2395        )
2396
2397        for child_player_id in player_ids:
2398            child_player = self.get_player(child_player_id)
2399            if not child_player:
2400                continue
2401
2402            self.logger.log(
2403                VERBOSE_LOG_LEVEL,
2404                "Processing child %s (type=%s, protocols=%s)",
2405                child_player.state.name,
2406                child_player.state.type,
2407                [p.protocol_domain for p in child_player.output_protocols],
2408            )
2409
2410            parent_protocol_player, parent_protocol_domain = self._select_grouping_for_member(
2411                child_player,
2412                parent_player,
2413                parent_protocol_player,
2414                parent_protocol_domain,
2415                parent_supports_native_grouping,
2416                protocol_members,
2417                native_members,
2418            )
2419
2420        # Post-pass: the protocol selected for the group is only known once every child has
2421        # been processed, so the members picked for native grouping are corrected here.
2422        self._move_native_members_to_group_protocol(
2423            parent_player,
2424            parent_protocol_player,
2425            parent_protocol_domain,
2426            protocol_members,
2427            native_members,
2428        )
2429
2430        return protocol_members, native_members, parent_protocol_player, parent_protocol_domain
2431
2432    def _select_grouping_for_member(
2433        self,
2434        child_player: Player,
2435        parent_player: Player,
2436        parent_protocol_player: Player | None,
2437        parent_protocol_domain: str | None,
2438        parent_supports_native_grouping: bool,
2439        protocol_members: list[str],
2440        native_members: list[str],
2441    ) -> tuple[Player | None, str | None]:
2442        """
2443        Pick the grouping method for a single member and add it to the matching member list.
2444
2445        Selection priority when grouping:
2446        0. If the parent is already playing natively and the child can be grouped
2447           natively, join that native session (a child joining an existing group must
2448           not force the whole group onto its own preferred output protocol)
2449        1. Try child's preferred output protocol (from player settings)
2450        2. Try parent's active output protocol (if any and child supports it)
2451        3. Try native grouping (if parent and child are compatible)
2452        4. Search for common protocol that supports set_members
2453        5. Log warning if no option works
2454
2455        Returns the protocol player/domain the group is on, which the picked method may have
2456        changed.
2457
2458        :param child_player: The player being added to the group.
2459        :param parent_player: The parent player being joined.
2460        :param parent_protocol_player: The protocol player selected for the group so far, if any.
2461        :param parent_protocol_domain: The protocol domain selected for the group so far, if any.
2462        :param parent_supports_native_grouping: Whether the parent can group natively.
2463        :param protocol_members: The protocol member list to append to.
2464        :param native_members: The native member list to append to.
2465        """
2466        # Priority 0: The parent is already playing natively and the child can join
2467        # that native session directly - adopt it before considering the child's own
2468        # preferred output protocol.
2469        if self._try_join_active_native_session(
2470            child_player,
2471            parent_player,
2472            parent_protocol_domain,
2473            parent_supports_native_grouping,
2474            native_members,
2475        ):
2476            return parent_protocol_player, parent_protocol_domain
2477
2478        # Priority 0.5: a player that runs its own multiroom (e.g. a LinkPlay control shell)
2479        # keeps grouping on its native path rather than routing it through a linked protocol
2480        # that is merely its preferred playback output. Native compatibility still decides
2481        # whether this is possible, so an incompatible/cross-backend pair falls through.
2482        if child_player.prefer_native_grouping and self._can_use_native_grouping(
2483            child_player, parent_player, parent_supports_native_grouping
2484        ):
2485            native_members.append(child_player.player_id)
2486            self.logger.log(
2487                VERBOSE_LOG_LEVEL,
2488                "Using native grouping (preferred) for %s",
2489                child_player.state.name,
2490            )
2491            return parent_protocol_player, parent_protocol_domain
2492
2493        # Priority 1: the child's preferred output protocol
2494        grouped, parent_protocol_player, parent_protocol_domain = (
2495            self._try_group_via_preferred_protocol(
2496                child_player,
2497                parent_player,
2498                parent_protocol_player,
2499                parent_protocol_domain,
2500                protocol_members,
2501            )
2502        )
2503        if grouped:
2504            return parent_protocol_player, parent_protocol_domain
2505
2506        # Priority 2: the protocol the group is already on
2507        grouped, parent_protocol_player, parent_protocol_domain = (
2508            self._try_group_via_active_protocol(
2509                child_player,
2510                parent_protocol_player,
2511                parent_protocol_domain,
2512                protocol_members,
2513            )
2514        )
2515        if grouped:
2516            return parent_protocol_player, parent_protocol_domain
2517
2518        # Priority 3: native grouping
2519        if self._can_use_native_grouping(
2520            child_player, parent_player, parent_supports_native_grouping
2521        ):
2522            native_members.append(child_player.player_id)
2523            self.logger.log(
2524                VERBOSE_LOG_LEVEL,
2525                "Using native grouping for %s",
2526                child_player.state.name,
2527            )
2528            return parent_protocol_player, parent_protocol_domain
2529
2530        # Priority 4: a protocol both players share that supports set_members
2531        grouped, parent_protocol_player, parent_protocol_domain = (
2532            self._try_group_via_common_protocol(
2533                child_player,
2534                parent_player,
2535                parent_protocol_player,
2536                parent_protocol_domain,
2537                protocol_members,
2538            )
2539        )
2540        if grouped:
2541            return parent_protocol_player, parent_protocol_domain
2542
2543        # Priority 5: no option worked
2544        self.logger.warning(
2545            "Cannot group %s with %s: no compatible grouping method found "
2546            "(tried: child preferred protocol, parent active protocol, "
2547            "native grouping, common protocols)",
2548            child_player.state.name,
2549            parent_player.state.name,
2550        )
2551        return parent_protocol_player, parent_protocol_domain
2552
2553    def _try_group_via_preferred_protocol(
2554        self,
2555        child_player: Player,
2556        parent_player: Player,
2557        parent_protocol_player: Player | None,
2558        parent_protocol_domain: str | None,
2559        protocol_members: list[str],
2560    ) -> tuple[bool, Player | None, str | None]:
2561        """
2562        Try to group the child through the output protocol it prefers in its player settings.
2563
2564        Only used when the group is not on a protocol yet or is already on that same protocol.
2565        Returns whether the child was grouped, together with the protocol player/domain the
2566        group is on: the child's preferred protocol may become the group's protocol.
2567
2568        :param child_player: The player being added to the group.
2569        :param parent_player: The parent player being joined.
2570        :param parent_protocol_player: The protocol player selected for the group so far, if any.
2571        :param parent_protocol_domain: The protocol domain selected for the group so far, if any.
2572        :param protocol_members: The protocol member list to append to.
2573        """
2574        child_protocol_id, protocol_domain = self._try_child_preferred_protocol(
2575            child_player, parent_player
2576        )
2577        if not (
2578            child_protocol_id
2579            and protocol_domain
2580            and (not parent_protocol_domain or protocol_domain == parent_protocol_domain)
2581        ):
2582            return False, parent_protocol_player, parent_protocol_domain
2583
2584        if not parent_protocol_player or parent_protocol_domain != protocol_domain:
2585            parent_protocol = parent_player.get_output_protocol_by_domain(protocol_domain)
2586            if parent_protocol:
2587                parent_protocol_player = parent_player.get_protocol_player(
2588                    parent_protocol.output_protocol_id
2589                )
2590                parent_protocol_domain = protocol_domain
2591        protocol_members.append(child_protocol_id)
2592        self.logger.log(
2593            VERBOSE_LOG_LEVEL,
2594            "Using child's preferred protocol %s for %s",
2595            protocol_domain,
2596            child_player.state.name,
2597        )
2598        return True, parent_protocol_player, parent_protocol_domain
2599
2600    def _try_group_via_active_protocol(
2601        self,
2602        child_player: Player,
2603        parent_protocol_player: Player | None,
2604        parent_protocol_domain: str | None,
2605        protocol_members: list[str],
2606    ) -> tuple[bool, Player | None, str | None]:
2607        """
2608        Try to group the child through the protocol the group is already on.
2609
2610        Returns whether the child was grouped, together with the protocol player/domain the
2611        group is on: the selection is dropped when that protocol cannot group members itself,
2612        so a later grouping method can select another one.
2613
2614        :param child_player: The player being added to the group.
2615        :param parent_protocol_player: The protocol player selected for the group so far, if any.
2616        :param parent_protocol_domain: The protocol domain selected for the group so far, if any.
2617        :param protocol_members: The protocol member list to append to.
2618        """
2619        if not parent_protocol_domain or not parent_protocol_player:
2620            return False, parent_protocol_player, parent_protocol_domain
2621
2622        if PlayerFeature.SET_MEMBERS not in parent_protocol_player.state.supported_features:
2623            self.logger.log(
2624                VERBOSE_LOG_LEVEL,
2625                "Parent's active protocol %s does not support SET_MEMBERS, "
2626                "will search for alternative",
2627                parent_protocol_domain,
2628            )
2629            # Drop the selection so a later grouping method can select a new protocol
2630            return False, None, None
2631
2632        child_protocol = child_player.get_output_protocol_by_domain(parent_protocol_domain)
2633        if not child_protocol or not child_protocol.available:
2634            return False, parent_protocol_player, parent_protocol_domain
2635
2636        # For native protocol players, use the child's player_id directly
2637        # (e.g., a native sendspin web player IS the protocol player)
2638        child_protocol_id = (
2639            child_player.player_id
2640            if child_protocol.is_native
2641            else child_protocol.output_protocol_id
2642        )
2643        protocol_members.append(child_protocol_id)
2644        self.logger.log(
2645            VERBOSE_LOG_LEVEL,
2646            "Using parent's active protocol %s for %s",
2647            parent_protocol_domain,
2648            child_player.state.name,
2649        )
2650        return True, parent_protocol_player, parent_protocol_domain
2651
2652    def _try_group_via_common_protocol(
2653        self,
2654        child_player: Player,
2655        parent_player: Player,
2656        parent_protocol_player: Player | None,
2657        parent_protocol_domain: str | None,
2658        protocol_members: list[str],
2659    ) -> tuple[bool, Player | None, str | None]:
2660        """
2661        Try to group the child through a protocol both players share.
2662
2663        Returns whether the child was grouped, together with the protocol player/domain the
2664        group is on: the shared protocol may become the group's protocol.
2665
2666        :param child_player: The player being added to the group.
2667        :param parent_player: The parent player being joined.
2668        :param parent_protocol_player: The protocol player selected for the group so far, if any.
2669        :param parent_protocol_domain: The protocol domain selected for the group so far, if any.
2670        :param protocol_members: The protocol member list to append to.
2671        """
2672        parent_protocol, child_protocol = self._try_find_common_protocol(
2673            child_player, parent_player
2674        )
2675        if not parent_protocol or not child_protocol:
2676            return False, parent_protocol_player, parent_protocol_domain
2677
2678        if not parent_protocol_player or parent_protocol_domain != parent_protocol.protocol_domain:
2679            parent_protocol_player = parent_player.get_protocol_player(
2680                parent_protocol.output_protocol_id
2681            )
2682            if parent_protocol_player:
2683                parent_protocol_domain = parent_protocol_player.provider.domain
2684        # For native protocol players, use the child's player_id directly
2685        child_protocol_id = (
2686            child_player.player_id
2687            if child_protocol.is_native
2688            else child_protocol.output_protocol_id
2689        )
2690        protocol_members.append(child_protocol_id)
2691        self.logger.log(
2692            VERBOSE_LOG_LEVEL,
2693            "Selected common protocol %s for grouping %s with %s",
2694            parent_protocol.protocol_domain,
2695            child_player.state.name,
2696            parent_player.state.name,
2697        )
2698        return True, parent_protocol_player, parent_protocol_domain
2699
2700    async def _forward_protocol_set_members(
2701        self,
2702        parent_player: Player,
2703        parent_protocol_player: Player,
2704        protocol_members_to_add: list[str],
2705        protocol_members_to_remove: list[str],
2706    ) -> None:
2707        """
2708        Forward protocol members to protocol player's set_members and manage active output protocol.
2709
2710        :param parent_player: The parent player (native/universal).
2711        :param parent_protocol_player: The protocol player to forward commands to.
2712        :param protocol_members_to_add: Protocol player IDs to add.
2713        :param protocol_members_to_remove: Protocol player IDs to remove.
2714        """
2715        filtered_protocol_add = self._filter_protocol_members(
2716            protocol_members_to_add, parent_protocol_player
2717        )
2718        filtered_protocol_remove = self._filter_protocol_members(
2719            protocol_members_to_remove, parent_protocol_player
2720        )
2721        self.logger.debug(
2722            "Protocol grouping on %s: filtered_add=%s, filtered_remove=%s",
2723            parent_protocol_player.state.name,
2724            filtered_protocol_add,
2725            filtered_protocol_remove,
2726        )
2727
2728        if not filtered_protocol_add and not filtered_protocol_remove:
2729            return
2730
2731        # Safety check: verify protocol player supports SET_MEMBERS
2732        if PlayerFeature.SET_MEMBERS not in parent_protocol_player.state.supported_features:
2733            self.logger.error(
2734                "Protocol player %s does not support SET_MEMBERS, cannot perform grouping. "
2735                "This should have been caught earlier in the flow.",
2736                parent_protocol_player.state.name,
2737            )
2738            return
2739
2740        # Members that ride the parent's own stream are stranded by the protocol switch below,
2741        # so they join the protocol group in this very same call and their native session is
2742        # torn down afterwards.
2743        stranded_native_members = (
2744            self._migrate_stranded_native_members(
2745                parent_player, parent_protocol_player, filtered_protocol_add
2746            )
2747            if filtered_protocol_add
2748            else []
2749        )
2750
2751        # This runs before set_members because a member's own stream starts inside that call
2752        # and the provider resolves the member's volume control as it starts: unless its parent
2753        # already points at this protocol, that resolution picks a sibling interface of the same
2754        # device (e.g. its cast side) over the one carrying the audio.
2755        self._activate_protocol_on_added_children(filtered_protocol_add)
2756
2757        self.logger.debug(
2758            "Calling set_members on protocol player %s with add=%s, remove=%s",
2759            parent_protocol_player.state.name,
2760            filtered_protocol_add,
2761            filtered_protocol_remove,
2762        )
2763        await parent_protocol_player.set_members(
2764            player_ids_to_add=filtered_protocol_add or None,
2765            player_ids_to_remove=filtered_protocol_remove or None,
2766        )
2767
2768        if filtered_protocol_add:
2769            await self._activate_group_output_protocol(
2770                parent_player, parent_protocol_player, stranded_native_members
2771            )
2772
2773        self.logger.debug(
2774            "After set_members, protocol player %s state: group_members=%s, synced_to=%s",
2775            parent_protocol_player.state.name,
2776            parent_protocol_player.group_members,
2777            parent_protocol_player.synced_to,
2778        )
2779
2780    def _activate_protocol_on_added_children(self, protocol_member_ids: list[str]) -> None:
2781        """
2782        Point the parent of each given protocol member at the protocol carrying the group audio.
2783
2784        :param protocol_member_ids: The protocol player IDs joining the group.
2785        """
2786        for child_protocol_id in protocol_member_ids:
2787            if not (child_protocol := self.get_player(child_protocol_id)):
2788                continue
2789            if not child_protocol.protocol_parent_id:
2790                continue
2791            if not (child_player := self.get_player(child_protocol.protocol_parent_id)):
2792                continue
2793            if child_player.active_output_protocol == child_protocol_id:
2794                continue
2795            self.logger.debug(
2796                "Setting active output protocol on child %s to %s",
2797                child_player.state.name,
2798                child_protocol_id,
2799            )
2800            child_player.set_active_output_protocol(child_protocol_id)
2801
2802    async def _activate_group_output_protocol(
2803        self,
2804        parent_player: Player,
2805        parent_protocol_player: Player,
2806        stranded_native_members: list[str],
2807    ) -> None:
2808        """
2809        Mark the given protocol as the parent's output and hand the playback over to it.
2810
2811        The handover only runs when the parent is actually switching protocol while it is
2812        rendering; playback is resumed only for a parent that was playing, so adding a member
2813        never starts playback on its own.
2814
2815        :param parent_player: The parent player that just gained protocol members.
2816        :param parent_protocol_player: The protocol player the members joined.
2817        :param stranded_native_members: The members left without a stream by the switch.
2818        """
2819        previous_protocol = parent_player.active_output_protocol
2820        was_playing = parent_player.state.playback_state == PlaybackState.PLAYING
2821        # A paused player still holds its output, so the handover has to run for it too.
2822        was_rendering = was_playing or parent_player.state.playback_state == PlaybackState.PAUSED
2823
2824        # Native protocol: parent_protocol_player is the same as parent_player
2825        is_native_protocol = parent_protocol_player.player_id == parent_player.player_id
2826        already_using_native = previous_protocol in (None, "native")
2827        already_using_this_protocol = previous_protocol == parent_protocol_player.player_id
2828        switching_protocols = not (
2829            (is_native_protocol and already_using_native) or already_using_this_protocol
2830        )
2831
2832        self.logger.debug(
2833            "Protocol grouping: is_native=%s, already_native=%s, already_this=%s, "
2834            "switching=%s, was_rendering=%s",
2835            is_native_protocol,
2836            already_using_native,
2837            already_using_this_protocol,
2838            switching_protocols,
2839            was_rendering,
2840        )
2841
2842        if not (is_native_protocol and already_using_native):
2843            parent_player.set_active_output_protocol(parent_protocol_player.player_id)
2844
2845        if not (was_rendering and switching_protocols):
2846            return
2847
2848        self.logger.info(
2849            "Handing the output of %s over to the %s protocol%s",
2850            parent_player.state.name,
2851            parent_protocol_player.provider.domain,
2852            " and resuming playback" if was_playing else "",
2853        )
2854        if stranded_native_members:
2855            await self._stop_native_session(
2856                parent_player, parent_protocol_player, stranded_native_members
2857            )
2858        old_parent_members = await self._stop_previous_protocol(
2859            parent_player, parent_protocol_player, previous_protocol
2860        )
2861        if was_playing:
2862            await self.mass.players.cmd_resume(parent_player.player_id)
2863        if old_parent_members:
2864            self.logger.debug(
2865                "Re-adding migrated members %s to %s on new protocol",
2866                old_parent_members,
2867                parent_player.state.name,
2868            )
2869            # Use internal handler because we are already inside a
2870            # _handle_set_members call chain that holds the play lock.
2871            await self.mass.players._handle_set_members(
2872                parent_player,
2873                player_ids_to_add=old_parent_members,
2874            )
2875
2876    async def _stop_previous_protocol(
2877        self,
2878        parent_player: Player,
2879        parent_protocol_player: Player,
2880        previous_protocol: str | None,
2881    ) -> list[str]:
2882        """
2883        Stop the protocol player the parent was rendering through and return its members.
2884
2885        The returned IDs are parent player IDs, so the caller can re-add them to the group
2886        once the new protocol carries the audio. Empty if there is nothing to hand over.
2887
2888        :param parent_player: The parent player that is switching protocol.
2889        :param parent_protocol_player: The protocol player taking the output over.
2890        :param previous_protocol: The parent's previous active output protocol, if any.
2891        """
2892        if previous_protocol in (None, "native"):
2893            return []
2894        if not (old_protocol_player := self.get_player(previous_protocol)):
2895            return []
2896        if old_protocol_player.player_id == parent_protocol_player.player_id:
2897            return []
2898        # Translate the old protocol's child members back to parent player IDs
2899        old_parent_members: list[str] = []
2900        for member_id in old_protocol_player.group_members:
2901            if member_id == old_protocol_player.player_id:
2902                continue
2903            if not (member_player := self.get_player(member_id)):
2904                continue
2905            parent_id = member_player.protocol_parent_id or member_id
2906            if parent_id != parent_player.player_id:
2907                old_parent_members.append(parent_id)
2908        self.logger.debug(
2909            "Stopping old protocol player %s before switching to %s, migrating members: %s",
2910            old_protocol_player.state.name,
2911            parent_protocol_player.state.name,
2912            old_parent_members,
2913        )
2914        # Use internal handler to stop the specific protocol player,
2915        # bypassing group/sync redirect and queue redirect logic.
2916        await self.mass.players._handle_cmd_stop(old_protocol_player.player_id)
2917        return old_parent_members
2918