music-assistant-server

1"""Sync Group Player implementation."""
2
3from __future__ import annotations
4
5import asyncio
6import time
7from contextlib import asynccontextmanager
8from typing import TYPE_CHECKING, Any, cast
9
10from music_assistant_models.config_entries import ConfigEntry, ConfigValueOption
11from music_assistant_models.constants import PLAYER_CONTROL_FAKE
12from music_assistant_models.enums import ConfigEntryType, PlaybackState, PlayerFeature, PlayerType
13from music_assistant_models.errors import PlayerCommandFailed, UnsupportedFeaturedException
14from propcache import under_cached_property as cached_property
15
16from music_assistant.constants import (
17    APPLICATION_NAME,
18    CONF_DYNAMIC_GROUP_MEMBERS,
19    CONF_GROUP_MEMBERS,
20    CONF_POWER_CONTROL,
21)
22from music_assistant.controllers.players.constants import PlayerLockPurpose
23from music_assistant.models.player import DeviceInfo, Player, PlayerMedia
24
25from .constants import (
26    CONF_ALLOWED_MEMBERS,
27    CONF_ENTRY_SGP_NOTE,
28    EXTRA_FEATURES_FROM_MEMBERS,
29    IDLE_GRACE_SECONDS,
30    PLAYBACK_START_TIMEOUT,
31    PROVIDERS_WITH_DYNAMIC_LEADER_SWITCH,
32    REFORM_DEBOUNCE_SECONDS,
33)
34
35if TYPE_CHECKING:
36    from collections.abc import AsyncIterator, Collection
37
38    from music_assistant_models.player import PlayerSource
39
40    from .provider import SyncGroupProvider
41
42
43class SyncGroupPlayer(Player):
44    """Sync Group Player implementation."""
45
46    _attr_type: PlayerType = PlayerType.GROUP
47    sync_leader: Player | None = None
48    """The active sync leader player for this syncgroup."""
49
50    def __init__(
51        self,
52        provider: SyncGroupProvider,
53        player_id: str,
54    ) -> None:
55        """Initialize SyncGroupPlayer instance."""
56        super().__init__(provider, player_id)
57        self._attr_name = self.config.name or self.config.default_name or f"SyncGroup {player_id}"
58        self._attr_available = True
59        self._attr_device_info = DeviceInfo(model=provider.name, manufacturer=APPLICATION_NAME)
60        # Group players default to "no opinion" on power. The session lifecycle
61        # (form on play, dissolve on stop, debounced idle deform) governs whether
62        # the group is considered active. Users who want an explicit on/off button
63        # can assign 'Fake power control' which is then reflected via extra_data.
64        self._attr_powered = None
65        self._attr_needs_poll = True
66        # task that dissolves the group after the idle grace window expires
67        self._idle_grace_task: asyncio.Task[None] | None = None
68        # task that re-forms the group (debounced) after the sync leader was removed
69        self._reform_task: asyncio.Task[None] | None = None
70        # protocol hint for the debounced re-form, snapshotted before the old
71        # leader was cleared so the new leader keeps protocol continuity
72        self._reform_protocol_domain: str | None = None
73        # monotonic timestamp of the last playback start issued to the leader
74        # (-inf means never)
75        self._playback_start_at: float = float("-inf")
76        self._update_attributes()
77
78    @cached_property
79    def is_dynamic(self) -> bool:
80        """Return if the player is a dynamic group player."""
81        return bool(self.config.get_value(CONF_DYNAMIC_GROUP_MEMBERS, False))
82
83    @property
84    def synced_to(self) -> str | None:
85        """Return the id of the player this player is synced to (sync leader)."""
86        # groups can't be synced
87        return None
88
89    @property
90    def is_active_session(self) -> bool:
91        """
92        Return whether this sync group is currently holding its members.
93
94        The session is considered active while a sync leader is set (formed and
95        potentially playing/paused), while the idle grace timer is still
96        pending, or while a debounced re-form is pending. ``__final_active_group``
97        reads this to decide whether the configured members should be marked as
98        ``active_group`` for this group.
99        """
100        return (
101            self.sync_leader is not None
102            or self._idle_grace_task is not None
103            or self._reform_task is not None
104        )
105
106    async def on_config_updated(self) -> None:
107        """Handle logic when the PlayerConfig is first loaded or updated."""
108        # Config is only available after the player was registered
109        self._cache.clear()  # clear to prevent loading old is_dynamic
110        preset_members = cast("list[str]", self.config.get_value(CONF_GROUP_MEMBERS, []))
111        if self.is_dynamic:
112            # In dynamic mode the configured members act as a preset: they are
113            # pulled in when the group is powered on
114            self._attr_static_group_members = []
115            self._attr_supported_features.add(PlayerFeature.SET_MEMBERS)
116        else:
117            self._attr_static_group_members = list(preset_members)
118            self._attr_supported_features.discard(PlayerFeature.SET_MEMBERS)
119        # Only realign the effective member list to the preset when we are
120        # dormant. Otherwise a config save (e.g. user toggling an unrelated
121        # field) would wipe any dynamic joins that happened during this session.
122        if not self.is_active_session:
123            self._attr_group_members = list(preset_members)
124
125    @property
126    def supported_features(self) -> set[PlayerFeature]:
127        """Return the supported features of the player."""
128        # PlayerFeature.POWER is intentionally NOT advertised by default: it forces
129        # users to remember to power the group off to release its members, which
130        # makes "play X on a single member from HA" silently redirect to the whole
131        # group long after playback ended. The new lifecycle forms the group on
132        # play and dissolves it on stop (with a short idle grace), so explicit
133        # power control is no longer required.
134        # Users who DO want an explicit on/off button can assign 'Fake power
135        # control' in the player config; we then advertise POWER so the UI shows
136        # the toggle. The raw config value is read here to avoid recursion via
137        # the power_control property (which itself may inspect supported features).
138        base_features: set[PlayerFeature] = {PlayerFeature.PLAY_MEDIA}
139        raw_power_conf = self.mass.config.get_raw_player_config_value(
140            self.player_id, CONF_POWER_CONTROL
141        )
142        if raw_power_conf == PLAYER_CONTROL_FAKE:
143            base_features.add(PlayerFeature.POWER)
144        if self.is_dynamic:
145            base_features.add(PlayerFeature.SET_MEMBERS)
146        if self.sync_leader:
147            # add features supported by the sync leader
148            for feature in EXTRA_FEATURES_FROM_MEMBERS:
149                if feature in self.sync_leader.state.supported_features:
150                    base_features.add(feature)
151        else:
152            # derive features from all (configured) group members
153            # so that features like volume control are always advertised
154            for member_id in self._attr_group_members:
155                member_player = self.mass.players.get_player(member_id)
156                if member_player and member_player.state.available:
157                    for feature in EXTRA_FEATURES_FROM_MEMBERS:
158                        if feature in member_player.state.supported_features:
159                            base_features.add(feature)
160        return base_features
161
162    @property
163    def requires_flow_mode(self) -> bool:
164        """Return if the player needs flow mode."""
165        if leader := self.sync_leader:
166            return leader.flow_mode
167        return False
168
169    @property
170    def supported_sample_rates(self) -> list[tuple[int, int]] | None:
171        """Return supported sample rates as defined by the sync leader."""
172        # not cached: sync_leader can change during dynamic group reforms,
173        # so we always re-resolve to stay in sync with the current leader
174        if leader := self.sync_leader:
175            return leader.get_supported_sample_rates()
176        return [(44100, 16), (48000, 16)]
177
178    @property
179    def active_source(self) -> str | None:
180        """Return the active source id of the current media (if any)."""
181        # NOTE: Not using 'state' here as we need the 'raw' value provided by the sync leader player
182        if not self.sync_leader:
183            return None
184        # deal with output protocols on the sync leader
185        output_protocol_domain: str | None = None
186        if (
187            self.sync_leader.active_output_protocol
188            and self.sync_leader.active_output_protocol != "native"
189        ):
190            if protocol_player := self.mass.players.get_player(
191                self.sync_leader.active_output_protocol
192            ):
193                output_protocol_domain = protocol_player.provider.domain
194        # active source as reported by the player itself
195        if (
196            self.sync_leader.active_source
197            # try to catch cases where player reports an active source
198            # that is actually from an active output protocol (e.g. AirPlay)
199            and self.sync_leader.active_source.lower() != output_protocol_domain
200            and not (
201                # try to handle sendspin bridge where the player itself
202                # is reporting the bridged protocol as active source
203                # we need to ignore that
204                output_protocol_domain == "sendspin"
205                and (
206                    self.sync_leader.active_source.lower()
207                    in ("airplay", "cast", "chromecast", "network")
208                )
209            )
210        ):
211            return self.sync_leader.active_source
212        return None
213
214    @property
215    def source_list(self) -> list[PlayerSource]:
216        """Return list of available (native) sources for this player."""
217        # NOTE: Not using 'state' here as we need the 'raw' value provided by the sync leader player
218        return self.sync_leader.source_list if self.sync_leader else []
219
220    @property
221    def can_group_with(self) -> set[str]:
222        """Return the id's of players this player can group with."""
223        if not self.is_dynamic:
224            # in case of static members,
225            # we can only group with the players defined in the config, so we return those directly
226            return set(self._attr_static_group_members)
227        # Aggregate can_group_with from ALL current group members (not just the leader).
228        # A sync group can accommodate protocol switches, so a player compatible with
229        # ANY current member is a valid candidate to join.
230        member_ids = self._attr_group_members if self._attr_group_members else []
231        # current members bypass the allow-list filter (filter constrains joiners only)
232        current_members = set(member_ids)
233        can_group_with: set[str] = set()
234        for member_id in member_ids:
235            member_player = self.mass.players.get_player(member_id)
236            if member_player and member_player.state.available:
237                can_group_with.add(member_player.player_id)
238                can_group_with.update(member_player.state.can_group_with)
239        if can_group_with:
240            return {
241                pid
242                for pid in can_group_with
243                if pid in current_members or self._is_member_allowed(pid)
244            }
245        # Without any available member to derive compatibility from (empty group or
246        # all members offline), offer any compatible player.
247        # Actual compatibility is validated when adding members
248        can_group_with = set()
249        for player in self.mass.players.iter_players(return_unavailable=False):
250            if not player.available or player.type == PlayerType.GROUP:
251                # let's avoid showing group players as options to group with
252                continue
253            if (
254                PlayerFeature.SET_MEMBERS in player.state.supported_features
255                and player.state.can_group_with
256                and not player.state.active_group
257            ):
258                can_group_with.add(player.player_id)
259        return {pid for pid in can_group_with if self._is_member_allowed(pid)}
260
261    @property
262    def group_members(self) -> list[str]:
263        """Return the list of parent player id's that are part of this sync group."""
264        if (sync_leader := self.sync_leader) and sync_leader.state.group_members:
265            # use state.group_members here so protocol specific id's get correctly translated
266            return sync_leader.state.group_members
267        return self._attr_group_members
268
269    async def get_config_entries(self) -> list[ConfigEntry]:
270        """Return all (provider/player specific) Config Entries for the given player (if any)."""
271        # keep saved player ids so the UI can render a user friendly name
272        # prevents the bug where only the player ids show up during playback
273        saved_ids = {
274            *cast("list[str]", self.config.get_value(CONF_GROUP_MEMBERS, []) or []),
275            *cast("list[str]", self.config.get_value(CONF_ALLOWED_MEMBERS, []) or []),
276        }
277        possible_players = sorted(
278            [
279                ConfigValueOption(x.player_id, title=x.display_name)
280                for x in self.mass.players.all_players(True, False)
281                if x.type != PlayerType.GROUP
282                and (
283                    x.player_id in saved_ids
284                    or (
285                        PlayerFeature.SET_MEMBERS in x.state.supported_features
286                        # also include synced followers: can_group_with returns empty
287                        # while slaved, but the player is still group-capable
288                        and (x.state.can_group_with or x.state.synced_to)
289                    )
290                )
291            ],
292            key=lambda x: x.title or "",
293        )
294        entries: list[ConfigEntry] = [
295            # syncgroup specific entries
296            CONF_ENTRY_SGP_NOTE,
297            ConfigEntry(
298                key=CONF_GROUP_MEMBERS,
299                type=ConfigEntryType.STRING,
300                multi_value=True,
301                default_value=[],
302                required=False,  # needed for dynamic members (which allows empty members list)
303                options=possible_players,
304            ),
305            ConfigEntry(
306                key=CONF_DYNAMIC_GROUP_MEMBERS,
307                type=ConfigEntryType.BOOLEAN,
308                default_value=False,
309                required=False,
310            ),
311            ConfigEntry(
312                key=CONF_ALLOWED_MEMBERS,
313                type=ConfigEntryType.STRING,
314                multi_value=True,
315                default_value=[],
316                required=False,
317                options=possible_players,
318                depends_on=CONF_DYNAMIC_GROUP_MEMBERS,
319                advanced=True,
320            ),
321        ]
322        return entries
323
324    async def power(self, powered: bool) -> None:
325        """
326        Handle POWER command to group player.
327
328        Only called when the user has assigned a power control (native or fake)
329        to the group. Powering ON pre-forms the group so its members are
330        captured immediately (matching the legacy behaviour for users who opt
331        in). Powering OFF stops any playback and dissolves the group.
332
333        :param powered: True to power on (form/capture), False to power off (dissolve).
334        """
335        # always cancel any pending idle-grace timer on explicit power transitions
336        self._cancel_idle_grace_timer()
337
338        if not powered and self.playback_state in (
339            PlaybackState.PLAYING,
340            PlaybackState.PAUSED,
341        ):
342            # stop directly via the leader to avoid re-entering our own stop()
343            # logic (which would dissolve before we re-dissolve below).
344            if sync_leader := self.sync_leader:
345                await self.mass.players._handle_cmd_stop(sync_leader.player_id)
346
347        if powered:
348            # apply the configured preset members on power-on so unjoins
349            # during a powered session stick until the next power cycle
350            preset_members = cast("list[str]", self.config.get_value(CONF_GROUP_MEMBERS, []))
351            self._attr_group_members = [
352                *preset_members,
353                *[x for x in self._attr_group_members if x not in preset_members],
354            ]
355            # form syncgroup when powering on
356            await self._form_syncgroup()
357        else:
358            # dissolve syncgroup when powering off
359            await self._dissolve_syncgroup()
360
361        if self._attr_powered != powered:
362            self._attr_powered = powered
363            self._update_attributes()
364            self.update_state()
365
366    async def stop(self) -> None:
367        """
368        Send STOP command to given player.
369
370        An explicit stop on the group dissolves the syncgroup immediately so the
371        members are released back to individual control. The idle grace timer is
372        intentionally only used when the queue ends naturally (playback_state
373        transitions to IDLE without a stop command). Users who want the group
374        to stay formed across stops can assign Fake power control and use that
375        to pin the group as 'active'.
376        """
377        self._cancel_idle_grace_timer()
378        # an explicit stop also voids any pending debounced re-form and the
379        # startup marker — the user asked for silence
380        self._cancel_reform_timer()
381        self._playback_start_at = float("-inf")
382        self._attr_current_media = None
383        if sync_leader := self.sync_leader:
384            # Use internal handler to target the sync leader directly,
385            # bypassing group/sync redirect that would loop back to this player.
386            await self.mass.players._handle_cmd_stop(sync_leader.player_id)
387        # Skip the dissolve when the user has explicitly powered the group on
388        # via Fake power control — they expect the group to stay 'active' until
389        # they power it off, even after a stop.
390        if self._attr_powered is True:
391            return
392        await self._dissolve_syncgroup()
393
394    async def play(self) -> None:
395        """Send PLAY (unpause) command to given player."""
396        # The controller has already powered us on, but the group may not be
397        # formed (e.g. after _dissolve_and_reform left us powered with no leader).
398        # _form_syncgroup is idempotent so calling it here is cheap when already formed.
399        await self._form_syncgroup()
400        # Hold the group's playback lock until the leader actually reports playing
401        # so a concurrent (un)group command can't race the in-flight start — which
402        # would otherwise leave a player streaming outside the group.
403        async with self._await_leader_playback():
404            await self.mass.players.cmd_resume(
405                self.player_id, self._attr_active_source, self._attr_current_media
406            )
407
408    async def poll(self) -> None:
409        """Poll player for state updates."""
410        self._update_attributes()
411        self.update_state()
412
413    async def play_media(self, media: PlayerMedia) -> None:
414        """Handle PLAY MEDIA on given player."""
415        self._attr_current_media = media
416        self._attr_active_source = media.source_id or None
417        # The controller has already powered us on, but the group may not be
418        # formed (e.g. after _dissolve_and_reform left us powered with no leader).
419        # _form_syncgroup is idempotent so calling it here is cheap when already formed.
420        await self._form_syncgroup()
421        if sync_leader := self.sync_leader:
422            # Use internal handler to target the sync leader directly,
423            # bypassing group/sync redirect that would loop back to this player.
424            # Hold the group's playback lock until the leader confirms playback
425            # (see play()) so a concurrent (un)group command can't race the start.
426            async with self._await_leader_playback():
427                await self.mass.players._handle_play_media(sync_leader.player_id, media)
428        else:
429            raise RuntimeError("An empty group cannot play media, consider adding members first")
430
431    async def enqueue_next_media(self, media: PlayerMedia) -> None:
432        """Handle enqueuing of a next media item on the player."""
433        if sync_leader := self.sync_leader:
434            if PlayerFeature.ENQUEUE not in sync_leader.state.supported_features:
435                # this may happen in race conditions where we just switched sync leaders
436                # and the new leader doesn't support enqueueing next media.
437                return
438            # Use internal handler to bypass group redirect logic and avoid infinite loop
439            await self.mass.players._handle_enqueue_next_media(sync_leader.player_id, media)
440
441    async def set_members(  # noqa: PLR0915
442        self,
443        player_ids_to_add: list[str] | None = None,
444        player_ids_to_remove: list[str] | None = None,
445    ) -> None:
446        """Handle SET_MEMBERS command on the player."""
447        if not self.is_dynamic:
448            raise UnsupportedFeaturedException(
449                f"Group {self.display_name} does not allow dynamically adding/removing members!",
450                translation_key="not_dynamic",
451                translation_owner=self.translation_owner,
452                translation_args=[self.display_name],
453            )
454        sync_leader = self.sync_leader or self._select_sync_leader(new_members=player_ids_to_add)
455        # A start that was just issued to the leader may not be reflected in the
456        # (transient) device state yet, so treat the startup window as playing —
457        # otherwise a (un)group command racing an in-flight start misreads the
458        # group as idle and skips the resume. An explicit pause always wins:
459        # PAUSED is deliberate user intent, never startup noise.
460        was_playing = self.playback_state == PlaybackState.PLAYING or (
461            self.playback_state != PlaybackState.PAUSED and self._playback_recently_started
462        )
463
464        # handle additions
465        final_players_to_add: list[str] = []
466        can_group_with = sync_leader.state.can_group_with.copy() if sync_leader else set()
467        for member_id in player_ids_to_add or []:
468            if member_id == self.player_id:
469                continue  # can not add self as member
470            if not self._is_member_allowed(member_id):
471                self.logger.warning(
472                    "Player %s is not allowed to join group %s by the configured player filters, "
473                    "skipping adding it as a member to the group",
474                    member_id,
475                    self.display_name,
476                )
477                continue
478            member = self.mass.players.get_player(member_id)
479            if member is None or not member.available:
480                continue
481            if not sync_leader:
482                # no leader yet (e.g. empty group) - just register the member
483                # the leader and protocol selection happen on the next form/play
484                if member_id not in self._attr_group_members:
485                    self._attr_group_members.append(member_id)
486                continue
487            if member_id != sync_leader.player_id and member_id not in can_group_with:
488                # incompatible with the current leader's protocols - do NOT register
489                # the member or it will linger in _attr_group_members forever without
490                # ever actually being synced.
491                self.logger.debug(
492                    f"Cannot add {member.display_name} to group {self.display_name} since it's "
493                    f"not compatible with the (current) sync leader"
494                )
495                continue
496            if member_id not in self._attr_group_members:
497                self._attr_group_members.append(member_id)
498            if member_id != sync_leader.player_id:
499                final_players_to_add.append(member_id)
500
501        # handle removals
502        final_players_to_remove: list[str] = []
503        leader_removed = False
504        for member_id in player_ids_to_remove or []:
505            if member_id not in self._attr_group_members:
506                # Fallback for a member that was grouped to the sync leader
507                # outside of MA (e.g. via the Sonos app): it isn't part of our
508                # tracked member list but does show up in group_members via the
509                # leader's live state. Forward its removal to the sync leader
510                # instead of silently skipping it.
511                if (
512                    self.sync_leader
513                    and member_id != self.sync_leader.player_id
514                    and member_id in self.sync_leader.state.group_members
515                ):
516                    final_players_to_remove.append(member_id)
517                continue
518            if member_id in self._attr_static_group_members:
519                # static members can not be removed from the group
520                raise PlayerCommandFailed(
521                    f"Cannot remove {member_id} from group {self.display_name} "
522                    "since it's a static member!"
523                )
524            if self.sync_leader and member_id == self.sync_leader.player_id:
525                leader_removed = True
526                continue
527            if member_id == self.player_id:
528                raise PlayerCommandFailed(
529                    f"Cannot remove {self.display_name} from itself as a member!",
530                    translation_key="remove_self",
531                    translation_owner=self.translation_owner,
532                    translation_args=[self.display_name],
533                )
534            self._attr_group_members.remove(member_id)
535            final_players_to_remove.append(member_id)
536
537        if self.sync_leader and leader_removed and self._attr_group_members:
538            # we removed the current sync leader, but we still have members in the group
539            old_leader_id = self.sync_leader.player_id
540            session_player = self._active_session_player()
541            supports_handoff = (
542                session_player is not None
543                and session_player.provider.domain in PROVIDERS_WITH_DYNAMIC_LEADER_SWITCH
544            )
545
546            if was_playing and supports_handoff:
547                # protocol supports dynamic leader switching: try to remove
548                # only the departing leader and keep remaining members playing.
549                # _dynamic_leader_switch will fall back to dissolve+reform
550                # automatically if no remaining member is part of the live
551                # session (e.g. only freshly-added players are left).
552                await self._dynamic_leader_switch(old_leader_id)
553            else:
554                # protocol doesn't support dynamic leader switching or not playing
555                await self._dissolve_and_reform(old_leader_id, resume_playback=was_playing)
556        elif self.sync_leader and (leader_removed or not self._attr_group_members):
557            # we removed the current sync leader, and we have no members left in the group
558            # or we just removed the last member from the group, so we dissolve the syncgroup
559            # Use internal handler to stop the sync leader directly,
560            # bypassing group redirect that would loop back to this player.
561            async with self.mass.players.wait_for_player_update(
562                self.sync_leader.player_id, timeout=5
563            ):
564                await self.mass.players._handle_cmd_stop(self.sync_leader.player_id)
565            await self._dissolve_syncgroup()
566
567        elif self.sync_leader:
568            # just a regular member(s) added/removed action,
569            # we can simply update the syncgroup members on the sync leader.
570            # `active_protocol_domain` is derived from live state, so the
571            # group will naturally downshift once it re-forms if every
572            # remaining member can play on the leader's native protocol.
573            # use _handle_set_members directly to avoid the redirect loop
574            # (cmd_set_members redirects sync-leader targets back to this syncgroup)
575            async with self.mass.players.get_player_lock(
576                self.sync_leader.player_id, PlayerLockPurpose.PLAYBACK
577            ):
578                await self.mass.players._handle_set_members(
579                    self.sync_leader,
580                    player_ids_to_add=final_players_to_add,
581                    player_ids_to_remove=final_players_to_remove,
582                )
583        elif self._reform_task is not None:
584            # leaderless with a debounced re-form pending: membership just changed,
585            # so re-arm the window — the re-form picks up the final member list.
586            self._schedule_reform_timer()
587        # NOTE: If we weren't playing before, we don't need to do anything else,
588        # since the syncing will be done once playback starts
589        self.mass.players.trigger_player_update(self.player_id)
590
591    def on_group_member_updated(
592        self, member_player: Player, changed_values: dict[str, tuple[Any, Any]]
593    ) -> None:
594        """Handle callback when a group member of the group player is updated."""
595        self._update_attributes()
596        super().on_group_member_updated(member_player, changed_values)
597
598    async def on_unload(self) -> None:
599        """Handle logic when the player is unloaded from the Player controller."""
600        self._cancel_idle_grace_timer()
601        self._cancel_reform_timer()
602        await super().on_unload()
603        # the player is going away; make sure we don't leave the protocol-level
604        # sync group standing with a now-nonexistent leader behind it.
605        if self.sync_leader is not None:
606            await self._dissolve_syncgroup()
607
608    @property
609    def active_protocol_domain(self) -> str | None:
610        """
611        Derive the active protocol domain for this sync group on the fly.
612
613        Returns the domain of the protocol currently carrying the live stream
614        session, EXCEPT when every remaining member can also play on the
615        leader's native domain — in which case the group should downshift and
616        this returns that native domain. Always computed from live state so it
617        cannot drift from reality.
618
619        Because of that downshift this is a hint for the next leader selection,
620        not an address for the live session: use ``_active_session_player()``
621        to reach the players that are carrying the stream right now.
622        """
623        session_player = self._active_session_player()
624        if session_player is None or self.sync_leader is None:
625            return None
626        domain = session_player.provider.domain
627        native_domain = self.sync_leader.provider.domain
628        # Keep a non-native protocol "active" for leader-selection purposes unless
629        # the whole group can be reached on the leader's native domain.
630        if domain != native_domain and self._all_members_can_play_on_domain(native_domain):
631            return native_domain
632        return domain
633
634    def _is_member_allowed(self, player_id: str) -> bool:
635        """Return whether a player is allowed to join this group given the configured filter."""
636        # preset members should always be allowed to re-join
637        preset_members = cast("list[str]", self.config.get_value(CONF_GROUP_MEMBERS, []) or [])
638        if player_id in preset_members:
639            return True
640        allowed_members = cast("list[str]", self.config.get_value(CONF_ALLOWED_MEMBERS, []) or [])
641        return not allowed_members or player_id in allowed_members
642
643    async def _form_syncgroup(self) -> None:
644        """Form syncgroup by syncing all (possible) members."""
645        # any in-flight grace or debounced re-form timer is moot now —
646        # we're (re)forming the group
647        self._cancel_idle_grace_timer()
648        self._cancel_reform_timer()
649        self.logger.debug(
650            "Forming syncgroup %s, _attr_group_members=%s, sync_leader=%s",
651            self.display_name,
652            self._attr_group_members,
653            self.sync_leader.display_name if self.sync_leader else None,
654        )
655        # select new sync leader if needed
656        if not self.sync_leader:
657            self.sync_leader = self._select_sync_leader()
658
659        # pin the leader ref: a concurrent command (e.g. a dissolve) may clear
660        # or replace self.sync_leader while we await below
661        leader = self.sync_leader
662        if not leader:
663            # we have no members in the group, so we can't form a syncgroup
664            return
665
666        # ensure the sync leader is first in the list
667        self._attr_group_members = [
668            leader.player_id,
669            *[x for x in self._attr_group_members if x != leader.player_id],
670        ]
671        # If the leader still believes it's synced to a previous leader (e.g. we
672        # just picked a new leader after dissolving the old session and the
673        # protocol-level state hasn't propagated yet), wait for it to settle.
674        # Without this, the subsequent play_media call hits the provider's
675        # "I'm synced to another player" guard and gets rejected.
676        if leader.state.synced_to is not None:
677            self.logger.debug(
678                "Waiting for new leader %s to report synced_to=None before forming",
679                leader.display_name,
680            )
681            if not await self._wait_member_unsynced(leader.player_id):
682                # Leader is genuinely stuck — bail out before issuing play_media
683                # so we don't trigger the provider's "synced to another player"
684                # rejection. The caller (play / play_media) will surface this as
685                # a no-op form; the next user action can retry once the
686                # protocol layer has caught up.
687                self.logger.error(
688                    "Aborting syncgroup form for %s: leader %s is stuck synced",
689                    self.display_name,
690                    leader.display_name,
691                )
692                self.sync_leader = None
693                return
694            if self.sync_leader is not leader:
695                # the group was dissolved or re-led while we waited —
696                # this form attempt is stale, abort
697                return
698        # Translate the leader's group_members (may be protocol IDs) to parent IDs
699        # so we can compare against our _attr_group_members (always parent IDs)
700        already_synced = set(self._translate_to_parent_ids(leader.state.group_members))
701        members_to_sync = [
702            x for x in self._attr_group_members if x != leader.player_id and x not in already_synced
703        ]
704        if members_to_sync:
705            # If the sync leader is playing something independently, stop it first
706            # to prevent protocol switching from trying to resume the previous playback
707            # (we're about to start new playback on the syncgroup).
708            # Wait for the leader to actually reach IDLE before adding members,
709            # since some providers reject set_members while still playing.
710            if leader.state.playback_state == PlaybackState.PLAYING:
711                async with self.mass.players.wait_for_player_update(
712                    leader.player_id,
713                    attribute_name="playback_state",
714                    attribute_value=PlaybackState.IDLE,
715                    timeout=5,
716                ):
717                    await self.mass.players._handle_cmd_stop(leader.player_id)
718                if self.sync_leader is not leader:
719                    # the group was dissolved or re-led while we waited —
720                    # this form attempt is stale, abort
721                    return
722            # use _handle_set_members directly to avoid the redirect loop
723            # (cmd_set_members redirects sync-leader targets back to this syncgroup)
724            async with self.mass.players.get_player_lock(
725                leader.player_id, PlayerLockPurpose.PLAYBACK
726            ):
727                await self.mass.players._handle_set_members(
728                    leader, player_ids_to_add=members_to_sync
729                )
730
731    @asynccontextmanager
732    async def _await_leader_playback(self) -> AsyncIterator[None]:
733        """
734        Wait for the sync leader to confirm playback for the command run in the body.
735
736        Wrap the play/resume call that targets the leader in this context manager.
737        The group's playback lock (held by the caller) then stays acquired until the
738        leader actually reports playing, so a concurrent (un)group command cannot
739        race a start that has not yet taken effect at the device. A no-op when there
740        is no leader to wait on.
741        """
742        if (leader := self.sync_leader) is None:
743            yield
744            return
745        # stamp the start: device state is unreliable while a start settles, so
746        # group-command decisions treat this window as playing (see set_members)
747        self._playback_start_at = time.monotonic()
748        async with self.mass.players.wait_for_player_update(
749            leader.player_id,
750            attribute_name="playback_state",
751            attribute_value=PlaybackState.PLAYING,
752            timeout=PLAYBACK_START_TIMEOUT,
753        ):
754            yield
755
756    async def _dissolve_syncgroup(self) -> None:
757        """Dissolve the current syncgroup by ungrouping all members."""
758        # a dissolve is happening now — any pending grace or re-form timer is no
759        # longer needed (_dissolve_and_reform re-arms the re-form right after)
760        # and the session whose start the marker tracked is gone
761        self._cancel_idle_grace_timer()
762        self._cancel_reform_timer()
763        self._playback_start_at = float("-inf")
764        if sync_leader := self.sync_leader:
765            # dissolve the temporary syncgroup from the player that holds the members:
766            # ungrouping from a leader that no longer holds them is a no-op and would
767            # leave the members grouped and streaming with no way back
768            group_leader = self._protocol_group_leader(sync_leader)
769            sync_children = [
770                x for x in group_leader.state.group_members if x != group_leader.player_id
771            ]
772            if sync_children:
773                # wait for the leader's state to reflect the ungroup
774                # use _handle_set_members directly to avoid the redirect loop
775                # (cmd_set_members redirects sync-leader targets back to this syncgroup)
776                async with (
777                    self.mass.players.wait_for_player_update(group_leader.player_id, timeout=5),
778                    self.mass.players.get_player_lock(
779                        group_leader.player_id, PlayerLockPurpose.PLAYBACK
780                    ),
781                ):
782                    await self.mass.players._handle_set_members(
783                        group_leader, player_ids_to_remove=sync_children
784                    )
785            if group_leader is not sync_leader:
786                # our callers only ever stop the leader we track, so a provider-promoted
787                # one would keep streaming on its own once the members are released
788                await self.mass.players._handle_cmd_stop(group_leader.player_id)
789                self.mass.players.schedule_active_output_protocol_clear(group_leader)
790        # Clear the leader's active protocol once it stops playing; the controller's
791        # clearing in _handle_cmd_stop is skipped for a still-grouped protocol player.
792        if sync_leader:
793            self.mass.players.schedule_active_output_protocol_clear(sync_leader)
794        self.sync_leader = None
795        self._update_attributes()
796        self.update_state()
797
798    def _select_sync_leader(
799        self,
800        new_members: list[str] | None = None,
801        preferred_protocol_domain: str | None = None,
802        preferred_member_ids: Collection[str] | None = None,
803    ) -> Player | None:
804        """
805        Select a (new) sync leader, preferring session and protocol continuity.
806
807        :param new_members: Optional list of newly added member ids to consider
808            when no current/static members are available.
809        :param preferred_protocol_domain: If provided, prefer members that
810            support this protocol domain so playback keeps using the same
811            protocol.
812        :param preferred_member_ids: If provided, prefer members from this
813            collection (e.g. the ones a live session already feeds). Outranks
814            ``preferred_protocol_domain``.
815        """
816        if self.group_members and self.sync_leader and self.sync_leader.state.available:
817            # current leader is still available, no need to select a new one
818            return self.sync_leader
819        # with selecting a new leader, we prioritize the static group members
820        group_members = self.static_group_members or self.group_members or new_members or []
821        candidates = [
822            member_player
823            for member_id in group_members
824            if (member_player := self.mass.players.get_player(member_id))
825            and member_player.state.available
826        ]
827        preferred_ids = set(preferred_member_ids or ())
828        # preference tiers, most specific first: a member that is already fed by the
829        # live session can take it over without restarting playback, and one that
830        # supports the active protocol at least keeps the session on that protocol
831        for reason, matches in (
832            (
833                "takes part in the live session",
834                [x for x in candidates if x.player_id in preferred_ids],
835            ),
836            (
837                f"supports active protocol {preferred_protocol_domain}",
838                [
839                    x
840                    for x in candidates
841                    if preferred_protocol_domain
842                    and self._member_supports_protocol_domain(x, preferred_protocol_domain)
843                ],
844            ),
845            ("first available member", candidates),
846        ):
847            if not matches:
848                continue
849            self.logger.debug(
850                "Auto-selected %s as sync leader for group %s (%s)",
851                matches[0].display_name,
852                self.display_name,
853                reason,
854            )
855            return matches[0]
856        return None
857
858    # -----------------------------------------------------------------------
859    # Protocol awareness
860    # -----------------------------------------------------------------------
861    # A sync group can contain members from multiple protocol domains (e.g. a
862    # Sonos that can play via either its native protocol or via AirPlay). The
863    # group needs to:
864    #   - track which protocol the live session is using (active_protocol_domain)
865    #   - resolve which player actually owns the protocol-level session
866    #     (_active_session_player) so leader/handoff bookkeeping is done on
867    #     the right object
868    #   - choose new leaders that keep protocol continuity
869    #     (_member_supports_protocol_domain / _select_sync_leader)
870    #   - downshift to the native protocol once every remaining member can play
871    #     on it (_all_members_can_play_on_domain)
872    #   - stay aligned with the protocol's own view of the group, both in member
873    #     order (_align_members_with_session) and in who leads it
874    #     (_protocol_group_leader)
875    # The helpers below cover those needs. Composition decisions (which protocol
876    # to use given the current member mix) intentionally live in the group:
877    # individual protocol providers don't have visibility into the rest of the
878    # group's members.
879
880    def _translate_to_parent_ids(self, player_ids: list[str]) -> list[str]:
881        """
882        Translate a list of (possibly protocol) player IDs to parent player IDs.
883
884        Protocol players (e.g. AirPlay `apc...`) are translated to their parent
885        (e.g. Sonos `RINCON_...`). Non-protocol IDs pass through unchanged.
886
887        :param player_ids: List of player IDs that may be protocol or parent IDs.
888        """
889        result: list[str] = []
890        for pid in player_ids:
891            if player := self.mass.players.get_player(pid):
892                parent_id = player.protocol_parent_id or pid
893                if parent_id not in result:
894                    result.append(parent_id)
895            elif pid not in result:
896                result.append(pid)
897        return result
898
899    def _member_supports_protocol_domain(self, player: Player, domain: str) -> bool:
900        """
901        Check if a player supports the given protocol domain.
902
903        :param player: The player to check.
904        :param domain: The protocol domain string (e.g. "airplay", "sonos").
905        """
906        if player.provider.domain == domain:
907            return True
908        for protocol in player.linked_output_protocols:
909            if protocol.protocol_domain == domain and protocol.available:
910                return True
911        return False
912
913    def _all_members_can_play_on_domain(self, domain: str) -> bool:
914        """
915        Return True if every current member has a playback path on the given domain.
916
917        A playback path is a member's own native playback or one of its
918        available linked output protocols. Members that are unavailable or
919        expose no playback path at all are ignored, so they never hold the
920        group on a protocol.
921
922        :param domain: The playback path domain to check (e.g. "airplay", "sonos").
923        """
924        for member_id in self._attr_group_members:
925            member = self.mass.players.get_player(member_id)
926            if member is None or not member.state.available:
927                continue
928            # Collect the set of available playback path domains for this member.
929            # UniversalPlayer wrappers have no native path of their own: their
930            # ``provider.domain`` is ``universal_player``, which is never a
931            # domain the group can play on.
932            paths: set[str] = set()
933            if member.is_native_player:
934                paths.add(member.provider.domain)
935            for protocol in member.linked_output_protocols:
936                if protocol.available:
937                    paths.add(protocol.protocol_domain)
938            if paths and domain not in paths:
939                return False
940        return True
941
942    def _active_session_player(self) -> Player | None:
943        """
944        Return the player that owns the live sync session.
945
946        If the current sync leader has a non-native active output protocol,
947        returns the protocol player that carries the stream; otherwise returns
948        the native sync leader itself. Returns ``None`` if there is no leader.
949        """
950        if not self.sync_leader:
951            return None
952        if (
953            self.sync_leader.active_output_protocol
954            and self.sync_leader.active_output_protocol != "native"
955            and (
956                protocol_player := self.mass.players.get_player(
957                    self.sync_leader.active_output_protocol
958                )
959            )
960        ):
961            return protocol_player
962        return self.sync_leader
963
964    def _align_members_with_session(self, session_player: Player | None) -> None:
965        """
966        Re-order the tracked members to match the live session's member order.
967
968        Members that are not part of the live session keep their relative order at
969        the end of the list.
970
971        :param session_player: The player that owns the live sync session.
972        """
973        if session_player is None:
974            return
975        # the provider's own group_members, not state.group_members: the latter is
976        # set-derived for non-protocol players and loses the member order. Not
977        # live_session_members either: that answers who is in the session, not in
978        # which order, and a provider may derive it without preserving any.
979        session_order = [
980            x
981            for x in self._translate_to_parent_ids(session_player.group_members)
982            if x in self._attr_group_members
983        ]
984        if not session_order:
985            return
986        self._attr_group_members = [
987            *session_order,
988            *[x for x in self._attr_group_members if x not in session_order],
989        ]
990
991    def _protocol_group_leader(self, sync_leader: Player) -> Player:
992        """
993        Return the member that currently holds the protocol-level group.
994
995        This is normally the sync leader itself, but a provider may have promoted a
996        different member at the protocol level. Falls back to the sync leader when no
997        member reports holding others.
998
999        :param sync_leader: The sync leader tracked by this group.
1000        """
1001        if sync_leader.state.group_members:
1002            return sync_leader
1003        for member_id in self._attr_group_members:
1004            if member_id == sync_leader.player_id:
1005                continue
1006            member = self.mass.players.get_player(member_id)
1007            if member is None or not member.state.available:
1008                continue
1009            # a leader always lists itself alongside its members; only adopt one that
1010            # holds members of this group, never a group formed outside of MA
1011            held = [x for x in member.state.group_members if x != member_id]
1012            if held and not set(held).isdisjoint(self._attr_group_members):
1013                self.logger.warning(
1014                    "Syncgroup %s tracks %s as leader but %s holds the group members",
1015                    self.display_name,
1016                    sync_leader.display_name,
1017                    member.display_name,
1018                )
1019                return member
1020        return sync_leader
1021
1022    def _update_attributes(self) -> None:
1023        """Update dynamic attributes."""
1024        # NOTE on what reads from `.state.*` vs the leader's raw attributes below:
1025        # `__final_current_media` and `__final_active_source` on a player that has
1026        # an ``active_group`` route through the active_group's state — so reading
1027        # ``sync_leader.state.current_media`` from inside the group would loop
1028        # back through our own state derivation (group → leader.state →
1029        # active_group=group → group). For those two we MUST use the leader's
1030        # raw attributes. ``playback_state`` / ``elapsed_time`` do not route via
1031        # active_group and are safe to read from ``.state.*``.
1032        if (sync_leader := self.sync_leader) is None:
1033            # no sync leader, reset playback-related attributes to default values
1034            self._attr_playback_state = PlaybackState.IDLE
1035            self._attr_elapsed_time = None
1036            self._attr_elapsed_time_last_updated = None
1037            self._attr_current_media = None
1038            self._attr_active_source = None
1039            self._attr_poll_interval = 30
1040            return
1041        prev_state = self._attr_playback_state
1042        new_state = sync_leader.state.playback_state
1043        self._attr_playback_state = new_state
1044        self._attr_elapsed_time = sync_leader.state.elapsed_time
1045        self._attr_elapsed_time_last_updated = sync_leader.state.elapsed_time_last_updated
1046        # don't use 'state' for current_media here since that points back to this group
1047        # player when we're active_group, we need the 'raw' value from the sync leader
1048        # itself to avoid circular dependency and ensure it reflects the actual media
1049        # on the leader rather than the group.
1050        self._attr_current_media = sync_leader.current_media
1051        self._attr_active_source = sync_leader.active_source
1052        self._attr_poll_interval = 1 if new_state == PlaybackState.PLAYING else 30
1053        # idle grace handling: schedule a debounced dissolve when the leader
1054        # naturally transitions from PLAYING/PAUSED to IDLE. The dissolve is
1055        # skipped if the user has pinned the group with Fake power control.
1056        if new_state == PlaybackState.IDLE and prev_state in (
1057            PlaybackState.PLAYING,
1058            PlaybackState.PAUSED,
1059        ):
1060            if self._attr_powered is not True:
1061                self._schedule_idle_grace_timer()
1062        elif new_state in (PlaybackState.PLAYING, PlaybackState.PAUSED):
1063            # leader resumed playing, cancel any pending grace
1064            self._cancel_idle_grace_timer()
1065
1066    async def _dissolve_and_reform(
1067        self,
1068        old_leader_id: str,
1069        leader_to_stop: Player | None = None,
1070        resume_playback: bool = True,
1071        preferred_protocol_domain: str | None = None,
1072    ) -> None:
1073        """
1074        Stop the current sync session, dissolve the syncgroup and schedule a re-form.
1075
1076        Used when a seamless handoff isn't possible (e.g. the new leader is not
1077        part of the live session). The stop/dissolve happens immediately; the
1078        re-form (with resume) is debounced so cascaded unjoins coalesce into a
1079        single restart with the final member list.
1080
1081        :param old_leader_id: The player_id of the departing leader.
1082        :param leader_to_stop: The player to stop before dissolving. Defaults
1083            to ``self.sync_leader`` but callers should pass the old leader
1084            explicitly when ``self.sync_leader`` has already been cleared.
1085        :param resume_playback: If True, schedule the debounced re-form which
1086            restarts playback on the new leader. Pass False when the group was
1087            not actively playing (e.g. paused or idle).
1088        :param preferred_protocol_domain: Optional snapshot of the active
1089            protocol domain taken before the old leader was cleared, passed to
1090            :meth:`_select_sync_leader` so the new leader is chosen to keep the
1091            protocol session continuous where possible.
1092        """
1093        leader_to_stop = leader_to_stop or self.sync_leader
1094        if leader_to_stop:
1095            self.logger.info(
1096                "Dissolving syncgroup %s (leader %s) and re-forming with a new leader",
1097                self.display_name,
1098                leader_to_stop.display_name,
1099            )
1100            async with self.mass.players.wait_for_player_update(
1101                leader_to_stop.player_id, timeout=5
1102            ):
1103                await self.mass.players._handle_cmd_stop(leader_to_stop.player_id)
1104        await self._dissolve_syncgroup()
1105        if old_leader_id in self._attr_group_members:
1106            self._attr_group_members.remove(old_leader_id)
1107        if resume_playback and self._attr_group_members:
1108            self._reform_protocol_domain = preferred_protocol_domain
1109            self._schedule_reform_timer()
1110
1111    async def _wait_member_unsynced(self, member_id: str, timeout: float = 5.0) -> bool:
1112        """
1113        Wait until the given member reports as unsynced (synced_to is None).
1114
1115        Returns ``True`` when the member is verified unsynced (downstream flows
1116        like leader selection / play_media on the leader are safe to proceed),
1117        or ``False`` when the player is genuinely stuck (the caller should
1118        abort rather than issue a play_media that will be rejected by the
1119        provider's "I'm synced to another player" guard).
1120
1121        :param member_id: The player to wait on.
1122        :param timeout: Seconds to wait for the first state propagation.
1123        """
1124        async with self.mass.players.wait_for_player_update(
1125            member_id,
1126            attribute_name="synced_to",
1127            attribute_value=None,
1128            timeout=timeout,
1129        ):
1130            pass
1131        member = self.mass.players.get_player(member_id)
1132        if member is None or member.synced_to is None:
1133            return True
1134        # The provider didn't propagate within the timeout. Kick the member
1135        # from its stale parent, then wait again with a tighter budget.
1136        # This rescues the common "Sonos UPnP event lag" case.
1137        # NOTE: not the public cmd_ungroup - it re-enters this syncgroup's set_members.
1138        # if the stale parent is gone, no kick is possible - fall through to the final check
1139        if stale_parent := self.mass.players.get_player(member.synced_to):
1140            self.logger.warning(
1141                "Player %s still reports synced_to=%s after %ss; "
1142                "removing it from its stale parent and re-waiting",
1143                member.display_name,
1144                member.synced_to,
1145                timeout,
1146            )
1147            try:
1148                async with (
1149                    self.mass.players.wait_for_player_update(
1150                        member_id,
1151                        attribute_name="synced_to",
1152                        attribute_value=None,
1153                        timeout=2.0,
1154                    ),
1155                    self.mass.players.get_player_lock(
1156                        stale_parent.player_id, PlayerLockPurpose.PLAYBACK
1157                    ),
1158                ):
1159                    await self.mass.players._handle_set_members(
1160                        stale_parent, player_ids_to_remove=[member_id]
1161                    )
1162            except asyncio.CancelledError:
1163                raise
1164            except Exception as err:
1165                self.logger.debug(
1166                    "stale-parent removal recovery for %s raised: %s", member.display_name, err
1167                )
1168        member = self.mass.players.get_player(member_id)
1169        if member is None or member.synced_to is None:
1170            return True
1171        self.logger.error(
1172            "Player %s is stuck synced_to=%s; aborting dissolve+reform path",
1173            member.display_name,
1174            member.synced_to,
1175        )
1176        return False
1177
1178    async def _dynamic_leader_switch(self, old_leader_id: str) -> None:
1179        """
1180        Switch the sync leader without tearing down the stream session.
1181
1182        Used when the provider supports dynamic leader selection (e.g. AirPlay,
1183        Snapcast). The old leader is removed from the live session and the
1184        remaining members keep playing uninterrupted on a newly selected leader.
1185
1186        If no remaining member takes part in the live session (e.g. only
1187        freshly-added players are left), a seamless handoff isn't possible. In
1188        that case we fall back to dissolve + reform, accepting a brief audio gap.
1189
1190        :param old_leader_id: The player_id of the leader being removed.
1191        """
1192        old_leader = self.sync_leader
1193        assert old_leader is not None
1194
1195        self.logger.info(
1196            "Dynamic leader switch: removing %s from group %s, remaining members keep playing",
1197            old_leader.display_name,
1198            self.display_name,
1199        )
1200
1201        # Snapshot the currently active protocol and session before clearing
1202        # the leader — we need both for new-leader selection and for the
1203        # handoff-eligibility check.
1204        preferred_domain = self.active_protocol_domain
1205        session_player = self._active_session_player()
1206        # The domain the live session actually runs on. It differs from
1207        # `preferred_domain` once the group is due to downshift to native, and
1208        # a seamless handoff must stay on the protocol carrying the stream.
1209        session_domain = session_player.provider.domain if session_player else None
1210        # The members the session feeds right now: only a member from this set can take
1211        # it over without a restart. Tracked membership is not enough — a member can be
1212        # dropped from the session (or never make it in) while still being listed.
1213        live_member_ids = (
1214            self._translate_to_parent_ids(session_player.live_session_members)
1215            if session_player
1216            else []
1217        )
1218
1219        # Remove the old leader from our group members list
1220        if old_leader_id in self._attr_group_members:
1221            self._attr_group_members.remove(old_leader_id)
1222
1223        # A provider may hand the live session to its own first remaining member, so our
1224        # member order has to match the session's before we pick from it — otherwise we
1225        # end up tracking a different leader than the one that inherits the session.
1226        self._align_members_with_session(session_player)
1227
1228        # Pick a new leader, preferring one that is already fed by the live session
1229        # so the session continuation is seamless.
1230        self.sync_leader = None
1231        new_leader = self._select_sync_leader(
1232            preferred_protocol_domain=session_domain,
1233            preferred_member_ids=live_member_ids,
1234        )
1235
1236        if not new_leader:
1237            # No remaining members to take over — stop the old leader's
1238            # session and dissolve the group entirely. Restore sync_leader
1239            # so _dissolve_syncgroup can properly ungroup protocol members.
1240            self.sync_leader = old_leader
1241            self.logger.info(
1242                "No remaining members for group %s after removing %s, stopping",
1243                self.display_name,
1244                old_leader.display_name,
1245            )
1246            async with self.mass.players.wait_for_player_update(old_leader.player_id, timeout=5):
1247                await self.mass.players._handle_cmd_stop(old_leader.player_id)
1248            await self._dissolve_syncgroup()
1249            return
1250
1251        # A seamless handoff requires the new leader to already be a sync_client of
1252        # the live session. Selection prefers such a member, so reaching this means
1253        # no remaining member has a stream to inherit: fall back to dissolve + reform.
1254        if new_leader.player_id not in live_member_ids:
1255            self.logger.info(
1256                "New leader %s is not in the live session; dissolving and re-forming syncgroup %s",
1257                new_leader.display_name,
1258                self.display_name,
1259            )
1260            # Restore sync_leader so _dissolve_and_reform -> _dissolve_syncgroup
1261            # can properly ungroup protocol-level members. Forward the protocol
1262            # hint so the new form keeps protocol continuity when possible.
1263            self.sync_leader = old_leader
1264            await self._dissolve_and_reform(
1265                old_leader_id,
1266                leader_to_stop=old_leader,
1267                preferred_protocol_domain=preferred_domain,
1268            )
1269            return
1270
1271        self.sync_leader = new_leader
1272        # Ensure the new leader is first in the members list
1273        self._attr_group_members = [
1274            new_leader.player_id,
1275            *[x for x in self._attr_group_members if x != new_leader.player_id],
1276        ]
1277        self.logger.info(
1278            "Dynamic leader switch complete: %s is now leader of group %s",
1279            new_leader.display_name,
1280            self.display_name,
1281        )
1282
1283        # Hand off at the protocol level. We already know:
1284        # - the old session player (the protocol player that owns the live session)
1285        # - the domain that session runs on
1286        # - the new leader (a parent player whose protocol player is in the session)
1287        # So we can talk to the protocol players directly and skip the controller's
1288        # protocol-translation overhead in cmd_set_members.
1289        new_target = self._resolve_session_target(new_leader, session_domain)
1290        remaining_protocol_ids: list[str] = []
1291        for member_id in self._attr_group_members:
1292            if member_id == new_leader.player_id:
1293                continue
1294            if member := self.mass.players.get_player(member_id):
1295                if target := self._resolve_session_target(member, session_domain):
1296                    remaining_protocol_ids.append(target.player_id)
1297
1298        # 1. Old leader's session protocol player steps out of the session.
1299        # Direct call (the controller's cmd_set_members would interpret this
1300        # self-removal as "dissolve the entire group"). The provider's set_members
1301        # implementation handles "remove self while other clients remain" by
1302        # promoting another sync_client at the protocol level.
1303        if session_player is not None:
1304            await session_player.set_members(player_ids_to_remove=[session_player.player_id])
1305
1306        # 2. New leader's protocol player takes over ownership tracking of the
1307        # remaining members. The members are already in the live session at the
1308        # protocol level (sync_clients), this just transfers the bookkeeping so
1309        # the new leader's protocol player reports them as its group members.
1310        if remaining_protocol_ids and new_target is not None:
1311            await new_target.set_members(player_ids_to_add=remaining_protocol_ids)
1312
1313        self.update_state()
1314
1315    def _schedule_idle_grace_timer(self) -> None:
1316        """Schedule a debounced dissolve after the leader becomes idle."""
1317        # any previously scheduled task is replaced so we don't end up with
1318        # two dissolves racing each other when the leader oscillates quickly
1319        self._cancel_idle_grace_timer()
1320        self.logger.debug(
1321            "Scheduling idle-grace dissolve for syncgroup %s in %ss",
1322            self.display_name,
1323            IDLE_GRACE_SECONDS,
1324        )
1325        self._idle_grace_task = self.mass.create_task(self._idle_grace_runner())
1326
1327    def _cancel_idle_grace_timer(self) -> None:
1328        """Cancel any pending idle-grace dissolve task."""
1329        if self._idle_grace_task is not None:
1330            if not self._idle_grace_task.done():
1331                self._idle_grace_task.cancel()
1332            self._idle_grace_task = None
1333
1334    async def _idle_grace_runner(self) -> None:
1335        """Wait the grace window, then dissolve if the group is still idle."""
1336        try:
1337            await asyncio.sleep(IDLE_GRACE_SECONDS)
1338        except asyncio.CancelledError:
1339            return
1340        # re-check state at fire time — playback may have resumed, the user
1341        # may have powered the group on, or another path may have dissolved
1342        # us already. Any of these means we should not dissolve here.
1343        self._idle_grace_task = None
1344        if self.sync_leader is None:
1345            return
1346        if self._attr_powered is True:
1347            return
1348        if self.sync_leader.state.playback_state != PlaybackState.IDLE:
1349            return
1350        self.logger.info(
1351            "Idle-grace expired for syncgroup %s, dissolving",
1352            self.display_name,
1353        )
1354        await self._dissolve_syncgroup()
1355
1356    @property
1357    def _playback_recently_started(self) -> bool:
1358        """Return whether a playback start was issued within the settle window."""
1359        return (time.monotonic() - self._playback_start_at) < PLAYBACK_START_TIMEOUT
1360
1361    def _schedule_reform_timer(self) -> None:
1362        """(Re)schedule the debounced re-form after the sync leader was removed."""
1363        # any previously scheduled task is replaced so cascaded unjoins coalesce
1364        # into a single re-form with the final member list
1365        self._cancel_reform_timer()
1366        self.logger.debug(
1367            "Scheduling debounced re-form for syncgroup %s in %ss",
1368            self.display_name,
1369            REFORM_DEBOUNCE_SECONDS,
1370        )
1371        self._reform_task = self.mass.create_task(self._reform_runner())
1372
1373    def _cancel_reform_timer(self) -> None:
1374        """Cancel any pending debounced re-form task."""
1375        if (task := self._reform_task) is None:
1376            return
1377        self._reform_task = None
1378        # never cancel ourselves: the runner ends up here via play() -> _form_syncgroup
1379        if task is not asyncio.current_task() and not task.done():
1380            task.cancel()
1381
1382    async def _reform_runner(self) -> None:
1383        """Wait the debounce window, then re-form the group and resume playback."""
1384        try:
1385            await asyncio.sleep(REFORM_DEBOUNCE_SECONDS)
1386        except asyncio.CancelledError:
1387            return
1388        try:
1389            # serialize with (un)group and playback commands targeting this group.
1390            # A cancellation (another unjoin re-arming the window, an explicit
1391            # stop) may still land while we wait for the lock.
1392            async with self.mass.players.get_player_lock(
1393                self.player_id, PlayerLockPurpose.PLAYBACK
1394            ):
1395                # re-check state at execution time — an explicit play may have
1396                # re-formed the group already and all members may have been
1397                # removed meanwhile
1398                if self.sync_leader is not None or not self._attr_group_members:
1399                    return
1400                # Wait for the remaining members to report as unsynced before
1401                # re-forming. Providers like Sonos propagate group state
1402                # asynchronously — the children can still report synced_to for
1403                # a few seconds after the leader's ungroup command returns.
1404                members = list(self._attr_group_members)
1405                unsync_results = await asyncio.gather(
1406                    *(self._wait_member_unsynced(m) for m in members),
1407                    return_exceptions=True,
1408                )
1409                stuck_members = [
1410                    members[i] for i, result in enumerate(unsync_results) if result is False
1411                ]
1412                if stuck_members:
1413                    self.logger.error(
1414                        "Members of group %s still report synced_to after recovery attempts: "
1415                        "%s; aborting re-form (no playback will resume on this call)",
1416                        self.display_name,
1417                        stuck_members,
1418                    )
1419                    return
1420                self.logger.info(
1421                    "Re-forming syncgroup %s with %s member(s) and resuming playback",
1422                    self.display_name,
1423                    len(members),
1424                )
1425                # Preselect the new leader with the protocol hint so the form
1426                # picks a member compatible with the previous session's protocol
1427                # (e.g. keep AirPlay if the session was AirPlay).
1428                if self._reform_protocol_domain is not None:
1429                    self.sync_leader = self._select_sync_leader(
1430                        preferred_protocol_domain=self._reform_protocol_domain
1431                    )
1432                await self.play()
1433        finally:
1434            # normal completion detaches us via play() -> _form_syncgroup already;
1435            # this covers the early-return paths so is_active_session settles
1436            if self._reform_task is asyncio.current_task():
1437                self._reform_task = None
1438                self.update_state()
1439
1440    def _resolve_session_target(self, player: Player, domain: str | None) -> Player | None:
1441        """
1442        Resolve the player that participates in the live session for ``domain``.
1443
1444        For a player whose own provider domain matches, returns the player itself.
1445        For a parent player with a linked protocol on that domain, returns the
1446        corresponding protocol player. Returns ``None`` when nothing matches.
1447
1448        :param player: The player to resolve (parent or protocol player).
1449        :param domain: The protocol domain string of the active session
1450            (e.g. "airplay"). May be None, in which case ``player`` is returned.
1451        """
1452        if domain is None:
1453            return player
1454        if player.provider.domain == domain:
1455            return player
1456        for linked in player.linked_output_protocols:
1457            if linked.protocol_domain == domain and linked.available:
1458                return self.mass.players.get_player(linked.output_protocol_id)
1459        return None
1460