Reported from a live install: with ADB enabled but unreachable and a paired,
healthy protocol transport, the media player went unavailable even though the
protocol still served power/app/volume.
The old rule was ``manager.connected or manager.awake is not None or not
manager.available`` — i.e. "a configured ADB manager that is down ⇒ the whole
entity is down" (t5-F2), which ignored transport B entirely. The ladder is now:
* protocol transport wired and not reported unreachable — usable;
* or ADB connected — usable;
* or fresh wake data (the poller has spoken) — usable;
* or a passive manager (no ADB configured at all) — usable, because nothing to
transport is not a broken transport.
Unavailable only when a CONFIGURED transport is actively down and no usable data
exists. One implementation, ``entity_available`` (media_player.py), is used by the
media player, the remote (whose ladder previously duplicated a weaker version of
this rule) and the diagnostics payload.
Diagnostics grew ``transport.entity_available`` plus ``adb.configured`` so a
support dump answers "why is my entity unavailable?" — the ladder inputs and its
verdict are now in the same place.
Pinned by tests: the exact user case (ADB configured+down, protocol up ⇒
available), all-down (⇒ unavailable), wake-data rescue, connected ADB without a
protocol, the passive manager, a configured-but-down transport with no data, the
remote following the same ladder, and the diagnostics verdict.
Verified: 310 passed / 2 skipped, 311 passed / 1 skipped (androidtvremote2),
16 passed in the HA drift suite, ruff clean.
James Mackay