`homeassistant.components.media_player` has not exported `BrowseMediaSource`
for years: the class lives in `homeassistant.components.media_source.models`,
where it exists to build `media_source://<domain>` ids and is the only place a
`domain` parameter belongs (t30 G18's note was about THAT class). The local
import therefore raised ImportError, and with it every real browse failed —
while the suite stayed green because the harness stubbed a `BrowseMediaSource`
that real HA does not expose from there.
`async_browse_media` now builds the standard tree exactly as core's own
androidtv_remote/media_player.py does: `BrowseMedia` imported from
homeassistant.components.media_player at module scope, every node carrying an
explicit media_content_id/media_content_type (MediaType.APP/APPS),
`children_media_class=MediaClass.APP` on the directory, and no `domain`.
Verified against a real install: the old import raises ImportError, the old
`domain=` kwarg raises TypeError, and the new node constructs.
The harness is now faithful so this cannot hide again:
* `entity_stublib` exposes a `BrowseMedia` with the real keyword-only
signature, `as_dict()` and `calculate_children_class()`, plus `MediaType`,
and deliberately NOT `BrowseMediaSource` — so both the drifted import and the
drifted kwarg fail in-suite;
* the app-directory test asserts the standard shape (classes, explicit ids and
types, children_media_class, the serialised payload) instead of the removed
`domain` attribute;
* TestFaithfulHaStubs pins the harness contract on the AST (no production
module imports BrowseMediaSource) rather than on prose.
Verified: 284 passed, 2 skipped (D1 stage); ruff clean. Full gate re-run on the
completed branch: 289 passed / 2 skipped and 290 passed / 1 skipped.
James Mackay