The live report: "Browse media seems to spin and never finish loading". The cause is
in what async_browse_media HANDS BACK, not in the method — it returns with no awaits,
so nothing inside it can hang. The root node's media_content_id was None, and HA core
never serves a node without a string id: across the 43 BrowseMedia constructions in
the installed core media_player platforms, zero pass None (the roots use a
literal/module constant — arcam_fmj's "root", "apps", BROWSE_ROOT,
TUNER_PRESETS_ROOT — or "" for a pure container). The media-browser frontend keys the
node it is loading on that id, so a null id left the dialog re-requesting the same
node for ever.
BROWSE_ROOT_ID = "root" is now what the entity serves for EVERY requested id — the
root id, None, or anything a stale frontend asks for — so a repeat request is
idempotent rather than a loop.
The type was reassessed as well: MediaType.APPS (t61's choice) is what core pairs
with children=[...] — a folder OF apps — so on a zero-child node it invited the
frontend to treat it as an unloaded collection. No MediaType member means "a
directory with nothing in it", so the node carries the class it already declares
(MediaClass.DIRECTORY -> "directory"), which is exactly what can_expand=False and
children=[] say.
Verified over the real path the frontend uses — websocket_browse_media ->
player.async_browse_media -> payload.as_dict() — by driving HA's own decorated
handler against a real entity (tests/test_ha_api_drift.py, which the CI drift job
runs with Home Assistant installed): the root is a genuine BrowseMedia, its as_dict()
survives json.dumps, the id is the string "root", and browse(root_id) == browse(None)
in shape. Red proof on the pre-fix source: the new real-HA test fails at
`assert isinstance(payload["media_content_id"], str)` -> `isinstance(None, str)`.
The frontend bundle is not installed here (no hass_frontend) and there is no browser
to drive, so the rendered dialog is NOT exercised: this pins the backend half of that
path, end to end through the handler's decorators.
engineer
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