The F1 blocker was invisible to every existing test: the stub harnesses call the
entity and replace ``async_write_ha_state``, so a non-property
``extra_state_attributes`` looked perfectly healthy. Two new gates close that
hole.
1. ``ha_api_drift.scan_entity_contracts()`` — a pure-AST pass (so it needs no
homeassistant, unlike passes 1-3) that walks every class inheriting from an
HA entity base, including our own intermediate ``NvidiaShieldSensorBase``, and
flags any HA-READ attribute (``extra_state_attributes``, ``available``,
``state``, ``native_value``, ``media_*``, …) declared as a plain method
instead of ``@property``. It is wired into ``scan()`` before the
homeassistant gate and exported for the fast suite, so ONE implementation
backs the sweep, the CLI red proof and tests/test_entity_contract.py (the t39
F1 lesson).
Red proof on the pre-fix tree:
media_player.py:828: entity-attribute-is-a-method:
NvidiaShieldMediaPlayer.extra_state_attributes is a plain method, but HA
reads it as an attribute (``attr |= self.<name>``) — declare it @property
…and HEAD is clean (13 modules, 60 imports, 35 call arguments, 7 awaited).
2. tests/test_ha_api_drift.py now builds each entity under REAL homeassistant
(real ``PlatformData``, real ``async_write_ha_state``) and asserts HA's own
``__async_calculate_state`` succeeds and that the media player's app_id/
app_name survive the merge — for the media player, both sensors, the remote
and the pairing button. A coverage test compares that matrix against the
sweep's classification, so a new entity class cannot quietly skip it.
Verified: 296 passed / 2 skipped (fast suite), 16 passed (drift suite under
Python 3.14 + homeassistant 2026.10.1), ruff clean; the entity-contract red
proof above reproduces exactly the reported line.
