Handle entity lifecycle for child add, deactivate, reactivate

The harness tracks entities per entry so a platform unload removes
exactly that entry's entities; lifecycle tests prove deactivated
children drop out on reload, reactivation restores the original
unique_ids, new children appear without disturbing existing ones,
and the restart equivalent restores live states.

tests/test_entity_lifecycle.py

@@ -0,0 +1,159 @@
+"""Entity lifecycle across child add/deactivate/reactivate (Feature 10, task 8)."""
+from __future__ import annotations
+
+import datetime
+
+from conftest import wire_entry_to_registry
+
+from custom_components.nestquest import async_setup_entry, async_unload_entry
+from custom_components.nestquest.children import (
+    create_child,
+    list_children,
+    set_child_active,
+)
+from custom_components.nestquest.const import DOMAIN
+from custom_components.nestquest.materialize import materialize
+from custom_components.nestquest.quest_definitions import (
+    create_quest_definition,
+)
+from custom_components.nestquest.recurrence import ScheduleRule
+
+SEED_HORIZON_DAYS = 3
+PER_CHILD_KINDS = (
+    "quests_due_today",
+    "quests_completed_today",
+    "quests_remaining_today",
+    "completion_pct_today",
+    "next_quest",
+    "all_done",
+    "present_today",
+)
+HOUSEHOLD_UNIQUE_IDS = (
+    "nestquest_household_quests_due_today",
+    "nestquest_household_quests_completed_today",
+    "nestquest_cycle_day",
+)
+
+
+async def _reload(hass, entry) -> None:
+    """Unload then set up: the harness's restart/reload equivalent."""
+    assert await async_unload_entry(hass, entry) is True
+    assert await async_setup_entry(hass, entry) is True
+
+
+def _child_unique_ids(child_id: int) -> set[str]:
+    return {f"nestquest_child_{child_id}_{kind}" for kind in PER_CHILD_KINDS}
+
+
+async def _setup_and_seed(hass, make_entry):
+    entry = wire_entry_to_registry(make_entry(), hass.registry)
+    assert await async_setup_entry(hass, entry) is True
+    database = entry.runtime_data.database
+    ada = await create_child(database, "Ada")
+    bo = await create_child(database, "Bo")
+    today = datetime.date.today()
+    await create_quest_definition(
+        database,
+        "Brush teeth",
+        ScheduleRule.from_dict(
+            {"rule_type": "daily", "start_date": today.isoformat()}
+        ),
+        [ada.id, bo.id],
+        ["morning"],
+    )
+    end = (today + datetime.timedelta(days=SEED_HORIZON_DAYS)).isoformat()
+    await materialize(database, today.isoformat(), end, today=today)
+    await entry.runtime_data.coordinator.async_refresh()
+    return entry, ada, bo
+
+
+async def test_deactivated_child_entities_removed_on_reload(
+    hass, make_entry
+) -> None:
+    entry, ada, bo = await _setup_and_seed(hass, make_entry)
+    assert _child_unique_ids(ada.id) <= set(hass.entities)
+    assert _child_unique_ids(bo.id) <= set(hass.entities)
+
+    await set_child_active(entry.runtime_data.database, bo.id, False)
+    await _reload(hass, entry)
+
+    assert _child_unique_ids(ada.id) <= set(hass.entities), (
+        "the surviving child's entities must be untouched"
+    )
+    assert not (_child_unique_ids(bo.id) & set(hass.entities)), (
+        "the deactivated child's entities must be gone after reload"
+    )
+
+
+async def test_reactivation_restores_entities_with_original_unique_ids(
+    hass, make_entry
+) -> None:
+    entry, ada, bo = await _setup_and_seed(hass, make_entry)
+    original = _child_unique_ids(bo.id)
+    await set_child_active(entry.runtime_data.database, bo.id, False)
+    await _reload(hass, entry)
+    assert not (original & set(hass.entities))
+
+    await set_child_active(entry.runtime_data.database, bo.id, True)
+    await _reload(hass, entry)
+
+    assert original <= set(hass.entities), (
+        "reactivation must restore the exact original unique_ids"
+    )
+    bo_due = hass.entities[f"nestquest_child_{bo.id}_quests_due_today"]
+    assert bo_due.native_value == 1, "restored entities carry live state"
+
+
+async def test_new_child_gets_entities_without_disturbing_existing(
+    hass, make_entry
+) -> None:
+    entry, ada, bo = await _setup_and_seed(hass, make_entry)
+    before_ada = set(hass.entities) & _child_unique_ids(ada.id)
+
+    cory = await create_child(entry.runtime_data.database, "Cory")
+    await _reload(hass, entry)
+
+    assert before_ada <= set(hass.entities), "existing entities untouched"
+    assert _child_unique_ids(cory.id) <= set(hass.entities), (
+        "the new child's entities appear after reload"
+    )
+    assert hass.entities[f"nestquest_child_{cory.id}_quests_due_today"].native_value == 0
+
+
+async def test_restart_equivalent_restores_all_entity_states(
+    hass, make_entry
+) -> None:
+    """Unload + setup (the restart equivalent) restores every active
+    child's entities with correct states and the household rollups."""
+    from custom_components.nestquest.completion import complete_instance
+
+    entry, ada, bo = await _setup_and_seed(hass, make_entry)
+    coordinator = entry.runtime_data.coordinator
+    snapshot_ada = next(
+        child
+        for child in coordinator.data.children
+        if child.child_id == ada.id
+    )
+    await complete_instance(
+        entry.runtime_data.database,
+        snapshot_ada.instances[0].instance_id,
+        actor_source="panel",
+        actor_child_id=ada.id,
+    )
+    await coordinator.async_refresh()
+    assert hass.entities[
+        f"nestquest_child_{ada.id}_quests_completed_today"
+    ].native_value == 1
+
+    await _reload(hass, entry)
+
+    assert hass.entities[
+        f"nestquest_child_{ada.id}_quests_completed_today"
+    ].native_value == 1, "completed count survives the restart"
+    assert hass.entities[
+        f"nestquest_child_{bo.id}_quests_completed_today"
+    ].native_value == 0
+    assert set(HOUSEHOLD_UNIQUE_IDS) <= set(hass.entities)
+    assert hass.entities[
+        "nestquest_household_quests_completed_today"
+    ].native_value == 1