HA-008 HA-009: add discovery and history pipeline

Closes #17

Closes #18

tests/ha/test_ha_client.py

@@ -1,5 +1,6 @@
 from __future__ import annotations
 
+from datetime import datetime, timezone
 from unittest.mock import Mock
 
 import pytest
@@ -68,4 +69,60 @@ def test_list_entities_rejects_invalid_json() -> None:
 def test_list_entities_rejects_non_list_payload() -> None:
     client = _client_with_response(_response(payload={"entity_id": "sensor.temperature"}))
     with pytest.raises(HaUnexpectedPayloadError):
-        client.list_entities()
+        client.list_entities()
+
+
+def test_get_history_calls_home_assistant_history_api() -> None:
+    response = _response(payload=[[{"entity_id": "sensor.temperature", "state": "21.0"}]])
+    client = _client_with_response(response)
+    start = datetime(2026, 6, 1, tzinfo=timezone.utc)
+    end = datetime(2026, 6, 2, tzinfo=timezone.utc)
+
+    payload = client.get_history(["sensor.temperature"], start, end)
+
+    assert payload == [[{"entity_id": "sensor.temperature", "state": "21.0"}]]
+    client._session.get.assert_called_once()  # type: ignore[attr-defined]
+    call = client._session.get.call_args  # type: ignore[attr-defined]
+    assert "/api/history/period/2026-06-01T00:00:00+00:00" in call.args[0]
+    assert call.kwargs["params"]["filter_entity_id"] == "sensor.temperature"
+    assert call.kwargs["params"]["end_time"] == "2026-06-02T00:00:00+00:00"
+
+
+@pytest.mark.parametrize(
+    ("entity_ids", "start", "end"),
+    [
+        (
+            [],
+            datetime(2026, 6, 1, tzinfo=timezone.utc),
+            datetime(2026, 6, 2, tzinfo=timezone.utc),
+        ),
+        (
+            ["sensor.temperature"],
+            datetime(2026, 6, 1),
+            datetime(2026, 6, 2, tzinfo=timezone.utc),
+        ),
+        (
+            ["sensor.temperature"],
+            datetime(2026, 6, 2, tzinfo=timezone.utc),
+            datetime(2026, 6, 1, tzinfo=timezone.utc),
+        ),
+        (
+            ["invalid entity"],
+            datetime(2026, 6, 1, tzinfo=timezone.utc),
+            datetime(2026, 6, 2, tzinfo=timezone.utc),
+        ),
+        (
+            ["sensor.temperature"],
+            datetime(2026, 5, 1, tzinfo=timezone.utc),
+            datetime(2026, 6, 2, tzinfo=timezone.utc),
+        ),
+    ],
+)
+def test_get_history_validates_request(
+    entity_ids: list[str],
+    start: datetime,
+    end: datetime,
+) -> None:
+    client = HaClient(HaClientSettings(url="http://ha.local", token="test-token"))
+    with pytest.raises(ValueError):
+        client.get_history(entity_ids, start, end)