Cache flattened service descriptions in websocket api

homeassistant/components/websocket_api/automation.py

@@ -24,9 +24,14 @@ from homeassistant.helpers.trigger import (
     async_get_all_descriptions as async_get_all_trigger_descriptions,
 )
 from homeassistant.helpers.typing import ConfigType
+from homeassistant.util.hass_dict import HassKey
 
 _LOGGER = logging.getLogger(__name__)
 
+FLAT_SERVICE_DESCRIPTIONS_CACHE: HassKey[
+    tuple[dict[str, dict[str, Any]], dict[str, dict[str, Any] | None]]
+] = HassKey("websocket_automation_flat_service_description_cache")
+
 
 @dataclass(slots=True, kw_only=True)
 class _EntityFilter:
@@ -217,12 +222,29 @@ async def async_get_services_for_target(
 ) -> set[str]:
     """Get services for a target."""
     descriptions = await async_get_all_service_descriptions(hass)
-    # Flatten dicts to be keyed by domain.name to match trigger/condition format
-    descriptions_flatten = {
-        f"{domain}.{service_name}": desc
-        for domain, services in descriptions.items()
-        for service_name, desc in services.items()
-    }
+
+    def get_flattened_service_descriptions() -> dict[str, dict[str, Any] | None]:
+        """Get flattened service descriptions, with caching."""
+        if FLAT_SERVICE_DESCRIPTIONS_CACHE in hass.data:
+            cached_descriptions, cached_flat_descriptions = hass.data[
+                FLAT_SERVICE_DESCRIPTIONS_CACHE
+            ]
+            # If the descriptions are the same, return the cached flattened version
+            if cached_descriptions is descriptions:
+                return cached_flat_descriptions
+
+        # Flatten dicts to be keyed by domain.name to match trigger/condition format
+        flat_descriptions = {
+            f"{domain}.{service_name}": desc
+            for domain, services in descriptions.items()
+            for service_name, desc in services.items()
+        }
+        hass.data[FLAT_SERVICE_DESCRIPTIONS_CACHE] = (
+            descriptions,
+            flat_descriptions,
+        )
+        return flat_descriptions
+
     return _async_get_automation_components_for_target(
-        hass, target_selector, expand_group, descriptions_flatten
+        hass, target_selector, expand_group, get_flattened_service_descriptions()
     )

tests/components/websocket_api/test_commands.py

@@ -4162,3 +4162,81 @@ async def test_get_services_for_target(
             "switch.turn_on",
         ],
     )
+
+
+@patch("annotatedyaml.loader.load_yaml")
+@patch.object(Integration, "has_services", return_value=True)
+async def test_get_services_for_target_caching(
+    mock_has_services: Mock,
+    mock_load_yaml: Mock,
+    hass: HomeAssistant,
+    websocket_client: MockHAClientWebSocket,
+) -> None:
+    """Test that flattened service descriptions are cached and reused."""
+
+    def get_common_service_descriptions(domain: str):
+        return f"""
+        turn_on:
+          target:
+            entity:
+              domain: {domain}
+        """
+
+    def _load_yaml(fname, secrets=None):
+        domain = fname.split("/")[-2]
+        with io.StringIO(get_common_service_descriptions(domain)) as file:
+            return parse_yaml(file)
+
+    mock_load_yaml.side_effect = _load_yaml
+    await hass.async_block_till_done()
+
+    hass.services.async_register("light", "turn_on", lambda call: None)
+    hass.services.async_register("switch", "turn_on", lambda call: None)
+    await hass.async_block_till_done()
+
+    async def call_command():
+        await websocket_client.send_json_auto_id(
+            {
+                "type": "get_services_for_target",
+                "target": {"entity_id": ["light.test1"]},
+            }
+        )
+        msg = await websocket_client.receive_json()
+        assert msg["success"]
+
+    with patch(
+        "homeassistant.components.websocket_api.automation._async_get_automation_components_for_target",
+        return_value=set(),
+    ) as mock_get_components:
+        # First call: should create and cache flat descriptions
+        await call_command()
+
+        assert mock_get_components.call_count == 1
+        first_flat_descriptions = mock_get_components.call_args_list[0][0][3]
+        assert first_flat_descriptions == {
+            "light.turn_on": {
+                "fields": {},
+                "target": {"entity": [{"domain": ["light"]}]},
+            },
+            "switch.turn_on": {
+                "fields": {},
+                "target": {"entity": [{"domain": ["switch"]}]},
+            },
+        }
+
+        # Second call: should reuse cached flat descriptions
+        await call_command()
+        assert mock_get_components.call_count == 2
+        second_flat_descriptions = mock_get_components.call_args_list[1][0][3]
+        assert first_flat_descriptions is second_flat_descriptions
+
+        # Register a new service to invalidate cache
+        hass.services.async_register("new_domain", "new_service", lambda call: None)
+        await hass.async_block_till_done()
+
+        # Third call: cache should be rebuilt
+        await call_command()
+        assert mock_get_components.call_count == 3
+        third_flat_descriptions = mock_get_components.call_args_list[2][0][3]
+        assert "new_domain.new_service" in third_flat_descriptions
+        assert third_flat_descriptions is not first_flat_descriptions