From 87ea96a3e0db65029f7eeafb974dc7aa4b63bb5b Mon Sep 17 00:00:00 2001
From: Erik Montnemery <erik@montnemery.com>
Date: Wed, 26 Nov 2025 16:03:14 +0100
Subject: [PATCH] Save entity registry store in worker thread (#157274)

---
 homeassistant/helpers/entity_registry.py | 11 ++++++++---
 homeassistant/helpers/registry.py        |  1 -
 2 files changed, 8 insertions(+), 4 deletions(-)

diff --git a/homeassistant/helpers/entity_registry.py b/homeassistant/helpers/entity_registry.py
index 3b0cb67f6a2..a6b26af4e02 100644
--- a/homeassistant/helpers/entity_registry.py
+++ b/homeassistant/helpers/entity_registry.py
@@ -824,6 +824,7 @@ class EntityRegistry(BaseRegistry):
             STORAGE_KEY,
             atomic_writes=True,
             minor_version=STORAGE_VERSION_MINOR,
+            serialize_in_event_loop=False,
         )
         self.hass.bus.async_listen(
             EVENT_DEVICE_REGISTRY_UPDATED,
@@ -1630,13 +1631,17 @@ class EntityRegistry(BaseRegistry):
         self.entities = entities
         self._entities_data = entities.data
 
-    @callback
     def _data_to_save(self) -> dict[str, Any]:
         """Return data of entity registry to store in a file."""
+        # Create intermediate lists to allow this method to be called from a thread
+        # other than the event loop.
         return {
-            "entities": [entry.as_storage_fragment for entry in self.entities.values()],
+            "entities": [
+                entry.as_storage_fragment for entry in list(self.entities.values())
+            ],
             "deleted_entities": [
-                entry.as_storage_fragment for entry in self.deleted_entities.values()
+                entry.as_storage_fragment
+                for entry in list(self.deleted_entities.values())
             ],
         }
 
diff --git a/homeassistant/helpers/registry.py b/homeassistant/helpers/registry.py
index 21f2178554e..6c5fd117140 100644
--- a/homeassistant/helpers/registry.py
+++ b/homeassistant/helpers/registry.py
@@ -77,7 +77,6 @@ class BaseRegistry[_StoreDataT: Mapping[str, Any] | Sequence[Any]](ABC):
         delay = SAVE_DELAY if self.hass.state is CoreState.running else SAVE_DELAY_LONG
         self._store.async_delay_save(self._data_to_save, delay)
 
-    @callback
     @abstractmethod
     def _data_to_save(self) -> _StoreDataT:
         """Return data of registry to store in a file."""