sandbox: B1 — get_translations wire protocol

Add the sandbox/get_translations message pair to the control-channel proto
and regenerate the checked-in gencode for both no-cross-import mirrors.
Mirror MSG_GET_TRANSLATIONS in both protocol.py files and register the
message pair in both messages.py REGISTRY copies.

Request {language, domains[]}; result {language, strings: {domain: raw
strings.json dict}} — main batches a group's custom domains into one call;
built-in domains never cross the wire.

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

homeassistant/components/sandbox/_proto/sandbox_pb2.pyi

@@ -183,6 +183,22 @@ class CallServiceResult(_message.Message):
     response: ServiceResponse
     def __init__(self, response: _Optional[_Union[ServiceResponse, _Mapping]] = ...) -> None: ...
 
+class GetTranslations(_message.Message):
+    __slots__ = ("language", "domains")
+    LANGUAGE_FIELD_NUMBER: _ClassVar[int]
+    DOMAINS_FIELD_NUMBER: _ClassVar[int]
+    language: str
+    domains: _containers.RepeatedScalarFieldContainer[str]
+    def __init__(self, language: _Optional[str] = ..., domains: _Optional[_Iterable[str]] = ...) -> None: ...
+
+class GetTranslationsResult(_message.Message):
+    __slots__ = ("language", "strings")
+    LANGUAGE_FIELD_NUMBER: _ClassVar[int]
+    STRINGS_FIELD_NUMBER: _ClassVar[int]
+    language: str
+    strings: _struct_pb2.Struct
+    def __init__(self, language: _Optional[str] = ..., strings: _Optional[_Union[_struct_pb2.Struct, _Mapping]] = ...) -> None: ...
+
 class Shutdown(_message.Message):
     __slots__ = ()
     def __init__(self) -> None: ...

homeassistant/components/sandbox/messages.py

@@ -38,6 +38,7 @@ REGISTRY: dict[str, tuple[type[Message], type[Message] | None]] = {
     "sandbox/entry_setup": (pb.EntrySetup, pb.EntrySetupResult),
     "sandbox/entry_unload": (pb.EntryUnload, pb.EntryUnloadResult),
     "sandbox/call_service": (pb.CallService, pb.CallServiceResult),
+    "sandbox/get_translations": (pb.GetTranslations, pb.GetTranslationsResult),
     "sandbox/shutdown": (pb.Shutdown, pb.ShutdownResult),
     "sandbox/ping": (pb.Ping, pb.PingResult),
     "sandbox/flow_init": (pb.FlowInit, pb.FlowResult),

homeassistant/components/sandbox/protocol.py

@@ -32,6 +32,14 @@ Main → Sandbox calls:
   the main→sandbox service mirroring path). Payload mirrors a
   ``ServiceCall``: ``(domain, service, target, service_data, context,
   return_response)``. Returns either ``None`` or a service-response dict.
+* ``sandbox/get_translations`` — pull a sandboxed integration's frontend
+  translation strings. Payload ``{language, domains: [str]}`` (main batches
+  every owned custom domain of one group into a single request). Response
+  ``{language, strings: {domain: <raw strings.json dict>}}`` — the
+  un-flattened nesting a ``translations/<lang>.json`` holds, with ``title``
+  pre-filled from the integration name (main has no ``Integration`` for a
+  custom domain, so it cannot run that fallback). Built-in domains never
+  cross the wire — main reads its byte-identical disk copy.
 
 Sandbox → Main calls:
 
@@ -92,6 +100,7 @@ MSG_READY: Final = "sandbox/ready"
 MSG_ENTRY_SETUP: Final = "sandbox/entry_setup"
 MSG_ENTRY_UNLOAD: Final = "sandbox/entry_unload"
 MSG_CALL_SERVICE: Final = "sandbox/call_service"
+MSG_GET_TRANSLATIONS: Final = "sandbox/get_translations"
 MSG_SHUTDOWN: Final = "sandbox/shutdown"
 
 # Sandbox → Main
@@ -111,6 +120,7 @@ __all__ = [
     "MSG_ENTRY_SETUP",
     "MSG_ENTRY_UNLOAD",
     "MSG_FIRE_EVENT",
+    "MSG_GET_TRANSLATIONS",
     "MSG_READY",
     "MSG_REGISTER_ENTITY",
     "MSG_REGISTER_SERVICE",

sandbox/hass_client/hass_client/_proto/sandbox_pb2.pyi

@@ -183,6 +183,22 @@ class CallServiceResult(_message.Message):
     response: ServiceResponse
     def __init__(self, response: _Optional[_Union[ServiceResponse, _Mapping]] = ...) -> None: ...
 
+class GetTranslations(_message.Message):
+    __slots__ = ("language", "domains")
+    LANGUAGE_FIELD_NUMBER: _ClassVar[int]
+    DOMAINS_FIELD_NUMBER: _ClassVar[int]
+    language: str
+    domains: _containers.RepeatedScalarFieldContainer[str]
+    def __init__(self, language: _Optional[str] = ..., domains: _Optional[_Iterable[str]] = ...) -> None: ...
+
+class GetTranslationsResult(_message.Message):
+    __slots__ = ("language", "strings")
+    LANGUAGE_FIELD_NUMBER: _ClassVar[int]
+    STRINGS_FIELD_NUMBER: _ClassVar[int]
+    language: str
+    strings: _struct_pb2.Struct
+    def __init__(self, language: _Optional[str] = ..., strings: _Optional[_Union[_struct_pb2.Struct, _Mapping]] = ...) -> None: ...
+
 class Shutdown(_message.Message):
     __slots__ = ()
     def __init__(self) -> None: ...

sandbox/hass_client/hass_client/messages.py

@@ -38,6 +38,7 @@ REGISTRY: dict[str, tuple[type[Message], type[Message] | None]] = {
     "sandbox/entry_setup": (pb.EntrySetup, pb.EntrySetupResult),
     "sandbox/entry_unload": (pb.EntryUnload, pb.EntryUnloadResult),
     "sandbox/call_service": (pb.CallService, pb.CallServiceResult),
+    "sandbox/get_translations": (pb.GetTranslations, pb.GetTranslationsResult),
     "sandbox/shutdown": (pb.Shutdown, pb.ShutdownResult),
     "sandbox/ping": (pb.Ping, pb.PingResult),
     "sandbox/flow_init": (pb.FlowInit, pb.FlowResult),

sandbox/hass_client/hass_client/protocol.py

@@ -18,6 +18,7 @@ MSG_READY: Final = "sandbox/ready"
 MSG_ENTRY_SETUP: Final = "sandbox/entry_setup"
 MSG_ENTRY_UNLOAD: Final = "sandbox/entry_unload"
 MSG_CALL_SERVICE: Final = "sandbox/call_service"
+MSG_GET_TRANSLATIONS: Final = "sandbox/get_translations"
 MSG_SHUTDOWN: Final = "sandbox/shutdown"
 
 # Sandbox → Main
@@ -37,6 +38,7 @@ __all__ = [
     "MSG_ENTRY_SETUP",
     "MSG_ENTRY_UNLOAD",
     "MSG_FIRE_EVENT",
+    "MSG_GET_TRANSLATIONS",
     "MSG_READY",
     "MSG_REGISTER_ENTITY",
     "MSG_REGISTER_SERVICE",

sandbox/proto/sandbox.proto

@@ -153,6 +153,26 @@ message CallServiceResult {
   optional ServiceResponse response = 1;    // unset when no response returned
 }
 
+// --- get_translations (main -> sandbox) -----------------------------------
+
+// Pull a sandboxed integration's frontend translation strings. Main issues
+// this per sandbox group, batching every owned (custom) domain into one
+// request. Built-in domains never cross the wire — main reads its own
+// byte-identical disk copy.
+message GetTranslations {
+  string language = 1;             // single language per request (e.g. "en")
+  repeated string domains = 2;     // the domains main wants strings for
+}
+
+message GetTranslationsResult {
+  string language = 1;
+  // { domain: <raw strings.json dict> } — the un-flattened nesting a
+  // translations/<lang>.json holds, with `title` already filled in from the
+  // integration name (main has no Integration for a custom domain so it
+  // cannot run that fallback). Domains the sandbox does not own are omitted.
+  google.protobuf.Struct strings = 2;
+}
+
 // --- shutdown / ping (main -> sandbox) ------------------------------------
 
 message Shutdown {}