fix(proto): stringify map values in encode_by_name

livekit-agents/livekit/agents/_proto.py

@@ -55,7 +55,8 @@ def encode_by_name(msg_type: type[_ProtoT], src: Any, **overrides: Any) -> _Prot
     """Build ``msg_type`` by copying same-named entries off ``src``, a mapping or an object.
 
     Only fields the proto declares are read, and a field ``src`` has nothing for is
-    left unset. Seconds-since-epoch floats fill Timestamp fields.
+    left unset. Seconds-since-epoch floats fill Timestamp fields, and map values are
+    stringified: every map these protos declare is ``map<string, string>``.
     """
 
     def lookup(name: str) -> Any:
@@ -70,6 +71,8 @@ def lookup(name: str) -> Any:
             continue
         if fd.message_type is not None and fd.message_type.full_name == "google.protobuf.Timestamp":
             value = encode_timestamp(value)
+        elif fd.message_type is not None and fd.message_type.GetOptions().map_entry:
+            value = {k: str(v) for k, v in value.items()}
         kwargs[fd.name] = value
     return msg_type(**kwargs)
 
@@ -94,7 +97,6 @@ def encode_chat_item(item: ChatItem) -> _pb.ChatContext.ChatItem:
                 role=ROLES[item.role],
                 content=content,
                 metrics=encode_metrics(item.metrics),
-                extra={k: str(v) for k, v in item.extra.items()},
             )
         )
     elif item.type == "function_call":

tests/test_chat_item_proto_coverage.py

@@ -63,7 +63,14 @@
             "llm_node_ttfs": 1.0,
         },
     ),
-    FunctionCall(id="item_fc", call_id="call-1", name="fn", arguments="{}", created_at=_TS),
+    FunctionCall(
+        id="item_fc",
+        call_id="call-1",
+        name="fn",
+        arguments="{}",
+        extra={"livekit": {"inference_deployment": "d"}},
+        created_at=_TS,
+    ),
     FunctionCallOutput(
         id="item_fco",
         call_id="call-1",
@@ -121,6 +128,13 @@ def test_message_content_is_one_entry_per_part() -> None:
     assert [c.text for c in msg.content] == ["hello", "bye"]
 
 
+def test_map_values_are_stringified() -> None:
+    # extra dicts hold provider payloads and flags, the wire maps only strings
+    extra = {"livekit": {"inference_deployment": "d"}, "flag": True}
+    msg = encode_by_name(agent_pb.ChatMessage, {"extra": extra})
+    assert dict(msg.extra) == {k: str(v) for k, v in extra.items()}
+
+
 def _saturated(src_type: Any, msg_type: type[Message]) -> Any:
     kwargs: dict[str, Any] = {}
     for fd in msg_type.DESCRIPTOR.fields: