Avoid emitting empty ASR config

When no STT vendor is configured, stop serializing an empty asr object. This prevents the generated Asr model from defaulting the vendor back to ares and keeps ASR fallback behavior owned by the API.

Author: seymourtang

src/agora_agent/agentkit/agent.py

@@ -1041,7 +1041,7 @@ def to_properties(
         allow_missing_tts = "tts" in allow_missing_categories
 
         turn_detection_config = self._resolve_turn_detection_config()
-        if not skip_asr_validation and (self._stt is not None or not allow_missing_asr):
+        if not skip_asr_validation and self._stt is not None:
             base_kwargs["asr"] = self._resolve_asr_config(turn_detection_config)
         base_kwargs["turn_detection"] = turn_detection_config
 

tests/custom/test_request_body.py

@@ -349,9 +349,7 @@ def test_session_start_properties_without_stt_does_not_inject_default_asr_vendor
 
     props = build_properties(agent, allow_missing={"asr"})
 
-    assert props["asr"] == {
-        "language": "zh-CN",
-    }
+    assert "asr" not in props
     assert props["turn_detection"] == {"language": "zh-CN"}
 
 

tests/custom/test_stt_language.py

@@ -81,7 +81,7 @@ def test_invalid_turn_detection_language_is_rejected() -> None:
 def test_default_turn_detection_language_is_sent_without_stt() -> None:
     props = properties(base_agent())
 
-    assert props["asr"] == {"language": "en-US"}
+    assert "asr" not in props
     assert props["turn_detection"] == {"language": "en-US"}