diff --git a/conf/model_providers.yaml b/conf/model_providers.yaml
index ba3f0ea48..58bb2e7cc 100644
--- a/conf/model_providers.yaml
+++ b/conf/model_providers.yaml
@@ -84,6 +84,7 @@ chat:
       endpoint_url: "/v1/models"
       default_base: "http://host.docker.internal:1234"
     kwargs:
+      a0_api_mode: chat
       api_base: "http://host.docker.internal:1234/v1"
       api_key: "lm-studio"
   llama_cpp:
@@ -93,6 +94,7 @@ chat:
       endpoint_url: "/v1/models"
       default_base: "http://host.docker.internal:8080"
     kwargs:
+      a0_api_mode: chat
       api_base: "http://host.docker.internal:8080/v1"
       api_key: "llama-cpp"
   mistral:
@@ -120,6 +122,7 @@ chat:
       format: "ollama"
       default_base: "http://host.docker.internal:11434"
     kwargs:
+      a0_api_mode: chat
       api_base: "http://host.docker.internal:11434"
   omlx:
     name: oMLX
@@ -128,6 +131,7 @@ chat:
       endpoint_url: "/v1/models"
       default_base: "http://host.docker.internal:8000"
     kwargs:
+      a0_api_mode: chat
       api_base: "http://host.docker.internal:8000/v1"
       api_key: "omlx"
   ollama_cloud:
@@ -136,6 +140,7 @@ chat:
     models_list:
       endpoint_url: "/models"
     kwargs:
+      a0_api_mode: chat
       api_base: https://ollama.com/v1
   openai:
     name: OpenAI
@@ -184,6 +189,7 @@ chat:
       endpoint_url: "/v1/models"
       default_base: "http://host.docker.internal:8000"
     kwargs:
+      a0_api_mode: chat
       api_base: "http://host.docker.internal:8000/v1"
       api_key: "vllm"
   xai:
@@ -208,6 +214,8 @@ chat:
   other:
     name: Other OpenAI compatible
     litellm_provider: openai
+    kwargs:
+      a0_api_mode: chat
 
 embedding:
   huggingface:
diff --git a/tests/test_model_config_api_keys.py b/tests/test_model_config_api_keys.py
index e1f62d2f0..a76c1cd0d 100644
--- a/tests/test_model_config_api_keys.py
+++ b/tests/test_model_config_api_keys.py
@@ -265,6 +265,7 @@ def test_ollama_cloud_provider_config_requires_key_and_base_url():
     ollama_cloud = provider_config["chat"]["ollama_cloud"]
 
     assert ollama_cloud["name"] == "Ollama Cloud"
+    assert ollama_cloud["kwargs"]["a0_api_mode"] == "chat"
     assert ollama_cloud["kwargs"]["api_base"] == "https://ollama.com/v1"
     assert ollama_cloud["models_list"]["endpoint_url"] == "/models"
     assert "api_key_mode" not in ollama_cloud
@@ -298,6 +299,36 @@ def test_direct_venice_chat_provider_defaults_to_chat_completions(monkeypatch):
     assert custom.kwargs["a0_api_mode"] == "responses"
 
 
+def test_local_chat_providers_default_to_chat_completions():
+    import yaml
+
+    provider_path = PROJECT_ROOT / "conf/model_providers.yaml"
+    provider_config = yaml.safe_load(provider_path.read_text(encoding="utf-8"))
+
+    chat_completions_default_providers = (
+        "lm_studio",
+        "llama_cpp",
+        "ollama",
+        "ollama_cloud",
+        "omlx",
+        "other",
+        "vllm",
+    )
+    local_embedding_providers = (
+        "lm_studio",
+        "llama_cpp",
+        "ollama",
+        "omlx",
+        "vllm",
+    )
+
+    for provider in chat_completions_default_providers:
+        assert provider_config["chat"][provider]["kwargs"]["a0_api_mode"] == "chat"
+
+    for provider in local_embedding_providers:
+        assert "a0_api_mode" not in provider_config["embedding"][provider]["kwargs"]
+
+
 def test_missing_api_key_banner_does_not_include_auto_modal_metadata(monkeypatch):
     from plugins._model_config.helpers import model_config