diff --git a/coworker/providers/registry.py b/coworker/providers/registry.py
index 04ed994e..1f7aea8e 100644
--- a/coworker/providers/registry.py
+++ b/coworker/providers/registry.py
@@ -211,7 +211,11 @@ def _openai_compat(vendor: str, default_base_url: str, env_key: Optional[str] =
 
 
 def _openai_responses_compat(
-    vendor: str, default_base_url: str, env_key: Optional[str] = None
+    vendor: str,
+    default_base_url: str,
+    env_key: Optional[str] = None,
+    *,
+    reasoning_summary: bool = True,
 ):
     """Builder factory for vendors that explicitly implement the OpenAI Responses API.
 
@@ -228,7 +232,11 @@ def _openai_responses_compat(
             raise RuntimeError(
                 f"No {vendor} API key configured — add it in Settings ▸ Models."
             )
-        return OpenAIResponsesProvider(api_key=api_key, base_url=base_url)
+        return OpenAIResponsesProvider(
+            api_key=api_key,
+            base_url=base_url,
+            reasoning_summary=reasoning_summary,
+        )
 
     return build
 
@@ -279,6 +287,7 @@ def _responses_compat(
     recommended_model: str,
     env_key: str,
     endpoint_help: str = "",
+    reasoning_summary: bool = True,
 ) -> ProviderDescriptor:
     """Descriptor for a vendor exposing the OpenAI Responses API."""
     return ProviderDescriptor(
@@ -301,7 +310,12 @@ def _responses_compat(
                 or f"Prefilled with {title}'s official Responses endpoint.",
             ),
         ],
-        build=_openai_responses_compat(title, base_url, env_key),
+        build=_openai_responses_compat(
+            title,
+            base_url,
+            env_key,
+            reasoning_summary=reasoning_summary,
+        ),
         recommended_model=recommended_model,
         env_key=env_key,
         blurb=f"Uses {title}'s OpenAI-compatible Responses API — the endpoint is prefilled, just add your key.",
@@ -532,6 +546,7 @@ DESCRIPTORS: list[ProviderDescriptor] = [
         recommended_model="dola-seed-evolving-latest-version",
         env_key="ARK_API_KEY",
         endpoint_help="BytePlus Ark's Asia Pacific endpoint. This provider is separate from Volcengine Ark Agent Plan.",
+        reasoning_summary=False,
     ),
     _responses_compat(
         "ark-agent-plan-cn",
diff --git a/tests/test_providers.py b/tests/test_providers.py
index ad886429..064926db 100644
--- a/tests/test_providers.py
+++ b/tests/test_providers.py
@@ -343,11 +343,13 @@ ARK_RESPONSES_VENDORS = {
         "base_url": "https://ark.ap-southeast.bytepluses.com/api/v3",
         "env_key": "ARK_API_KEY",
         "recommended_model": "dola-seed-evolving-latest-version",
+        "reasoning_summary": False,
     },
     "ark-agent-plan-cn": {
         "base_url": "https://ark.cn-beijing.volces.com/api/plan/v3",
         "env_key": "ARK_AGENT_PLAN_CN_API_KEY",
         "recommended_model": "doubao-seed-evolving",
+        "reasoning_summary": True,
     },
 }
 
@@ -366,7 +368,7 @@ def test_ark_responses_descriptors_are_separate():
         assert not base.required
 
 
-def test_ark_responses_builders_use_their_own_keys_and_endpoints(monkeypatch):
+def test_ark_responses_builder_capabilities_PathsUnchanged(monkeypatch):
     from coworker.providers.openai_responses import OpenAIResponsesProvider
     from coworker.providers.registry import build_provider_client
 
@@ -384,6 +386,10 @@ def test_ark_responses_builders_use_their_own_keys_and_endpoints(monkeypatch):
         "plan-key",
         ARK_RESPONSES_VENDORS["ark-agent-plan-cn"]["base_url"],
     )
+    assert bp._reasoning_summary is ARK_RESPONSES_VENDORS["ark"]["reasoning_summary"]
+    assert plan._reasoning_summary is ARK_RESPONSES_VENDORS["ark-agent-plan-cn"][
+        "reasoning_summary"
+    ]
 
 
 def test_ark_responses_never_leak_the_openai_key(monkeypatch):