diff --git a/src/langbot/pkg/agent/runner/context_builder.py b/src/langbot/pkg/agent/runner/context_builder.py
index 6f8d5822..834a9c70 100644
--- a/src/langbot/pkg/agent/runner/context_builder.py
+++ b/src/langbot/pkg/agent/runner/context_builder.py
@@ -115,7 +115,7 @@ class AgentRuntimeContext(typing.TypedDict):
     """Agent runtime context."""
 
     langbot_version: str | None
-    sdk_protocol_version: str
+    protocol_version: str
     trace_id: str | None
     deadline_at: float | None
     metadata: dict[str, typing.Any]
@@ -263,7 +263,7 @@ class AgentRunContextBuilder:
         # Build runtime context
         runtime: AgentRuntimeContext = {
             'langbot_version': self.ap.ver_mgr.get_current_version(),
-            'sdk_protocol_version': descriptor.protocol_version,
+            'protocol_version': descriptor.protocol_version,
             'trace_id': run_id,
             'deadline_at': self._build_deadline_from_binding(binding),
             'metadata': {
diff --git a/tests/unit_tests/agent/test_context_validation.py b/tests/unit_tests/agent/test_context_validation.py
index b9fe3df1..ac0ef594 100644
--- a/tests/unit_tests/agent/test_context_validation.py
+++ b/tests/unit_tests/agent/test_context_validation.py
@@ -144,6 +144,10 @@ class TestContextValidation:
         assert isinstance(validated.resources, AgentResources)
         assert validated.runtime is not None
         assert isinstance(validated.runtime, AgentRuntimeContext)
+        assert validated.runtime.protocol_version == "1"
+        assert "protocol_version" in validated.runtime.model_dump()
+        assert "sdk_protocol_version" not in validated.runtime.model_dump()
+        assert "sdk_protocol_version" not in context_dict["runtime"]
 
         # Verify event context
         assert validated.event.event_id == "evt_1"