diff --git a/src/google/adk/cli/conformance/test_case.py b/src/google/adk/cli/conformance/test_case.py
new file mode 100644
index 00000000..e68182f0
--- /dev/null
+++ b/src/google/adk/cli/conformance/test_case.py
@@ -0,0 +1,107 @@
+# Copyright 2025 Google LLC
+#
+# Licensed under the Apache License, Version 2.0 (the "License");
+# you may not use this file except in compliance with the License.
+# You may obtain a copy of the License at
+#
+#     http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+# See the License for the specific language governing permissions and
+# limitations under the License.
+
+from __future__ import annotations
+
+from typing import Optional
+
+from google.genai import types
+from pydantic import BaseModel
+from pydantic import ConfigDict
+from pydantic import Field
+
+from ...models.llm_request import LlmRequest
+from ...models.llm_response import LlmResponse
+
+
+class TestSpec(BaseModel):
+  """Test specification for conformance test cases.
+
+  This is the human-authored specification that defines what should be tested.
+  Category and name are inferred from folder structure.
+  """
+
+  model_config = ConfigDict(
+      extra="forbid",
+  )
+
+  description: str
+  """Human-readable description of what this test validates."""
+
+  agent: str
+  """Name of the ADK agent to test against."""
+
+  user_messages: list[str]
+  """Sequence of user messages to send to the agent during test execution."""
+
+
+class LlmRecording(BaseModel):
+  """Paired LLM request and response."""
+
+  model_config = ConfigDict(
+      extra="forbid",
+  )
+
+  llm_request: LlmRequest
+  """The LLM request."""
+
+  llm_response: LlmResponse
+  """The LLM response."""
+
+
+class ToolRecording(BaseModel):
+  """Paired tool call and response."""
+
+  model_config = ConfigDict(
+      extra="forbid",
+  )
+
+  tool_call: types.FunctionCall
+  """The tool call."""
+
+  tool_response: types.FunctionResponse
+  """The tool response."""
+
+
+class Recording(BaseModel):
+  """Single interaction recording, ordered by request timestamp."""
+
+  model_config = ConfigDict(
+      extra="forbid",
+  )
+
+  invocation_id: str
+  """Unique invocation identifier."""
+
+  agent_name: str
+  """Name of the agent."""
+
+  # oneof fields - start
+  llm_recording: Optional[LlmRecording] = None
+  """LLM request-response pair."""
+
+  tool_recording: Optional[ToolRecording] = None
+  """Tool call-response pair."""
+  # oneof fields - end
+
+
+class Recordings(BaseModel):
+  """All recordings in chronological order."""
+
+  model_config = ConfigDict(
+      extra="forbid",
+  )
+
+  recordings: list[Recording] = Field(default_factory=list)
+  """Chronological list of all recordings."""