diff --git a/tests/test_protocols.py b/tests/test_protocols.py
index e7c016ec..a06bad17 100644
--- a/tests/test_protocols.py
+++ b/tests/test_protocols.py
@@ -930,6 +930,98 @@ async def test_task_id_cleared_on_unknown_state(self, a2a_config):
 
         assert adapter.active_task_id is None
 
+    @pytest.mark.asyncio
+    async def test_rejected_task_result_content(self, a2a_config):
+        """TASK_STATE_REJECTED — adapter returns SUBMITTED status with 'rejected'
+        in metadata and the TextPart message. REJECTED is terminal (task_id is
+        cleared) but routes through the non-COMPLETED else-branch in
+        _process_task_response, so data=None."""
+        adapter = A2AAdapter(a2a_config)
+
+        rejected = create_mock_a2a_task(
+            task_id="task-rejected-content",
+            context_id="ctx-rej",
+            state="rejected",
+            parts=[TextPart(text="policy violation: brand safety")],
+        )
+        mock_a2a_client = AsyncMock()
+        mock_a2a_client.send_message = AsyncMock(
+            return_value=SendMessageSuccessResponse(result=rejected)
+        )
+
+        with patch.object(adapter, "_get_a2a_client", return_value=mock_a2a_client):
+            result = await adapter._call_a2a_tool("create_media_buy", {})
+
+        assert result.status == TaskStatus.SUBMITTED
+        assert result.data is None
+        assert result.message == "policy violation: brand safety"
+        assert result.metadata is not None
+        assert result.metadata["status"] == "rejected"
+
+    @pytest.mark.asyncio
+    async def test_rejected_task_adcp_error_datapart_not_extracted(self, a2a_config):
+        """TASK_STATE_REJECTED with a DataPart carrying adcp_error — the
+        DataPart is silently dropped because _process_task_response only
+        calls _extract_result_from_task for COMPLETED tasks.  This test
+        documents the current gap: callers cannot read structured error
+        detail from a rejected task's artifact without a separate fix."""
+        adapter = A2AAdapter(a2a_config)
+
+        rejected = create_mock_a2a_task(
+            task_id="task-rejected-err",
+            context_id="ctx-rej-err",
+            state="rejected",
+            parts=[
+                DataPart(data={"adcp_error": {"code": "POLICY_VIOLATION", "message": "rejected"}}),
+                TextPart(text="rejected by server"),
+            ],
+        )
+        mock_a2a_client = AsyncMock()
+        mock_a2a_client.send_message = AsyncMock(
+            return_value=SendMessageSuccessResponse(result=rejected)
+        )
+
+        with patch.object(adapter, "_get_a2a_client", return_value=mock_a2a_client):
+            result = await adapter._call_a2a_tool("create_media_buy", {})
+
+        assert result.status == TaskStatus.SUBMITTED
+        # Gap: adcp_error DataPart is not extracted for non-COMPLETED states.
+        # A future fix should surface structured error detail here.
+        assert result.data is None
+        assert result.message == "rejected by server"
+        assert result.metadata is not None
+        assert result.metadata["status"] == "rejected"
+
+    @pytest.mark.asyncio
+    async def test_auth_required_task_result_content(self, a2a_config):
+        """TASK_STATE_AUTH_REQUIRED — non-terminal state. Adapter returns
+        SUBMITTED status with 'auth-required' in metadata and the challenge
+        message from the TextPart.  Callers should surface this to trigger
+        an auth flow before re-submitting."""
+        adapter = A2AAdapter(a2a_config)
+
+        auth_task = create_mock_a2a_task(
+            task_id="task-auth-content",
+            context_id="ctx-auth",
+            state="auth-required",
+            parts=[TextPart(text="OAuth required: redirect to https://auth.example.com")],
+        )
+        mock_a2a_client = AsyncMock()
+        mock_a2a_client.send_message = AsyncMock(
+            return_value=SendMessageSuccessResponse(result=auth_task)
+        )
+
+        with patch.object(adapter, "_get_a2a_client", return_value=mock_a2a_client):
+            result = await adapter._call_a2a_tool("create_media_buy", {})
+
+        assert result.status == TaskStatus.SUBMITTED
+        assert result.data is None
+        assert result.message == "OAuth required: redirect to https://auth.example.com"
+        assert result.metadata is not None
+        assert result.metadata["status"] == "auth-required"
+        assert result.metadata["task_id"] == "task-auth-content"
+        assert result.metadata["context_id"] == "ctx-auth"
+
     @pytest.mark.asyncio
     async def test_state_not_committed_when_post_processing_raises(self, a2a_config):
         """If _process_task_response raises, the adapter must NOT advance