diff --git a/src/clean_agent_preview.py b/src/clean_agent_preview.py
index 1d5b466a5..4589f7329 100644
--- a/src/clean_agent_preview.py
+++ b/src/clean_agent_preview.py
@@ -3899,6 +3899,7 @@ def provider_wire_messages(messages):
             item.get('role') == 'assistant'
             and not item.get('content')
             and not item.get('tool_calls')
+            and not item.get('reasoning_content')
         ):
             continue
         cleaned.append(item)
@@ -4483,7 +4484,7 @@ async def stream_preview(*, endpoint_url, model, messages, headers, turn_contrac
                                 'function': {'name': private_browser_name},
                             }
                         force_private_browser_next_round = False
-                pending, content = {}, ''
+                pending, content, round_reasoning = {}, '', ''
                 streamed_round_text = False
                 request = search_tool_choice_request(request)
                 request = provider_compatible_tool_choice_request(request, model)
@@ -4528,6 +4529,14 @@ async def stream_preview(*, endpoint_url, model, messages, headers, turn_contrac
                         if not choices:
                             continue
                         delta = choices[0].get('delta') or {}
+                        reasoning = (
+                            delta.get('reasoning_content')
+                            or delta.get('reasoning')
+                            or delta.get('thinking')
+                            or ''
+                        )
+                        if reasoning:
+                            round_reasoning += str(reasoning)
                         text = delta.get('content') or ''
                         if text:
                             first_token = first_token or time.monotonic()
@@ -4610,6 +4619,12 @@ async def stream_preview(*, endpoint_url, model, messages, headers, turn_contrac
                         yield event({'type': 'model_tool_proposal', 'round': round_number,
                                      'function': proposal.get('function', {})})
                 message = {'role': 'assistant', 'content': content or None}
+                if round_reasoning and 'deepseek' in str(model or '').casefold():
+                    # DeepSeek requires each tool-round reasoning payload to
+                    # be echoed verbatim on subsequent requests. Unlike local
+                    # Qwen/Nemotron templates, its API owns this structured
+                    # field and does not reinterpret it as visible output.
+                    message['reasoning_content'] = round_reasoning
                 if proposed:
                     message['tool_calls'] = protocol_safe_tool_calls(proposed)
                 history.append(message)
diff --git a/tests/test_clean_agent_preview.py b/tests/test_clean_agent_preview.py
index 5dd85663b..05c8376c3 100644
--- a/tests/test_clean_agent_preview.py
+++ b/tests/test_clean_agent_preview.py
@@ -531,18 +531,30 @@ def test_repeated_off_contract_artifact_calls_trigger_single_file_body_handoff()
     )
 
 
+def test_provider_wire_keeps_deepseek_reasoning_only_turn_for_continuity():
+    import src.clean_agent_preview as module
+
+    messages = [{
+        'role': 'assistant',
+        'content': None,
+        'reasoning_content': 'private provider reasoning token stream',
+    }]
+
+    assert module.provider_wire_messages(messages) == messages
+
+
 @pytest.mark.asyncio
 async def test_repeated_off_contract_calls_recover_via_required_artifact_body(monkeypatch):
     import src.clean_agent_preview as module
 
     responses = iter([
-        {'choices': [{'delta': {'tool_calls': [{
+        {'choices': [{'delta': {'reasoning_content': 'reasoning-one', 'tool_calls': [{
             'index': 0, 'id': 'bad-bash',
             'function': {'name': 'bash', 'arguments': json.dumps({
                 'command': 'echo nope',
             })},
         }]}}]},
-        {'choices': [{'delta': {'tool_calls': [{
+        {'choices': [{'delta': {'reasoning_content': 'reasoning-two', 'tool_calls': [{
             'index': 0, 'id': 'bad-python',
             'function': {'name': 'python', 'arguments': json.dumps({
                 'code': 'print("nope")',
@@ -566,11 +578,14 @@ async def test_repeated_off_contract_calls_recover_via_required_artifact_body(mo
             yield 'data: ' + json.dumps(self.payload)
             yield 'data: [DONE]'
 
+    requests = []
+
     class Client:
         def __init__(self, **kwargs): pass
         async def __aenter__(self): return self
         async def __aexit__(self, *args): pass
         def stream(self, *args, **kwargs):
+            requests.append(kwargs['json'])
             return Response(next(responses))
 
     executed = []
@@ -602,6 +617,11 @@ async def test_repeated_off_contract_calls_recover_via_required_artifact_body(mo
     )]
 
     assert [block.tool_type for block in executed] == ['write_file']
+    prior_tool_turn = next(
+        message for message in requests[1]['messages']
+        if message.get('role') == 'assistant' and message.get('tool_calls')
+    )
+    assert prior_tool_turn['reasoning_content'] == 'reasoning-one'
     assert executed[0].content == (
         '/workspace/output.html\n<html><body>Recovered</body></html>'
     )