diff --git a/application/api/answer/services/stream_processor.py b/application/api/answer/services/stream_processor.py
index e7ebec6d..e537d30e 100644
--- a/application/api/answer/services/stream_processor.py
+++ b/application/api/answer/services/stream_processor.py
@@ -715,6 +715,9 @@ class StreamProcessor:
             self.agent_config["json_schema_strict"] = self.data.get("json_schema_strict")
         if self.data.get("json_object"):
             self.agent_config["json_object"] = True
+            # An explicit json_object request beats an agent-configured schema
+            # (otherwise the configured json_schema would silently override it).
+            self.agent_config["json_schema"] = None
 
     def _configure_retriever(self):
         """Assemble retriever config; agent's values are authoritative when bound."""
@@ -1309,6 +1312,18 @@ class StreamProcessor:
         if client_tools:
             tool_executor.client_tools = client_tools
 
+        # OpenAI-style image_url content parts are only understood by the
+        # OpenAI-family providers; drop multimodal content for others (Google,
+        # Anthropic, ...) so a multimodal request degrades to text rather than
+        # erroring upstream.
+        from application.llm.openai import OpenAILLM
+
+        request_multimodal = (
+            self.data.get("multimodal_content")
+            if isinstance(llm, OpenAILLM)
+            else None
+        )
+
         agent_kwargs = {
             "endpoint": "stream",
             "llm_name": provider or settings.LLM_PROVIDER,
@@ -1326,7 +1341,7 @@ class StreamProcessor:
             "json_schema_strict": self.agent_config.get("json_schema_strict", True),
             "json_object": self.agent_config.get("json_object", False),
             "llm_params": self.data.get("llm_params") or {},
-            "multimodal_content": self.data.get("multimodal_content"),
+            "multimodal_content": request_multimodal,
             "compressed_summary": self.compressed_summary,
             "llm": llm,
             "llm_handler": llm_handler,
diff --git a/application/api/v1/routes.py b/application/api/v1/routes.py
index 336bc9bc..1b4bfb72 100644
--- a/application/api/v1/routes.py
+++ b/application/api/v1/routes.py
@@ -158,6 +158,12 @@ def chat_completions():
             return usage_error
 
         should_save_conversation = bool(internal_data.get("save_conversation", False))
+        # Only strip leaked reasoning from content for structured requests -- the
+        # only path where models echo reasoning into content -- so legitimate
+        # answers that mention the marker text are never corrupted.
+        strip_reasoning_leak = bool(
+            internal_data.get("json_schema") or internal_data.get("json_object")
+        )
 
         if is_stream:
             return Response(
@@ -169,6 +175,7 @@ def chat_completions():
                     model_name,
                     continuation,
                     should_save_conversation,
+                    strip_reasoning_leak,
                 ),
                 mimetype="text/event-stream",
                 headers={
@@ -185,6 +192,7 @@ def chat_completions():
                 model_name,
                 continuation,
                 should_save_conversation,
+                strip_reasoning_leak,
             )
 
     except ValueError as e:
@@ -215,6 +223,7 @@ def _stream_response(
     model_name: str,
     continuation: Optional[Dict],
     should_save_conversation: bool,
+    strip_reasoning_leak: bool = False,
 ) -> Generator[str, None, None]:
     """Generate translated SSE chunks for streaming response."""
     completion_id = f"chatcmpl-{int(time.time())}"
@@ -258,11 +267,13 @@ def _stream_response(
         # Update completion_id when we get the conversation id
         if event_data.get("type") == "id":
             conv_id = event_data.get("id", "")
-            if conv_id:
+            if conv_id and conv_id != "None":
                 completion_id = f"chatcmpl-{conv_id}"
 
         # Translate to standard format
-        translated = translate_stream_event(event_data, completion_id, model_name)
+        translated = translate_stream_event(
+            event_data, completion_id, model_name, strip_reasoning_leak
+        )
         for chunk in translated:
             yield chunk
 
@@ -275,6 +286,7 @@ def _non_stream_response(
     model_name: str,
     continuation: Optional[Dict],
     should_save_conversation: bool,
+    strip_reasoning_leak: bool = False,
 ) -> Response:
     """Collect full response and return as single JSON."""
     stream = helper.complete_stream(
@@ -309,6 +321,7 @@ def _non_stream_response(
         thought=result["thought"] or "",
         model_name=model_name,
         pending_tool_calls=pending,
+        strip_reasoning_leak=strip_reasoning_leak,
     )
     return make_response(jsonify(response), 200)
 
diff --git a/application/api/v1/translator.py b/application/api/v1/translator.py
index f55f7c3c..94b4f9e7 100644
--- a/application/api/v1/translator.py
+++ b/application/api/v1/translator.py
@@ -243,6 +243,10 @@ def translate_request(
     ):
         if data.get(_k) is not None:
             sampling_params[_k] = data[_k]
+    # OpenAI rejects sending both; the provider maps max_tokens ->
+    # max_completion_tokens, so drop the alias when the canonical key is present.
+    if "max_completion_tokens" in sampling_params:
+        sampling_params.pop("max_tokens", None)
 
     # Check for continuation (tool results after assistant tool_calls)
     if is_continuation(messages):
@@ -259,11 +263,13 @@ def translate_request(
             # rebuilt from the resent messages instead of server-side state.
             "messages": messages,
         }
-        # A continuation only exists if turn 1 was saved, so default to True —
-        # otherwise the final turn and its WAL row are never persisted. An
-        # explicit override is honoured if the client resends it.
+        # Stateful continuations (with a conversation_id) default to True so the
+        # final turn / WAL row is persisted. Stateless continuations (no
+        # conversation_id, e.g. opencode) default to False — otherwise every
+        # tool round persists an orphan conversation with an empty question. An
+        # explicit ``docsgpt.save_conversation`` override is honoured either way.
         result["save_conversation"] = bool(
-            data.get("docsgpt", {}).get("save_conversation", True)
+            data.get("docsgpt", {}).get("save_conversation", bool(conversation_id))
         )
         # Carry tools forward for next iteration
         if data.get("tools"):
@@ -273,6 +279,8 @@ def translate_request(
             result["json_schema_strict"] = json_schema_strict
         if json_object_mode:
             result["json_object"] = True
+        if sampling_params:
+            result["llm_params"] = sampling_params
         return result
 
     # Normal request — extract the question (text) from the last user message,
@@ -337,6 +345,7 @@ def translate_response(
     thought: str,
     model_name: str,
     pending_tool_calls: Optional[List[Dict]] = None,
+    strip_reasoning_leak: bool = False,
 ) -> Dict[str, Any]:
     """Translate DocsGPT response to chat completions format.
 
@@ -378,7 +387,10 @@ def translate_response(
         ]
         finish_reason = "tool_calls"
     else:
-        clean_answer, leaked_reasoning = _split_leaked_reasoning(answer)
+        if strip_reasoning_leak:
+            clean_answer, leaked_reasoning = _split_leaked_reasoning(answer)
+        else:
+            clean_answer, leaked_reasoning = answer, ""
         message["content"] = clean_answer
         combined_reasoning = (thought or "") + leaked_reasoning
         if combined_reasoning:
@@ -470,6 +482,7 @@ def translate_stream_event(
     event_data: Dict[str, Any],
     completion_id: str,
     model_name: str,
+    strip_reasoning_leak: bool = False,
 ) -> List[str]:
     """Translate a DocsGPT SSE event dict to standard streaming chunks.
 
@@ -490,7 +503,10 @@ def translate_stream_event(
     chunks: List[str] = []
 
     if event_type == "answer":
-        clean, leaked = _split_leaked_reasoning(event_data.get("answer", ""))
+        raw = event_data.get("answer", "")
+        clean, leaked = (
+            _split_leaked_reasoning(raw) if strip_reasoning_leak else (raw, "")
+        )
         if leaked:
             chunks.append(
                 _make_chunk(completion_id, model_name, {"reasoning_content": leaked})
@@ -589,7 +605,10 @@ def translate_stream_event(
         chunks.append(f"data: {json.dumps(error_data)}\n\n")
 
     elif event_type == "structured_answer":
-        clean, leaked = _split_leaked_reasoning(event_data.get("answer", ""))
+        raw = event_data.get("answer", "")
+        clean, leaked = (
+            _split_leaked_reasoning(raw) if strip_reasoning_leak else (raw, "")
+        )
         if leaked:
             chunks.append(
                 _make_chunk(completion_id, model_name, {"reasoning_content": leaked})