diff --git a/acp_adapter/server.py b/acp_adapter/server.py
index def8ec18b53..7646f332534 100644
--- a/acp_adapter/server.py
+++ b/acp_adapter/server.py
@@ -1623,6 +1623,13 @@ class HermesACPAgent(acp.Agent):
                     user_text,
                     final_response,
                     state.history,
+                    main_runtime={
+                        "model": getattr(state.agent, "model", None),
+                        "provider": getattr(state.agent, "provider", None),
+                        "base_url": getattr(state.agent, "base_url", None),
+                        "api_key": getattr(state.agent, "api_key", None),
+                        "api_mode": getattr(state.agent, "api_mode", None),
+                    },
                     title_callback=_notify_title_update,
                 )
             except Exception:
diff --git a/tests/acp/test_server.py b/tests/acp/test_server.py
index 9b7ac1bc796..c9c9820a577 100644
--- a/tests/acp/test_server.py
+++ b/tests/acp/test_server.py
@@ -1323,6 +1323,11 @@ class TestPrompt:
     async def test_prompt_auto_titles_session(self, agent):
         new_resp = await agent.new_session(cwd=".")
         state = agent.session_manager.get_session(new_resp.session_id)
+        state.agent.model = "gpt-5.6-sol"
+        state.agent.provider = "openai-codex"
+        state.agent.base_url = "https://chatgpt.example.test/backend-api/codex"
+        state.agent.api_key = object()
+        state.agent.api_mode = "codex_responses"
         state.agent.run_conversation = MagicMock(return_value={
             "final_response": "Here is the fix.",
             "messages": [
@@ -1343,6 +1348,13 @@ class TestPrompt:
         assert mock_title.call_args.args[1] == new_resp.session_id
         assert mock_title.call_args.args[2] == "fix the broken ACP history"
         assert mock_title.call_args.args[3] == "Here is the fix."
+        assert mock_title.call_args.kwargs["main_runtime"] == {
+            "model": "gpt-5.6-sol",
+            "provider": "openai-codex",
+            "base_url": "https://chatgpt.example.test/backend-api/codex",
+            "api_key": state.agent.api_key,
+            "api_mode": "codex_responses",
+        }
         assert callable(mock_title.call_args.kwargs["title_callback"])
 
     @pytest.mark.asyncio
diff --git a/tests/test_tui_gateway_server.py b/tests/test_tui_gateway_server.py
index adaeeefb93d..6be6f85ed83 100644
--- a/tests/test_tui_gateway_server.py
+++ b/tests/test_tui_gateway_server.py
@@ -7457,6 +7457,12 @@ def test_prompt_submit_auto_titles_session_on_complete(monkeypatch):
     """maybe_auto_title is called after a successful (complete) prompt."""
 
     class _Agent:
+        model = "gpt-5.6-sol"
+        provider = "openai-codex"
+        base_url = "https://chatgpt.example.test/backend-api/codex"
+        api_key = object()
+        api_mode = "codex_responses"
+
         def run_conversation(
             self, prompt, conversation_history=None, stream_callback=None
         ):
@@ -7489,6 +7495,13 @@ def test_prompt_submit_auto_titles_session_on_complete(monkeypatch):
     assert args[1] == "session-key"
     assert args[2] == "Tell me about Rome"
     assert args[3] == "Rome was founded in 753 BC."
+    assert mock_title.call_args.kwargs["main_runtime"] == {
+        "model": "gpt-5.6-sol",
+        "provider": "openai-codex",
+        "base_url": "https://chatgpt.example.test/backend-api/codex",
+        "api_key": _Agent.api_key,
+        "api_mode": "codex_responses",
+    }
 
 
 def test_prompt_submit_skips_auto_title_when_interrupted(monkeypatch):
diff --git a/tui_gateway/server.py b/tui_gateway/server.py
index 2f92833d33b..3e405268d84 100644
--- a/tui_gateway/server.py
+++ b/tui_gateway/server.py
@@ -9684,6 +9684,17 @@ def _run_prompt_submit(rid, sid: str, session: dict, text: Any) -> None:
                         text,
                         raw,
                         session.get("history", []),
+                        # Keep auxiliary auto-detection aligned with the active
+                        # Desktop/Webapp session. Without this, providers that
+                        # rely on runtime auth (for example OpenAI Codex OAuth)
+                        # are skipped and the new session remains untitled.
+                        main_runtime={
+                            "model": getattr(agent, "model", None),
+                            "provider": getattr(agent, "provider", None),
+                            "base_url": getattr(agent, "base_url", None),
+                            "api_key": getattr(agent, "api_key", None),
+                            "api_mode": getattr(agent, "api_mode", None),
+                        },
                         # Push the generated title live so the sidebar renames
                         # without waiting for the next list refresh (the titler
                         # runs async, after this turn's refresh already fired).