fix(agent): keep Nous GPT-5 fallback on chat completions

run_agent.py

@@ -3065,6 +3065,10 @@ class AIAgent:
     ) -> bool:
         """Return True when this provider/model pair should use Responses API."""
         normalized_provider = (provider or "").strip().lower()
+        # Nous serves GPT-5.x models via its OpenAI-compatible chat
+        # completions endpoint; its /v1/responses endpoint returns 404.
+        if normalized_provider == "nous":
+            return False
         if normalized_provider == "copilot":
             try:
                 from hermes_cli.models import _should_use_copilot_responses_api

tests/run_agent/test_run_agent.py

@@ -3729,8 +3729,8 @@ class TestMaxTokensParam:
         assert result == {"max_completion_tokens": 4096}
 
 
-class TestAzureOpenAIRouting:
-    """Verify Azure OpenAI endpoints stay on chat_completions for gpt-5.x."""
+class TestGpt5ApiModeRouting:
+    """Verify provider-specific GPT-5 API-mode routing."""
 
     def test_azure_gpt5_stays_on_chat_completions(self, agent):
         """Azure serves gpt-5.x on /chat/completions — must not upgrade to codex_responses."""
@@ -3769,6 +3769,25 @@ class TestAzureOpenAIRouting:
             agent.api_mode = "codex_responses"
         assert agent.api_mode == "codex_responses"
 
+    def test_nous_gpt5_stays_on_chat_completions(self, agent):
+        """Nous serves gpt-5.x on /chat/completions — must not upgrade to codex_responses."""
+        agent.provider = "nous"
+        agent.base_url = "https://inference-api.nousresearch.com/v1"
+        agent.api_mode = "chat_completions"
+        agent.model = "openai/gpt-5.5"
+        if (
+            agent.api_mode == "chat_completions"
+            and not agent._is_azure_openai_url()
+            and (
+                agent._is_direct_openai_url()
+                or agent._provider_model_requires_responses_api(
+                    agent.model, provider=agent.provider,
+                )
+            )
+        ):
+            agent.api_mode = "codex_responses"
+        assert agent.api_mode == "chat_completions"
+
     def test_is_azure_openai_url_detection(self, agent):
         assert agent._is_azure_openai_url("https://foo.openai.azure.com/openai/v1") is True
         assert agent._is_azure_openai_url("https://api.openai.com/v1") is False