From 21afc9502aa3c78fb88496d0dc7c68598729b6fa Mon Sep 17 00:00:00 2001
From: Teknium <127238744+teknium1@users.noreply.github.com>
Date: Wed, 15 Apr 2026 16:10:56 -0700
Subject: [PATCH] fix: respect explicit api_mode for custom GPT-5 endpoints
 (#10473) (#10548)

The GPT-5 auto-upgrade logic unconditionally overrode api_mode to
codex_responses for any model starting with gpt-5, even when the
user explicitly set api_mode=chat_completions. Custom proxies that
serve GPT-5 via /chat/completions became unusable.

Fix: check api_mode is None before the override fires. If the caller
passed any explicit api_mode, it is final -- no auto-upgrade.

Closes #10473
---
 run_agent.py | 5 ++++-
 1 file changed, 4 insertions(+), 1 deletion(-)

diff --git a/run_agent.py b/run_agent.py
index 3a017f739..d229dcfe0 100644
--- a/run_agent.py
+++ b/run_agent.py
@@ -721,8 +721,11 @@ class AIAgent:
         # Responses there. ACP runtimes are excluded: CopilotACPClient
         # handles its own routing and does not implement the Responses API
         # surface.
+        # When api_mode was explicitly provided, respect it — the user
+        # knows what their endpoint supports (#10473).
         if (
-            self.api_mode == "chat_completions"
+            api_mode is None
+            and self.api_mode == "chat_completions"
             and self.provider != "copilot-acp"
             and not str(self.base_url or "").lower().startswith("acp://copilot")
             and not str(self.base_url or "").lower().startswith("acp+tcp://")