fix(api): ignore inherited v1 base URL for Codex (#1718)

hindsight-api-slim/hindsight_api/engine/providers/codex_llm.py

@@ -110,9 +110,15 @@ class CodexLLM(LLMInterface):
                 "Or use a different provider (openai, anthropic, gemini) with API keys."
             ) from e
 
-        # Use ChatGPT backend API endpoint
-        if not self.base_url:
+        # Use ChatGPT backend API endpoint. Codex auth is tied to
+        # chatgpt.com/backend-api, not the OpenAI-compatible base URL used by
+        # other providers. Deployments often set a global LLM_BASE_URL for an
+        # OpenAI-compatible proxy; ignore that inherited value unless the user
+        # explicitly provides a Codex backend URL.
+        if not self.base_url or self.base_url.rstrip("/").endswith("/v1"):
             self.base_url = "https://chatgpt.com/backend-api"
+        else:
+            self.base_url = self.base_url.rstrip("/")
 
         # Normalize model name (strip openai/ prefix if present)
         if self.model.startswith("openai/"):

hindsight-api-slim/tests/test_codex_base_url.py

@@ -0,0 +1,30 @@
+"""Tests for Codex provider base URL handling."""
+
+from unittest.mock import patch
+
+from hindsight_api.engine.providers.codex_llm import CodexLLM
+
+
+def _make(base_url: str) -> CodexLLM:
+    with (
+        patch.object(CodexLLM, "_load_codex_auth", return_value=("at", "acct")),
+        patch.object(CodexLLM, "_load_codex_refresh_token", return_value="rt"),
+    ):
+        return CodexLLM(
+            provider="openai-codex",
+            api_key="ignored",
+            base_url=base_url,
+            model="gpt-5.4-mini",
+        )
+
+
+def test_codex_uses_chatgpt_backend_when_base_url_empty():
+    assert _make("").base_url == "https://chatgpt.com/backend-api"
+
+
+def test_codex_ignores_inherited_openai_compatible_v1_base_url():
+    assert _make("https://newapi.example.com/v1").base_url == "https://chatgpt.com/backend-api"
+
+
+def test_codex_preserves_explicit_codex_backend_base_url_without_trailing_slash():
+    assert _make("https://chatgpt.example.com/backend-api/").base_url == "https://chatgpt.example.com/backend-api"