diff --git a/agent/auxiliary_client.py b/agent/auxiliary_client.py
index 1ea6f21384..497484ac0c 100644
--- a/agent/auxiliary_client.py
+++ b/agent/auxiliary_client.py
@@ -2787,13 +2787,14 @@ def _build_codex_client(model: str) -> Tuple[Optional[Any], Optional[str]]:
         return None, None
     pool_present, entry = _select_pool_entry("openai-codex")
     codex_token = _pool_runtime_api_key(entry) if pool_present else None
+    codex_override = os.getenv("HERMES_CODEX_BASE_URL", "").strip().rstrip("/")
     if codex_token:
-        base_url = _pool_runtime_base_url(entry, _CODEX_AUX_BASE_URL) or _CODEX_AUX_BASE_URL
+        base_url = codex_override or _pool_runtime_base_url(entry, _CODEX_AUX_BASE_URL) or _CODEX_AUX_BASE_URL
     else:
         codex_token = _read_codex_access_token()
         if not codex_token:
             return None, None
-        base_url = _CODEX_AUX_BASE_URL
+        base_url = codex_override or _CODEX_AUX_BASE_URL
     logger.debug("Auxiliary client: Codex OAuth (%s via Responses API)", model)
     real_client = _create_openai_client(
         api_key=codex_token, base_url=base_url,
diff --git a/hermes_cli/runtime_provider.py b/hermes_cli/runtime_provider.py
index 0becf6eb69..f389f2c53a 100644
--- a/hermes_cli/runtime_provider.py
+++ b/hermes_cli/runtime_provider.py
@@ -449,6 +449,13 @@ def _pool_entry_mode_and_url(provider, entry, model_cfg, effective_model, base_u
         base_url = _config_base_url_for_provider(model_cfg, provider) or base_url
     if provider in _POOL_ENTRY_SIMPLE_MODES:
         api_mode, default_url = _POOL_ENTRY_SIMPLE_MODES[provider]
+        if provider == "openai-codex":
+            # Pool entries retain the canonical ChatGPT URL, but the profile-wide
+            # HERMES_CODEX_BASE_URL override must apply consistently to every
+            # credential source, including pooled OAuth credentials.
+            override_url = get_secret_str("HERMES_CODEX_BASE_URL", "").strip().rstrip("/")
+            if override_url:
+                return api_mode, override_url
         return api_mode, base_url or (default_url() if callable(default_url) else default_url)
     if provider == "anthropic":
         return "anthropic_messages", _anthropic_cfg_base_url(model_cfg) or base_url or _ANTHROPIC_DEFAULT_BASE_URL
diff --git a/tests/agent/test_auxiliary_client.py b/tests/agent/test_auxiliary_client.py
index a8e09d8b87..c25064cd44 100644
--- a/tests/agent/test_auxiliary_client.py
+++ b/tests/agent/test_auxiliary_client.py
@@ -724,6 +724,26 @@ class TestBuildCodexClient:
         assert mock_openai.call_args.kwargs["api_key"] == "codex-auth-token"
         assert mock_openai.call_args.kwargs["base_url"] == "https://chatgpt.com/backend-api/codex"
 
+    def test_profile_codex_base_url_overrides_pool_endpoint(self, monkeypatch):
+        """Auxiliary Codex calls use the same profile endpoint override as the main client."""
+        entry = SimpleNamespace(
+            runtime_api_key="codex-pool-token",
+            runtime_base_url="https://chatgpt.com/backend-api/codex",
+        )
+        with (
+            patch("agent.auxiliary_client._select_pool_entry", return_value=(True, entry)),
+            patch("agent.auxiliary_client.OpenAI") as mock_openai,
+        ):
+            monkeypatch.setenv("HERMES_CODEX_BASE_URL", "http://127.0.0.1:8787/v1")
+            mock_openai.return_value = MagicMock()
+            from agent.auxiliary_client import _build_codex_client
+
+            client, model = _build_codex_client("gpt-5.4")
+
+        assert client is not None
+        assert model == "gpt-5.4"
+        assert mock_openai.call_args.kwargs["base_url"] == "http://127.0.0.1:8787/v1"
+
     def test_rejects_missing_model(self):
         """Callers must pass an explicit model; no hardcoded default."""
         from agent.auxiliary_client import _build_codex_client
diff --git a/tests/hermes_cli/test_runtime_provider_resolution.py b/tests/hermes_cli/test_runtime_provider_resolution.py
index 725465382b..d841a3e6bd 100644
--- a/tests/hermes_cli/test_runtime_provider_resolution.py
+++ b/tests/hermes_cli/test_runtime_provider_resolution.py
@@ -86,6 +86,30 @@ def test_resolve_runtime_provider_uses_credential_pool(monkeypatch):
     assert resolved["source"] == "manual"
 
 
+def test_codex_pool_honors_hermes_codex_base_url(monkeypatch):
+    """The profile-wide Codex endpoint override must apply to pool credentials too."""
+    class _Entry:
+        access_token = "pool-token"
+        source = "manual"
+        base_url = "https://chatgpt.com/backend-api/codex"
+
+    class _Pool:
+        def has_credentials(self):
+            return True
+
+        def select(self):
+            return _Entry()
+
+    monkeypatch.setattr(rp, "resolve_provider", lambda *a, **k: "openai-codex")
+    monkeypatch.setattr(rp, "load_pool", lambda provider: _Pool())
+    monkeypatch.setenv("HERMES_CODEX_BASE_URL", "http://127.0.0.1:8787/v1")
+
+    resolved = rp.resolve_runtime_provider(requested="openai-codex")
+
+    assert resolved["provider"] == "openai-codex"
+    assert resolved["base_url"] == "http://127.0.0.1:8787/v1"
+
+
 class TestCustomProviderPoolLoopbackNoKeyExemption:
     """Regression for issue #86864: legacy custom_providers configs often
     used short/placeholder api_keys ('123', 'm') for local no-auth