fix(codex): stop injecting api key placeholder

tests/unit/test_agent_provider.py

@@ -0,0 +1,23 @@
+"""Unit: provider runtime defaults."""
+
+from __future__ import annotations
+
+import unittest
+
+from bot_bottle.agent_provider import runtime_for
+
+
+class TestAgentProviderRuntime(unittest.TestCase):
+    def test_claude_keeps_oauth_placeholder(self):
+        runtime = runtime_for("claude")
+        self.assertEqual("claude_code_oauth", runtime.auth_role)
+        self.assertEqual("CLAUDE_CODE_OAUTH_TOKEN", runtime.placeholder_env)
+
+    def test_codex_does_not_inject_openai_api_key_placeholder(self):
+        runtime = runtime_for("codex")
+        self.assertEqual("", runtime.auth_role)
+        self.assertEqual("", runtime.placeholder_env)
+
+
+if __name__ == "__main__":
+    unittest.main()