Normalize OpenAI base URLs

tests/test_core_flow.py

@@ -8,6 +8,7 @@ from pathlib import Path
 from unittest import mock
 
 from aituner.cli import main as cli_main
+from aituner.http_client import _openai_url
 from aituner.job import append_job, build_trial_job
 from aituner.llm import build_prompt, parse_proposal_text
 from aituner.search import ThresholdProbe, binary_search_max_feasible
@@ -717,6 +718,16 @@ class CoreFlowTests(unittest.TestCase):
         self.assertEqual(len(replayed), 3)
         self.assertEqual(replayed[1].error, "slo_pass_rate_unrecoverable")
 
+    def test_openai_url_avoids_double_v1(self) -> None:
+        self.assertEqual(
+            _openai_url("http://example.com", "/v1/chat/completions"),
+            "http://example.com/v1/chat/completions",
+        )
+        self.assertEqual(
+            _openai_url("http://example.com/v1", "/v1/chat/completions"),
+            "http://example.com/v1/chat/completions",
+        )
+
 
 if __name__ == "__main__":
     unittest.main()