fix: preserve URL query params for Azure OpenAI and custom endpoints

Azure OpenAI requires an `api-version` query parameter on every request.
When users include it in the base_url (e.g. `?api-version=2025-04-01-preview`),
the OpenAI SDK silently drops it during URL construction, causing 404 errors.

Extract query params from base_url and pass them via `default_query` so the
SDK appends them to every request. This is a generic solution that works for
any custom endpoint requiring query parameters, not just Azure.

No-op for URLs without query params — fully backward compatible.

agent/auxiliary_client.py

@@ -42,6 +42,7 @@ import time
 from pathlib import Path  # noqa: F401 — used by test mocks
 from types import SimpleNamespace
 from typing import Any, Dict, List, Optional, Tuple
+from urllib.parse import urlparse, parse_qs, urlunparse
 
 from openai import OpenAI
 
@@ -52,6 +53,17 @@ from utils import base_url_host_matches, base_url_hostname, normalize_proxy_env_
 
 logger = logging.getLogger(__name__)
 
+
+def _extract_url_query_params(url: str):
+    """Extract query params from URL, return (clean_url, default_query dict or None)."""
+    parsed = urlparse(url)
+    if parsed.query:
+        clean = urlunparse(parsed._replace(query=""))
+        params = {k: v[0] for k, v in parse_qs(parsed.query).items()}
+        return clean, params
+    return url, None
+
+
 # Module-level flag: only warn once per process about stale OPENAI_BASE_URL.
 _stale_base_url_warned = False
 
@@ -1157,8 +1169,10 @@ def _try_custom_endpoint() -> Tuple[Optional[Any], Optional[str]]:
         return None, None
     model = _read_main_model() or "gpt-4o-mini"
     logger.debug("Auxiliary client: custom endpoint (%s, api_mode=%s)", model, custom_mode or "chat_completions")
+    _clean_base, _dq = _extract_url_query_params(custom_base)
+    _extra = {"default_query": _dq} if _dq else {}
     if custom_mode == "codex_responses":
-        real_client = OpenAI(api_key=custom_key, base_url=custom_base)
+        real_client = OpenAI(api_key=custom_key, base_url=_clean_base, **_extra)
         return CodexAuxiliaryClient(real_client, model), model
     if custom_mode == "anthropic_messages":
         # Third-party Anthropic-compatible gateway (MiniMax, Zhipu GLM,
@@ -1172,12 +1186,12 @@ def _try_custom_endpoint() -> Tuple[Optional[Any], Optional[str]]:
                 "Custom endpoint declares api_mode=anthropic_messages but the "
                 "anthropic SDK is not installed — falling back to OpenAI-wire."
             )
-            return OpenAI(api_key=custom_key, base_url=custom_base), model
+            return OpenAI(api_key=custom_key, base_url=_clean_base, **_extra), model
         return (
             AnthropicAuxiliaryClient(real_client, model, custom_key, custom_base, is_oauth=False),
             model,
         )
-    return OpenAI(api_key=custom_key, base_url=custom_base), model
+    return OpenAI(api_key=custom_key, base_url=_clean_base, **_extra), model
 
 
 def _try_codex() -> Tuple[Optional[Any], Optional[str]]:
@@ -1825,12 +1839,15 @@ def resolve_provider_client(
                 provider,
             )
             extra = {}
+            _clean_base, _dq = _extract_url_query_params(custom_base)
+            if _dq:
+                extra["default_query"] = _dq
             if base_url_host_matches(custom_base, "api.kimi.com"):
                 extra["default_headers"] = {"User-Agent": "claude-code/0.1.0"}
             elif base_url_host_matches(custom_base, "api.githubcopilot.com"):
                 from hermes_cli.models import copilot_default_headers
                 extra["default_headers"] = copilot_default_headers()
-            client = OpenAI(api_key=custom_key, base_url=custom_base, **extra)
+            client = OpenAI(api_key=custom_key, base_url=_clean_base, **extra)
             client = _wrap_if_needed(client, final_model, custom_base)
             return (_to_async_client(client, final_model) if async_mode
                     else (client, final_model))
@@ -1867,6 +1884,8 @@ def resolve_provider_client(
                     model or custom_entry.get("model") or _read_main_model() or "gpt-4o-mini",
                     provider,
                 )
+                _clean_base2, _dq2 = _extract_url_query_params(custom_base)
+                _extra2 = {"default_query": _dq2} if _dq2 else {}
                 logger.debug(
                     "resolve_provider_client: named custom provider %r (%s, api_mode=%s)",
                     provider, final_model, entry_api_mode or "chat_completions")
@@ -1884,7 +1903,7 @@ def resolve_provider_client(
                             "installed — falling back to OpenAI-wire.",
                             provider,
                         )
-                        client = OpenAI(api_key=custom_key, base_url=custom_base)
+                        client = OpenAI(api_key=custom_key, base_url=_clean_base2, **_extra2)
                         return (_to_async_client(client, final_model) if async_mode
                                 else (client, final_model))
                     sync_anthropic = AnthropicAuxiliaryClient(
@@ -1893,7 +1912,7 @@ def resolve_provider_client(
                     if async_mode:
                         return AsyncAnthropicAuxiliaryClient(sync_anthropic), final_model
                     return sync_anthropic, final_model
-                client = OpenAI(api_key=custom_key, base_url=custom_base)
+                client = OpenAI(api_key=custom_key, base_url=_clean_base2, **_extra2)
                 # codex_responses or inherited auto-detect (via _wrap_if_needed).
                 # _wrap_if_needed reads the closed-over `api_mode` (the task-level
                 # override). Named-provider entry api_mode=codex_responses also

run_agent.py

@@ -40,6 +40,7 @@ from types import SimpleNamespace
 import urllib.request
 import uuid
 from typing import List, Dict, Any, Optional
+from urllib.parse import urlparse, parse_qs, urlunparse
 from openai import OpenAI
 import fire
 from datetime import datetime
@@ -1314,7 +1315,22 @@ class AIAgent:
             if api_key and base_url:
                 # Explicit credentials from CLI/gateway — construct directly.
                 # The runtime provider resolver already handled auth for us.
-                client_kwargs = {"api_key": api_key, "base_url": base_url}
+                # Extract query params (e.g. Azure api-version) from base_url
+                # and pass via default_query to prevent loss during SDK URL
+                # joining (httpx drops query string when joining paths).
+                _parsed_url = urlparse(base_url)
+                if _parsed_url.query:
+                    _clean_url = urlunparse(_parsed_url._replace(query=""))
+                    _query_params = {
+                        k: v[0] for k, v in parse_qs(_parsed_url.query).items()
+                    }
+                    client_kwargs = {
+                        "api_key": api_key,
+                        "base_url": _clean_url,
+                        "default_query": _query_params,
+                    }
+                else:
+                    client_kwargs = {"api_key": api_key, "base_url": base_url}
                 if _provider_timeout is not None:
                     client_kwargs["timeout"] = _provider_timeout
                 if self.provider == "copilot-acp":