fix(llm): avoid blocking Kimi Code async header probes (#5231)

src/llm_core.py

@@ -766,6 +766,36 @@ def apply_kimi_code_headers(headers: Optional[Dict], url: str) -> Dict[str, str]
     return h
 
 
+async def apply_kimi_code_headers_async(client, headers: Optional[Dict], url: str) -> Dict[str, str]:
+    """Pick a Kimi Code User-Agent without blocking the event loop."""
+    h = dict(headers or {})
+    if not _is_kimi_code_url(url):
+        return h
+    base_key = _kimi_code_base_key(url)
+    cached = _kimi_code_ua_cache.get(base_key)
+    if cached:
+        h["User-Agent"] = cached
+        return h
+    models_url = base_key.rstrip("/") + "/models"
+    for ua in KIMI_CODE_USER_AGENTS:
+        trial = dict(h)
+        trial["User-Agent"] = ua
+        try:
+            r = await client.get(models_url, headers=trial, timeout=8)
+        except Exception:
+            continue
+        if _is_kimi_code_access_denied(r.status_code, r.content):
+            logger.debug("Kimi Code rejected User-Agent %s (403), trying next", ua)
+            continue
+        if r.status_code < 400:
+            _remember_kimi_code_user_agent(url, ua)
+            h["User-Agent"] = ua
+            return h
+        break
+    h.setdefault("User-Agent", KIMI_CODE_USER_AGENT)
+    return h
+
+
 def httpx_get_kimi_aware(url: str, headers: Optional[Dict], **kwargs):
     h = apply_kimi_code_headers(headers, url)
     if not _is_kimi_code_url(url):
@@ -799,7 +829,7 @@ def httpx_post_kimi_aware(url: str, headers: Optional[Dict], **kwargs):
 
 
 async def httpx_post_kimi_aware_async(client, url: str, headers: Optional[Dict], **kwargs):
-    h = apply_kimi_code_headers(headers, url)
+    h = await apply_kimi_code_headers_async(client, headers, url)
     if not _is_kimi_code_url(url):
         return await client.post(url, headers=h, **kwargs)
     last = None
@@ -2466,9 +2496,9 @@ async def _stream_llm_inner(url: str, model: str, messages: List[Dict], temperat
             events.append(_stream_delta_event(part))
         return events
 
-    h = apply_kimi_code_headers(h, target_url)
     try:
         client = _get_http_client()
+        h = await apply_kimi_code_headers_async(client, h, target_url)
         async with client.stream('POST', target_url, json=payload, headers=h, timeout=stream_timeout) as r:
             _clear_host_dead(target_url)
             if r.status_code != 200: