fix(kimi): resolve Kimi Code API 403 errors and User-Agent restrictions (#3549)

* fix(kimi): resolve Kimi Code API 403 errors and User-Agent restrictions

Kimi Code subscription keys require a whitelisted coding-agent User-Agent to avoid access_terminated_error 403s. This adds User-Agent probing and caching for Kimi Code endpoints.

Co-authored-by: Cursor <cursoragent@cursor.com>

* fix(kimi): omit temperature for kimi-for-coding API calls

Kimi Code rejects any non-default temperature with HTTP 400, which broke deep research probes and low-temp LLM rounds.

Co-authored-by: Cursor <cursoragent@cursor.com>

---------

Co-authored-by: Cursor <cursoragent@cursor.com>

src/endpoint_resolver.py

@@ -12,7 +12,7 @@ from typing import Optional, Tuple, Dict
 from urllib.parse import urlparse, urlunparse
 
 from core.database import SessionLocal, ModelEndpoint
-from src.llm_core import _detect_provider, _host_match, _ollama_api_root
+from src.llm_core import _detect_provider, _host_match, _is_kimi_code_url, KIMI_CODE_USER_AGENT, _ollama_api_root
 
 logger = logging.getLogger(__name__)
 
@@ -230,6 +230,8 @@ def build_headers(api_key: Optional[str], base: str) -> Dict[str, str]:
     if provider == "openrouter":
         headers.setdefault("HTTP-Referer", "https://github.com/pewdiepie-archdaemon/odysseus")
         headers.setdefault("X-OpenRouter-Title", "Odysseus")
+    if _is_kimi_code_url(base):
+        headers.setdefault("User-Agent", KIMI_CODE_USER_AGENT)
     return headers