refactor: centralize llm backend configuration

utils/ai/llm_registry.py

@@ -0,0 +1,64 @@
+from __future__ import annotations
+
+from pathlib import Path
+from typing import Any, Dict, Optional
+
+import yaml
+
+
+class LLMRegistry:
+    """从项目根 config.yaml 读取集中式 LLM 后端配置。"""
+
+    _cache: Dict[str, Any] = {"mtime": None, "data": {}}
+
+    @classmethod
+    def get_root_config_path(cls) -> Path:
+        return Path(__file__).resolve().parents[2] / "config.yaml"
+
+    @classmethod
+    def load_root_config(cls) -> Dict[str, Any]:
+        path = cls.get_root_config_path()
+        if not path.exists():
+            return {}
+
+        stat = path.stat()
+        if cls._cache["mtime"] == stat.st_mtime and cls._cache["data"]:
+            return cls._cache["data"]
+
+        with open(path, "r", encoding="utf-8") as fp:
+            data = yaml.safe_load(fp) or {}
+        cls._cache = {"mtime": stat.st_mtime, "data": data}
+        return data
+
+    @classmethod
+    def get_llm_config(cls) -> Dict[str, Any]:
+        config = cls.load_root_config()
+        llm_config = config.get("llm", {}) or {}
+        return llm_config if isinstance(llm_config, dict) else {}
+
+    @classmethod
+    def get_backend(cls, backend_name: str) -> Dict[str, Any]:
+        if not backend_name:
+            return {}
+        llm_config = cls.get_llm_config()
+        backends = llm_config.get("backends", {}) or {}
+        backend = backends.get(backend_name, {}) or {}
+        return dict(backend) if isinstance(backend, dict) else {}
+
+    @classmethod
+    def resolve(cls, local_config: Optional[Dict[str, Any]] = None) -> Dict[str, Any]:
+        local = dict(local_config or {})
+        backend_name = (
+            local.get("backend")
+            or local.get("backend_name")
+            or local.get("backend_ref")
+            or ""
+        )
+        if not backend_name:
+            return local
+
+        merged = cls.get_backend(str(backend_name).strip())
+        merged.update(local)
+        merged["backend"] = backend_name
+        return merged
+