MAESTRO: add backend settings config

backend/app/core/config.py

@@ -0,0 +1,64 @@
+from __future__ import annotations
+
+import json
+from functools import lru_cache
+from typing import Any
+
+from pydantic import Field, field_validator
+from pydantic_settings import BaseSettings, SettingsConfigDict
+
+
+class Settings(BaseSettings):
+    """Application configuration loaded from environment variables.
+
+    Environment variables are prefixed with `WHA_` by default.
+    """
+
+    model_config = SettingsConfigDict(env_prefix="WHA_", case_sensitive=False)
+
+    cors_origins: list[str] = Field(
+        default_factory=lambda: ["http://localhost:3000"],
+        description="Allowed CORS origins.",
+    )
+    rate_limit_requests: int = Field(
+        default=60,
+        ge=1,
+        description="Max requests per window for rate limiting.",
+    )
+    rate_limit_window_seconds: int = Field(
+        default=60,
+        ge=1,
+        description="Rate limit window in seconds.",
+    )
+    analysis_timeout_seconds: int = Field(
+        default=30,
+        ge=1,
+        description="Hard timeout for analysis in seconds.",
+    )
+    debug: bool = Field(default=False, description="Enable debug mode.")
+
+    @field_validator("cors_origins", mode="before")
+    @classmethod
+    def parse_cors_origins(cls, value: Any) -> list[str]:
+        if value is None:
+            return ["http://localhost:3000"]
+        if isinstance(value, list):
+            return [str(item).strip() for item in value if str(item).strip()]
+        if isinstance(value, str):
+            text = value.strip()
+            if not text:
+                return []
+            if text.startswith("["):
+                try:
+                    parsed = json.loads(text)
+                    if isinstance(parsed, list):
+                        return [str(item).strip() for item in parsed if str(item).strip()]
+                except json.JSONDecodeError:
+                    pass
+            return [item.strip() for item in text.split(",") if item.strip()]
+        return [str(value).strip()]
+
+
+@lru_cache
+def get_settings() -> Settings:
+    return Settings()