feat(mcp): add environment-based configuration

surfsense_mcp/src/surfsense_mcp/config.py

@@ -0,0 +1,62 @@
+"""Runtime configuration, read once from the environment.
+
+Secrets never live in code or client config files — the client (Cursor/Claude)
+passes them as environment variables when it launches this server (see README).
+"""
+
+from __future__ import annotations
+
+import os
+from dataclasses import dataclass
+
+DEFAULT_BASE_URL = "http://localhost:8000"
+DEFAULT_API_PREFIX = "/api/v1"
+DEFAULT_TIMEOUT_SECONDS = 180.0
+
+
+@dataclass(frozen=True)
+class Settings:
+    """Resolved configuration for a server process."""
+
+    base_url: str
+    pat: str
+    api_prefix: str
+    timeout: float
+    default_workspace: str | None
+
+    @property
+    def api_base(self) -> str:
+        return f"{self.base_url}{self.api_prefix}"
+
+    @classmethod
+    def from_env(cls) -> Settings:
+        pat = os.environ.get("SURFSENSE_PAT", "").strip()
+        if not pat:
+            raise SystemExit(
+                "SURFSENSE_PAT is required. Create a Personal Access Token in "
+                "SurfSense (Settings -> API) and pass it via the SURFSENSE_PAT "
+                "environment variable."
+            )
+
+        base_url = (
+            os.environ.get("SURFSENSE_BASE_URL", DEFAULT_BASE_URL).strip().rstrip("/")
+        )
+        api_prefix = "/" + os.environ.get(
+            "SURFSENSE_API_PREFIX", DEFAULT_API_PREFIX
+        ).strip().strip("/")
+
+        raw_timeout = os.environ.get("SURFSENSE_TIMEOUT", "").strip()
+        try:
+            timeout = float(raw_timeout) if raw_timeout else DEFAULT_TIMEOUT_SECONDS
+        except ValueError:
+            timeout = DEFAULT_TIMEOUT_SECONDS
+
+        default_workspace = os.environ.get("SURFSENSE_WORKSPACE", "").strip() or None
+
+        return cls(
+            base_url=base_url,
+            pat=pat,
+            api_prefix=api_prefix,
+            timeout=timeout,
+            default_workspace=default_workspace,
+        )