refactor: tighten backend, flows, frontend, tests; push flows to Langflow

backend/app/flows/base_client.py

@@ -0,0 +1,27 @@
+"""Shared base for LFX + Langflow async HTTP clients.
+
+Consolidates base_url stripping, header building, per-request client
+construction, and HTTPError → domain-error mapping. Subclasses only
+declare their error types and endpoint calls.
+"""
+
+from __future__ import annotations
+
+import httpx
+
+
+class BaseApiClient:
+    """Thin wrapper around httpx.AsyncClient construction."""
+
+    def __init__(self, base_url: str, timeout: float = 60.0, api_key: str | None = None) -> None:
+        self.base_url = base_url.rstrip("/")
+        self.timeout = timeout
+        self.api_key = api_key or ""
+
+    def _headers(self) -> dict[str, str]:
+        return {"x-api-key": self.api_key} if self.api_key else {}
+
+    def _client(self) -> httpx.AsyncClient:
+        return httpx.AsyncClient(
+            base_url=self.base_url, timeout=self.timeout, headers=self._headers()
+        )