faet(handle): add isConnectableStart and isConnectableEnd

packages/core/src/components/Handle/utils.ts

@@ -92,6 +92,8 @@ export function isValidHandle(
     const handleType = getHandleType(undefined, handleToCheck);
     const handleNodeId = handleToCheck.getAttribute('data-nodeid');
     const handleId = handleToCheck.getAttribute('data-handleid');
+    const connectable = handleToCheck.classList.contains('connectable');
+    const connectableEnd = handleToCheck.classList.contains('connectableend');
 
     const connection: Connection = {
       source: isTarget ? handleNodeId : fromNodeId,
@@ -102,9 +104,10 @@ export function isValidHandle(
 
     result.connection = connection;
 
+    const isConnectable = connectable && connectableEnd;
     // in strict mode we don't allow target to target or source to source connections
     const isValid =
-      handleToCheck.classList.contains('connectable') &&
+      isConnectable &&
       (connectionMode === ConnectionMode.Strict
         ? (isTarget && handleType === 'source') || (!isTarget && handleType === 'target')
         : handleNodeId !== fromNodeId || handleId !== fromHandleId);