feat: add deprecated GetState

compose/state.go

@@ -110,6 +110,25 @@ func streamConvertPostHandler[O, S any](handler StreamStatePostHandler[O, S]) *c
 	return runnableLambda[O, O](nil, nil, nil, rf, false)
 }
 
+// GetState gets the state from the context.
+// Notice: The returned state isn't concurrency-safe that may cause data race in graph execution.
+// Deprecated: use ProcessState instead.
+func GetState[S any](ctx context.Context) (S, error) {
+	state := ctx.Value(stateKey{})
+
+	iState := state.(*internalState)
+	iState.mu.Lock()
+	defer iState.mu.Unlock()
+	cState, ok := iState.state.(S)
+	if !ok {
+		var s S
+		return s, fmt.Errorf("unexpected state type. expected: %v, got: %v",
+			generic.TypeOf[S](), reflect.TypeOf(iState.state))
+	}
+
+	return cState, nil
+}
+
 // ProcessState processes the state from the context in a concurrency-safe way.
 // This is the recommended way to access and modify state in custom nodes.
 // The provided function handler will be executed with exclusive access to the state (protected by mutex).