feat: AI Workflow Builder backend (no-changelog) (#14837)

packages/@n8n/ai-workflow-builder/src/workflow-state.ts

@@ -0,0 +1,22 @@
+import type { BaseMessage } from '@langchain/core/messages';
+import { Annotation, END } from '@langchain/langgraph';
+
+import type { SimpleWorkflow } from './types';
+
+export const WorkflowState = Annotation.Root({
+	messages: Annotation<BaseMessage[]>({
+		reducer: (x, y) => x.concat(y),
+	}),
+	// The original prompt from the user.
+	prompt: Annotation<string>({ reducer: (x, y) => y ?? x ?? '' }),
+	// The list of logically derived workflow steps.
+	steps: Annotation<string[]>({ reducer: (x, y) => y ?? x ?? [] }),
+	// The list of candidate or selected n8n node names.
+	nodes: Annotation<string[]>({ reducer: (x, y) => y ?? x ?? [] }),
+	// The JSON representation of the workflow being built.
+	workflowJSON: Annotation<SimpleWorkflow>({
+		reducer: (x, y) => y ?? x ?? { nodes: [], connections: {} },
+	}),
+	// The next phase to be executed in the workflow graph.
+	next: Annotation<string>({ reducer: (x, y) => y ?? x ?? END, default: () => END }),
+});