fix(n8n): pass connected tools to models and use core 1.x memory API in CascadeFlow Agent

[saschabuehrle]

Problem

Two defects in the n8n CascadeFlow Agent node (@cascadeflow/n8n-nodes-cascadeflow, present since #134), found while preparing a demo on n8n 2.4.6:

1. Tools are never offered to the models. execute() reads the nodes on the Tools port and hands them to CascadeFlowAgentExecutor, but the executor only uses them to run tool calls. The drafter, verifier and domain models are invoked without the tool definitions, so no model can ever request a tool. In practice a prompt like "what is the weather in X" ends with the model answering "shall I run the Weather tool?".
2. A connected memory node crashes the agent on n8n 2.x. Persisting the turn calls chatHistory.addUserMessage / addAIChatMessage, which were removed in @langchain/core 1.x (addAIChatMessage is not a function). Our peer range allows core 1.x.

Neither was caught by tests: the executor test mocks a cascade model that already returns tool_calls, so tool binding was never exercised.

Fix

• CascadeFlowAgentExecutor.withTools() merges the connected tools into the model call options (LangChain tools call option, the same thing bindTools sets) for invoke, invokeVerifierDirect and stream. No tools connected: options are passed through untouched. Caller-provided options.tools win.
• New exported persistTurnToMemory() writes the turn via chatHistory.addMessage(new HumanMessage(...)) / addMessage(new AIMessage(...)), available in core 0.3 and 1.x. ChatMemoryLike updated accordingly.
• CHANGELOG: Unreleased / Fixed entries.

Tests

• New executor tests: tools forwarded to invoke and invokeVerifierDirect, no tools key without connected tools, caller override kept.
• New persistTurnToMemory tests (core 1.x style history, and null memory).
• vitest run in packages/integrations/n8n: 55 passed. tsc --noEmit and eslint clean for the changed files. npm run build bundles fine.
• Verified end to end on n8n 2.4.6 with the equivalent change applied to the installed node: Calculator, Wikipedia and OpenWeatherMap tools are called by the drafter and verifier, and Window Buffer Memory works across turns.

Version is left at 1.3.0; bump separately when publishing.

https://claude.ai/code/session_018SnqMYYEDpG72ZGubKLtx6