fix(langchain/createAgent): fix LangGraph integration

[christian-bromann]

Instead of using a Proxy as proposed in #9016 this patch just adds additional methods needed by LangGraph to fetch graph information, making it run successfully:

npx @langchain/langgraph-cli dev

          Welcome to

╦  ┌─┐┌┐┌┌─┐╔═╗┬─┐┌─┐┌─┐┬ ┬
║  ├─┤││││ ┬║ ╦├┬┘├─┤├─┘├─┤
╩═╝┴ ┴┘└┘└─┘╚═╝┴└─┴ ┴┴  ┴ ┴.js

- 🚀 API: http://localhost:2024
- 🎨 Studio UI: https://smith.langchain.com/studio?baseUrl=http://localhost:2024

This in-memory server is designed for development and testing.
For production use, please use LangGraph Cloud.


info:    ▪ Starting server...
warn:    ┏ Some LangGraph.js dependencies are not up to date. Please make sure to update them to the required version.
warn:    ┗ [1] { '@langchain/langgraph-checkpoint': { version: '0.0.0', required: '~0.0.16 || ^0.1.0' } }
info:    ▪ Initializing storage...
info:    ▪ Registering graphs from /Users/christian.bromann/Sites/LangChain/langchainjs
info:    ┏ Registering graph with id 'agent'
info:    ┗ [1] { graph_id: 'agent' }
info:    ▪ Starting 10 workers
info:    ▪ Server running at ::1:2024
info:    ▪ <-- POST /assistants/search
info:    ▪ --> POST /assistants/search 200 5ms
info:    ▪ <-- GET /assistants/fe096781-5601-53d2-b2f6-0d3403f7e9ca
info:    ▪ --> GET /assistants/fe096781-5601-53d2-b2f6-0d3403f7e9ca 200 0ms
info:    ▪ <-- GET /assistants/fe096781-5601-53d2-b2f6-0d3403f7e9ca/schemas
info:    ▪ <-- POST /assistants/search
info:    ▪ --> POST /assistants/search 200 1ms
info:    ▪ <-- GET /info
info:    ▪ <-- POST /assistants/search
info:    ▪ --> POST /assistants/search 200 0ms
info:    ▪ <-- GET /assistants/fe096781-5601-53d2-b2f6-0d3403f7e9ca/graph?xray=true
info:    ▪ --> GET /assistants/fe096781-5601-53d2-b2f6-0d3403f7e9ca/graph?xray=true 200 5ms
info:    ▪ <-- GET /assistants/fe096781-5601-53d2-b2f6-0d3403f7e9ca/subgraphs?recurse=true
info:    ▪ --> GET /assistants/fe096781-5601-53d2-b2f6-0d3403f7e9ca/subgraphs?recurse=true 200 0ms
info:    ▪ --> GET /info 200 11ms
Failed to obtain symbol "__langgraph__agent_simple__update": Unsupported type: never
info:    ▪ --> GET /assistants/fe096781-5601-53d2-b2f6-0d3403f7e9ca/schemas 200 2s
info:    ▪ <-- POST /assistants/search
info:    ▪ --> POST /assistants/search 200 1ms
info:    ▪ <-- GET /assistants/fe096781-5601-53d2-b2f6-0d3403f7e9ca/schemas
info:    ▪ <-- GET /assistants/fe096781-5601-53d2-b2f6-0d3403f7e9ca/graph?xray=true
info:    ▪ --> GET /assistants/fe096781-5601-53d2-b2f6-0d3403f7e9ca/graph?xray=true 200 0ms
info:    ▪ <-- GET /assistants/fe096781-5601-53d2-b2f6-0d3403f7e9ca/subgraphs?recurse=true
info:    ▪ --> GET /assistants/fe096781-5601-53d2-b2f6-0d3403f7e9ca/subgraphs?recurse=true 200 0ms
info:    ▪ --> GET /assistants/fe096781-5601-53d2-b2f6-0d3403f7e9ca/schemas 200 2ms
info:    ▪ <-- GET /assistants/fe096781-5601-53d2-b2f6-0d3403f7e9ca
info:    ▪ --> GET /assistants/fe096781-5601-53d2-b2f6-0d3403f7e9ca 200 0ms
info:    ▪ <-- POST /assistants/search
info:    ▪ --> POST /assistants/search 200 1ms

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Latest commit: 59992aa

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