docs: Add javascript version of langgraph/sql-agent

[pokey]

Just translates the Python version of the langgraph sql-agent tutorial to js.

• Depends on feat(core): Add BaseMessage.toFormattedString() langchainjs#9228
• See also feat(examples): Add sql_agent example langgraphjs#1750

[Copilot]

Pull Request Overview

This PR adds the JavaScript/TypeScript version of the SQL agent tutorial, translating the Python implementation to JS. The tutorial demonstrates how to build a custom SQL agent using LangGraph that can interact with a SQLite database to answer questions.

Key changes:

• Adds JavaScript implementations alongside existing Python code using custom language fences (:::python and :::js)
• Includes JS-specific installation instructions with npm/yarn/pnpm examples
• Implements the complete SQL agent workflow in TypeScript, including database setup, tool creation, graph construction, and human-in-the-loop features

[Copilot]

Inconsistent link reference: Line 899 uses /oss/langgraph/add-human-in-the-loop while line 1003 uses /oss/langgraph/human-in-the-loop. These should point to the same guide. Please verify the correct path and update for consistency.

Suggested change

	The above implementation follows the [tool interrupt example](/oss/langgraph/add-human-in-the-loop#add-interrupts-to-any-tool) in the broader [human-in-the-loop](/oss/langgraph/add-human-in-the-loop) guide. Refer to that guide for details and alternatives.
	The above implementation follows the [tool interrupt example](/oss/langgraph/human-in-the-loop#add-interrupts-to-any-tool) in the broader [human-in-the-loop](/oss/langgraph/human-in-the-loop) guide. Refer to that guide for details and alternatives.

[pokey]

I'm using this wrapper as we already have it. Did we want to modify this to directly use typeorm rather than pulling from classic?

[eyurtsev]

OK to pull from classic if it's doing enough work for users, alternatively better to use typeorm if the code foot print is sufficiently small.

cc @hntrl

[pokey]

Yeah it's doing a bit of work. Mainly around getting db schema in dialect-agnostic way

[Copilot]

Pull Request Overview

Copilot reviewed 1 out of 1 changed files in this pull request and generated no new comments.

[christian-bromann]

I am not feeling to strong about whether to import things from @langchain/core vs langchain. IMHO if we re-export primitives from langchain we should do this consistently across all docs to avoid confusions.

[christian-bromann]

Suggested change

	import { tool } from "@langchain/core/tools";
	import { tool } from "langchain";

[christian-bromann]

Suggested change

	import { AIMessage, ToolMessage, SystemMessage, HumanMessage } from "@langchain/core/messages";
	import { AIMessage, ToolMessage, SystemMessage, HumanMessage } from "langchain";

[christian-bromann]

Suggested change

	import { tool } from "@langchain/core/tools";
	import { tool } from "langchain";