@activefs/core

Install @activefs/core to program a live file tree or to use ActiveFS from application code. It provides the generic tree contract, path router, authoring helpers, errors, and logical client. It does not include HTTP, MCP, or OS mount adapters.

The package requires Node.js 22 or newer.

Install

npm install @activefs/core

Program a file from current state

fsTree can compute file contents when the file is read:

import { createActiveFS, fsTree, json } from "@activefs/core";

let serviceStatus = { ok: true };

const tree = fsTree({
  "/status.json": json(() => serviceStatus)
});

const activefs = createActiveFS().mount("/", tree);
const result = await activefs.read({}, "/status.json");

console.log(result.content);

Output:

{
  "ok": true
}

Change serviceStatus and read the file again to receive the new value. The factory runs at read time; ActiveFS does not need to copy the value into a new store first.

What this package owns

• ActiveFS paths and longest-prefix routing;
• the ActiveFSTree contract and helpers such as fsTree, dir, text, bytes, and json;
• generic list, stat, read, search, mutation, and watch contracts; and
• createActiveFSClient for promise-based application access.

Core forwards auth and metadata without interpreting them. The tree or source decides what that context means and makes the final visibility and mutation decisions. Mounting a tree into the core router is not the same as creating an OS-visible mounted folder.

Documentation

• ActiveFSTree authoring
• Core API
• Programmable-tree concepts