JFSecure

jfs — secrets for AI agents that never see them

jfs is the command line and MCP server of JFSecure, an offline password and snippet manager. It lets Claude Code, Cursor or any MCP agent use a secret without ever getting it — and you approve every use in the app.

This repository is the source of jfs itself, so you can read exactly what an agent talks to. It is a thin client: it sends one JSON request over a local pipe to the running, unlocked JFSecure app and prints the answer. It never opens vault files, never sees the vault password and has no crypto. (The app is a separate download; jfs ships with it.)

MCP tools

Tool	What it does	What the agent gets back
list_secrets	Lists secret and key names, with the environment variable each key becomes	Names only
run_with_secrets	Runs a command with a secret's keys as environment variables (all, some, or one on stdin)	Exit code and output, every value masked as [JFSecure: NAME]
render_template	Fills {{Secret:key}} in a template and writes the file (e.g. .env)	Which names were filled in

There is no "get" tool, on purpose. Every use opens an approval window in JFSecure that shows the program, the exact command and the secret: allow once, allow 15 minutes, or deny. For Claude Code a 15-minute approval covers only that command and that secret.

# the agent called run_with_secrets(secret: "github", command: …)
exit code 0
variables set: TOKEN
--- stdout ---
token is [JFSecure: TOKEN]
{"login": "octocat", "plan": {"name": "pro"}}

Set up

1. Install JFSecure and open your vault: brew install theone55/jfsecure/jfsecure (macOS), scoop bucket add jfsecure https://github.com/theone55/scoop-jfsecure; scoop install jfsecure/jfsecure (Windows), or the installer (Windows, macOS, Linux). jfs comes with it: on Windows the app puts it on PATH at its first start (open a new terminal afterwards); on macOS (.dmg) and the Linux AppImage use Settings → Install the jfs command; Homebrew and the .deb install it for you.
2. Add the MCP server:

claude mcp add --scope user jfsecure -- jfs mcp

Cursor (~/.cursor/mcp.json), Claude Desktop, Windsurf, VS Code — any stdio MCP client:

{ "mcpServers": { "jfsecure": { "command": "jfs", "args": ["mcp"] } } }

More: https://secure.jfolio.org/agents

Also as an MCP bundle (.mcpb, Windows / macOS / Linux) on the releases page, and in the official MCP Registry as io.github.theone55/jfs.

Command line

jfs status                       is the app running and unlocked
jfs ls [secret|folder]           names only, no approval needed
jfs get github/token             print a value (approved in the app)
jfs copy github/token            to the clipboard, nothing printed
jfs run github -- gh api user    run with the secret's keys as env vars ($token → TOKEN); output masked when piped
jfs render .env.tpl -o .env      fill {{Secret:key}} into a file
git config --global credential.helper "!jfs git-credential"

Full guide: https://secure.jfolio.org/cli

What it protects — and what it doesn't

• The model never receives a value, so it can't end up in a transcript or a log.
• A prompt-injected agent can only ask; you see the exact command.
• The pipe is your OS user's only, and the app identifies the caller through the OS, not by what it says.
• Masking is a seatbelt, not a wall: a command you approve can still send a value away. Read the command.

Build

cargo build --release   # Rust stable; Windows, macOS, Linux
cargo test

The copy here follows each JFSecure release (version in Cargo.toml = the app's version it shipped with). Issues and questions are welcome here.

MIT License.