julia-client

Persistent Julia REPL client and daemon.

Runs Julia code in long-lived sessions over a Unix socket so that state (variables, loaded packages) survives between calls. The project is auto-detected from $PWD by default; see Sessions for routing.

Quickstart

curl -fsSL https://raw.githubusercontent.com/Beforerr/julia-client/main/install.sh | bash
# Override destination with `INSTALL_DIR=/usr/local/bin`.

This installs julia-client to ~/.local/bin. The single binary acts as both client and daemon (daemon auto-starts on first eval).

To uninstall: rm "$(which julia-client)".

Agent skill

The included skill at skills/julia-client/SKILL.md teaches Agent how to use julia-client.

npx skills add https://github.com/Beforerr/julia-client

Or manually by adding this repo's skills/ directory to your Agent skill search paths.

Usage

# Evaluate code (daemon starts automatically)
julia-client -e 'println("hello")'

# Use a custom Julia binary via JULIA_EXE environment variable
JULIA_EXE=/path/to/julia julia-client -e 'println("hello")'

# Explicit project: each distinct --project is its own session
julia-client --project /path/to/project -e 'using MyPackage'
julia-client --project @temp -e 'using Pkg; Pkg.add("Example")'
julia-client --project @myenv -e 'using Example'

# Read from stdin
echo 'println("hello")' | julia-client

# Session management
julia-client sessions   # list active sessions
julia-client trace      # show the last saved Julia traceback without rerunning
julia-client stop       # shut down the daemon

# Traceback levels
julia-client --trace full -e 'error("boom")'
julia-client trace --trace smart

Traceback levels:

• short: exception message only.
• smart: default eval output; user/project frames plus nearby boundary frames, hiding Julia/client internals.
• full: Julia's full traceback, including runtime and REPL frames.

Sessions

Each call is routed to a persistent Julia process by a key, in priority order:

1. --session LABEL — explicit label, shared across directories and projects.
2. --project PROJECT (not @.) — the selector (@temp, @myenv) or absolute path.
3. default (@. or omitted) — the current directory; Julia uses the nearest Project.toml up from $PWD.

A session's project is fixed at launch: a different --project routes to (and starts) a different session, not a reactivation. Same key reuses the same process, so its state persists; different keys are isolated. --fresh restarts the targeted session.

Architecture

A single julia-client binary serves as both client and daemon:

• Client mode (default) — sends JSON requests over a Unix socket (~/.local/share/julia-client/julia-daemon.sock)
• Daemon mode (julia-client daemon) — background server managing persistent Julia processes; auto-started on first eval, shuts down after 1 hour of inactivity

Alternatives

• julia-mcp is very similar but uses MCP server instead
• DaemonicCabal.jl only runs on Linux
• Malt.jl manages isolated Julia worker processes from within Julia (used by Pluto). Both run code in persistent, crash-isolated subprocesses, but Malt is a Julia library: its driver must be Julia, and it returns native typed values over Julia's serialization. julia-client targets non-Julia callers — a single dependency-free binary speaking a text protocol, so any language/shell/agent can drive it and Julia versions can be mixed freely (no cross-version serialization constraint). Reach for Malt when your caller is Julia and you need real objects back; reach for julia-client when it isn't.