jprototerm

JavaFX canvas terminal prototype using jlibghostty for terminal emulation and Nix for the build environment. It builds a plain JavaFX application (JDK 25, JavaFX 25 via Gradle) packaged as a Nix derivation — no GraalVM/GluonFX native image. It supports tiled and floating panes and tabs.

Caution

nix profile add has only been tested on Debian with the proprietary NVIDIA driver. The runtime GL shim hardcodes Debian's /lib/x86_64-linux-gnu driver paths and selects the NVIDIA GLX/EGL vendor, so it likely won't work yet on other distros, Wayland-only setups, or Mesa/AMD/Intel GPUs. I'm happy to accept pull requests that broaden host support.

Build

nix build
./result/bin/jprototerm

Install it into a profile (see the caution above on host support):

nix profile add .
jprototerm

Or install straight from the remote — note the git+https:// scheme (a bare https:// URL is treated as a tarball, not a git repo):

nix profile add git+https://gitea.gregorlohaus.com/gregor/jprototerm

Add ?ref=<branch-or-tag> to pin a revision. The target machine needs Nix with the nix-command and flakes features enabled and network access — the build fetches the jlibghostty/ghostty flake inputs plus the JDK and Gradle from the binary caches.

The flake bundles everything the app needs — the JDK 25 runtime, the Maven JavaFX modules and their native libraries, and the gtk/glib/freetype/X11 libraries they load — except the system OpenGL/graphics drivers. libGL is supplied by the host at runtime through a GL shim in the launcher wrapper, so the same closure runs against NixOS, Mesa, or vendor (e.g. NVIDIA) GPU drivers.

Gradle dependencies are vendored in deps.json for the pure Nix sandbox. Regenerate it after changing dependencies in build.gradle (the update script writes deps.json in the current directory):

$(nix build .#gradleDepsUpdateScript --no-link --print-out-paths)

For development:

nix develop
gradle run

The Gradle project is the source of truth for the JavaFX build.

Daemon (optional, faster launches)

Cold start pays for JVM + JavaFX + GL/X11 init every time. The optional daemon keeps one JVM (one toolkit) running and hosts every window in it, so a jprototerm launch just asks the daemon to open a window — it appears without paying that startup cost again.

Run it once in the background:

jprototerm --daemon &

After that, a bare jprototerm connects to the daemon and opens a window in the current directory. If no daemon is running, jprototerm falls back to a standalone in-process window (today's behavior), so it always works.

For development testing, use jprototerm --standalone to skip the daemon even when one is running.

To start the daemon automatically with your graphical session, enable the bundled user service (it's a user service, not a system one, because X11 needs a display — which only exists after you log in):

mkdir -p ~/.config/systemd/user
ln -sf "$(dirname "$(readlink -f "$(command -v jprototerm)")")/../share/systemd/user/jprototerm.service" \
  ~/.config/systemd/user/jprototerm.service
systemctl --user enable --now jprototerm.service

After upgrading via nix profile upgrade:

systemctl --user disable jprototerm
ln -sf "$(dirname "$(readlink -f "$(command -v jprototerm)")")/../share/systemd/user/jprototerm.service" \
  ~/.config/systemd/user/jprototerm.service
systemctl --user enable --now jprototerm.service
systemctl --user restart jprototerm.service

If the daemon can't reach your display (e.g. systemctl --user status jprototerm shows it failing to open a window), import the session variables once and restart it:

systemctl --user import-environment DISPLAY XAUTHORITY
systemctl --user restart jprototerm.service

Closing a window (the WM close button, or the close-pane key on the last pane) tears that window down — its shell processes are signalled with the configured close_signal — without affecting other windows or the daemon. Stop the daemon (and all its windows) with systemctl --user stop jprototerm.service, or pkill -f 'jprototerm --daemon'.

Config

Configuration is read from:

$XDG_CONFIG_HOME/jprototerm/config.toml

If XDG_CONFIG_HOME is unset, the fallback is:

$HOME/.config/jprototerm/config.toml

If no config file exists, jprototerm writes the default config on startup.

Example, also available in config.example.toml:

[terminal]
columns = 100
rows = 30
shell = "/bin/bash"
font_family = "JetBrainsMono Nerd Font"
font_size = 15

[window]
width = 1200
height = 760

[kitty_graphics]
enabled = true

[scrollback]
editor_command = "vi {file}"

[worktree]
relative_worktree_path = "./.worktrees"
split_regex = ","
# One of: "none", "cd", "create_panes", "create_panes_floating".
post_create_action = "none"
commands = []
sync_panes = false

[env.override]
ZELLIJ_SESSION_NAME = ""

[keybindings]
navigate_left = "ALT+H"
navigate_down = "ALT+J"
navigate_up = "ALT+K"
navigate_right = "ALT+L"
toggle_floating = "ALT+F"
new_pane = "ALT+N"
next_floating = "ALT+F12"
close_pane = "ALT+X"
new_tab = "ALT+A"
previous_tab = "ALT+SHIFT+H"
next_tab = "ALT+SHIFT+L"
open_font_selector = "ALT+T"
open_scrollback = "ALT+S"
create_worktree = "ALT+W"
pane_sync_toggle = "ALT+Y"
pane_sync_select = "SPACE"
paste = "CTRL+SHIFT+V"

Defaults

• Alt+h/j/k/l: navigate panes
• Alt+n: new pane — a floating pane when floating panes are shown, otherwise a new tiled pane (tiled panes are split equally across the width)
• Alt+f: show or hide all floating panes
• Alt+F12: cycle floating panes
• Alt+x: close the active pane; closing a tab's last pane closes the tab, and closing the last pane of the last tab quits
• Alt+a: new tab
• Alt+Shift+h / Alt+Shift+l: previous / next tab
• Alt+t: open the font selector
• Alt+s: open the active pane scrollback in $EDITOR
• Alt+w: edit one or more worktree names, split by worktree.split_regex, then run git worktree add <relative_worktree_path>/<name> for each name from the previously focused pane's working directory. worktree.post_create_action can then do nothing with none, cd the previously active pane to the last created worktree, create one tiled pane per worktree with create_panes, or create one floating pane per worktree with create_panes_floating. worktree.commands, for example ["npm install", "git status"], can run commands in created panes; commands are assigned in order and repeat when fewer commands than panes are created. worktree.sync_panes = true syncs those created panes after the configured commands are sent.
• Alt+y: enter pane-sync selection mode, commit the selection, or stop an active pane sync
• Space: toggle the focused pane in the sync set while pane-sync selection mode is active
• Once committed, input typed or pasted into any synced pane is mirrored to the other synced panes
• Ctrl+Shift+v: paste
• Font default: JetBrainsMono Nerd Font
• Kitty graphics protocol parsing is enabled by default

Each tab has its own stack of tiled and floating panes; only the active tab is rendered. A thin tab bar appears at the top when more than one tab is open. Closing the last tiled pane while floating panes exist promotes the most recently active floating pane to a tiled pane.