A tab is now a view holding an ordered list of panes rather than a single
terminal. New panes open side by side; moving one against a top or bottom
edge restacks the view, and against a side edge returns it to a row.
Layout is a flat list with one orientation per view rather than a split
tree. That covers a shell beside an agent without the structure a tree
needs, and it can be replaced once mixed layouts actually matter.
Panes live in a GtkBox and are reordered in place, so rearranging never
unparents a terminal and running processes and scrollback survive the move.
Dragging a pane uses its header as the handle so it never competes with the
terminal's own mouse handling, and drops go through the same moveRelative
path as the Ctrl+Shift+arrow shortcuts.
Also fixes an ordering bug this surfaced: View.create used to add its first
pane immediately, firing the title callback into a Tab that had not been
initialized yet. The view is now created empty and the caller adds the pane
once it has finished wiring itself up.
Uses libghostty-vt (the API Ghostty documents for external embedders) for
the terminal core. Ghostty's other C API, ghostty.h, exposes a full terminal
surface but only supports macOS and iOS platform tags, so it cannot be
embedded on Linux.
We supply the layers libghostty-vt deliberately leaves out: PTY and process
management, a Cairo/Pango cell renderer, and a GTK4/libadwaita UI with a
Zen-style vertical tab sidebar.
Nix pins the whole toolchain (Zig 0.16 via zig-overlay, GTK 4.22, libadwaita)
so no host setup is needed.
Greyson Parrelli