facsimile

(noun) : something clever, trevor

Terminal text editor written in Fortran. VSCode-style keybindings.

Build

Using Make (Recommended)

The Makefile provides optimized, platform-specific builds:

• macOS arm64: Uses flang-new for better apple silicon support
• macOS Intel/Linux: Uses gfortran with standard optimization flags

make
./fac [filename]

Using fpm (Development)

fpm build
./build/gfortran_*/app/fac [filename]
or 
fpm run -- [filename]

Keybindings

Navigation

• arrows - move cursor
• ctrl-a / home - smart home (toggle between first non-whitespace and column 1)
• ctrl-e / end - end of line
• alt-left/right - jump by word/punctuation group
• pageup/pagedown - page scroll
• alt-[ / alt-] - jump to matching bracket

Mouse

• click - position the cursor; with the file tree open this also takes focus and closes the tree, since the tree owns the keyboard while it is up
• drag - select text (left button only)
• alt-click - add or remove a cursor
• right-click (or ctrl-click, for a one-button pointer) - context menu at the pointer; in a split document it also offers Close Pane, which closes the pane you clicked; shift-f10 or alt-z opens the same menu at the caret. Right-clicking inside a selection keeps it, so Cut and Copy act on the selection rather than the line
• wheel - scrolls whatever is under the pointer: the pane, an inactive pane, or the terminal panel's scrollback. Over the tab bar or status bar it does nothing rather than moving a document you are not pointing at
• drag a tab along the bar to reorder it. A ghost follows the pointer and the bar shows where it will land; release to commit, release anywhere else to snap back. Holding over a </> chevron scrolls the bar, so a tab can be carried off-screen. Picking a tab up does not open it — only a click does
• drag a tab off the bar and into the document to make a split: near the left, right or bottom quarter of the pane a band shows the shape the new pane will take, and releasing puts the file there and takes it off the tab bar. Save it first if it has unsaved changes
• drag a tab GROUP entry and its members travel with it. Drag a member off the member row onto the bar to take it out of the group, or hold a tab over a group for a moment to open its members and drop it in. Resting on a group holds the bar still and lights the entry up, so it can actually be pointed at; sweeping past one leaves it alone. Once its members are showing, moving down among them shows exactly where the tab will land. Moving a file from one group to another is one continuous drag: pick it up, rest on the other group until its members appear, drop
• click a [n: name] tab to switch to it; right-click one for Close Tab, Close Other Tabs, Copy Path and Remove from Group. These act on the tab you clicked, not the one you are looking at
• right-click a tab GROUP entry for Edit, Rename and Dissolve
• click a file tree row to open it, a directory row to expand it; right-click a row for open-in-split and the git actions (stage, unstage, diff) that otherwise hide behind the ctrl-g prefix
• click the »/« chevron in the bottom-left corner to toggle the file tree; it points the way the tree will move (ctrl-b still does the same)

Selection

• shift-arrows - character selection
• shift-alt-left/right - word selection
• shift-ctrl-a/e - select to line start/end
• shift-home/end - select to line boundaries
• shift-pageup/pagedown - page selection
• alt-a - select all
• esc - clear selection / exit multi-cursor mode

Editing

• backspace / ctrl-h - delete backward
• delete - delete forward
• tab - indent to the next tab stop, or indent the selection (a hard tab in Makefiles, where spaces are a syntax error)
  • on a line holding only whitespace it jumps straight to where the line belongs, read from the block above, so re-entering a nested block is one press
• backspace in leading whitespace - removes a whole indent level, not one space
• shift-tab - dedent selection or current line
• ctrl-/ - toggle line comment (indent-aware; comments whole lines for a partial selection)
• ctrl-k - kill line forward (yank stack)
• ctrl-shift-k - delete line outright (no clipboard, no yank stack)
• ctrl-u - kill line backward (yank stack)
• ctrl-y - yank from stack
• ctrl-w / alt-backspace - delete word backward (at column 1 it takes the line break, so it eats blank lines)
• alt-d / alt-delete / fn-alt-backspace - delete word forward
• ctrl-t - transpose characters
• ctrl-j - join lines

Clipboard

• ctrl-x - cut line/selection
• ctrl-c - copy line/selection
• ctrl-v - paste

Lines

• alt-up/down - move line up/down
• alt-shift-up/down - duplicate line up/down

Multiple Cursors

• ctrl-d - select next match (creates selections + cursors)
• alt-click - add/remove cursor at position
• ctrl-alt-up / ctrl-alt-down - add cursor on the line above / below
• super-up / super-down or ctrl-shift-alt-up / down - the same
• esc - exit multi-cursor mode (keep active cursor only)

Three chords for one command because most desktops claim the first two: ctrl+alt+arrows switches workspace on GNOME and KDE, and super+arrows tiles the window. ctrl+shift+alt+arrows is the one neither of them wants.

Search

• ctrl-f - search forward
• ctrl-r - find and replace

Special

• alt-' - cycle quotes: " → ' → ` → "
• alt-shift-' - remove surrounding brackets/quotes
• ctrl-z - undo
• ctrl-] / ctrl-shift-z - redo (use ctrl-] if terminal intercepts ctrl-shift-z)
• ctrl-l - clear/redraw screen

File

• ctrl-s - save
• ctrl-q - quit
• ctrl-b - toggle file tree (fuss mode)

Tab Management

• ctrl-t - create new tab
• ctrl-pageup / ctrl-pagedown - previous / next tab
• alt-1 .. alt-9 - jump to a tab by number (alt-0 is tab 10)
  • a further digit within half a second extends it: alt-1 then 5 goes to tab 15
  • if the first digit lands on a tab inside a group, the next digit picks that group's Nth member instead; the status bar says which it will be

Integrated Terminal

• f5 / alt-t - toggle the terminal panel
• ctrl-shift-up / ctrl-shift-down - taller / shorter, while the terminal has focus
• ctrl-shift-m - maximize, or go back to the previous height
• drag the separator bar (marked ⇕) to resize it with the mouse

The height is kept as a fraction of the screen, so the panel holds its proportion when the window is resized, and it is remembered per workspace. Set "terminal.height_percent" in settings.json to change where it starts.

fac typed at the panel's prompt opens in the session you are already in, rather than starting a second editor inside the first:

$ fac notes.md      # opens as a tab here
$ fac src/parser    # opens as a tab group here

A directory means something different in the panel than outside it. From a normal shell fac src/parser opens that directory as a whole new workspace, which is unchanged; from the panel you already have a workspace, so it opens the group dialog instead. Focus moves out of the terminal either way. Pass -w to opt out and get a separate editor.

Tab Groups

Open a directory as a sub-workspace: press enter on a directory in the file tree and tick the files you want. The group appears in the tab bar as src/ (4), and its members get their own row while you are inside it.

Right-click a group entry for Edit, Rename and Dissolve. Editing reopens the same dialog with the current members already ticked, so ticking another file adds it and unticking one closes its tab — with the usual save prompt if it has unsaved changes, which the dialog marks with a • beforehand. The dialog opens on the group's own directory, or on wherever most of its members live, and .. still walks anywhere: ticks are kept by path, so a group can span directories. Dissolve breaks the group up and leaves every member open. The same three are in the command palette as Edit/Rename/Dissolve Tab Group.

• super+ctrl+left / right - previous / next file; steps through a group's members, and off the end of one leaves it
• super+ctrl+down / up - enter a group / leave it from any member in one press
• ctrl-pageup / ctrl-pagedown or alt-ctrl-left / right - the same, for terminals that do not report Super

Left/right is one continuous line through every open file, so it always gets you out of a group even if your window manager eats the Super bindings.

Hovering a group previews its members without moving your text, and the preview stays while the pointer is over the group's own area, so you can move down into the members rather than watching them vanish as you reach for them. Group members are read from disk the first time you look at them, so a forty-file group costs one file read, not forty. Groups are saved in workspace.json and come back on restart. See docs/KEYBINDINGS.md for detail.

Pane Management

Split your view into multiple panes for side-by-side editing of the same file.

Creating Panes:

• alt-v - split pane vertically (creates pane to the right)
• alt-s - split pane horizontally (creates pane below)

Navigating Panes:

• alt-h / ctrl-shift-left - move to left pane
• alt-l / ctrl-shift-right - move to right pane
• alt-k / ctrl-shift-up - move to pane above
• alt-j / ctrl-shift-down - move to pane below

Managing Panes:

• alt-q - close current pane only
• ctrl-w - close current pane (closes tab when last pane)

Features:

• Each pane has independent viewport and cursor
• Line numbers display in all panes
• Active pane shows with visible cursor
• Inactive panes have subtle dark background
• Minimum pane size enforced (20 columns)

File Tree (Fuss Mode)

When in fuss mode (ctrl-b), you get a split view with a git-aware file tree on the left (30%) and editor on the right (70%).

Navigation:

• ↑ / ↓ - move to the previous/next visible row, whatever its depth
• → - descend into a directory (expanding it first if needed)
• ← - collapse an open directory, or go back out to the parent

Opening Files:

• enter or o - open file in new tab

Display Options:

• . - toggle hiding dotfiles and gitignored files
  • When enabled, both dotfiles and gitignored files are hidden from view
  • Directories containing only hidden files are greyed out but remain visible
  • Uses git check-ignore to detect gitignored files

Git Operations:

• a - stage file (git add)
• u - unstage file (git restore --staged)

Status Indicators:

• Green ↑ - staged changes
• Red ✗ - modified tracked files
• Gray ✗ - untracked files

Memory:

• closing and reopening the tree keeps the directories you had open, and whether hidden files were showing
• folders holding an open file are opened up to, even hidden or gitignored ones; everything else hidden stays hidden. Open tabs are saved with the workspace, so this survives a restart

Exit:

• esc - exit fuss mode back to editor
• ctrl-b - toggle fuss mode off

AI inline completion (opt-in)

Complete code inline from a local model, shown as dim shadow text. Reads the comment above the caret and the code on both sides of it, so it completes intent rather than matching identifiers that already exist.

Off by default — nothing runs, connects, or leaves your machine until you turn it on with alt-i (or ctrl-p → AI: Toggle Inline Completion). alt-i is also the quick off switch — instant, and it clears anything on screen.

• tab - accept the suggestion
• right - accept, at end of line
• ctrl-right / alt-right - accept one word / one line
• alt-\ - deep completion here (bigger model, longer budget)
• any other key dismisses it

Reaching a remote model is a second, separate opt-in, and shows a permanent [AI->host] badge in the status bar while active.

See docs/AI_COMPLETION.md for setup, settings and troubleshooting.

Help

• ctrl-? (ctrl-shift-/) or F1 - show keybindings

ctrl-/ and ctrl-? are the same byte (0x1F) in the legacy terminal encoding, so fac negotiates the kitty keyboard protocol at startup to tell them apart. In terminals that decline it (and inside tmux without set -g extended-keys on), ctrl-/ toggles a comment and F1 opens help.

Terminal Compatibility Notes

Some keybindings may be intercepted by your terminal emulator:

• Ctrl+A: Often intercepted by tmux/screen (use Home instead)
• Ctrl+Shift+Z: Intercepted by WezTerm in multi-pane mode (use Ctrl+] instead)
• Ctrl+': Most terminals send plain apostrophe (use Alt+' instead)
• Ctrl+Alt+Backspace: Most terminals send alt-backspace (use Alt+Shift+' instead)
• F2: Frequently grabbed by the window manager or desktop shell (GNOME, KDE and several tiling WMs bind it for "rename"), so no program ever sees it — use Alt+N for rename symbol instead. python3 tools/keycap.py shows whether a key reaches the terminal at all.

For WezTerm users, add to ~/.wezterm.lua to enable Ctrl+Shift+Z:

config.keys = {
  { key = 'Z', mods = 'CTRL|SHIFT', action = wezterm.action.DisableDefaultAssignment },
}

Implementation

Gap buffer for text storage. Pure Fortran with ANSI escape sequences.

License

MIT