# Tags and columns

Pardes has three levels of command text: the workspace tag, a tag per
column, and each pane's tag. A column tag's words act on that column and run
in its active pane (its first pane when focus comes from another column). A
command or `Tty` run from the workspace or a column tag starts in the
session's directory (where pardes started), as acme's row and column tags
have none of their own; one run from a pane's tag or text starts in that
pane's directory. Over 9P the tags are `/tag`, `/col/<n>/tag` and
`/pane/<n>/tag` ([fs.md](fs.md#columns-and-tags)).

## Default words

- Workspace: `Newcol Joincol Find Grep Help Changelog Tutor Dump NextColor
  Debug Exit`.
- Column: `New Tty Find Grep Joincol Delcol`.
- File pane: `Save Tty Collapse Del`; a source file with a grammar adds
  `TreeContext`, a result list `LocationsConfig`. PDF: `manual.pdf [1/12]
  Tty Del PdfSections PdfTint Collapse`.
- Terminal: `Tty+bash Save Mode Filter Collapse Del`. `Tty+bash` is one word
  for `Tty bash`, opening another terminal on that shell (only `Tty` reads a
  `+` so). `Mode` cycles raw terminal input, normal mode and insert mode.
- Command pane: `<dir> (<line>) running`, then `exit N`, and `Kill`.

`Undo`, `Redo` and `Mode` (on files) work typed or clicked though they are
not in the default tags. Customized tags keep their text.

A tag word runs as acme's does, in the pane's directory with no file named:
`wc` alone waits on stdin. There is no `$%`; name the file (`wc notes.txt`),
or select the name and middle-click `wc`, which takes a held selection as its
argument.

`Repl python` in a terminal's tag binds it as that language's REPL
([fs.md](fs.md#repls)). `Repl` takes the languages a code fence names: ada,
bash, c, c_sharp, clojure, cpp, css, elixir, erlang, fortran, go, haskell,
html, java, javascript, json, kotlin, ocaml, markdown, pascal, php,
powershell, python, ruby, rust, scala, typst, zig, and aliases such as `py`
and `sh`.

## Pane builtins

`Collapse` folds a pane to its tagline, giving its rows to the nearest
expanded pane above (else below); again, it takes them back. Its text and
process are kept.

`Del` closes a pane, giving its rows to one neighbour. `Del k` (`DelAbove`)
gives them to the nearest expanded pane above, `Del j` (`DelBelow`) below,
each falling back to the other side. Bare `Del` from the keyboard (`SPC d`),
with expanded panes above and below, asks on the notice band (`k`/Up above,
`j`/Down below, any other key keeps the pane); a click, a 9P write or an
`init` line never asks and gives the rows above.

A pane with unsaved text is refused once: a notice `1 unsaved pane — Del
again to discard`, the pane listed in `+Unsaved`, and over 9P the write
fails (EIO). The same `Del` again, nothing edited since, discards. `Delcol`
refuses a column holding such a pane the same way, without opening
`+Unsaved` or moving focus. `Exit` and `Restore` do the same over the whole
session. A `+New` scratch under 100 bytes is never asked about.

`Edit` runs sam's command language on the body ([fs.md](fs.md#edit)).
`Undo` and `Redo` step the body through its last 256 edits, as `u` and `U`.

Unsaved text shows on the pane's grip, as acme's modbutton, not in the tag.
In a terminal the grip is two cells: the pane's mode (blank normal, `^`
insert, `$` tty mode), then `*` while unsaved.

## Editing tags

A tag is text like a body, with the body's normal and insert modes and undo.
A pane tag may hold several lines and wraps, taking a row per shown line up
to eight and leaving its body at least one; a collapsed pane shows the first.
Up on its first row in insert mode (or Alt-Up in either mode) folds a tag to
one row, Down on its last (Alt-Down) unfolds it. Column and workspace tags are
one line: a newline typed, pasted or written into one becomes a space.

The path (and a PDF's page) at the start of a pane tag is computed and
read-only; `0` goes to its start, and motions select and yank across it.
Typing into a file's path, or clicking it, starts a draft of a new name:
Enter or Tab confirms it, Escape or leaving the pane cancels. Confirming
changes the buffer's save target and marks it unsaved; nothing on disk is
renamed until `Save`. A pane-tag command confirms a valid draft first.

Left-click a tag to type at the click, in insert mode. Esc is normal mode:
there Tab executes the word under the cursor (or the selection); Enter looks
it up in a pane's tag and runs it in a column or workspace tag. Executing
gives the keyboard back to the body first. Paste goes to the focused tag.

`:` in a body's normal mode focuses its tag (the first time, on `Save`); `:`
in a tag goes back. The window keys (`Ctrl-w`, `SPC w` with `h/j/k/l`) move
between panes; up from the top pane reaches its column's tag, then the
workspace's, and Left/Right walk the column tags. Search, `s`/`S`, pipe and
Save's path prompt get a line on the pane's notice band; in a tag `s`, `S`
and `|` act on the tag's own text, while `/` searches the body.

## Moving and resizing

Drag a pane's grip up or down its column and its top follows, the pane
above giving or taking rows, down to its tag alone; drop it in another
column and it moves there. In the GUI the 2 px rule between panes drags too.
A column's right edge drags its width. Drag a column's grip past a
neighbour's middle to move the whole column there; short of that it moves
the column's left edge.

A terminal keeps its tag and 2 body rows: no drag, squeeze or smaller
window takes it below that, and `pty/ctl`'s `winsize` gives a pty 2 rows at
least. A text pane can be dragged down to its tag.

## Empty columns

A column can hold no pane, as acme's can: its tag stands over blank space in
the theme's `empty_col` colour. `Newcol` makes one right of the keyboard's
and gives its tag the keyboard. Closing a column's last pane leaves the
column empty, the keyboard on its tag. Only `Delcol` and `Joincol` take a
column away; `Joincol` keeps the right column's tag, its panes below. A pane
dragged onto an empty column fills it. `Delcol` of the last column leaves
the workspace tag alone; `Newcol` or `New` starts again. Unlike acme, pardes
quits when the session's last pane closes.

## Where new panes go

Every new pane goes through one placement, chosen by `Placement acme` (the
default) or `Placement pardes` (bare flips it; `SPC c p`).

No placement leaves a pane shorter than its tag and 2 body rows. Where the
chosen place has not that room, the column's tallest pane is halved; where
no one pane can give it but the column holds every pane's minimum with the
new one's, the rows are shared out again; otherwise the pane is refused,
`no space for a pane in that column: each keeps its tag and 2 rows` (ENOSPC
over 9P). A pane alone in its column always fits.

`Placement acme` is acme's makenewwindow. The active column is the one last
typed or clicked in, dropped into, whose tag was given the keyboard, or that
was given the last new pane; a Look moves the keyboard, not the active
column. A new pane goes into the column whose tag the command came from,
else the active column, never into a new column:

- an empty column it takes whole;
- from a tag, or 9P's `pane/new`, it takes the bottom half of the column's
  last pane;
- from a pane's text (a Look, `Tty`, `Alt-n`, a Grep or Find listing), it
  goes under the text of the pane with the most blank rows when that is
  more than 15 rows, or more than 3 and more than half the biggest pane;
  otherwise it halves the biggest pane, or the asking pane when that is in
  the column and not much smaller;
- `New` goes to the bottom half of its own column's last pane;
- a command pane or `+Errors` pane goes to the last column's last pane (a
  command from a column's tag to that column, reusing a finished command
  pane only there). With no room anywhere, `+Errors` text is logged as `msg`
  records.

`Placement pardes`: an empty column whose tag asked, or has the keyboard, is
filled; a scratch goes under the pane that asked; a shell under it or the
nearest pane with room; a document beside the last one read, or in a column
of its own on the left when there is none and the column is at least 200
cells wide; a command pane at the foot of the last column.

## Saved workspaces

`Dump` and `Restore` keep workspace and column tags (empty ones too) and
empty columns ([config.md](config.md#dumps)). The column row stays above
the panes with `Tagbottom` on; on screens under three rows it is left out.