Files, buffers and windows

bi keeps the project in reach without plugins: a tree that edits the filesystem, a picker over every file, a switcher over what is open, and a key that knows lstring.c belongs with lstring.h.

The other file: ga and gA

Every language has a pair — a .c and its .h, thing.go and thing_test.go. ga (:alt) opens the other one without typing a path.

lstring.c ga — the other file 1 / 3 play

1. start lstring.c, in luaS_resize.
2. 1 ga ga opens the alternate: *.c pairs with *.h, so lstring.h.
3. 2 ga Again, and you are back in lstring.c.

gA (:valt) does the same in a vertical split, so both halves stay on screen.

lstring.c gA — the other file, beside this one 1 / 3 play

1. start lstring.c, in luaS_resize.
2. 1 gA gA (:valt) opens lstring.h in a vertical split on the right, and focus goes there.
3. 2 Ctrl-Wh Ctrl-W h back to the source.

The pairs are rules in [alternate], walked in order: the first pattern that matches your path decides, then the first of its targets that exists is opened. * matches anything, separators included, and stands for the same text on the right.

[alternate]
"*_test.go" = ["*.go"]
"*.go"      = ["*_test.go"]
"*.c"       = ["*.h"]
"*.h"       = ["*.c"]
"*.cpp"     = ["*.hpp", "*.h"]

Go, C and C++ are built in; a pattern you write replaces bi’s for that pattern. Order matters — *_test.go has to come before *.go, or a test file becomes its own alternate. :alt never creates a file: if nothing exists it tells you which names it tried.

The file tree

bi . opens a directory, and so do :e, :sp and :vs given one. - goes from a file back up into the tree, and Ctrl-W e shows or hides it as a sidebar beside the file you are reading.

lstring.c Ctrl-W e — the tree beside the file 1 / 5 play

1. start lstring.c, opened from the project root.
2. 1 Ctrl-We The tree opens on the left, rooted at the session’s directory.
3. 2 jjjj It is a pane: j / k move, l and h open and close directories.
4. 3 Enter Enter on a file opens it in the window you came from. The tree stays.
5. 4 Ctrl-We Pressed again, from anywhere, it puts the tree away.

There is only ever one tree, and its root is the session’s: whatever directory you opened. Opening a file never moves it — only naming a directory, + and - do. Enter on a file opens it in the window you came from, so the sidebar stays put.

. The tree: open, mark, forget 1 / 6 play

1. start bi . opens the directory as a tree.
2. 1 jl l opens a directory in place.
3. 2 h h closes it again.
4. 3 jjjc c marks a file for copying — a + in the mark column.
5. 4 jcjx Another copy, then x marks one for moving — a ~. The footer counts both; p on a directory would put them there.
6. 5 Esc Esc forgets every mark.

Marks are per path, so one p can copy some files and move others. Marked rows carry a + or ~ in a column that is always there, so marking never shifts the tree sideways. A paste never overwrites: it stops on the first clash and offers the path on the : line to edit.

The keymap is an allowlist. Anything the tree does not name does nothing, and nothing in it enters insert mode.

gf — the file picker

lstring.c gf — find a file by name 1 / 4 play

1. start Any file, somewhere in the project.
2. 1 gf gf opens the picker over every file under the root, .gitignore respected.
3. 2 ltmh Paths match as a subsequence: ltmh finds ltm.h.
4. 3 Enter Enter opens it.

gf opens a picker over every file under the root. It skips hidden entries and whatever .gitignore excludes — :set gitignore false lists everything. File names match as a subsequence, so sfr finds src/find/render.rs, and results are ranked: consecutive characters beat characters at a word boundary, which beat scattered ones, and a shorter path breaks a tie.

Buffers

Every file you open stays in the buffer list until you :bd it.

lstring.c gb — the buffer switcher 1 / 4 play

1. start Three files opened in turn: lstring.c, lapi.c, then ltm.c.
2. 1 gb gb lists the buffers, newest first, and opens on the second row — the one you were in before.
3. 2 Enter So gb then Enter goes back to lapi.c.
4. 3 Ctrl-^ Ctrl-^ flips to the alternate buffer — ltm.c again.

gb opens the switcher. It is ordered by when each buffer was last shown and starts on the second row, so gb Enter always takes you back to where you just were, and doing it twice returns. Ctrl-Tab is the same where the terminal can send it.

Splits

lstring.c Splits and Ctrl-W f 1 / 6 play

1. start One window on lstring.c.
2. 1 :vs lstring.hEnter :vs opens lstring.h on the right, and focus goes there.
3. 2 Ctrl-Ws Ctrl-W s splits it again, below. Three windows.
4. 3 Ctrl-Wf Ctrl-W f puts a letter in the middle of every window.
5. 4 f Press one and you are in that window.
6. 5 :resize 1:2Enter :resize 1:2 divides the left-right split one to two.

Ctrl-W f labels start on the home row, f and j first. With only two windows it skips the labels and goes straight to the other one.

Two windows may show one buffer, each with its own cursor and scroll; an edit in one moves the other’s cursor with the text. Closing a window never loses anything — the buffer stays in the list — so it never asks about unsaved changes.

:resize

Ctrl-W + moves a divider one cell; :resize says how far in one go.

:resize 30       the width, in cells      :resize 1:2      divide one to two
:resize 30y      the height               :resize 1:2:1    three panes
:resize +3  -3   relative                 :resize 1:2y     vertically
:resize +3,-3    both axes                :resize 1:2,1:2  both

A y names the vertical axis; otherwise a comma separates across from down. A ratio needs one term per pane in that split, and shares are normalised, so 20:40 is 1:2.

:zen

lstring.c :zen 1 / 3 play

1. start The usual chrome: signs, line numbers, a status row.
2. 1 :zenEnter :zen takes them away. The command line stays.
3. 2 :zenEnter Again, and everything is back where it was.

:zen strips the chrome — sign column, line numbers, every status row — and leaves the text where it was. The command line stays, because you still need somewhere to type :zen again. It hides; it does not rearrange: no centring, no margins.