Set up your app

prec runs inside your app’s git repository and reads render/terminal.toml at its top, or in the folder --app-dir names. The recipe says how to build the app, what its pty looks like, and which shots it has; each shot points at a tape of keystrokes. Everything prec writes lands under that repository’s tmp/.

A recipe

app = "myapp"
bin = "myapp"
grid = [120, 34]
frame = "bare"
setup = "{bin}/myapp-fixture >/dev/null"
teardown = "myapp server --stop || true"

[build]
command = "cargo build --release --locked --bin myapp --bin myapp-fixture"
bin_dir = "{target}/release"

[env]
MYAPP_DATA = "{scratch}/data"
MYAPP_NOW = "2026-09-29T10:00:00Z"

[theme]
background = "#eff1f5"
foreground = "#4c4f69"

[shots.tour]
kind = "clip"
line = "The terminal workspace stepping through its views"
tape = "render/terminal/tour.tape"
launch = "myapp tui"
settle = "3s"
closure = "palindrome"

Then:

prec shots myapp
prec clip myapp tour --size 1080p --fps 60

The top level

key	meaning
app	the product’s slug, the first argument of every command
bin	the app’s binary name
grid	the pty’s [cols, rows]; it never changes with the render size
frame	window or bare (Frame, closure and poster)
font	the font family; default JetBrainsMono Nerd Font
ground	the colour around the window, #rrggbb
prompt	the shell prompt in the pty; default $
typing	the delay between typed characters; default 40ms
cwd	the folder the shell starts in; default this run’s scratch folder
setup, teardown	shell commands run before and after the recording; teardown runs even when the recording fails or prec is cancelled
fixtures_env	the variable that names --fixtures to the app; default PITO_<APP>_FIXTURES
[build]	command builds the app and bin_dir is where its binaries land; bin_dir alone uses prebuilt binaries in the tree
[env]	variables for the pty, as written
[theme]	the app’s own palette (Choose a theme)

An unknown key is refused, so a typo never passes silently.

Shots

Each [shots.<name>] is one render:

key	meaning
kind	clip or still; prec clip refuses a still shot and the other way round
tape	the tape, relative to the recipe’s folder
line	one line for prec shots
launch	a command typed hidden before the recording shows
settle	how long to wait after launch before the recording shows; default 800ms
closure	how a clip ends: "palindrome", { crossfade = 0.5 }, or none
poster	"first", "before-closure" or seconds of shown time
size, fps	the defaults for --size and --fps (otherwise 1080p and 120 fps)
grid	this shot’s own grid
status	a free word shown by prec shots
fixtures	the name of the fixture set this shot needs; prec refuses to record it without --fixtures naming that set (Render a tag or commit)

Placeholders

{tmp} (the repository’s tmp/), {scratch} (this run’s scratch), {app} (the checkout), {bin} (the cached build of this commit), {target} (the repository’s shared cargo target dir in the machine cache) and {fixtures} expand the same way in setup, teardown, launch, cwd, every [env] value and the [build] command. bin_dir takes {tmp}, {app} and {target}.

The pty’s environment

The pty starts from a clean environment, so the recording doesn’t depend on your shell: TZ=UTC, LANG=C.UTF-8, TERM=xterm-256color, COLORTERM=truecolor, a scratch HOME, USER, LOGNAME, every [env] value as written, and PATH=<bin>:<system PATH>. Pin anything else your app reads, such as a clock or a data folder, through [env], as MYAPP_NOW and MYAPP_DATA do above.

A working example

prec’s own repository has two: examples/demo/render/terminal.toml, a sample app with prebuilt scripts (bin_dir = "{app}/render/terminal/bin", no build command), and the repository’s own render/terminal.toml, which builds prec and records the clip at the top of the overview.