baeru

baeru is a Rust wrapper for existing terminal applications and command output. It adds animation, color transformation, and command-specific input behavior without patching the target application itself.

At the moment, baeru focuses on:

• TUI startup reveal effects
• live ANSI color rewriting
• per-command key remapping
• inline animation for ordinary CLI output
• profile-driven behavior from baeru.yml

Note

baeru is still a PoC, but the current codebase is already usable as a base for experiments around htop, lazygit, and animated CLI wrappers.

Demo

TUI reveal + live color

CLI inline animation

Why baeru

Many terminal customization ideas fall into one of two extremes:

• patch or fork the target application
• build a brand-new terminal UI from scratch

baeru explores a middle path: keep the original app, but wrap it with presentation and interaction layers.

That makes it possible to experiment with things like:

• cinematic startup reveals for TUIs
• theme-driven ANSI recoloring
• per-command keymaps
• lightweight animation for normal CLI output

Core model

baeru is organized around two concepts:

• backend The execution path: tui, cli, or raw
• features Layered behaviors such as reveal, live_color, keymap, and inline_animation

This separation makes it easy to express profiles like:

• htop uses reveal + live_color + keymap
• vim stays close to passthrough
• ls uses CLI animation only

Installation

Release binaries

Prebuilt binaries are published on the GitHub Releases page.

• Linux: x86_64-unknown-linux-gnu
• macOS: aarch64-apple-darwin
• Windows: x86_64-pc-windows-msvc

Download an archive from Releases, then place baeru somewhere on your PATH.

crates.io

If you already have a Rust toolchain installed, you can install from crates.io:

cargo install baeru

Build from source

git clone https://github.com/blacknon/baeru
cd baeru
cargo build --release
./target/release/baeru -- htop

Quick start

Run using the default profile lookup:

cargo run -- -- htop
cargo run -- -- lazygit
cargo run -- -- ls -la

Explicit examples:

cargo run -- --mode reveal -- htop
cargo run -- --mode color-live --theme-file examples/themes/jirai-pink.yml -- htop
cargo run -- --mode reveal --theme-file examples/themes/jirai-pink.yml --keymap-file examples/keymaps/htop-vim.yml -- htop
cargo run -- --mode live-render --theme-file examples/themes/jirai-pink.yml -- htop
cargo run -- --backend cli -- ls -la
cargo run -- --backend cli -- git status

If ./baeru.yml exists, it is loaded automatically:

cargo run -- -- htop
cargo run -- -- ls -la

You can also point to a config explicitly:

cargo run -- --config-file baeru.yml -- htop

If no command is specified and stdin is a terminal, htop is used as the default PoC target:

cargo run

Backends

tui

For interactive terminal applications such as htop or lazygit.

baeru --backend tui -- htop
baeru --mode reveal -- htop

cli

For ordinary commands such as ls, df, or git status.

baeru --backend cli -- ls -la
baeru --backend cli -- git status
printf 'hello\nworld\n' | baeru --backend cli

raw

For plain passthrough behavior without added effects.

Features

Current matrix

Area	Name	Kind	Status	Notes
TUI	reveal	startup animation	stable PoC	startup capture + animated reveal
TUI	live_color	live color transform	stable PoC	ANSI SGR rewrite, supports palette replacement
TUI	keymap	input remap	stable PoC	YAML-driven byte-sequence remapping
TUI	splash	startup animation	stable PoC	simple pre-launch splash
TUI	live-render	live redraw animation	experimental	VT100 rebuild + changed-cell flash
CLI	inline_animation + coalesce	inline animation	stable PoC	noisy symbols converge into final text
CLI	inline_animation + sweep	inline animation	stable PoC	left-to-right reveal
CLI	inline_animation + fade	inline animation	stable PoC	delayed text appearance
CLI	inline_animation + plain	passthrough-style	stable PoC	same backend path, no animation

reveal

Starts the target command in a PTY, captures the initial screen briefly, renders a startup animation, then switches to PTY passthrough.

baeru --mode reveal -- htop
baeru --mode reveal --capture-ms 420 --duration-ms 900 -- htop

Sample GIFs:

coalesce

sweep

fade

plain

live_color

Passes PTY output through while rewriting ANSI SGR colors.

baeru --mode color-live --theme-file examples/themes/jirai-pink.yml -- htop

Current approaches include:

• gradient-based recoloring
• indexed ANSI palette replacement via palette_map

keymap

Rewrites key input per command using YAML-defined mapping rules.

inline_animation

Animates CLI output inline below the prompt.

Supported effects:

• coalesce
• sweep
• fade
• plain

baeru --backend cli --effect coalesce -- ls -la
baeru --backend cli --effect sweep -- git status

Sample GIFs:

coalesce

sweep

fade

live-render experimental

Rebuilds the target TUI screen from VT100 state, redraws it from baeru, and flashes changed cells.

baeru --mode live-render --theme-file examples/themes/jirai-pink.yml -- htop

This mode is intentionally experimental and much more fragile than reveal or live_color.

Configuration

baeru.yml

baeru resolves behavior from profiles matched against:

• executable basename
• exact executable path
• optional args_prefix

Example:

profiles:
  - name: htop-jirai-vim
    match:
      command: htop
    backend: tui
    features:
      - reveal
      - live_color
      - keymap
    effect: coalesce
    keymap_file: examples/keymaps/htop-vim.yml
    theme_file: examples/themes/jirai-pink.yml
    capture_ms: 360
    duration_ms: 720
    frames: 24

  - name: ls-inline
    match:
      command: ls
    backend: cli
    features:
      - inline_animation
    effect: coalesce
    theme_file: themes/matrix-green.yml

Theme YAML

Themes support the original gradient-based recoloring style:

name: jirai-pink
default_fg: "#ffcdeb"
default_bg: "#120018"
force_default: true
foreground:
  - { at: 0.00, color: "#84205c" }
  - { at: 0.30, color: "#ff45ac" }
  - { at: 0.62, color: "#ff8fd6" }
  - { at: 0.84, color: "#ffcdeb" }
  - { at: 1.00, color: "#fff2fa" }
background:
  - { at: 0.00, color: "#120018" }
  - { at: 0.55, color: "#570a41" }
  - { at: 1.00, color: "#ff8fcf" }

They also support indexed ANSI palette replacement:

name: gundam-tricolor-htop
default_fg: "#f3f6ff"
default_bg: "#08111f"
force_default: true
palette_map:
  1: "#ff5a5f"
  3: "#ffd84a"
  4: "#3f7dff"
  15: "#ffffff"
background_palette_map:
  4: "#0f214a"

This is especially useful for htop-style TUIs where preserving rough semantic color roles matters more than pure luminance mapping.

Keymap YAML

keymap:
  j: down
  k: up
  h: left
  l: right
  ctrl-d: page-down
  ctrl-u: page-up
  r: f5
  "/": f3

Supported key names include:

• arrows: up, down, left, right
• navigation: home, end, page-up, page-down
• function keys: f1 ... f10
• control keys: ctrl-a ... ctrl-z
• special keys: enter, esc, tab, backspace
• printable single characters such as j, k, /

Themes

There are two theme buckets right now:

• themes/ More baseline examples
• examples/themes/ More expressive or experimental sample themes

Current example themes include:

• jirai-pink
• eva-unit-01
• eva-unit-01-htop
• gundam-tricolor-htop

Keymaps

Example keymap files live under:

• examples/keymaps/

Limitations

• This is still a PoC. Terminal restoration and signal handling can be hardened further.
• reveal captures a single approximate startup screen. Very unstable startup screens may need capture_ms tuning.
• live-render is experimental and may flicker or desynchronize on complex TUIs.
• CLI inline animation is still less robust than plain passthrough for some terminals and very large outputs.
• Key remapping is byte-sequence based. Complex keyboard protocols, mouse input, bracketed paste, and emulator-reserved shortcuts need more careful handling.
• Mouse mapping is not implemented yet, though the architecture leaves room for a future mousemap layer.
• Command-specific semantic adapters are still future work.

License

MIT. See LICENSE.

ASW-G-01?

? "Here stands the truth of Gjallarhorn. All of you... gather beneath Bael!"

? "It's Bael!"

? "The soul of Agnika Kaieru!"

? "That's the other Bael, it is Baeru"