Lexer

A fast, keyboard-driven Markdown viewer built with Rust and Tauri v2.

Features

• Tree-sitter highlighting -- grammar-based syntax coloring for 13+ languages
• Helix-style navigation -- modal keys (g, Space, z, /), which-key popup
• Block Select -- structural selection of Markdown blocks, copy as Markdown/plain text, send to AI agents
• Command palette -- fuzzy file search, heading jump, theme picker, commands
• Visual effects -- frosted glass, particle canvas, parallax, cursor spotlight
• Custom themes -- TOML-based, hot-reloading, full CSS variable control
• Multi-window -- single process, independent windows, shared state
• Focus layouts -- Default, Focus (centered column), Zen (fullscreen), Split (pinned ToC)
• Live reload -- file watcher auto-refreshes on save
• GFM support -- tables, task lists, footnotes, strikethrough

Install

# Build and install to ~/.cargo/bin
cargo install --path src-tauri

# Or build the .app bundle
cargo install tauri-cli
cargo tauri build

The lexer command launches the GUI and returns the terminal immediately.

lexer README.md
lexer --theme lexer-nord --layout zen docs/*.md

Tech Stack

Layer	Technology
Shell	Tauri v2 (wry/webview)
Backend	Rust
Parser	pulldown-cmark
Highlight	tree-sitter + tree-sitter-highlight
Frontend	HTML + CSS + vanilla JS

Keyboard

Navigation

Key	Action
j / k	Scroll down / up
d / u	Half-page down / up
] / [	Next / prev heading
g g	Go to top
G	Go to end
/	Search in document
n / N	Next / prev match
?	Show keymap help

Modes

Key	Action
g	Goto mode
Space	Command mode
z	View mode
Space f	File search
Space t	Theme picker
Space w z	Zen layout
g w	Link hints (jump)

Block Select

Key	Action
v	Enter block select mode
V	Select current section
j / k	Move cursor block
] / [	Jump to heading
x	Toggle individual block
a	Select all
y	Copy as Markdown
Y	Copy as plain text
c	Copy as AI context block
Enter	Agent action menu
Escape	Cancel selection

In the agent menu (Enter):

Key	Action
c	Copy as <context> XML block
o	Open in Claude desktop
p	Pipe to shell command
u	Send to URL endpoint

Themes

Five built-in themes: Dark, Light, Nord, Solarized, Mono.

Custom themes are TOML files in ~/.config/lexer/themes/:

[meta]
name = "My Theme"
base = "dark"

[colors]
accent = "#ff6b6b"
select_bar = "#ff6b6b"
select_bg = "rgba(255, 107, 107, 0.08)"

All selection indicator colors are themeable via select_bar, select_bg, select_cursor_bar, select_cursor_bg, select_bar_width, and select_bar_offset.

Development

cargo install tauri-cli
cargo tauri dev -- -- path/to/file.md

Docs

Full specification in docs/.

License

MIT