nvmd

Lightweight native Markdown preview for Neovim.

nvmd is a small native preview window for Markdown files. Neovim remains the editor; nvmd opens beside it, renders the current file, watches for saves, and reloads the preview.

Why

Most Markdown preview flows either open a browser tab or embed browser technology. nvmd is intentionally native: Rust, egui, pulldown-cmark, notify, and native Mermaid rendering. No Electron, no WebView, no browser process.

Run

cargo run -- README.md

The preview launches as a detached process, so the terminal prompt returns immediately.

cargo run -- --help

Neovim Plugin

The plugin uses prebuilt release binaries, so users do not need Rust unless they want to build from source. With packer.nvim:

use {
  "ryuux05/nvmd",
  run = "sh scripts/install-binary.sh",
  config = function()
    require("nvmd").setup({
      live_reload = true,
      debounce_ms = 150,
    })
  end,
}

With lazy.nvim:

{
  "ryuux05/nvmd",
  build = "sh scripts/install-binary.sh",
  config = function()
    require("nvmd").setup({
      live_reload = true,
      debounce_ms = 150,
    })
  end,
}

Run :PackerSync (or Lazy sync), open a Markdown file, and use :NvmdOpen.

Available commands:

• :NvmdOpen — open a viewer for the current buffer, a file argument, or the filename under the cursor
• :NvmdClose — close that file's viewer
• :NvmdToggle — toggle the viewer
• :NvmdRefresh — republish cursor position or open if closed
• :NvmdInstallBinary — download the matching prebuilt binary
• :NvmdBuild — build from source with cargo build --release

Keyboard Shortcuts

Press : in the preview window to open the command palette.

Key	Action
j / k	Scroll down / up
/	Open in-document search
T	Toggle table of contents sidebar
:	Open command palette
q	Close the viewer
Esc	Toggle settings / exit Mermaid control
Space j/k	Select next / previous Mermaid diagram
Enter	Open selected Mermaid diagram in large view
h/j/k/l	Pan inside Mermaid canvas
[ / ]	Zoom out / in Mermaid diagram
f	Fit Mermaid diagram to viewport

All keys except Esc and Enter are remappable via ~/.config/nvmd/config.toml.

Search

Press / to open the search bar at the bottom of the window. Matching blocks are highlighted with an accent bar. Press n / N to cycle through matches, Enter to confirm and scroll, Esc to close.

Table of Contents

Press T to toggle a sidebar listing all headings. Click any heading to scroll the document to that section. The sidebar updates automatically on document reload.

Configuration

Settings are stored in ~/.config/nvmd/config.toml. Edit it directly or use the in-app settings panel (Esc to open).

# Theme: "Dark" or "Light"
preset = "Dark"

# Window size on next launch
window_width = 1280.0
window_height = 900.0

# Enable Mermaid rendering by default (--no-mermaid CLI flag still overrides)
enable_mermaid = true

# Document layout
page_max_width = 1012.0
page_inner_margin = 32.0
line_height = 1.5
paragraph_gap = 16.0

# Typography
body_font_size = 16.0
code_font_size = 13.6

# Keybindings — single characters or named keys: "space", "enter", "escape", ":"
[keys]
scroll_down = "j"
scroll_up = "k"
palette = ":"
quit = "q"
toc = "t"
search = "/"

Markdown Support

• Headings (H1–H6) with proportional sizing
• Paragraphs with configurable line height and spacing
• Bold, italic, strikethrough, inline code
• Fenced code blocks with syntax highlighting (Rust, Python, JS/TS, Go, Bash, JSON, TOML, YAML, and more via syntect)
• Bullet lists, ordered lists, and task list checkboxes (- [x] / - [ ])
• Blockquotes with accent border
• Horizontal rules
• Tables with alternating row stripes
• Images — local file paths are loaded and rendered inline; alt text shown as caption
• Hyperlinks — http://, https://, and mailto: links open in the default browser on click
• Mermaid fenced code blocks (see below)
• Footnotes, definition lists, HTML blocks (shown as source), math blocks (shown as source)

Mermaid Support

Mermaid blocks are detected from fenced code blocks:

```mermaid
flowchart LR
  A[Neovim] --> B[nvmd]
```

Rendering uses mermaid-rs-renderer natively. SVG is rasterized with resvg/usvg/tiny-skia. Renders are bounded to 4 concurrent jobs and cancelled automatically on document reload to avoid stale work on large files.

Diagram controls when a Mermaid block is selected:

• Enter — open in large resizable view; press again to grow step by step
• h/j/k/l — pan the canvas
• [ / ] — zoom
• f — fit to viewport
• Esc — close large view

Code Block Features

• Copy button — hover over any code block to reveal a "copy" button in the top-right corner; clicking it copies the raw source to the clipboard and shows a ✓ confirmation for 1.4 seconds
• Syntax highlighting — colors powered by syntect with built-in themes that match the active dark/light preset

Themes

Two built-in presets:

• Dark — deep navy/blue palette inspired by Tokyo Night
• Light — clean white/grey palette

Switch with :theme in the command palette, the ☀/☾ toggle in the settings panel, or by setting preset = "Light" in config.toml.

Cursor Follow

While a viewer is open, moving the Neovim cursor scrolls the preview to the corresponding rendered block. Entering a Mermaid fenced block also focuses that diagram for keyboard controls.

By default, the plugin previews unsaved buffer edits after a short 150ms pause. Set live_reload = false to preview only saved file changes.

Non-goals

nvmd does not use Electron, Chromium, WebView, browser windows, Node.js, npm, Puppeteer, Mermaid CLI, or mmdc.