A lightweight, offline Markdown viewer and editor built with React + Tauri. A premium, bloat-free alternative to opening an IDE just to read a .md file.

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Features

• Live Split Preview — edit on the left, see the rendered output on the right in real time
• Synchronized Scrolling — the preview tracks your cursor position automatically
• Command Palette — Cmd+K / Ctrl+K spotlight search across files and app commands
• Document Outline — floating heading navigator, Typora-style (Cmd+I)
• Mermaid Diagrams — lazy-loaded, zero cost unless your document uses them
• Export to PDF — native OS print dialog (Cmd+P)
• Workspace Support — open an entire folder of .md files
• Custom CSS Themes — write your own markdown stylesheet live
• Zen Mode — distraction-free fullscreen writing
• Offline — zero network dependency, all data stays on disk

Showcase

Live Split Preview

Command Palette

Zen Mode (Distraction-Free)

Mermaid Diagrams

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Tech Stack

Layer	Technology
Frontend	React 19, Vite, Tailwind CSS 4
State	Zustand 5
Markdown	react-markdown, remark-gfm, PrismJS
Diagrams	Mermaid (lazy-loaded)
Desktop	Tauri v2 (Rust)
Icons	Lucide React
Tests	Vitest, React Testing Library

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Getting Started

Prerequisites

• Node.js 24+
• Rust stable (for desktop builds only)

Web Dev Mode (no Rust needed)

git clone https://github.com/IanMcNelly/fosgail
cd fosgail
npm install
npm run dev        # → http://localhost:3000

Native Desktop Dev Mode

npm install
npm run desktop    # runs `tauri dev`

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Testing

npm test              # run all 106 tests once
npm run test:watch    # interactive watch mode
npm run test:coverage # generate coverage report (HTML + lcov)

The test suite covers:

• 31 utility unit tests — normalizePath, slugify, simpleHash, calculateWordCharCount, parseHeadings
• 21 Zustand store tests — all state actions, recently-viewed tracking, feature flags
• 14 OutlinePanel tests — heading extraction, empty state, theme classes, scroll
• 18 MarkdownOutput tests — rendering, heading IDs (regression), code blocks, task lists
• 22 CommandPalette tests — file search, command mode, keyboard navigation (↑↓↵Esc)

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CI/CD

Two GitHub Actions workflows are included:

ci.yml — runs on every push and PR

Job	Trigger	What it does
Lint & Test	every push/PR	TypeScript check + 106 tests
Frontend Build	after tests pass	vite build
Tauri Smoke Build	pushes to main only	cross-platform Tauri build on Win/Mac/Linux

release.yml — triggered by a git tag

git tag v1.2.3
git push origin v1.2.3

The workflow automatically:

1. Patches package.json, tauri.conf.json, and Cargo.toml with the version from the tag — you never need to update version strings manually
2. Runs the full test suite as a gate
3. Builds native installers for all 3 platforms in parallel
4. Publishes a GitHub Release with download links

Pre-release tags are supported too (v1.0.0-beta.1, v2.0.0-rc.1).

Optional: Code Signing

Set these repository secrets to enable signed builds:

Secret	Description
TAURI_SIGNING_PRIVATE_KEY	Your Tauri signing private key
TAURI_SIGNING_PRIVATE_KEY_PASSWORD	The key password

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Keyboard Shortcuts

Action	macOS	Windows/Linux
Command Palette	⌘K	Ctrl+K
File Switcher	⌘T	Ctrl+T
Save to Disk	⌘S	Ctrl+S
Open Workspace	⌘O	Ctrl+O
New Draft	⌘N	Ctrl+N
Toggle Outline	⌘I	Ctrl+I
Toggle Sidebar	⌘B	Ctrl+B
Cycle View Mode	⌘M	Ctrl+M
Zen Mode / Exit	⌘Esc	Ctrl+Esc

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License

MIT — see LICENSE.