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Mermix/README.md

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# Mermix
A cross-platform Mermaid diagram editor and viewer with Git-backed projects.
Organize many diagrams into projects, edit them with a live preview, export to
SVG or PNG, and version everything with real Git branches and commits in a
native desktop app.
Built with Rust + Tauri 2, SQLite (sqlx), git2, and a Svelte 5 + TypeScript
frontend using CodeMirror 6 and Mermaid 11.
---
## Features
- Projects: Each project is a folder on disk that is a real Git repository
with a `mermix.toml` config and a `diagrams/` directory of `.mmd` files.
- Many diagrams per project: Create, rename, and delete diagrams via the
sidebar explorer.
- Live editor and preview: CodeMirror source on the left, debounced Mermaid
render on the right, with zoom, pan, and inline syntax-error reporting.
- Git version control: View working-tree status, write commit messages,
browse history, create and switch branches. Each branch keeps its own
set of diagrams, just like normal Git.
- Remote sync: Configure an origin remote, then fetch, pull (fast-forward),
and push from the Git panel with live ahead/behind counts. Network
operations use your system git, reusing existing credentials (SSH agent,
keychain, credential helpers) — no separate login.
- Optimize panel (Diagram Doctor): Analyze a tangled flowchart or state
diagram and declutter it in one click. Provides a readability score and
metrics (hubs, density, cross-group edges), plus source rewrites for:
ELK layered layout (flowcharts), extra spacing, layout-direction toggle,
de-emphasizing cross-cutting hubs (e.g. event-bus fan-ins, faded sink
states), and removing duplicate edges. A non-destructive focus mode
spotlights any node and its neighbors so you can read a dense graph
without changing it. Every rewrite lands in the editor and is reversible
with Command + Z.
- Export the current diagram to SVG or PNG (2x scale), or copy a PNG
straight to the clipboard. PNG export re-renders flowcharts with text
labels so the bitmap rasterizes cleanly across platforms.
- Project registry: Recently opened projects are remembered in a local
SQLite database so you can jump back in from the start screen.
- Themes: Switch the Mermaid theme (default, neutral, dark, forest, or
base) per project.
## Architecture
```
Mermix/
├─ src/ # Svelte 5 + TS frontend
│ ├─ App.svelte # layout, resizable editor/preview split
│ ├─ lib/
│ │ ├─ api.ts # typed wrappers over Tauri commands
│ │ ├─ store.svelte.ts # central rune-based app state
│ │ ├─ mermaid.ts # render + error capture (registers ELK layout)
│ │ ├─ optimize.ts # flowchart analysis + declutter transforms (pure)
│ │ ├─ export.ts # SVG / PNG export via save dialog
│ │ └─ components/ # Sidebar, Editor, Preview, GitPanel, OptimizePanel, …
│ └─ main.ts
└─ src-tauri/ # Rust backend
├─ src/
│ ├─ lib.rs # Tauri builder, state, command registry
│ ├─ commands.rs # the IPC surface
│ ├─ db.rs # sqlx/SQLite project registry + settings
│ ├─ project.rs # mermix.toml, create/open, slugify
│ ├─ diagram.rs # .mmd CRUD, frontmatter titles
│ ├─ git_ops.rs # git2: commit, history, branches, status
│ ├─ error.rs / state.rs
│ └─ tests.rs # headless core-logic tests
└─ tauri.conf.json
```
Data model: A single app-level SQLite database (in the OS app data directory)
tracks the project registry and user settings. All content lives on disk
inside each project's Git repository — projects are portable, inspectable,
and work with any other Git tooling.
A project on disk looks like:
```
my-diagrams/
├─ mermix.toml # project id, name, description, default theme
├─ README.md
├─ .gitignore
├─ .git/ # full Git history
└─ diagrams/
├─ welcome.mmd
└─ login-flow.mmd # Mermaid source, optional YAML frontmatter title
```
## Prerequisites
- Rust (stable) and Cargo
- Node.js 18+ and npm
- Platform webview dependencies:
- macOS: nothing extra (system WebKit)
- Windows: WebView2 (preinstalled on Windows 11)
- Linux: webkit2gtk and related packages (see Tauri docs)
## Getting started
```bash
npm install # install frontend dependencies and Tauri CLI
npm run app:dev # run the desktop app in dev mode (hot reload)
npm run app:build # build a production bundle for your platform
```
Other useful scripts:
```bash
npm run dev # frontend only (Vite) on http://localhost:1420
npm run build # type-check and build the frontend bundle
npm run check # svelte-check type checking
```
Backend logic is covered by headless tests:
```bash
cd src-tauri && cargo test
```
## Keyboard shortcuts
| Shortcut | Action |
| ---------------------- | ---------------------- |
| Command / Ctrl + S | Save current diagram |
| Command / Ctrl + Enter | Commit (in commit box) |
| Command / Ctrl + scroll| Zoom the preview |
## How Git is used
- Creating a project runs `git init` (default branch `main`) and makes an
initial commit.
- Commit stages every change (adds, edits, deletes) and records it with
your message. The author defaults to your global Git identity, falling
back to `Mermix <mermix@localhost>` if none is configured.
- Branches are listed in the Git panel; creating one checks it out
automatically. Switching branches reloads the diagram list.
- History shows recent commits with short SHA, message, author, and
relative time.
- Remote sync configures an origin remote. Fetch updates remote-tracking
refs; pull is fast-forward only; push uses `--set-upstream`. All
require the system `git` binary on PATH.
## License
MIT