MosuWhat you type is what you see

These screenshots are taken by a script driving the real app (pnpm screenshots), not mockups — the column widths, the typeset formula and the diagram below are all computed by the product itself.

Markers appear only when the cursor arrives ​

This is the whole interaction, and it is what separates the editor from "source on the left, preview on the right": normally you see typeset text; move the cursor in, and the Markdown markers for that one element appear in place so you can edit them. No mode switch, no second pane.

Cursor outside — formatting only

Cursor inside — the ** come back

Code, math and diagrams live in the same surface ​

Code blocks are highlighted per language and do not wrap along with prose; math goes through KaTeX; a ```mermaid fence renders straight to a diagram. All of it is lazy-loaded — a document that uses none of these pays no startup cost for them.

Where the project stands ​

Usable, but not formally released yet. Version 0.1.0. The most recent batch of work (milestone "M4.5") is done:

GFM (tables, task lists, strikethrough, footnotes), math, Mermaid diagrams, an outline panel, a command palette, crash recovery, six themes, HTML and PDF export, copy-as-rich-text, paste-HTML-as-Markdown, table editing, a file tree, tabs, session restore, a settings panel, inline HTML rendering, customisable shortcuts, focus mode, typewriter mode and a Chinese/English/Japanese interface are all working.

Not there yet: the plugin system, cross-file search, user theme directories with hot reload, block-level HTML rendering (that one is a deliberate no, see the roadmap), drag-to-resize table columns, PDF headers/footers and TOC page numbers, rename/create/delete in the file tree, and Pandoc-based export (DOCX / ePub).

Every milestone ends with a "what actually differed from the plan" section listing exactly what was cut and why. That list is part of the project, not an embarrassment to hide.

Trying it ​

There is no tagged release yet, but every push to main produces installers for all three platforms under Actions.

⚠️ Those builds are unsigned. macOS will refuse them on first launch (right-click → Open, or allow them under System Settings → Privacy & Security) and Windows SmartScreen will warn. This is not a problem with the app — the signing certificates simply are not configured yet.

Running from source is easier:

pnpm install
pnpm dev

A note on the documentation ​

The design documents are written in Chinese and are not translated. That is a deliberate trade-off rather than unfinished work: there are nine design documents plus five architecture decision records, they change as development goes on, and translating a moving target costs not one translation but one per revision, forever.

They are worth a machine translation if you are curious, because they are not feature lists — they record trade-offs and mistakes:

• Why CodeMirror 6 and not ProseMirror — a rich-text editor's document model inherently requires an intermediate representation, which is exactly what conflicts with "the source is the truth";
• Why two Markdown parsers — editing needs incremental, position-exact parsing; export needs full semantics. One parser doing both does neither well;
• Chasing a blank-page PDF bug on macOS through seven CI rounds — six conclusions proposed and disproved before measuring the variable space found a single font at fault;
• Rendering HTML in a document without parsing HTML — sidestepping the sanitiser entirely, because one gap in a sanitiser inside Electron is XSS escalating to RCE.

Relationship to Typora ​

The commercial product with a comparable experience is Typora. This project is an independent implementation: it reuses none of its code, assets or interface materials, and borrows only the seamless live-preview interaction model. The two are not affiliated.