Features

What it does

A WYSIWYG Markdown editor for macOS. Writing, looking things up, revising and publishing all happen in one window, and all of it lands on your own pile of plain .md.

None of this is a roadmap. It is what the current build already does, in the order you meet it while writing something long.

01Writing

What you type is the page

Marks fade when they should and appear when they should. There is only one rule behind it: whether the caret is on that line.

WYSIWYG isn't a preview pinned beside the text; there is no preview step at all. Formulas, tables, diagrams and canvases all grow on the same sheet.

## March review

This build folds exporting into **two steps**, with fonts ==embedded by default==.

Inline maths is still $E = mc^2$, rendered once the caret leaves.

- Finish the two manual pages before Friday

Click the paper and write — only the line under the caret shows its source

Fig. 1That sheet is the Folding Mirror editor itself, not a screenshot. Click in and write — only the line holding the caret shows its ##, **, ==.

## Wednesday

Tables, formulas, code blocks — I remember the names, not the punctuation.

Type a / on an empty line, then keep typing to filter

Fig. 2The same sheet: type / on an empty line and what you might insert is listed under the caret; keep typing and you are filtering (/tab for a table,/h1 for a heading). The first rows are the things that are most tedious to type by hand — the pipes of a table, the dollars of a formula, the brackets of a link;# and - take two keystrokes, so headings and lists come later. The app has two more rows, drawings and diagrams: they create a file in the library, and a web page has no disk.

# Going home

## Before leaving

- [x] Tickets confirmed, alarm set early
- [x] ID and travel pass packed
- [ ] Windows shut, power off, rubbish out

## On the way

1. Reach the station 40 minutes early
2. Take some water and something to eat
3. Tell them at home you're on the way

> Sleep in on the first morning back.

The bags weigh $m = 18\,\mathrm{kg}$, which is fine.

Change a word on the left and the right follows — the divider can be dragged

Fig. 3When you do need to watch the source, fold the sheet in half: numbered source on the left, the page on the right, one keystroke on the left moving the right. Both halves are real instances, and the divider between them can be dragged.

## The exporting section

```mermaid
flowchart LR
  A[written] --> B{where to}
  B -->|PDF| C[⌘⇧P]
  B -->|article| D[pick a theme]
  D --> E[paste it]
```

![Two sides|360](drawings/two-sides.excalidraw)

Diagrams and sketches grow inside the document — double-click to edit, come back and it is new

Fig. 4One editor, one document: a ```mermaid fence, a standalone .mmd, and an .excalidraw canvas — all drawn on the spot, none of them an illustration. The assistant can work on them too: the built-in draw and diagram skills each carry an MCP server.

Live preview

# ## **

The marks stay behind the words. A heading looks like a heading, bold is bold, and there is no “preview” step.

Inline source

the caret line

Only the line your caret is on shows its source; the rest stays set. For the whole file as source, press ⌘ / .

Slash menu

/

Type a slash on an empty line and everything you might insert is listed under the caret: tables, formulas, code, drawings, diagrams. Keep typing to filter, press return to place it.

Split view

live · split

When you do want to watch the source, fold the sheet in half: source on the left, page on the right, and a divider you can drag.

LaTeX formulas

$…$　$$…$$

Rendered with KaTeX, inline and display alike. Rendering waits until the caret leaves the pair, so editing never fights you.

Tables

| … | … |

Real tables edited in place — not a dialog, not a read-only picture. Add, remove, move and align from the right-click menu.

Mermaid diagrams

```mermaid

Flowcharts, sequence diagrams, Gantt charts. Write them in a fence, or keep them as a .mmd file you open like any document.

Drawings

.excalidraw

An Excalidraw canvas embedded in the page. Drag to resize it in place, double-click to enter the canvas, and it saves back into drawings/.

Images and files

![](…)

Drag one in and it is an image; the file lands beside the document. Nothing is uploaded, re-hosted or renamed.

Focus and typewriter

F8　F9

Focus mode dims everything but the paragraph you are in; typewriter mode keeps the line you are writing at the middle of the screen.

02Library

A pile of .md, with nothing in between

Point it at a folder, and everything after that happens inside that folder.

There is no layer between Folding Mirror and your files. Uninstall it and every file is still there — no “export” step required.

Leave the structure of Friday's draft alone.

The exporting section follows the order set in [[Writing plan]],

with formulas and tables after it.

Fig. 5The mentions panel on the left, the same editor on the right. Join two notes with brackets and the backlinks grow on their own — no index to build.

An ordinary folder

*.md

Nothing is imported, moved or indexed into a database. The tree in the sidebar is the tree on disk, and renaming or deleting there is real.

Several libraries

switch library

One library for work, another for writing; switch at the foot of the sidebar. Switching means a different set of things — the two never share a row of tabs.

Links and mentions

[[document]]

Join two notes with square brackets and the backlinks grow on their own. The mentions panel lists who cites this piece, and on which line.

Outline

⌃ ⌘ 1

Navigate a long piece by its heading levels. The outline follows your caret — wherever you are reading is where it lights up.

Search and quick open

⌘ ⇧ F　⌘ P

Search names and text across the library and click a result to land on that line; quick open finds by title and path in a couple of keystrokes.

Tabs and history

⌘ T　⌃ ⌘ ←

Several documents open at once, with back and forward like a browser. ⌘ ⇧ T brings back a closed tab, still scrolled where you left it.

03Assistant

An assistant you call for

Your key, your account. ⌘ ⇧ A brings it out; close it when you are done.

This section is the back of the sheet. Here the AI is an assistant you call for, not a second author sitting in the room.

Rewrite the exporting section in the order set in [[Writing plan]].

Right — let me see how both read at the moment.

Readnotes/first-frost.md

SearchWriting plan · export

The plan puts the two steps first, fonts second. This section has it the other way round, so I will follow the plan and add ⌘ ⇧ P while I am there.

Edit filenotes/first-frost.md

 The exporting section follows the order set in the writing plan.
 
-Exporting goes through File → Export, then pick a format.
+Exporting folds into two steps: ⌘ ⇧ P gives a PDF,
+with the font subset embedded by default.
  ⋯ 24 lines folded
 Formulas and tables come after it.

Editnotes/first-frost.md

Done: the two steps first, the font subset after.

Now draw an export flowchart for the opening.

Mermaidvalidate · export flow

Edit filenotes/first-frost.md

 # First frost
 
+```mermaid
+flowchart LR
+  A[written] --> B{where to}
  ⋯ 5 lines folded
+```
 
 Once it turns cold, the lamp on the desk is on more of the time.

Editnotes/first-frost.md · +9

Placed at the top. To change its shape or direction, double-click the diagram.

And turn on focus mode, one size bigger.

InterfaceFocus Mode · Text size

Done — 15.5 up to 17.5. Say the word and I will put it back.

Fig. 6One full turn: you ask, it reads two documents, proposes an edit, and stops to wait for “Apply”; then you ask for a diagram and it goes through the built-in Mermaid server. Touching a document, running a command or reaching an outside tool all pass this gate. The last line — “turn on focus mode” — gets no card: that one moves the interface, and you are looking right at it.

Bring your own key: Twenty-two providers are preset — Anthropic, OpenAI, DeepSeek, Moonshot, Zhipu — and any compatible endpoint can be typed in by hand. Keys are stored encrypted by the system and never leave the machine.
Edits go through you: Before the assistant writes a file, runs a command or reaches an outside tool, you get a card: which document, what it adds, what it removes, line by line. It reaches disk when you apply it; refuse and nothing happened.
It works the app for you: “Turn on focus mode.” “One size bigger.” “Show me the source alongside.” “Open my November note.” Say it and it happens, with no hunting for the menu — and it reads the state first, so “bigger again” and “put it back” work too. Interface changes get no approval card: they happen in front of you and one sentence undoes them. Files still wait for your nod.
Skills: Seven are built in — continue, polish, outline, draw, diagram, web search and the handbook — and any folder with a SKILL.md can be imported. An enabled skill only puts its name and one-line summary in the prompt; the body is read when it is actually needed.
MCP: Three remote servers are built in (Exa, Excalidraw, Mermaid) and work with nothing to install. You can add your own too: give it a URL, or let Folding Mirror start a local process.
Context you can see: How much of the window is used, and how this turn splits between fresh input, cache hits and the reply — the indicator is always there. No guessing, no overrun, no silent truncation.
Sessions kept: Every conversation stays, grouped by date or by document, and can be filtered to the piece you are in. Edits still waiting for approval are right where you left them, across sessions and restarts.

04Versions

Every edit has a way back

Nothing to remember to press. It records as you write, and you pick a moment when you need one.

Checkpoints live in their own place outside the library, so your own Git repository never fills up with commits you didn't make.

Fig. 7The version history dialog, on the “whole library” tab: pick a moment on the left, and the right lists the files changed at that moment and how they differ from now.

This document

⌘ ⇧ H

Checkpoints happen as you write, and one is taken before the assistant edits anything. Pick a version on the left; the right shows how it differs from now.

The whole library

whole library

Not just one file. The library can go back to a moment in time, with every file added, changed or deleted at that moment listed out.

Restoring has a way back

restore

Restoring takes a checkpoint of the current state first — so “I restored the wrong one” is also recoverable.

05Publishing

Ready to go out

The fonts travel with the file, which is the part that usually breaks.

Whatever you write ends up somewhere else. Folding Mirror's job is to make sure it is still set properly when it gets there — and to stay out of the way when the shortest route is simply handing over the .md.

PDF

⌘ ⇧ P

A4 pages in the body font you chose in settings, with the glyphs it used embedded — so it looks the same on a machine that has none of your fonts.

HTML

⌘ ⇧ E

One self-contained .html file that opens in a browser on a double-click. It asks whether to embed the font: send it to someone, or keep it small.

The file itself

*.md

The shortest route out: your document already is a Markdown file. Hand it over, commit it, publish it — there is no export step in between.

06Small things

The rest is detail

Not one line in this section belongs on a poster. Together they decide whether you feel like opening it again tomorrow.

Shortcuts

click to rebind

The defaults follow Typora. Click any row in settings to rebind it, and a conflict tells you on the spot who already holds that key.

Three separate fonts

UI · body · assistant

The interface, the page and the AI panel each get their own. Move the body size and headings, source and code blocks follow in proportion.

Two interface languages

中文 · English

Simplified Chinese and English, switched instantly. Everything moves together — menus, panels, the assistant and this manual.

Status bar

words · minutes

Words, characters, how much is selected, and roughly how many minutes it reads. Select a passage and it counts only that passage.

Formatting by right-click

right-click

Select a passage and turn it into a heading, a quote or a list, or insert a table, image, link, formula block or rule. If your hands are on the keys, / is quicker.

Stays where you were

close and reopen

Each document remembers how far you had read. Quit Folding Mirror, restart the machine, open it again — same line.

07Specs

One table, and that's it

Requirements: macOS 12 and later. Separate builds for Apple silicon and Intel.
File format: Plain .md. Drawings as .excalidraw, diagrams as .mmd, attachments beside the document.
Interface language: Simplified Chinese · English
AI billing: Folding Mirror sells no credits. You bring your own API key and usage is settled between you and your provider.
Account: None. No sign-up, no login, no online check.
Telemetry: None. No usage reports, no document contents.
Price: A one-time purchase. Pay once, keep it — not a subscription. Announced with the release build.
Current version: download opening soon

08Download

The paper is laid out.
The rest is yours.

Try it in the browser macOS build · coming soon

macOS 12+ · download opening soon