The diary

Diary: your ink sinks into the page and it writes back. Study: everything stays; it annotates alongside. Quiz: it tests you on the page.
Ink: the reply resolves out of a blot, through a wrong mark, into the word. Taught hand: replayed as pen strokes from the characters you taught it.
No hand taught yet — replies use a font. Teach ~70 characters (5 minutes) and it writes in real pen strokes.
Swipe left from the right-hand edge, or tap the page number, to turn the page. Each page keeps its own ink; the conversation carries across. Turn off on a tablet so your palm doesn't draw. Off by default. On, replies simply appear, ink and pages stop fading. For a tablet mounted the other way up. Turns the whole interface and the pen with it. Keeps the page, the status line and the page number clear of a frame along the bottom. Switched on by itself on a slower machine. Drops the blur and reveals a word at a time instead of a letter, which keeps the sweep smooth. Tick or untick to decide for yourself. Leave as-is inside claude.ai. On your own hosting, point this at your Cloudflare Worker (see worker.js) and leave the key blank.