[httpsphl]

What

A cursor in the design area, in the spirit of Google Stitch: while a bot writes an HTML screen, its cursor follows each part being built, and the artboard scrolls along with it.

Daemon (spec 22.3)

• Every draft served at /view starts with a small script. It goes after the doctype so the page keeps its layout mode, or at the top when there is no doctype. The file on disk is served as it is.
• When the page is read, and again on load, the script:
  • finds where the content ends: the newest text, or the newest element;
  • scrolls so that spot stays in view;
  • posts {botloft: "cursor", view, point, box} to the app.
• It waits for resize when the frame does not know its size yet. A cross-origin iframe can read the page with innerHeight 0, which was seen in the real test.

App (spec 22.5)

• The cursor is the browser's own, now shared as BotCursor: the arrow in the bot's color with its name and the typing dots.
• It glides to the point, and a frame in the bot's color marks the part being built. This works on the artboard and on the screen in focus.
• Only the frame on show counts, because the version loading behind posts before it is swapped in. Measures are scaled by the view the script saw, since the preview's CSS zoom widens the iframe's view.
• While only styles exist, the cursor waits at the top. Near the right or bottom edge, its name moves aside.
• The preview's drafts import the daemon's cursor.js. Vite serves that one folder outside the app, only in dev.

Security (spec 22.6)

• The script runs in the same sandbox as the page and only posts numbers.
• The app accepts the message only from its own iframes, reads finite numbers only and clamps them to the page.

Tests

• Rust: cargo test (256 tests), clippy and fmt pass.
  • Unit tests for where the script goes (doctype, BOM, a doctype still being written).
  • The screens integration test checks that the draft carries the script and the file does not.
• App: pnpm check (144 tests) passes.
  • New cursor.test.tsx: the cursor scales to the artboard, parks while there is no point, shows the next version's mark only once it is on show, ignores other windows and hides when writing ends.
  • Unit tests for reading marks: clamping, the zoomed view, and messages that are not marks.
• Real Claude Code (2.1.284, Haiku, Manual mode), with the app captured in headless Edge:
  • Four pages written live. The cursor followed the title, each card, each plan item and each table row, and the artboard scrolled along.
  • Page content never reached the daemon log.

Manual step

• pnpm tauri dev with a dev BOTLOFT_HOME: ask a bot for a page and watch the cursor in the WebView2 window.