[iamnbutler]

Settings → Host gets a Phone section with a QR code of this host's HTTPS address on the tailnet (https://<machine>.ts.net:<port + 1000>). It also shows the address as text with a copy button. A phone on the tailnet scans the code and opens Ace. Related to g12 in the onboarding review and #182; it closes neither.

• The host records the address only once the HTTPS listener has started. Diagnostics reports it as web.
• The section shows only when Tailscale is running and the host isn't loopback.
• Without a tailnet certificate, it says to turn on HTTPS in the Tailscale admin console and restart Ace Helper.
• The code is always dark on a white quiet zone, in both themes, because phone cameras often fail on inverted codes.

New dependency: uqr 0.1.3, from unjs, MIT. It has no dependencies of its own. It's added through the ui catalog and used only for encode(); the SVG is drawn in React. A QR encoder needs Reed-Solomon error correction, version selection and masking, which isn't worth hand-rolling, and nothing in the tree already did it.

Smoke-tested:

• A source host on port 4431 with its own ACE_HOME, joined to the real tailnet, served https://natembp.tail93a054.ts.net:5431, and that address returned 200.
• Settings → Host, opened in headless Chrome, showed the section in both themes.
• jsQR, run from a temporary directory outside the repo, decoded the screenshot to exactly that URL.

Built in Ace

No. Claude Code built this outside Ace while the user was away. Ace can't yet run an unattended polish pass across several lanes. Tracked under #5.