archy/docs/companion-pairing-qr.md

Companion app pairing QR — integration handoff

Status: web-UI side SHIPPED (CompanionIntroOverlay.vue, 2026-07-16). This doc is the contract + requirements for the companion-app side (worked on separately, on the Mac).

What the web UI now does

The "Remote Companion" intro modal (shown once after first dashboard login, and in the public demo) gained a second screen:

1. Screen 1 (existing): APK download QR (desktop) / download button, plus a new "I've installed it" button to the right of the download button.
2. Screen 2 (new, slide transition): a pairing QR the companion app scans to auto-fill the server entry, with a Back button returning to screen 1. On small screens (where you can't scan your own display) an "Open in companion app" deep-link button is shown above Back, using the same URI as the QR.

The QR payload / deep link (the contract)

A single URI, also usable as an OS deep link:

archipelago://pair?v=1&url=<percent-encoded server URL>[&pw=<percent-encoded password>]

Query parameters:

param	required	meaning
v	yes	Payload version, currently 1. Reject/ignore unknown majors gracefully — show "please update the app".
url	yes	Full origin the app should connect to, scheme included: https://demo.archipelago-foundation.org, http://archipelago.local, http://192.168.1.228, etc. No trailing slash guaranteed either way — normalize.
pw	no	Login password. Only present in the public demo (shared demo password entertoexit). Real nodes never embed a password — the frontend doesn't have it.

Examples the web UI actually emits:

• Demo: archipelago://pair?v=1&url=https%3A%2F%2Fdemo.archipelago-foundation.org&pw=entertoexit
• Real node, browsed via LAN IP: archipelago://pair?v=1&url=http%3A%2F%2F192.168.1.228
• Real node kiosk (UI runs on localhost, so it advertises the mDNS name from system.get-hostname): archipelago://pair?v=1&url=http%3A%2F%2Farchipelago.local

Companion app requirements

1. Scan entry point: the app's action is labeled "Scan Node's QR" (implemented 2026-07-17; the modal copy in CompanionIntroOverlay.vue was updated to match).
2. Parse the URI (from camera scan AND from an OS deep-link intent — register the archipelago:// scheme so the "Open in companion app" button on phones works).
3. On success, create/update a saved server entry:
   • Server address = url exactly as given (respect the scheme — the demo is https, LAN nodes are typically http, .local mDNS names must work).
   • If pw present, prefill the password and attempt auto-login; otherwise land on the password prompt for that server.
   • If an entry with the same origin already exists, update it rather than duplicating.
4. Demo flow (the showcase): scanning the demo QR should take a fresh install to a logged-in demo session in one step — url https://demo.archipelago-foundation.org, password entertoexit, no manual typing.
5. Robustness:
   • Tolerate unknown extra query params (forward compat — we may add name, cert fingerprint, etc. under v=1).
   • Self-signed HTTPS on .local/LAN addresses may appear later; don't hard-fail the parse on scheme.
   • Bad/foreign QR → clear error, stay on the scan screen.

Notes / future extensions (not in v1)

• A real-node pairing token instead of a password (backend mints a one-time token, QR carries it, app exchanges it for a session) — needs a backend RPC; the v param exists so we can bump when this lands.
• Optional name param (node display name) so the app labels the entry nicely.

Testing checklist (app side)

• Scan demo QR from https://demo.archipelago-foundation.org → auto-connected demo session.
• Scan a real node's QR (LAN IP origin) → entry created, password prompt shown.
• Scan a kiosk node's QR (http://<name>.local) → mDNS resolution works on the phone.
• Tap "Open in companion app" on a phone browser → deep link opens the app with the same behavior.
• Re-scan same node → no duplicate entry.