Kiosk: self-heal a busy device on fresh page load

A browser refresh mid-checkin bypasses the Cancel button entirely (no
React unmount cleanup runs), so a device stayed locked 'busy' with no
route back except a manual admin reset — hit for real 2026-09-01.
registerAndGoIdle() only runs on a genuine fresh mount, so if the device
comes back 'busy' at exactly that moment, nothing on this browser is
actually mid-checkin (state was just initialized) — self-correct via the
same reset the Cancel button already uses, rather than trusting stale
server-side status. Uses kioskReset (krequest, throws KioskSessionError
on 401) not resetDevice (request, redirects to the staff /login page on
401) — the latter would be wrong on a kiosk tablet.

Co-Authored-By: Claude Sonnet 5 <noreply@anthropic.com>

frontend/src/pages/kiosk/Kiosk.tsx

@@ -1,6 +1,6 @@
 import { useEffect, useRef, useState } from 'react'
 import { UserCheck } from 'lucide-react'
-import { kioskLogin, kioskRegisterDevice, kioskHeartbeat, kioskStreamUrl, KioskSessionError } from '../../api'
+import { kioskLogin, kioskRegisterDevice, kioskHeartbeat, kioskStreamUrl, kioskReset, KioskSessionError } from '../../api'
 import type { Device } from '../../types'
 import CheckinFlow from './CheckinFlow'
 
@@ -48,12 +48,26 @@ export default function Kiosk() {
       const storedId = localStorage.getItem(DEVICE_ID_KEY)
       const d = await kioskRegisterDevice(storedId)
       localStorage.setItem(DEVICE_ID_KEY, d.device_id)
+
+      // This effect only runs on a genuine fresh mount (empty-deps useEffect
+      // below) — a browser refresh, crash, or power cycle. If the device
+      // comes back 'busy' at exactly this moment, nothing on THIS browser
+      // is actually mid-checkin (React state was just initialized), so
+      // whatever 'busy' the server thinks is stale by definition — the
+      // in-flow Cancel button only fires its own reset on a clean unmount,
+      // which a raw page refresh never triggers at all. Self-correct here
+      // rather than leaving the device invisibly locked with no route back
+      // except a manual admin reset (hit for real 2026-09-01, see
+      // project_checkin memory — refreshing mid-checkin instead of using
+      // Cancel). Best-effort: even if the reset call itself fails, still
+      // show idle locally so the tablet is at least usable again once
+      // staff/an admin clears it some other way.
+      if (d.status === 'busy') {
+        await kioskReset(d.device_id).catch(() => {})
+        d.status = 'idle'
+      }
+
       setDevice(d)
-      // Always land on the idle screen regardless of the device's last known
-      // status — if it was left 'busy' from a session that never completed
-      // (tablet lost power mid-checkin), the idle screen's own SSE
-      // connection is what would receive a fresh 'navigate' push anyway, and
-      // a stuck busy device is fixed from the Devices admin page, not here.
       setView('idle')
     } catch (err) {
       if (err instanceof KioskSessionError) {