When a new version is deployed, open tabs no longer silently run stale code
until a manual F5.
- Server stamps every response with X-App-Version (src/middleware/version.ts,
onSend hook in server.ts).
- Client bakes its build version via Vite define (__APP_VERSION__); apiFetch
compares the header to it (no polling — piggybacks existing traffic) and
latches a mismatch in a small store (appVersion.ts).
- UpdateBanner: a persistent bottom Snackbar "Je k dispozici nová verze
aplikace. — Obnovit" → location.reload(). User-initiated, so an in-progress
form is never interrupted.
- lazyWithReload: every React.lazy page reloads once if its hashed chunk 404s
after a deploy (sessionStorage-guarded against loops), fixing the "old chunk
gone" error screen.
Approach chosen after researching current SPA practice (version header + banner
beats polling / a service worker for a non-PWA admin app).
Tests: +4 (server header, client store latch/notify). Full suite 669 pass,
tsc -b clean, lint 0. Verified live via Playwright (header emitted; banner
appears on a simulated mismatch). Detection applies to deploys from the NEXT
release onward (current clients lack the detection code).
Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>
