Spike on 2026-05-01 confirmed HMR works end-to-end through Traefik
when ALL of these are set:
server: {
host: '0.0.0.0',
port: <3000-3009>,
strictPort: true,
hmr: { clientPort: 443, protocol: 'wss', host: '<previewUrl host>' },
}
The previous prompt omitted hmr.host, which lets Vite's HMR client
guess the wrong host and silently fail the WS upgrade. Adding the
host explicitly. Verified test: 101 Switching Protocols, vite-hmr
subprotocol negotiated, js-update messages fire within ~1s.
Co-authored-by: Cursor <cursoragent@cursor.com>
Mark Henderson
f7fdc34af1