feat(ui): reload the SPA on maintenance recovery

The deploy that ends a maintenance window may ship a client-incompatible change
(wire/schema bump), and the in-session bundle is the old one. On recovery, reload to
pick up the fresh client instead of just hiding the overlay. Ordering is safe: the edge
maintenance flag (deploy/prod-deploy.sh) spans the WHOLE roll and clears only at script
exit — after the gateway (which serves the embedded SPA) has rolled — so the edge 503s
everything until the entire deploy is live; recovery therefore always serves the new SPA.
A window.__maint.recover() hook + e2e cover the reload.

ui/src/lib/gateway.ts

@@ -6,7 +6,7 @@ import type { GatewayClient } from './client';
 import { MockGateway } from './mock/client';
 import { createTransport } from './transport';
 import { reportOffline, reportOnline } from './connection.svelte';
-import { clearMaintenance, reportMaintenance } from './maintenance.svelte';
+import { clearMaintenance, maintenanceRecovered, reportMaintenance } from './maintenance.svelte';
 
 const isMock = import.meta.env.MODE === 'mock';
 
@@ -23,9 +23,12 @@ if (isMock && typeof window !== 'undefined') {
   };
   // The mock never produces a real 503, so the e2e drives the maintenance overlay directly
   // (the store's poll is inert in mock — no probe is registered — so `off` clears it).
-  (window as unknown as { __maint?: { on(retryAfterMs?: number): void; off(): void } }).__maint = {
+  (
+    window as unknown as { __maint?: { on(retryAfterMs?: number): void; off(): void; recover(): void } }
+  ).__maint = {
     on: (retryAfterMs = 15000) => reportMaintenance(retryAfterMs),
     off: clearMaintenance,
+    recover: maintenanceRecovered,
   };
   // Drive the auto-match opponent join deterministically from the e2e (the mock otherwise
   // attaches a robot on a timer).

ui/src/lib/maintenance.svelte.ts

@@ -41,7 +41,8 @@ export function reportMaintenance(retryAfterMs: number): void {
   if (probe) schedulePoll();
 }
 
-/** clearMaintenance lowers the overlay and stops the poll (a successful read, or reset). */
+/** clearMaintenance lowers the overlay and stops the poll without reloading (a reset, or the
+ *  e2e hook). Prod recovery goes through maintenanceRecovered instead. */
 export function clearMaintenance(): void {
   active = false;
   if (pollTimer) {
@@ -50,6 +51,21 @@ export function clearMaintenance(): void {
   }
 }
 
+/** maintenanceRecovered runs when the edge answers again after a window we were showing.
+ *  The deploy that ended the window may have shipped a client-incompatible change (a wire /
+ *  schema bump), and the running bundle is the OLD one — so reload to pick up the fresh
+ *  client instead of merely hiding the overlay. A no-op unless the overlay was up; the cover
+ *  stays over the brief reload flash. In prod recovery is the only way the overlay clears. */
+export function maintenanceRecovered(): void {
+  if (!active) return;
+  active = false;
+  if (pollTimer) {
+    clearTimeout(pollTimer);
+    pollTimer = null;
+  }
+  if (typeof location !== 'undefined') location.reload();
+}
+
 /** retryNow forces an immediate re-check (the overlay's button). It never closes the
  *  overlay itself — only a successful probe does. A no-op while a probe is in flight. */
 export function retryNow(): void {
@@ -73,7 +89,7 @@ function runProbe(): void {
   probe().then(
     () => {
       probing = false;
-      clearMaintenance();
+      maintenanceRecovered();
     },
     () => {
       probing = false;

ui/src/lib/transport.ts

@@ -12,7 +12,7 @@ import { GatewayError, type GatewayClient } from './client';
 import * as codec from './codec';
 import { browserOffset } from './profileValidation';
 import { registerProbe, reportOffline, reportOnline } from './connection.svelte';
-import { clearMaintenance, registerMaintenanceProbe, reportMaintenance } from './maintenance.svelte';
+import { maintenanceRecovered, registerMaintenanceProbe, reportMaintenance } from './maintenance.svelte';
 import { maintenanceRetryMs } from './maintenance';
 import { backoffMs, isConnectionCode, retryable, toGatewayError } from './retry';
 
@@ -67,7 +67,9 @@ export function createTransport(baseUrl: string): GatewayClient {
         throw err;
       }
       reportOnline();
-      clearMaintenance();
+      // A read got through: if the maintenance overlay was up, the deploy window has ended —
+      // reload to pick up the (possibly incompatible) fresh client (maintenance.svelte.ts).
+      maintenanceRecovered();
       if (res.resultCode && res.resultCode !== 'ok') throw new GatewayError(res.resultCode);
       return res.payload;
     }