diff --git a/docs/ARCHITECTURE.md b/docs/ARCHITECTURE.md
index 06f07af..a1e76e6 100644
--- a/docs/ARCHITECTURE.md
+++ b/docs/ARCHITECTURE.md
@@ -572,7 +572,10 @@ renders the next turn without a self-refetch. The `notify` package owns the Flat
 (fed wire-agnostic input structs by the domain services) and the gateway forwards every payload
 verbatim. Auto-match needs no match poll — `Enqueue` returns the game the player enters
 synchronously, and an opponent later taking the open seat arrives as the in-app **opponent-joined**
-event; for the lobby **notification badge** (incoming friend requests + open
+event. Unlike a move, that event has no follow-up delta to trigger the move-count gap recovery, so
+the waiting game screen recovers a missed join itself: it **polls `game.state` while the stream is
+down and refetches once on stream reconnect**, so a join missed during an outage or while the app
+was backgrounded still resolves the open game in place. For the lobby **notification badge** (incoming friend requests + open
 invitations) the client re-polls on the `notify` event and on lobby open / focus, covering a push
 missed while the app was hidden. **Out-of-app platform push** is a fallback
 the **gateway** routes from the same firehose: for an event whose recipient has **no
diff --git a/ui/e2e/quickmatch.spec.ts b/ui/e2e/quickmatch.spec.ts
index 903649f..0c74a13 100644
--- a/ui/e2e/quickmatch.spec.ts
+++ b/ui/e2e/quickmatch.spec.ts
@@ -29,3 +29,38 @@ test('quick game: enter immediately, wait for an opponent, then it joins', async
   await expect(page.getByText(/Searching for opponent/)).toHaveCount(0);
   await expect(page.getByRole('button', { name: 'Drop game' })).toBeEnabled();
 });
+
+// The opponent_joined push is best-effort and never replayed, so a join that lands while the live
+// stream is down is lost. The waiting game screen recovers it without a push: a poll while the
+// stream is down, and a refetch on stream reconnect. The __stream hook (lib/app.svelte.ts) drops /
+// restores the stream; while it is dropped the mock has no subscriber, so joinOpponent emits to
+// no one — exactly the missed-event case.
+async function enterOpenGame(page: import('@playwright/test').Page): Promise<void> {
+  await page.goto('/');
+  await page.getByRole('button', { name: /guest/i }).click();
+  await page.getByRole('button', { name: /New/ }).click();
+  await page.locator('.variant').first().click();
+  await page.getByRole('button', { name: /Start game/i }).click();
+  await expect(page.getByText(/Searching for opponent/)).toBeVisible();
+}
+
+test('quick game: a poll recovers a join missed while the live stream is down', async ({ page }) => {
+  await enterOpenGame(page);
+  // Drop the stream (no auto-reconnect), then let the opponent join: the push reaches no one, so
+  // only the poll fallback can restore the UI.
+  await page.evaluate(() => (window as unknown as { __stream: { drop(): void } }).__stream.drop());
+  await page.evaluate(() => (window as unknown as { __mock: { joinOpponent(): void } }).__mock.joinOpponent());
+  await expect(page.getByText('Robo')).toBeVisible();
+  await expect(page.getByText(/Searching for opponent/)).toHaveCount(0);
+});
+
+test('quick game: a stream reconnect recovers a join missed while it was down', async ({ page }) => {
+  await enterOpenGame(page);
+  // The opponent joins while the stream is down (the push is lost), then it reconnects before the
+  // poll could tick — the reconnect refetch is what catches up.
+  await page.evaluate(() => (window as unknown as { __stream: { drop(): void } }).__stream.drop());
+  await page.evaluate(() => (window as unknown as { __mock: { joinOpponent(): void } }).__mock.joinOpponent());
+  await page.evaluate(() => (window as unknown as { __stream: { restore(): void } }).__stream.restore());
+  await expect(page.getByText('Robo')).toBeVisible();
+  await expect(page.getByText(/Searching for opponent/)).toHaveCount(0);
+});
diff --git a/ui/src/game/Game.svelte b/ui/src/game/Game.svelte
index 80018c4..546eb40 100644
--- a/ui/src/game/Game.svelte
+++ b/ui/src/game/Game.svelte
@@ -238,6 +238,31 @@
     }
   });
 
+  // The live-event hub is best-effort and never replays (see lib/app.svelte.ts): an event dropped
+  // while the stream is down — or shed from a full subscriber buffer — is gone for good.
+  // opponent_moved and game_over self-heal via the next event's move-count gap check, but
+  // opponent_joined has no follow-up event, so the open-game wait needs its own recovery. Two
+  // fallbacks, mirroring the matchmaking poll PR #51 moved in here from the lobby:
+
+  // (A) On a stream reconnect (alive false -> true) refetch once to catch up on anything missed
+  // while it was down. The common case is a mobile suspend that drops the stream, the opponent
+  // joining during it, then a silent resume; this also rescues a missed opponent_moved/game_over.
+  let wasStreamAlive = app.streamAlive;
+  $effect(() => {
+    const alive = app.streamAlive;
+    if (alive && !wasStreamAlive) void load();
+    wasStreamAlive = alive;
+  });
+
+  // (B) While still waiting for an opponent with the stream down, the opponent_joined push cannot
+  // reach us at all; poll the game state until the seat fills (then waitingForOpponent flips and
+  // the timer is torn down) or the stream returns and (A) takes over.
+  $effect(() => {
+    if (!waitingForOpponent || app.streamAlive) return;
+    const timer = setInterval(() => void load(), 2500);
+    return () => clearInterval(timer);
+  });
+
   function isCoarse(): boolean {
     return typeof matchMedia !== 'undefined' && matchMedia('(pointer: coarse)').matches;
   }
diff --git a/ui/src/lib/app.svelte.ts b/ui/src/lib/app.svelte.ts
index a9d8714..866de45 100644
--- a/ui/src/lib/app.svelte.ts
+++ b/ui/src/lib/app.svelte.ts
@@ -36,7 +36,9 @@ export interface Toast {
 
 export const app = $state<{
   ready: boolean;
-  /** Whether the live-event stream is connected; drives the matchmaking poll fallback. */
+  /** Whether the live-event stream is connected. The event hub is best-effort and never replays a
+   *  missed event, so an open game waiting for an opponent uses this to recover: it polls the game
+   *  state while the stream is down and refetches once on reconnect (see game/Game.svelte). */
   streamAlive: boolean;
   session: Session | null;
   profile: Profile | null;
@@ -500,3 +502,14 @@ if (typeof window !== 'undefined') {
 }
 telegramOnEvent('activated', goForeground);
 telegramOnEvent('deactivated', goBackground);
+
+// Mock-mode e2e seam (tree-shaken from a production build): drive the live-stream lifecycle so the
+// e2e can exercise the open-game fallbacks for a missed opponent_joined. `drop` tears the stream
+// down without scheduling a reconnect — so only the in-game poll can then recover — and `restore`
+// reopens it (the reconnect catch-up path). Never wired outside mock mode.
+if (import.meta.env.MODE === 'mock' && typeof window !== 'undefined') {
+  (window as unknown as { __stream?: { drop(): void; restore(): void } }).__stream = {
+    drop: closeStream,
+    restore: openStream,
+  };
+}