The keeper can bring back a seat a browser lost: a new token on the ledger, the old one refused and any phrase it minted voided, and a link that carries it in the fragment, minted by waving-hands-reseat.sh through a /keeper door Caddy does not proxy; the join page keeps a linked seat only once the server takes it and never over a seat that still opens, a watcher at a duel in play is told both ways back, the hall asks before forgetting a duel in play, and the server's rooms have tests of their own

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01MbtUPJ24P6vc6tE1x6RS3m

src/routes/join/[code]/+page.svelte

@@ -1,10 +1,10 @@
 <script lang="ts">
-	import { goto } from '$app/navigation';
+	import { goto, replaceState } from '$app/navigation';
 	import { page } from '$app/state';
 	import Board from '$lib/components/Board.svelte';
 	import ReportSlip from '$lib/components/ReportSlip.svelte';
 	import TableTalk from '$lib/components/TableTalk.svelte';
-	import { seatFor } from '$lib/game/client';
+	import { rememberSeat, seatFor, seatInLink, trustSeat, type HeldSeat } from '$lib/game/client';
 	import { COMPACT_QUERY, Duel, NAME_MAX, playerName } from '$lib/game/duel.svelte';
 
 	const roomId = $derived((page.params.code ?? '').toUpperCase());
@@ -71,23 +71,34 @@
 	/** A watcher may still sit while the table is laid and a seat is free. */
 	const seatFree = $derived(!!room?.remote && !room.remote.started && room.remote.seats.length < room.remote.size);
 
-	// Return to a held seat, or take a place in the gallery and offer one.
+	// Return to a held seat, or take a place in the gallery and offer one. A link from the keeper carries a seat:
+	// it leaves the address bar at once, is kept only once the server takes it, and never replaces a seat that
+	// still opens, so a link someone else sends cannot take a working seat away.
 	$effect(() => {
 		const id = roomId;
 		room = null;
 		error = '';
+		const sent = seatInLink(location.hash);
+		if (sent) replaceState(location.pathname + location.search, {});
 		const held = seatFor(id);
-		if (!held) {
-			name = playerName();
-			joining = true;
-			Duel.watchRoom(id)
-				.then((remote) => (room = new Duel(remote)))
-				.catch((e: Error) => (error = e.message));
-			return;
-		}
-		joining = false;
-		Duel.resumeRoom(id, held)
-			.then((remote) => (room = new Duel(remote)))
+		const take = (s: HeldSeat) =>
+			Duel.resumeRoom(id, s).then((remote) => {
+				rememberSeat(id, s);
+				trustSeat(id);
+				return remote;
+			});
+		const arrive = held
+			? Duel.resumeRoom(id, held).catch((e: Error) => (sent ? take(sent) : Promise.reject(e)))
+			: sent
+				? take(sent).catch(() => Duel.watchRoom(id))
+				: Duel.watchRoom(id);
+		joining = !held && !sent;
+		if (!held) name = playerName();
+		arrive
+			.then((remote) => {
+				room = new Duel(remote);
+				if (remote.spectating) joining = true;
+			})
 			.catch((e: Error) => (error = e.message));
 	});
 
@@ -191,6 +202,10 @@
 	<p class="notice muted">On the other device, open the hall and claim this phrase within ten minutes: <b class="phrase">{phrase.phrase}</b></p>
 {/if}
 
+{#if watching && room?.remote?.started && !room.state.over}
+	<p class="notice muted">Had a seat at this table on another device? Transfer it from there and claim the phrase in the hall, or <a href="mailto:eric@ericwagoner.com?subject={encodeURIComponent(`My seat in room ${roomId}`)}">write to the keeper</a> for a link that brings it back.</p>
+{/if}
+
 {#if room?.remote?.started && room.state.over && !watching}
 	{@const r = room.remote}
 	<p class="notice muted">