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/guide/+page.svelte

@@ -104,7 +104,7 @@
 		<p>A room's link is an invitation to sit while the table is laid and to watch once the duel has begun. Anyone who opens it without a seat takes a place in the Peanut Gallery. They see the ledger, the result of each turn and the chronicle, and the table can see how many are watching. The gallery is shown only what every wizard at the table could see. A gesture hidden from any one wizard is a question mark to the whole gallery, and the turn being written shows nothing at all.</p>
 		<p><em>Table talk</em>, in the rail, is for the wizards seated. A line goes to everyone at the table and in the gallery, and it is kept with the duel. When you come back, the hall says how many lines were said while you were away. The gallery only listens unless the host lets it talk. Then a watcher signs a name, and their lines read <em>Name (gallery)</em>.</p>
 		<p>Before a duel begins, any seated wizard may <strong>challenge the keeper</strong>, who looks after this site. A seat is held under the keeper's name and the keeper's phone rings. The note beside the button gives the hour where the keeper lives, so you know whether to wait or come back later.</p>
-		<p>When a duel is over, anyone at the table may call for <strong>a rematch</strong>. That opens a new table of the same size with the same bots, and holds a seat for everyone who played. <strong>Transfer seat</strong> at the top of the page gives you four words that move your seat to another device. They work for ten minutes, and you enter them in the hall on the other device.</p>
+		<p>When a duel is over, anyone at the table may call for <strong>a rematch</strong>. That opens a new table of the same size with the same bots, and holds a seat for everyone who played. <strong>Transfer seat</strong> at the top of the page gives you four words that move your seat to another device. They work for ten minutes, and you enter them in the hall on the other device. If your browser has lost your seat altogether, write to the keeper from the room's page, and the keeper can send you a link that brings it back.</p>
 	</section>
 
 	<section id="first">

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">