From a52e6892ccc4dae9156b6e51f3e277fd46be66dc Mon Sep 17 00:00:00 2001
From: WardPearce <wardpearce@pm.me>
Date: Tue, 3 Mar 2026 22:53:29 +1300
Subject: [PATCH] Progress on watch party logic using trystero

---
 .../src/lib/components/WatchParty.svelte      | 141 ++++++++++++++++++
 .../lib/components/watch/WatchParty.svelte    |   1 -
 materialious/src/lib/i18n/locales/en.json     |   5 +-
 materialious/src/routes/(app)/+layout.svelte  |  10 ++
 .../routes/(app)/watch/[slug]/+page.svelte    |   6 -
 5 files changed, 155 insertions(+), 8 deletions(-)
 create mode 100644 materialious/src/lib/components/WatchParty.svelte
 delete mode 100644 materialious/src/lib/components/watch/WatchParty.svelte

diff --git a/materialious/src/lib/components/WatchParty.svelte b/materialious/src/lib/components/WatchParty.svelte
new file mode 100644
index 00000000..5728511a
--- /dev/null
+++ b/materialious/src/lib/components/WatchParty.svelte
@@ -0,0 +1,141 @@
+<script lang="ts">
+	import { _ } from '$lib/i18n';
+	import { playerState } from '$lib/store';
+	import sodium from 'libsodium-wrappers-sumo';
+	import { joinRoom, type ActionReceiver, type DataPayload, type Room } from 'trystero';
+	import z from 'zod';
+
+	const zWatchPartyEvent = z.object({
+		event: z.union([z.literal('pause'), z.literal('play'), z.literal('seek')]),
+		videoId: z.regex(/^[a-zA-Z0-9_-]{11}$/),
+		sent: z.date(),
+		currentTime: z.number()
+	});
+
+	type WatchPartyEvent = z.infer<typeof zWatchPartyEvent>;
+
+	let room: Room | undefined = $state();
+
+	const appId = 'materialious_';
+
+	type SendEvent = (message: WatchPartyEvent) => void;
+
+	// If room not in use message just get sent nowhere.
+	let sendEvent: SendEvent = (message: WatchPartyEvent) => {};
+
+	function actionReceiver(receiver: ActionReceiver<DataPayload>) {
+		receiver((data) => {
+			const dataParsed = zWatchPartyEvent.safeParse(data);
+			if (!dataParsed.success) return;
+
+			const player = $playerState;
+			if (!player?.playerElement) return;
+
+			const playerElement = player.playerElement;
+
+			switch (dataParsed.data.event) {
+				case 'play':
+					playerElement.play();
+					break;
+				case 'pause':
+					playerElement.pause();
+					break;
+				case 'seek':
+					playerElement.currentTime = dataParsed.data.currentTime;
+					break;
+			}
+		});
+	}
+
+	async function createRoom() {
+		await sodium.ready;
+
+		const roomId = sodium.to_base64(sodium.randombytes_buf(24));
+
+		room = joinRoom({ appId }, roomId);
+
+		const [sendAction, getAction] = room.makeAction('watchParty');
+
+		sendEvent = sendAction as unknown as SendEvent;
+
+		actionReceiver(getAction);
+	}
+
+	playerState.subscribe((player) => {
+		if (!player?.playerElement) return;
+
+		const playerElement = player.playerElement;
+
+		playerElement.addEventListener('play', () => {
+			if (!room) return;
+
+			sendEvent({
+				event: 'play',
+				videoId: player.data.video.videoId,
+				sent: new Date(),
+				currentTime: playerElement.currentTime
+			});
+		});
+
+		playerElement.addEventListener('playing', () => {
+			if (!room) return;
+
+			sendEvent({
+				event: 'play',
+				videoId: player.data.video.videoId,
+				sent: new Date(),
+				currentTime: playerElement.currentTime
+			});
+		});
+
+		playerElement.addEventListener('seeked', () => {
+			sendEvent({
+				event: 'seek',
+				videoId: player.data.video.videoId,
+				sent: new Date(),
+				currentTime: playerElement.currentTime
+			});
+		});
+
+		playerElement.addEventListener('pause', () => {
+			sendEvent({
+				event: 'pause',
+				videoId: player.data.video.videoId,
+				sent: new Date(),
+				currentTime: playerElement.currentTime
+			});
+		});
+
+		playerElement.addEventListener('waiting', () => {
+			sendEvent({
+				event: 'pause',
+				videoId: player.data.video.videoId,
+				sent: new Date(),
+				currentTime: playerElement.currentTime
+			});
+		});
+
+		playerElement.addEventListener('error', () => {
+			sendEvent({
+				event: 'pause',
+				videoId: player.data.video.videoId,
+				sent: new Date(),
+				currentTime: playerElement.currentTime
+			});
+		});
+	});
+</script>
+
+<article>
+	<h4>{$_('watchParty.header')}</h4>
+	<div class="space"></div>
+
+	{#if !room}
+		<button onclick={createRoom} class="surface-container-highest">
+			<span>{$_('watchParty.createRoom')}</span>
+		</button>
+		<button class="surface-container-high">
+			<span>{$_('watchParty.joinRoom')}</span>
+		</button>
+	{/if}
+</article>
diff --git a/materialious/src/lib/components/watch/WatchParty.svelte b/materialious/src/lib/components/watch/WatchParty.svelte
deleted file mode 100644
index 5bf03f4a..00000000
--- a/materialious/src/lib/components/watch/WatchParty.svelte
+++ /dev/null
@@ -1 +0,0 @@
-<script lang="ts"></script>
diff --git a/materialious/src/lib/i18n/locales/en.json b/materialious/src/lib/i18n/locales/en.json
index 00663fe0..63002191 100644
--- a/materialious/src/lib/i18n/locales/en.json
+++ b/materialious/src/lib/i18n/locales/en.json
@@ -86,7 +86,10 @@
 		"streams": "Streams"
 	},
 	"watchParty": {
-		"start": "Start a watch party"
+		"start": "Start a watch party",
+		"header": "Watch party",
+		"createRoom": "Create room",
+		"joinRoom": "Join room"
 	},
 	"subscriptions": {
 		"manageSubscriptions": "Manage subscriptions"
diff --git a/materialious/src/routes/(app)/+layout.svelte b/materialious/src/routes/(app)/+layout.svelte
index 5fba828d..7782412d 100644
--- a/materialious/src/routes/(app)/+layout.svelte
+++ b/materialious/src/routes/(app)/+layout.svelte
@@ -33,6 +33,7 @@
 	import Author from '$lib/components/Author.svelte';
 	import Toast from '$lib/components/Toast.svelte';
 	import { isOwnBackend } from '$lib/shared';
+	import WatchParty from '$lib/components/WatchParty.svelte';
 
 	let { children } = $props();
 
@@ -41,6 +42,7 @@
 	let mobileSearchShow = $state(false);
 	let notifications: Notification[] = $state([]);
 	let playerIsPip: boolean = $state(false);
+	let showWatchParty = $state(false);
 
 	let pages = $state(getPages());
 	invidiousAuthStore.subscribe(() => {
@@ -245,6 +247,10 @@
 					<Search on:searchCancelled={() => (mobileSearchShow = false)} />
 				</div>
 			{:else}
+				<button onclick={() => (showWatchParty = !showWatchParty)} class="circle large transparent">
+					<i>groups</i>
+					<div class="tooltip bottom">{$_('watchParty.start')}</div>
+				</button>
 				{#if $invidiousAuthStore && !isYTBackend()}
 					<button
 						class="circle large transparent"
@@ -317,6 +323,10 @@
 	</dialog>
 
 	<main id="main-content" tabindex="0" class="responsive max root">
+		{#if showWatchParty}
+			<WatchParty />
+		{/if}
+
 		{#if $playerState}
 			<div class="grid">
 				<div
diff --git a/materialious/src/routes/(app)/watch/[slug]/+page.svelte b/materialious/src/routes/(app)/watch/[slug]/+page.svelte
index 9da6b66c..5a65db4a 100644
--- a/materialious/src/routes/(app)/watch/[slug]/+page.svelte
+++ b/materialious/src/routes/(app)/watch/[slug]/+page.svelte
@@ -297,12 +297,6 @@
 							{$_('transcript')}
 						</div>
 					</button>
-					<button class="surface-container-highest">
-						<i>sync</i>
-						<div class="tooltip">
-							{$_('watchParty.start')}
-						</div>
-					</button>
 					<Share
 						includePromptText={$_('player.share.includeTimestamp')}
 						shares={[