feat(matrix-web): add emoji reactions support

- Add MessageReaction type with count, users, and includesMe tracking
- Implement getReactionsForEvent helper to collect m.annotation events
- Add reactToMessage method using m.reaction event type
- Display reactions below message bubbles with toggle support
- Add emoji picker dropdown in message actions (6 quick emojis)
- Clicking existing reaction toggles it on/off

Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

apps/matrix/apps/web/src/lib/components/chat/Message.svelte

@@ -15,6 +15,7 @@
 		Image as ImageIcon,
 		Lock,
 		Warning,
+		Smiley,
 	} from '@manacore/shared-icons';
 
 	interface Props {
@@ -41,9 +42,18 @@
 	);
 
 	let showActions = $state(false);
+	let showEmojiPicker = $state(false);
 	let imageLoading = $state(true);
 	let imageError = $state(false);
 
+	// Quick reaction emojis
+	const quickEmojis = ['👍', '❤️', '😂', '😮', '😢', '🎉'];
+
+	async function handleReaction(emoji: string) {
+		showEmojiPicker = false;
+		await matrixStore.reactToMessage(message.id, emoji);
+	}
+
 	// Audio player state
 	let audioElement: HTMLAudioElement | null = $state(null);
 	let isPlaying = $state(false);
@@ -367,6 +377,25 @@
 			{/if}
 		</div>
 
+		<!-- Reactions display -->
+		{#if message.reactions && message.reactions.length > 0}
+			<div class="flex flex-wrap gap-1 mt-1.5 {message.isOwn ? 'justify-end' : 'justify-start'}">
+				{#each message.reactions as reaction}
+					<button
+						class="flex items-center gap-1 px-2 py-0.5 rounded-full text-xs transition-colors
+							   {reaction.includesMe
+							? 'bg-primary/20 border border-primary/40 text-primary'
+							: 'bg-black/5 dark:bg-white/10 border border-black/10 dark:border-white/10 hover:bg-black/10 dark:hover:bg-white/20'}"
+						title={reaction.users.join(', ')}
+						onclick={() => handleReaction(reaction.key)}
+					>
+						<span>{reaction.key}</span>
+						<span class="font-medium">{reaction.count}</span>
+					</button>
+				{/each}
+			</div>
+		{/if}
+
 		<!-- Time (shown on hover) -->
 		<div
 			class="flex items-center gap-2 mt-1.5 px-1 opacity-0 group-hover:opacity-100 transition-opacity"
@@ -378,9 +407,42 @@
 		{#if showActions && !message.redacted}
 			<div
 				class="absolute {message.isOwn
-					? '-left-24'
-					: '-right-24'} top-0 flex items-center gap-1 rounded-xl glass p-1.5 shadow-lg"
+					? '-left-28'
+					: '-right-28'} top-0 flex items-center gap-1 rounded-xl glass p-1.5 shadow-lg"
 			>
+				<!-- Emoji reaction button -->
+				<div class="relative">
+					<button
+						class="p-1.5 rounded-lg hover:bg-black/5 dark:hover:bg-white/10 transition-colors"
+						title="Reaktion"
+						onclick={() => (showEmojiPicker = !showEmojiPicker)}
+					>
+						<Smiley class="h-4 w-4 text-muted-foreground" />
+					</button>
+					{#if showEmojiPicker}
+						<!-- Emoji picker backdrop -->
+						<button
+							class="fixed inset-0 z-40"
+							onclick={() => (showEmojiPicker = false)}
+							aria-label="Schließen"
+						></button>
+						<!-- Emoji picker dropdown -->
+						<div
+							class="absolute {message.isOwn
+								? 'right-0'
+								: 'left-0'} bottom-full mb-2 z-50 flex gap-1 rounded-xl bg-white dark:bg-zinc-800 border border-black/10 dark:border-white/10 p-2 shadow-xl"
+						>
+							{#each quickEmojis as emoji}
+								<button
+									class="text-xl hover:scale-125 transition-transform p-1"
+									onclick={() => handleReaction(emoji)}
+								>
+									{emoji}
+								</button>
+							{/each}
+						</div>
+					{/if}
+				</div>
 				<button
 					class="p-1.5 rounded-lg hover:bg-black/5 dark:hover:bg-white/10 transition-colors"
 					title="Antworten"

apps/matrix/apps/web/src/lib/matrix/store.svelte.ts

@@ -6,6 +6,7 @@ import type {
 	SimpleRoom,
 	SimpleMessage,
 	MessageType,
+	MessageReaction,
 	RoomMember,
 	VerificationStatus,
 	DeviceInfo,
@@ -120,7 +121,7 @@ class MatrixStore {
 	messages = $derived<SimpleMessage[]>(
 		this._timeline
 			.filter((e) => e.getType() === 'm.room.message')
-			.map((e) => this.eventToSimpleMessage(e))
+			.map((e) => this.eventToSimpleMessage(e, this._timeline))
 	);
 
 	/** Users currently typing in current room */
@@ -1219,7 +1220,7 @@ class MatrixStore {
 	/**
 	 * Convert SDK MatrixEvent to SimpleMessage
 	 */
-	private eventToSimpleMessage(event: MatrixEvent): SimpleMessage {
+	private eventToSimpleMessage(event: MatrixEvent, timeline?: MatrixEvent[]): SimpleMessage {
 		const content = event.getContent();
 		const relatesTo = content['m.relates_to'];
 		const msgtype = content.msgtype || 'm.text';
@@ -1254,6 +1255,9 @@ class MatrixStore {
 			}
 		}
 
+		// Collect reactions for this message
+		const reactions = this.getReactionsForEvent(event.getId() || '', timeline);
+
 		return {
 			id: event.getId() || '',
 			sender: event.getSender() || '',
@@ -1268,9 +1272,62 @@ class MatrixStore {
 			edited: !!event.replacingEvent(),
 			redacted: isRedacted,
 			media,
+			reactions: reactions.length > 0 ? reactions : undefined,
 		};
 	}
 
+	/**
+	 * Get reactions for a specific event
+	 */
+	private getReactionsForEvent(eventId: string, timeline?: MatrixEvent[]): MessageReaction[] {
+		if (!timeline || !eventId) return [];
+
+		const myUserId = this._client?.getUserId();
+		const reactionMap = new Map<string, { users: string[]; senders: Set<string> }>();
+
+		// Find all m.reaction events that relate to this event
+		for (const event of timeline) {
+			if (event.getType() !== 'm.reaction') continue;
+
+			const content = event.getContent();
+			const relatesTo = content['m.relates_to'];
+
+			if (
+				relatesTo?.rel_type === 'm.annotation' &&
+				relatesTo?.event_id === eventId &&
+				relatesTo?.key
+			) {
+				const emoji = relatesTo.key;
+				const sender = event.getSender() || '';
+
+				if (!reactionMap.has(emoji)) {
+					reactionMap.set(emoji, { users: [], senders: new Set() });
+				}
+
+				const entry = reactionMap.get(emoji)!;
+				// Avoid duplicates from same user
+				if (!entry.senders.has(sender)) {
+					entry.senders.add(sender);
+					entry.users.push(sender);
+				}
+			}
+		}
+
+		// Convert to MessageReaction array
+		const reactions: MessageReaction[] = [];
+		for (const [key, data] of reactionMap) {
+			reactions.push({
+				key,
+				count: data.users.length,
+				users: data.users,
+				includesMe: myUserId ? data.senders.has(myUserId) : false,
+			});
+		}
+
+		// Sort by count descending
+		return reactions.sort((a, b) => b.count - a.count);
+	}
+
 	/**
 	 * Get display name for message sender
 	 */

apps/matrix/apps/web/src/lib/matrix/types.ts

@@ -29,6 +29,16 @@ export interface MediaInfo {
 	duration?: number; // For audio/video
 }
 
+/**
+ * Reaction on a message
+ */
+export interface MessageReaction {
+	key: string; // The emoji
+	count: number;
+	users: string[]; // User IDs who reacted
+	includesMe: boolean;
+}
+
 /**
  * Simplified message for UI rendering
  */
@@ -46,6 +56,7 @@ export interface SimpleMessage {
 	edited?: boolean;
 	redacted?: boolean;
 	media?: MediaInfo;
+	reactions?: MessageReaction[];
 }
 
 export type MessageType =