diff --git a/fluxer_api/src/api/channel/repositories/IMessageInteractionRepository.ts b/fluxer_api/src/api/channel/repositories/IMessageInteractionRepository.ts
index 43cecd99c..26ad1b952 100644
--- a/fluxer_api/src/api/channel/repositories/IMessageInteractionRepository.ts
+++ b/fluxer_api/src/api/channel/repositories/IMessageInteractionRepository.ts
@@ -29,6 +29,7 @@ export abstract class IMessageInteractionRepository {
 		emojiName: string,
 		emojiId?: EmojiID,
 		emojiAnimated?: boolean,
+		knownHasReaction?: boolean | null,
 	): Promise<MessageReaction>;
 
 	abstract removeReaction(
diff --git a/fluxer_api/src/api/channel/repositories/MessageInteractionRepository.test.ts b/fluxer_api/src/api/channel/repositories/MessageInteractionRepository.test.ts
new file mode 100644
index 000000000..080b9e33b
--- /dev/null
+++ b/fluxer_api/src/api/channel/repositories/MessageInteractionRepository.test.ts
@@ -0,0 +1,95 @@
+// SPDX-License-Identifier: AGPL-3.0-or-later
+
+import * as BucketUtils from '@fluxer/snowflake/src/SnowflakeBuckets';
+import {afterEach, beforeEach, describe, expect, it} from 'vitest';
+import {type ChannelID, createChannelID, createMessageID, createUserID, type MessageID} from '../../BrandedTypes';
+import {fetchOne, setCassandraQueryExecutorForTesting} from '../../database/CassandraQueryExecution';
+import type {PreparedQuery} from '../../database/CassandraTypes';
+import type {MessageRow} from '../../database/types/MessageTypes';
+import {Messages} from '../../Tables';
+import {InMemoryCassandraQueryExecutor} from '../../test/InMemoryCassandraQueryExecutor';
+import {ChannelDataRepository} from './ChannelDataRepository';
+import {MessageInteractionRepository} from './MessageInteractionRepository';
+import {MessageRepository} from './MessageRepository';
+
+const FETCH_MESSAGE_HAS_REACTION = Messages.selectCql({
+	columns: ['has_reaction'],
+	where: [Messages.where.eq('channel_id'), Messages.where.eq('bucket'), Messages.where.eq('message_id')],
+	limit: 1,
+});
+
+class RecordingCassandraQueryExecutor extends InMemoryCassandraQueryExecutor {
+	executed: Array<PreparedQuery> = [];
+
+	override async executeQuery<T = Record<string, unknown>>(query: PreparedQuery): Promise<Array<T>> {
+		this.executed.push(query);
+		return super.executeQuery<T>(query);
+	}
+
+	override reset(): void {
+		this.executed = [];
+		super.reset();
+	}
+
+	countHasReactionWrites(): number {
+		return this.executed.filter(
+			(query) =>
+				query.kvMeta?.action === 'patch' &&
+				query.kvMeta.table.name === 'messages' &&
+				(query.kvMeta.patchKeys ?? []).includes('has_reaction'),
+		).length;
+	}
+}
+
+let executor: RecordingCassandraQueryExecutor;
+
+function createRepository(): MessageInteractionRepository {
+	return new MessageInteractionRepository(new MessageRepository(new ChannelDataRepository()));
+}
+
+async function loadHasReaction(channelId: ChannelID, messageId: MessageID): Promise<boolean | null | undefined> {
+	const row = await fetchOne<Pick<MessageRow, 'has_reaction'>>(FETCH_MESSAGE_HAS_REACTION, {
+		channel_id: channelId,
+		bucket: BucketUtils.makeBucket(messageId),
+		message_id: messageId,
+	});
+	return row?.has_reaction;
+}
+
+describe('MessageInteractionRepository has_reaction writes', () => {
+	beforeEach(() => {
+		executor = new RecordingCassandraQueryExecutor();
+		setCassandraQueryExecutorForTesting(executor);
+	});
+	afterEach(() => {
+		executor.reset();
+		setCassandraQueryExecutorForTesting(null);
+	});
+	it('flags the message when the first reaction is added', async () => {
+		const channelId = createChannelID(10n);
+		const messageId = createMessageID(100n);
+		const repository = createRepository();
+		await repository.addReaction(channelId, messageId, createUserID(1n), '🔥');
+		expect(executor.countHasReactionWrites()).toBe(1);
+		expect(await loadHasReaction(channelId, messageId)).toBe(true);
+	});
+	it('skips the flag write when the message is already known to be flagged', async () => {
+		const channelId = createChannelID(10n);
+		const messageId = createMessageID(100n);
+		const repository = createRepository();
+		await repository.addReaction(channelId, messageId, createUserID(1n), '🔥');
+		await repository.addReaction(channelId, messageId, createUserID(2n), '🔥', undefined, false, true);
+		expect(executor.countHasReactionWrites()).toBe(1);
+		expect(await repository.listMessageReactions(channelId, messageId)).toHaveLength(2);
+		expect(await loadHasReaction(channelId, messageId)).toBe(true);
+	});
+	it('flags the message when the loaded flag is not already true', async () => {
+		const channelId = createChannelID(10n);
+		const messageId = createMessageID(100n);
+		const repository = createRepository();
+		await repository.addReaction(channelId, messageId, createUserID(1n), '🔥', undefined, false, null);
+		await repository.addReaction(channelId, messageId, createUserID(2n), '🔥', undefined, false, false);
+		expect(executor.countHasReactionWrites()).toBe(2);
+		expect(await loadHasReaction(channelId, messageId)).toBe(true);
+	});
+});
diff --git a/fluxer_api/src/api/channel/repositories/MessageInteractionRepository.ts b/fluxer_api/src/api/channel/repositories/MessageInteractionRepository.ts
index aee1348ad..8b99ac034 100644
--- a/fluxer_api/src/api/channel/repositories/MessageInteractionRepository.ts
+++ b/fluxer_api/src/api/channel/repositories/MessageInteractionRepository.ts
@@ -170,6 +170,7 @@ export class MessageInteractionRepository extends IMessageInteractionRepository
 		emojiName: string,
 		emojiId?: EmojiID,
 		emojiAnimated: boolean = false,
+		knownHasReaction?: boolean | null,
 	): Promise<MessageReaction> {
 		const bucket = BucketUtils.makeBucket(messageId);
 		const normalizedEmojiId = emojiId ? emojiId : createEmojiID(0n);
@@ -184,7 +185,9 @@ export class MessageInteractionRepository extends IMessageInteractionRepository
 			created_at: new Date(),
 		};
 		await upsertOne(MessageReactions.upsertAll(reactionData));
-		await this.setHasReaction(channelId, messageId, true);
+		if (knownHasReaction !== true) {
+			await this.setHasReaction(channelId, messageId, true);
+		}
 		return new MessageReaction(reactionData);
 	}
 
diff --git a/fluxer_api/src/api/channel/services/interaction/MessageReactionService.ts b/fluxer_api/src/api/channel/services/interaction/MessageReactionService.ts
index 191ffb0f3..ea43d8295 100644
--- a/fluxer_api/src/api/channel/services/interaction/MessageReactionService.ts
+++ b/fluxer_api/src/api/channel/services/interaction/MessageReactionService.ts
@@ -260,6 +260,7 @@ export class MessageReactionService extends MessageInteractionBase {
 			parsedEmoji.name,
 			emojiId,
 			parsedEmoji.animated ?? false,
+			message.hasReaction,
 		);
 		await this.dispatchMessageReactionAdd({
 			channel,