From 71487f7881caa280ed0504f4ba8a563a24846ed7 Mon Sep 17 00:00:00 2001
From: Hazelnoot <acomputerdog@gmail.com>
Date: Sat, 26 Jul 2025 19:21:19 -0400
Subject: [PATCH] render Update(*) activities with deterministic IDs

---
 packages/backend/src/core/activitypub/ApRendererService.ts | 6 ++++--
 packages/backend/src/core/activitypub/type.ts              | 6 +++---
 2 files changed, 7 insertions(+), 5 deletions(-)

diff --git a/packages/backend/src/core/activitypub/ApRendererService.ts b/packages/backend/src/core/activitypub/ApRendererService.ts
index 9f55be11ac..800b00f8a7 100644
--- a/packages/backend/src/core/activitypub/ApRendererService.ts
+++ b/packages/backend/src/core/activitypub/ApRendererService.ts
@@ -750,9 +750,11 @@ export class ApRendererService {
 	}
 
 	@bindThis
-	public renderUpdate(object: string | IObject, user: { id: MiUser['id'] }): IUpdate {
+	public renderUpdate(object: IObject, user: { id: MiUser['id'] }): IUpdate {
+		// Deterministic activity IDs to allow de-duplication by remote instances
+		const updatedAt = object.updated ? new Date(object.updated).getTime() : Date.now();
 		return {
-			id: `${this.config.url}/users/${user.id}#updates/${new Date().getTime()}`,
+			id: `${this.config.url}/users/${user.id}#updates/${updatedAt}`,
 			actor: this.userEntityService.genLocalUserUri(user.id),
 			type: 'Update',
 			to: ['https://www.w3.org/ns/activitystreams#Public'],
diff --git a/packages/backend/src/core/activitypub/type.ts b/packages/backend/src/core/activitypub/type.ts
index 5d4b2b01c5..abe142e812 100644
--- a/packages/backend/src/core/activitypub/type.ts
+++ b/packages/backend/src/core/activitypub/type.ts
@@ -28,8 +28,9 @@ export interface IObject {
 	inReplyTo?: any;
 	replies?: ICollection | IOrderedCollection | string;
 	content?: string | null;
-	startTime?: Date;
-	endTime?: Date;
+	startTime?: Date; // TODO these are wrong - should be string
+	endTime?: Date; // TODO these are wrong - should be string
+	updated?: string;
 	icon?: any;
 	image?: any;
 	mediaType?: string;
@@ -216,7 +217,6 @@ export interface IPost extends IObject {
 	quoteUrl?: string;
 	quoteUri?: string;
 	quote?: string;
-	updated?: string;
 }
 
 export interface IQuestion extends IObject {