Sent Like/Unlike to the author of the object

refs https://linear.app/tryghost/issue/AP-286

We want to make sure that the original author is notified of the activity as
well as our followers. This is wrapped in guards because it's possible the
property doesn't exist.

src/handlers.ts

@@ -9,6 +9,7 @@ import {
     Create,
     Note,
     Update,
+    Actor,
     PUBLIC_COLLECTION
 } from '@fedify/fedify';
 import { Context, Next } from 'hono';
@@ -22,6 +23,7 @@ import type { PersonData } from './user';
 import { ACTOR_DEFAULT_HANDLE } from './constants';
 import { Temporal } from '@js-temporal/polyfill';
 import { createHash } from 'node:crypto';
+import { lookupActor } from 'lookup-helpers';
 
 type StoredThing = {
     id: string;
@@ -121,6 +123,16 @@ export async function unlikeAction(
     await removeFromList(ctx.get('db'), ['liked'], likeId!.href);
     await ctx.get('globaldb').delete([likeId!.href]);
 
+    let attributionActor: Actor | null = null;
+    if (objectToLike.attributionId) {
+        attributionActor = await lookupActor(apCtx, objectToLike.attributionId.href);
+    }
+    if (attributionActor) {
+        apCtx.sendActivity({ handle: ACTOR_DEFAULT_HANDLE }, attributionActor, undo, {
+            preferSharedInbox: true
+        });
+    }
+
     apCtx.sendActivity({ handle: ACTOR_DEFAULT_HANDLE }, 'followers', undo, {
         preferSharedInbox: true
     });
@@ -171,6 +183,16 @@ export async function likeAction(
 
     await addToList(ctx.get('db'), ['liked'], like.id!.href);
 
+    let attributionActor: Actor | null = null;
+    if (objectToLike.attributionId) {
+        attributionActor = await lookupActor(apCtx, objectToLike.attributionId.href);
+    }
+    if (attributionActor) {
+        apCtx.sendActivity({ handle: ACTOR_DEFAULT_HANDLE }, attributionActor, like, {
+            preferSharedInbox: true
+        });
+    }
+
     apCtx.sendActivity({ handle: ACTOR_DEFAULT_HANDLE }, 'followers', like, {
         preferSharedInbox: true
     });