Update

priv/repo/migrations/20250615131856_create_activities.exs

@@ -4,15 +4,16 @@ defmodule Nulla.Repo.Migrations.CreateActivities do
   def change do
     create table(:activities, primary_key: false) do
       add :id, :bigint, primary_key: true
+      add :ap_id, :string, null: false
       add :type, :string, null: false
-      add :actor, :string, null: false
+      add :actor_id, references(:actors, type: :bigint, on_delete: :nothing), null: false
       add :object, :map, null: false
       add :to, {:array, :string}, default: []
 
       timestamps()
     end
 
-    create index(:activities, [:actor])
     create index(:activities, [:type])
+    create index(:activities, [:actor_id])
   end
 end