AP ingest: fill missing attributedTo from activity

test/fixtures/fedidev.fun/missing_attributed_to.json

@@ -0,0 +1,25 @@
+{
+  "@context": [
+    "https://www.w3.org/ns/activitystreams"
+  ],
+  "type": "Create",
+  "id": "https://fedidev.fun/activity/missing-attributedto",
+  "actor": "https://fedidev.fun/users/alice",
+  "to": [
+    "https://www.w3.org/ns/activitystreams#Public"
+  ],
+  "cc": [],
+  "published": "2025-11-21T14:42:00Z",
+  "object": {
+    "type": "Note",
+    "id": "https://fedidev.fun/objects/note-missing-attributedto",
+    "attributedTo": null,
+    "to": [
+      "https://www.w3.org/ns/activitystreams#Public"
+    ],
+    "cc": [],
+    "published": "2025-11-21T14:42:00Z",
+    "content": "object without attributedTo"
+  }
+}
+

test/pleroma/web/activity_pub/transmogrifier/fedidev_fun_missing_attributed_to_test.exs

@@ -0,0 +1,49 @@
+# Pleroma: A lightweight social networking server
+# Copyright © 2017-2022 Pleroma Authors <https://pleroma.social/>
+# SPDX-License-Identifier: AGPL-3.0-only
+
+defmodule Pleroma.Web.ActivityPub.Transmogrifier.FedidevFunMissingAttributedToTest do
+  use Oban.Testing, repo: Pleroma.Repo
+  use Pleroma.DataCase
+
+  alias Pleroma.Object
+  alias Pleroma.User
+  alias Pleroma.Web.ActivityPub.Transmogrifier
+
+  import Pleroma.Factory
+
+  setup_all do
+    Tesla.Mock.mock_global(fn env -> apply(HttpRequestMock, :request, [env]) end)
+    :ok
+  end
+
+  defp ensure_remote_actor!(ap_id) when is_binary(ap_id) do
+    case User.get_cached_by_ap_id(ap_id) do
+      %User{} ->
+        :ok
+
+      _ ->
+        insert(:user,
+          local: false,
+          ap_id: ap_id,
+          follower_address: ap_id <> "/followers",
+          following_address: ap_id <> "/following",
+          featured_address: ap_id <> "/collections/featured",
+          inbox: ap_id <> "/inbox"
+        )
+
+        :ok
+    end
+  end
+
+  test "inherits attributedTo from surrounding activity" do
+    data = File.read!("test/fixtures/fedidev.fun/missing_attributed_to.json") |> Jason.decode!()
+    ensure_remote_actor!(data["actor"])
+
+    assert {:ok, activity} = Transmogrifier.handle_incoming(data)
+    object = Object.normalize(activity.data["object"], fetch: false)
+
+    assert object.data["attributedTo"] == data["actor"]
+    assert object.data["actor"] == data["actor"]
+  end
+end