Rewrite all federation-domain URLs in object_data for per-app delivery

Mastodon requires object IDs to match the actor's domain. The
object_data stored in DB uses federation.rose-ash.com but per-app
delivery uses blog.rose-ash.com etc. Now rewrites id and
attributedTo in object_data, not just the activity-level fields.

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

events/handlers/ap_delivery_handler.py

@@ -15,6 +15,7 @@ On retry (at-least-once reaper), already-delivered inboxes are skipped.
 from __future__ import annotations
 
 import logging
+import os
 from collections import defaultdict
 
 import httpx
@@ -44,16 +45,25 @@ def _build_activity_json(activity: APActivity, actor: ActorProfile, domain: str)
 
     obj = dict(activity.object_data or {})
 
-    # Rewrite activity ID to match the delivery domain so Mastodon's
-    # origin check passes (activity ID host must equal actor host).
-    # The stored activity_id uses the federation domain; we replace
-    # just the host portion for per-app delivery.
+    # Rewrite all URLs from the federation domain to the delivery domain
+    # so Mastodon's origin check passes (all IDs must match actor host).
     import re
-    activity_id = re.sub(
-        r"^https://[^/]+/", f"https://{domain}/", activity.activity_id,
-    )
+    fed_domain = os.getenv("AP_DOMAIN", "federation.rose-ash.com")
+
+    def _rewrite(url: str) -> str:
+        if isinstance(url, str) and fed_domain in url:
+            return url.replace(f"https://{fed_domain}", f"https://{domain}")
+        return url
+
+    activity_id = _rewrite(activity.activity_id)
     object_id = activity_id + "/object"
 
+    # Rewrite any federation-domain URLs in object_data
+    if "id" in obj:
+        obj["id"] = _rewrite(obj["id"])
+    if "attributedTo" in obj:
+        obj["attributedTo"] = _rewrite(obj["attributedTo"])
+
     if activity.activity_type == "Delete":
         obj.setdefault("id", object_id)
         obj.setdefault("type", "Tombstone")