- Default actor_id to @username when not in token claims - Support both artdag_session (base64 JSON) and auth_token (JWT) cookies - Check both 'username' and 'sub' claims for username - Check both 'actor_id' and 'actor' claims for actor_id This fixes authentication when L2 tokens don't include actor_id. Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>