Update agent skill to allow self-assign only on explicit @-mention handoff with PAPERCLIP_WAKE_COMMENT_ID. Enrich wake contextSnapshot with taskId, wakeCommentId, and wakeReason fields so agents can identify mention-triggered runs. Clarify api-reference exception for handoff-by-mention pattern. Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>