- AST check moves to AFTER judging (only on AC submissions) - AST_CHECK_FAILED treated as AC for accepted_number and user profile - statistic_info keeps separate count for drill-down visibility - Status code changed to 10 (9 conflicts with frontend submitting) - Added frontend impact analysis for SubmissionResult, WebSocket, problem list Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>