Clarify finalize verdict semantics

src/message-runtime-prompts.ts

@@ -140,5 +140,7 @@ export function buildFinalizePendingPrompt(args: {
     ? `\n\nReviewer's final assessment:\n${lastReviewerOutput.output_text.slice(0, 2000)}`
     : '';
 
-  return `The reviewer approved your work (DONE). Finalize and report the result.${reviewerSummary}`;
+  return `The reviewer approved your work (DONE). Finalize and report the result.
+If you intend to close this paired turn now, your first line must be DONE.
+If your first line is DONE_WITH_CONCERNS, the system will reopen review instead of finishing.${reviewerSummary}`;
 }