fix(web): keep composer enabled while generating and treat stop as neutral (BUG-551, BUG-552)

Enter now queues one follow-up instead of dropping it, and a rectification stop leaves the streamed reply with a grey notice instead of an error alert.

Co-authored-by: Cursor <cursoragent@cursor.com>

frontend/src/lib/queued-draft.ts

@@ -0,0 +1,17 @@
+export const COMPOSER_QUEUE_LABEL = "已排队，回答结束后发出";
+export const COMPOSER_QUEUE_RECALL_LABEL = "撤回";
+
+export type QueuedDraftSettle = "send" | "restore";
+
+export function appendQueuedText(current: string, incoming: string): string {
+  const next = incoming.trim();
+  if (!next) return current.trim();
+  if (!current.trim()) return next;
+  return `${current.trimEnd()}\n${next}`;
+}
+
+export function queuedDraftSettleAction(
+  phase: "completed" | "succeeded" | "stopped" | "failed" | "recovering" | "readonly",
+): QueuedDraftSettle {
+  return phase === "completed" || phase === "succeeded" ? "send" : "restore";
+}

frontend/src/lib/rectification-surface-state.ts

@@ -34,6 +34,10 @@ export const RECTIFICATION_EMPTY_COPY = "这段校正还没有开始。";
 export const RECTIFICATION_EMPTY_ACTION_LABEL = "开始提问";
 export const RECTIFICATION_HYDRATION_INCOMPLETE_NOTICE = "校正记录没有完全加载，可以继续。";
 export const RECTIFICATION_STOPPED_NOTICE = "已停止，已生成的内容保留；本次不会扣点。";
+
+export function isAbortError(caught: unknown): boolean {
+  return (caught instanceof DOMException || caught instanceof Error) && caught.name === "AbortError";
+}
 export const RECTIFICATION_INSUFFICIENT_CREDITS_NOTICE = "校正点数不足，正在前往兑换…";
 export const RECTIFICATION_INSUFFICIENT_CREDITS_REDIRECT_MS = 600;