fix(ui): 优化历史导航和粘贴处理逻辑

- 在历史导航中同步捕获当前草稿，避免异步状态不一致
- 修正使用最新捕获草稿替代旧状态以设置缓冲区文本
- 在粘贴处理钩子中引入 useEffect 钩子以响应缓冲区文本变化
- 通过副作用保持衍生标志状态与缓冲区文本同步
- 移除潜在的异步更新问题，提升用户交互体验

Author: hqwlkj

src/ui/hooks/useHistoryNavigation.ts

@@ -38,13 +38,15 @@ export function useHistoryNavigation(
 
     const previousCursor = historyCursor === -1 ? promptHistory.length : historyCursor;
     const nextCursor = Math.max(0, Math.min(promptHistory.length, previousCursor + direction));
+    // Capture the current draft synchronously before `setDraftBeforeHistory`.
+    const draft = historyCursor === -1 ? buffer.text : draftBeforeHistory;
 
     if (historyCursor === -1) {
       setDraftBeforeHistory(buffer.text);
     }
 
     if (nextCursor === promptHistory.length) {
-      const text = draftBeforeHistory ?? "";
+      const text = draft ?? "";
       setBuffer({ text, cursor: text.length });
       setHistoryCursor(-1);
       setDraftBeforeHistory(null);

src/ui/hooks/usePasteHandling.ts

@@ -1,5 +1,5 @@
 import type React from "react";
-import { useRef, useState } from "react";
+import { useEffect, useRef, useState } from "react";
 import type { PromptBufferState } from "../core/prompt-buffer";
 import { cleanPasteContent, findPasteMarkerContaining, hasActivePasteMarkers, insertText } from "../core/prompt-buffer";
 
@@ -51,6 +51,13 @@ export function usePasteHandling(
     setHasExpandedRegions(expandedRegionsRef.current.size > 0);
   }
 
+  // Recompute derived flags whenever the buffer text changes, so they stay
+  // in sync after any state update (e.g. large paste, expand/collapse, undo).
+  useEffect(() => {
+    refreshDerivedFlags();
+    // eslint-disable-next-line react-hooks/exhaustive-deps
+  }, [buffer.text]);
+
   function handlePaste(pastedText: string): void {
     const totalChars = pastedText.length;