fix(chat): restore collapse max height in block mode

static/src/components/chat/ChatArea.vue

@@ -959,10 +959,11 @@ const registerCollapseContent = (key: string, el: Element | null) => {
   if (!(el instanceof HTMLElement)) {
     return;
   }
+  const COLLAPSE_MAX_HEIGHT = 600;
   requestAnimationFrame(() => {
     const h = el.scrollHeight || el.offsetHeight || 0;
     if (h > 0) {
-      el.style.setProperty('--collapse-max', `${h}px`);
+      el.style.setProperty('--collapse-max', `${Math.min(h, COLLAPSE_MAX_HEIGHT)}px`);
     }
   });
 };

static/src/components/chat/StackedBlocks.vue

@@ -211,6 +211,7 @@ const viewportHeight = ref(0);
 const contentHeights = ref<Record<string, number>>({});
 const ANIMATION_SYNC_MS = 360;
 const MORE_ANIMATION_MS = 300;
+const COLLAPSE_MAX_HEIGHT = 600;
 let syncRaf: number | null = null;
 let syncUntil = 0;
 const isMoreAnimating = ref(false);
@@ -293,7 +294,9 @@ const setShellMetrics = () => {
     const action = stackableActions.value[idx];
     const key = blockKey(action, idx);
     const content = el.querySelector('.collapsible-content') as HTMLElement | null;
-    const contentHeight = content ? Math.ceil(content.scrollHeight) : 0;
+    const contentHeight = content
+      ? Math.min(Math.ceil(content.scrollHeight), COLLAPSE_MAX_HEIGHT)
+      : 0;
     nextContentHeights[key] = contentHeight;
 
     // 使用当前真实高度而非「展开/折叠」状态推导值，避免在折叠动画过程中出现高度骤减导致的闪烁