diff --git a/static/icons/git-fork.svg b/static/icons/git-fork.svg
new file mode 100644
index 0000000..7ad04cf
--- /dev/null
+++ b/static/icons/git-fork.svg
@@ -0,0 +1 @@
+<svg xmlns="http://www.w3.org/2000/svg" viewBox="0 0 24 24" width="24" height="24" fill="none" stroke="#000000" stroke-width="2" stroke-linecap="round" stroke-linejoin="round" style="opacity:1;"><circle cx="12" cy="18" r="3"/><circle cx="6" cy="6" r="3"/><circle cx="18" cy="6" r="3"/><path d="M18 9v2c0 .6-.4 1-1 1H7c-.6 0-1-.4-1-1V9m6 3v3"/></svg>
\ No newline at end of file
diff --git a/static/src/components/chat/ChatArea.vue b/static/src/components/chat/ChatArea.vue
index 4150aa5..430f3eb 100644
--- a/static/src/components/chat/ChatArea.vue
+++ b/static/src/components/chat/ChatArea.vue
@@ -20,10 +20,18 @@
               <span class="icon icon-sm" :style="iconStyleSafe(userHeaderIconKey(msg))" aria-hidden="true"></span>
               <span>{{ userHeaderLabel(msg) }}</span>
             </div>
-            <div class="message-text user-bubble-text">
+            <div
+              class="message-text user-bubble-text"
+              :class="{
+                'is-collapsed': isUserBubbleCollapsed(msg, index),
+                'is-expandable': isUserBubbleExpandable(msg, index)
+              }"
+            >
               <div
                 v-if="msg.content"
                 class="bubble-text"
+                :class="{ 'is-expanded': isUserBubbleExpanded(msg, index) }"
+                :ref="(el) => registerUserBubbleRef(msg, index, el)"
                 v-html="renderUserMessageContent(msg.content)"
               ></div>
               <div v-if="msg.images && msg.images.length" class="image-inline-row">
@@ -53,6 +61,29 @@
                 </div>
               </div>
             </div>
+            <div class="user-bubble-actions">
+              <button
+                class="user-bubble-action-btn copy"
+                :class="{ copied: isUserBubbleCopied(msg, index) }"
+                :title="isUserBubbleCopied(msg, index) ? '已复制' : '复制'"
+                :aria-label="isUserBubbleCopied(msg, index) ? '已复制' : '复制'"
+                @click="copyUserMessage(msg, index)"
+              ></button>
+              <button
+                class="user-bubble-action-btn branch"
+                title="分支"
+                aria-label="分支"
+                @click="branchUserMessage(msg)"
+              ></button>
+              <button
+                v-if="isUserBubbleExpandable(msg, index)"
+                class="user-bubble-action-btn expand-toggle"
+                :class="{ expanded: isUserBubbleExpanded(msg, index) }"
+                :title="isUserBubbleExpanded(msg, index) ? '收起' : '展开'"
+                :aria-label="isUserBubbleExpanded(msg, index) ? '收起' : '展开'"
+                @click="toggleUserBubble(msg, index)"
+              ></button>
+            </div>
           </template>
         </div>
         <div v-else-if="msg.role === 'assistant'" class="assistant-message">
@@ -605,7 +636,7 @@
 </template>
 
 <script setup lang="ts">
-import { computed, onBeforeUnmount, onMounted, provide, ref, watch } from 'vue';
+import { computed, nextTick, onBeforeUnmount, onMounted, provide, ref, watch } from 'vue';
 import { useStickToBottom } from 'vue-stick-to-bottom';
 import { useBlockExpansionAnchor } from '@/composables/useBlockExpansionAnchor';
 import ToolAction from '@/components/chat/actions/ToolAction.vue';
@@ -666,6 +697,118 @@ const userName = computed(() => {
   }
   return personalization.form.user_name || '用户';
 });
+
+// 用户输入气泡折叠相关状态与逻辑
+interface UserBubbleFoldState {
+  needsFold: boolean;
+  expanded: boolean;
+  foldHeight: number;
+  fullHeight: number;
+}
+
+const USER_BUBBLE_FOLD_LINES = 10;
+const userBubbleRefs = new Map<string, HTMLElement>();
+const userBubbleFoldStates = ref<Record<string, UserBubbleFoldState>>({});
+const copiedBubbleKeys = ref<Set<string>>(new Set());
+let userBubbleResizeObserver: ResizeObserver | null = null;
+let copiedBubbleTimeouts = new Map<string, number>();
+
+const getUserBubbleKey = (msg: any, index: number) => msg?.id || `user-bubble-${index}`;
+
+const registerUserBubbleRef = (msg: any, index: number, el: Element | null) => {
+  const key = getUserBubbleKey(msg, index);
+  if (el instanceof HTMLElement) {
+    userBubbleRefs.set(key, el);
+  } else {
+    userBubbleRefs.delete(key);
+  }
+};
+
+const measureUserBubbles = () => {
+  userBubbleRefs.forEach((el, key) => {
+    if (!el.isConnected) {
+      userBubbleRefs.delete(key);
+      return;
+    }
+    const computed = window.getComputedStyle(el);
+    const rawLineHeight = parseFloat(computed.lineHeight);
+    const lineHeight = Number.isFinite(rawLineHeight) ? rawLineHeight : 24;
+    const foldHeight = Math.round(lineHeight * USER_BUBBLE_FOLD_LINES);
+    const fullHeight = Math.ceil(el.scrollHeight);
+    const needsFold = fullHeight > foldHeight + 1;
+    const existing = userBubbleFoldStates.value[key];
+    userBubbleFoldStates.value[key] = {
+      needsFold,
+      expanded: existing?.expanded ?? false,
+      foldHeight,
+      fullHeight
+    };
+    el.style.setProperty('--bubble-fold-height', `${foldHeight}px`);
+    el.style.setProperty('--bubble-full-height', `${fullHeight}px`);
+  });
+};
+
+const isUserBubbleExpandable = (msg: any, index: number) => {
+  const key = getUserBubbleKey(msg, index);
+  return !!userBubbleFoldStates.value[key]?.needsFold;
+};
+
+const isUserBubbleExpanded = (msg: any, index: number) => {
+  const key = getUserBubbleKey(msg, index);
+  return !!userBubbleFoldStates.value[key]?.expanded;
+};
+
+const isUserBubbleCollapsed = (msg: any, index: number) => {
+  const key = getUserBubbleKey(msg, index);
+  const state = userBubbleFoldStates.value[key];
+  return !!state?.needsFold && !state?.expanded;
+};
+
+const toggleUserBubble = (msg: any, index: number) => {
+  const key = getUserBubbleKey(msg, index);
+  const state = userBubbleFoldStates.value[key];
+  if (!state || !state.needsFold) return;
+  userBubbleFoldStates.value[key] = { ...state, expanded: !state.expanded };
+};
+
+const isUserBubbleCopied = (msg: any, index: number) => {
+  const key = getUserBubbleKey(msg, index);
+  return copiedBubbleKeys.value.has(key);
+};
+
+const copyUserMessage = async (msg: any, index: number) => {
+  const key = getUserBubbleKey(msg, index);
+  const text = typeof msg?.content === 'string' ? msg.content : '';
+  if (!text || copiedBubbleKeys.value.has(key)) return;
+  try {
+    await navigator.clipboard.writeText(text);
+    copiedBubbleKeys.value.add(key);
+    const existing = copiedBubbleTimeouts.get(key);
+    if (existing) window.clearTimeout(existing);
+    const timeout = window.setTimeout(() => {
+      copiedBubbleKeys.value.delete(key);
+      copiedBubbleTimeouts.delete(key);
+    }, 5000);
+    copiedBubbleTimeouts.set(key, timeout);
+  } catch (err) {
+    console.warn('复制用户消息失败:', err);
+  }
+};
+
+const branchUserMessage = (_msg: any) => {
+  // TODO: 分支功能占位
+  void _msg;
+  console.log('[ChatArea] 分支功能待实现');
+};
+
+const observeUserBubbles = () => {
+  if (!userBubbleResizeObserver) return;
+  userBubbleResizeObserver.disconnect();
+  userBubbleRefs.forEach((el) => {
+    if (el.isConnected) userBubbleResizeObserver!.observe(el);
+  });
+};
+
 const isSystemAutoUserMessage = (message: any) => {
   if (!message || message.role !== 'user') {
     return false;
@@ -1603,6 +1746,19 @@ function compactBriefLabel(msg: any): string {
   }
 }
 
+watch(
+  () => filteredMessages.value.map((m) => m?.id ?? m?.content?.slice(0, 80)),
+  () => {
+    nextTick(() => {
+      requestAnimationFrame(() => {
+        measureUserBubbles();
+        observeUserBubbles();
+      });
+    });
+  },
+  { immediate: true }
+);
+
 onMounted(() => {
   attachBounceListener();
   updateChatScrollbarWidth();
@@ -1610,6 +1766,12 @@ onMounted(() => {
     scrollbarResizeObserver = new ResizeObserver(updateChatScrollbarWidth);
     scrollbarResizeObserver.observe(scrollRef.value);
   }
+  if (typeof ResizeObserver !== 'undefined') {
+    userBubbleResizeObserver = new ResizeObserver(() => {
+      requestAnimationFrame(measureUserBubbles);
+    });
+    nextTick(() => observeUserBubbles());
+  }
   console.warn('[SCROLL_BOUNCE_TRACE]', 'mounted', {
     hasScrollRef: !!scrollRef.value
   });
@@ -1638,6 +1800,13 @@ onBeforeUnmount(() => {
     scrollbarResizeObserver.disconnect();
     scrollbarResizeObserver = null;
   }
+  if (userBubbleResizeObserver) {
+    userBubbleResizeObserver.disconnect();
+    userBubbleResizeObserver = null;
+  }
+  userBubbleRefs.clear();
+  copiedBubbleTimeouts.forEach((t) => window.clearTimeout(t));
+  copiedBubbleTimeouts.clear();
   if (timerHandle !== null) {
     clearInterval(timerHandle);
     timerHandle = null;
diff --git a/static/src/styles/components/chat/_chat-area.scss b/static/src/styles/components/chat/_chat-area.scss
index e58e021..af84492 100644
--- a/static/src/styles/components/chat/_chat-area.scss
+++ b/static/src/styles/components/chat/_chat-area.scss
@@ -576,6 +576,100 @@
   margin: 0 0.25em;
 }
 
+/* 用户输入气泡：超长折叠、展开动画与悬停操作按钮 */
+.user-message .message-text.user-bubble-text .bubble-text {
+  overflow: hidden;
+  transition: max-height 300ms cubic-bezier(0.4, 0, 0.2, 1);
+  max-height: var(--bubble-full-height, 9999px);
+  white-space: pre-wrap;
+  word-break: break-all;
+}
+
+.user-message .message-text.user-bubble-text.is-expandable .bubble-text:not(.is-expanded) {
+  max-height: var(--bubble-fold-height, 240px);
+}
+
+.user-bubble-actions {
+  display: flex;
+  align-items: center;
+  justify-content: flex-end;
+  gap: 6px;
+  margin-top: 6px;
+  opacity: 0;
+  transform: translateY(4px);
+  pointer-events: none;
+  transition:
+    opacity 180ms ease,
+    transform 180ms ease;
+  white-space: normal;
+  align-self: flex-end;
+}
+
+.user-message:not(.user-message--compact):not(.user-message--brief):hover .user-bubble-actions,
+.user-message:not(.user-message--compact):not(.user-message--brief):focus-within .user-bubble-actions {
+  opacity: 1;
+  transform: translateY(0);
+  pointer-events: auto;
+}
+
+.user-bubble-action-btn {
+  width: 28px;
+  height: 28px;
+  border: none;
+  border-radius: 8px;
+  padding: 0;
+  background: transparent;
+  color: var(--claude-text-secondary);
+  cursor: pointer;
+  display: inline-flex;
+  align-items: center;
+  justify-content: center;
+  transition:
+    background-color 140ms ease,
+    color 140ms ease;
+  flex-shrink: 0;
+}
+
+.user-bubble-action-btn:hover {
+  background-color: var(--theme-tab-active);
+  color: var(--claude-text);
+}
+
+.user-bubble-action-btn::before {
+  content: '';
+  width: 18px;
+  height: 18px;
+  display: block;
+  background: currentColor;
+  mask: center / contain no-repeat;
+  -webkit-mask: center / contain no-repeat;
+}
+
+.user-bubble-action-btn.copy::before {
+  mask-image: url('/static/icons/copy.svg');
+  -webkit-mask-image: url('/static/icons/copy.svg');
+}
+
+.user-bubble-action-btn.copy.copied::before {
+  mask-image: url('/static/icons/check.svg');
+  -webkit-mask-image: url('/static/icons/check.svg');
+}
+
+.user-bubble-action-btn.branch::before {
+  mask-image: url('/static/icons/git-fork.svg');
+  -webkit-mask-image: url('/static/icons/git-fork.svg');
+}
+
+.user-bubble-action-btn.expand-toggle::before {
+  mask-image: url("data:image/svg+xml,%3Csvg xmlns='http://www.w3.org/2000/svg' viewBox='0 0 24 24' fill='none' stroke='%23000' stroke-width='2' stroke-linecap='round' stroke-linejoin='round'%3E%3Cpath d='m6 9 6 6 6-6'/%3E%3C/svg%3E");
+  -webkit-mask-image: url("data:image/svg+xml,%3Csvg xmlns='http://www.w3.org/2000/svg' viewBox='0 0 24 24' fill='none' stroke='%23000' stroke-width='2' stroke-linecap='round' stroke-linejoin='round'%3E%3Cpath d='m6 9 6 6 6-6'/%3E%3C/svg%3E");
+  transition: transform 260ms cubic-bezier(0.4, 0, 0.2, 1);
+}
+
+.user-bubble-action-btn.expand-toggle.expanded::before {
+  transform: rotate(180deg);
+}
+
 .assistant-message .message-text {
   background: var(--claude-highlight);
   border-left: 4px solid var(--claude-accent);