diff --git a/package.json b/package.json
index 0979390..736a3c6 100644
--- a/package.json
+++ b/package.json
@@ -61,6 +61,7 @@
         "@jupyterlab/notebook": "^4.0.0",
         "@jupyterlab/services": "^7.0.0",
         "@jupyterlab/settingregistry": "^4.0.0",
+        "@jupyterlab/ui-components": "^4.0.0",
         "@lumino/signaling": "^2.0.0",
         "@lumino/widgets": "^2.0.0",
         "diff": "^5.2.0",
diff --git a/src/index.ts b/src/index.ts
index 7fa28e9..83a7aa9 100644
--- a/src/index.ts
+++ b/src/index.ts
@@ -5,6 +5,7 @@ import {
 import { INotebookTracker, NotebookPanel } from '@jupyterlab/notebook';
 import { ToolbarButton, MainAreaWidget } from '@jupyterlab/apputils';
 import { ISettingRegistry } from '@jupyterlab/settingregistry';
+import { saveIcon } from '@jupyterlab/ui-components';
 
 import { requestAPI } from './request';
 import { registerCommands, CommandIDs } from './commands';
@@ -59,7 +60,11 @@ const plugin: JupyterFrontEndPlugin<void> = {
       onOpenDiff: openDiff
     });
     panel.id = 'snapshot:panel';
-    panel.title.label = '快照历史';
+    // Icon-only panel tab: the title text becomes a hover caption so the
+    // sidebar stays compact. saveIcon is reused for visual consistency with
+    // the commit toolbar button (both signal "save" semantics).
+    panel.title.icon = saveIcon;
+    panel.title.caption = '快照历史';
     app.shell.add(panel, 'left', { rank: 200 });
 
     // Keep the model in sync with the current notebook.
@@ -73,13 +78,14 @@ const plugin: JupyterFrontEndPlugin<void> = {
 
     registerCommands(app, tracker, model);
 
-    // Add a "保存快照" button to every notebook panel's toolbar.
+    // Add an icon-only "保存快照" button to every notebook panel's toolbar.
+    // The tooltip on hover carries the full description.
     // NOTE: docRegistry.addWidgetExtension('Notebook', ...) places its
     // returned widget in the *main area* (a new tab), not on the toolbar.
     // The toolbar wants panel.toolbar.addItem directly.
     const addCommitButton = (panelHost: NotebookPanel) => {
       const button = new ToolbarButton({
-        label: '保存快照',
+        icon: saveIcon,
         tooltip: '保存当前 notebook 为快照',
         onClick: () => {
           void app.commands.execute(CommandIDs.commit);
diff --git a/src/widgets/SnapshotPanel.tsx b/src/widgets/SnapshotPanel.tsx
index b25b172..a8e542e 100644
--- a/src/widgets/SnapshotPanel.tsx
+++ b/src/widgets/SnapshotPanel.tsx
@@ -1,6 +1,7 @@
 import * as React from 'react';
 import { ReactWidget } from '@jupyterlab/apputils';
 import { ServerConnection } from '@jupyterlab/services';
+import { refreshIcon } from '@jupyterlab/ui-components';
 
 import { getSnapshotContent } from '../api';
 import { INotebook } from '../diff';
@@ -50,14 +51,18 @@ const Panel: React.FC<PanelProps> = ({ model, app, tracker, serverSettings, onOp
     <div className="jp-snapshot-panel-container">
       <div className="jp-snapshot-panel-toolbar">
         <button
-          className="jp-snapshot-panel-refresh-button"
+          className={
+            'jp-snapshot-panel-refresh-button' +
+            (model.loading ? ' is-loading' : '')
+          }
           onClick={() => {
             void model.refresh();
           }}
           disabled={model.loading}
           title="重新拉取版本列表"
+          aria-label="刷新"
         >
-          {model.loading ? '刷新中…' : '刷新'}
+          <refreshIcon.react className="jp-Icon jp-Icon-16" tag="span" />
         </button>
       </div>
       {model.loading && model.versions.length === 0 ? (
diff --git a/style/base.css b/style/base.css
index 859dc83..a980803 100644
--- a/style/base.css
+++ b/style/base.css
@@ -26,13 +26,18 @@
 }
 
 .jp-snapshot-panel-refresh-button {
-  font-size: 0.8em;
-  padding: 2px 8px;
+  display: inline-flex;
+  align-items: center;
+  justify-content: center;
+  width: 28px;
+  height: 24px;
+  padding: 0;
   border: 1px solid var(--jp-border-color2, #ccc);
   border-radius: 3px;
   background: var(--jp-layout-color2, #f5f5f5);
   color: var(--jp-ui-font-color1, #333);
   cursor: pointer;
+  line-height: 0;
 }
 
 .jp-snapshot-panel-refresh-button:hover:not(:disabled) {
@@ -44,6 +49,20 @@
   cursor: not-allowed;
 }
 
+.jp-snapshot-panel-refresh-button.is-loading svg,
+.jp-snapshot-panel-refresh-button.is-loading .jp-Icon {
+  animation: jp-snapshot-spin 1s linear infinite;
+}
+
+@keyframes jp-snapshot-spin {
+  from {
+    transform: rotate(0deg);
+  }
+  to {
+    transform: rotate(360deg);
+  }
+}
+
 .jp-snapshot-panel-empty {
   color: var(--jp-ui-font-color2, #555);
   padding: 12px;
diff --git a/uv.lock b/uv.lock
index 5421989..d3398d7 100644
--- a/uv.lock
+++ b/uv.lock
@@ -1969,7 +1969,6 @@ wheels = [
 name = "snapshot"
 source = { editable = "." }
 dependencies = [
-    { name = "boto3" },
     { name = "jupyter-server" },
 ]
 
@@ -1978,6 +1977,9 @@ dev = [
     { name = "jupyter-builder" },
     { name = "jupyterlab" },
 ]
+s3 = [
+    { name = "boto3" },
+]
 test = [
     { name = "coverage" },
     { name = "pytest" },
@@ -1988,7 +1990,7 @@ test = [
 
 [package.metadata]
 requires-dist = [
-    { name = "boto3", specifier = ">=1.43.52" },
+    { name = "boto3", marker = "extra == 's3'", specifier = ">=1.34.0" },
     { name = "coverage", marker = "extra == 'test'" },
     { name = "jupyter-builder", marker = "extra == 'dev'", specifier = ">=1.0.0" },
     { name = "jupyter-server", specifier = ">=2.4.0,<3" },
@@ -1998,7 +2000,7 @@ requires-dist = [
     { name = "pytest-cov", marker = "extra == 'test'" },
     { name = "pytest-jupyter", extras = ["server"], marker = "extra == 'test'", specifier = ">=0.6.0" },
 ]
-provides-extras = ["dev", "test"]
+provides-extras = ["dev", "s3", "test"]
 
 [[package]]
 name = "soupsieve"
diff --git a/yarn.lock b/yarn.lock
index 1673c6d..3b7330e 100644
--- a/yarn.lock
+++ b/yarn.lock
@@ -2785,7 +2785,7 @@ __metadata:
   languageName: node
   linkType: hard
 
-"@jupyterlab/ui-components@npm:^4.6.1":
+"@jupyterlab/ui-components@npm:^4.0.0, @jupyterlab/ui-components@npm:^4.6.1":
   version: 4.6.1
   resolution: "@jupyterlab/ui-components@npm:4.6.1"
   dependencies:
@@ -9222,6 +9222,7 @@ __metadata:
     "@jupyterlab/settingregistry": ^4.0.0
     "@jupyterlab/testing": ^4.6.1
     "@jupyterlab/testutils": ^4.0.0
+    "@jupyterlab/ui-components": ^4.0.0
     "@lumino/signaling": ^2.0.0
     "@lumino/widgets": ^2.0.0
     "@module-federation/runtime-tools": ^2.0.0