diff --git a/mindspace-assets.mjs b/mindspace-assets.mjs
index bbc1f70..1bc85d5 100644
--- a/mindspace-assets.mjs
+++ b/mindspace-assets.mjs
@@ -8,7 +8,7 @@ import {
   ensureHtmlThumbnail,
   scheduleHtmlThumbnail,
 } from './mindspace-thumbnails.mjs';
-import { mirrorAssetToZone, removeZoneMirror, resolveUserWorkspaceRoot } from './user-space.mjs';
+import { mirrorAssetToZone, removeZoneMirror, resolveUserWorkspaceRoot, resolveZoneFilePath } from './user-space.mjs';
 import { canPreviewAsset, renderAssetPreviewHtml } from './mindspace-asset-preview.mjs';
 import { createWorkspaceAssetSync } from './mindspace-workspace-sync.mjs';
 
@@ -828,10 +828,21 @@ export function createAssetService(pool, options = {}) {
       [assetId],
     );
     const html = await fs.readFile(assetPath, 'utf8');
+    const contentBaseDir =
+      asset.sourceType === 'workspace' && h5Root
+        ? path.dirname(
+            resolveZoneFilePath(
+              resolveUserWorkspaceRoot(h5Root, { id: userId }),
+              asset.categoryCode,
+              asset.filename,
+            ),
+          )
+        : undefined;
     return ensureHtmlThumbnail(storageRoot, assetThumbnailKey(userId, assetId), html, {
       title: asset.displayName,
       subtitle: asset.categoryCode?.toUpperCase?.() ?? 'HTML',
       contentStorageKey: versions[0]?.storage_key,
+      contentBaseDir,
     });
   };
 
diff --git a/mindspace-pages.mjs b/mindspace-pages.mjs
index 723993e..e0821ba 100644
--- a/mindspace-pages.mjs
+++ b/mindspace-pages.mjs
@@ -10,6 +10,7 @@ import {
   pageThumbnailKey,
   writeThumbnail,
   bufferToImageDataUri,
+  resolveWorkspaceHtmlContentBaseDir,
 } from './mindspace-thumbnails.mjs';
 import { resolvePublishDir } from './user-publish.mjs';
 import { ensureWorkspaceHtmlThumbnail, workspaceThumbnailRelativePath } from './mindspace-workspace-thumbnails.mjs';
@@ -951,6 +952,10 @@ export function createPageService(pool, options = {}) {
       title,
       subtitle: summary || `草稿 v${asNumber(ctx.row.version_no)}`,
       contentStorageKey: ctx.row.storage_key,
+      contentBaseDir: resolveWorkspaceHtmlContentBaseDir(
+        ctx.workspacePublishDir,
+        ctx.workspaceHtmlRelativePath,
+      ),
       force: true,
       ...metaOverrides,
     };
diff --git a/mindspace-thumbnails.mjs b/mindspace-thumbnails.mjs
index c0b83cd..ec2db5d 100644
--- a/mindspace-thumbnails.mjs
+++ b/mindspace-thumbnails.mjs
@@ -451,6 +451,30 @@ export function isModernFeedThumbnail(svg) {
   return /width="540" height="720"/.test(svg) && /filter id="grain"/.test(svg);
 }
 
+export function thumbnailHasEmbeddedPhoto(svg) {
+  return /href="data:image\//.test(String(svg ?? ''));
+}
+
+export function resolveWorkspaceHtmlContentBaseDir(workspacePublishDir, workspaceHtmlRelativePath) {
+  if (!workspacePublishDir || !workspaceHtmlRelativePath) return undefined;
+  const dir = path.posix.dirname(String(workspaceHtmlRelativePath).replace(/^\/+/, ''));
+  return dir === '.' ? workspacePublishDir : path.join(workspacePublishDir, dir);
+}
+
+async function shouldRegenerateThumbnailForCover(storageRoot, html, meta, existing) {
+  if (!existing || !isModernFeedThumbnail(existing) || meta.force) return Boolean(meta.force);
+  const signals = extractCoverSignals(html, meta);
+  if (!signals.image) return false;
+  if (thumbnailHasEmbeddedPhoto(existing)) return false;
+  const coverDataUri = await resolveCoverDataUri({
+    storageRoot,
+    contentStorageKey: meta.contentStorageKey,
+    contentBaseDir: meta.contentBaseDir,
+    imageUrl: signals.image,
+  });
+  return Boolean(coverDataUri);
+}
+
 export async function generateHtmlThumbnail(storageRoot, storageKey, html, meta = {}) {
   const signals = extractCoverSignals(html, meta);
   const coverDataUri = await resolveCoverDataUri({
@@ -467,7 +491,13 @@ export async function generateHtmlThumbnail(storageRoot, storageKey, html, meta
 export async function ensureHtmlThumbnail(storageRoot, storageKey, html, meta = {}) {
   const existing = await readThumbnailIfExists(storageRoot, storageKey);
   if (existing && isModernFeedThumbnail(existing) && !meta.force) {
-    return existing;
+    const needsCoverRefresh = await shouldRegenerateThumbnailForCover(
+      storageRoot,
+      html,
+      meta,
+      existing,
+    );
+    if (!needsCoverRefresh) return existing;
   }
   return generateHtmlThumbnail(storageRoot, storageKey, html, meta);
 }
@@ -480,17 +510,34 @@ export async function ensurePageThumbnail({
   workspacePublishDir = null,
   workspaceHtmlRelativePath = null,
 }) {
+  const contentBaseDir =
+    meta.contentBaseDir ??
+    resolveWorkspaceHtmlContentBaseDir(workspacePublishDir, workspaceHtmlRelativePath);
+  const enrichedMeta = contentBaseDir ? { ...meta, contentBaseDir } : meta;
+
   if (workspacePublishDir && workspaceHtmlRelativePath) {
     const sidecar = await readThumbnailIfExists(
       workspacePublishDir,
       workspaceThumbnailRelativePath(workspaceHtmlRelativePath),
     );
     if (sidecar && isModernFeedThumbnail(sidecar)) {
-      await writeThumbnail(storageRoot, pageThumbnailStorageKey, sidecar);
-      return sidecar;
+      if (thumbnailHasEmbeddedPhoto(sidecar)) {
+        await writeThumbnail(storageRoot, pageThumbnailStorageKey, sidecar);
+        return sidecar;
+      }
+      const needsCoverRefresh = await shouldRegenerateThumbnailForCover(
+        workspacePublishDir,
+        html,
+        enrichedMeta,
+        sidecar,
+      );
+      if (!needsCoverRefresh) {
+        await writeThumbnail(storageRoot, pageThumbnailStorageKey, sidecar);
+        return sidecar;
+      }
     }
   }
-  return ensureHtmlThumbnail(storageRoot, pageThumbnailStorageKey, html, meta);
+  return ensureHtmlThumbnail(storageRoot, pageThumbnailStorageKey, html, enrichedMeta);
 }
 
 export async function readThumbnailIfExists(storageRoot, storageKey) {
diff --git a/mindspace-thumbnails.test.mjs b/mindspace-thumbnails.test.mjs
index 3916fac..a1d8c6a 100644
--- a/mindspace-thumbnails.test.mjs
+++ b/mindspace-thumbnails.test.mjs
@@ -8,7 +8,9 @@ import {
   generateHtmlThumbnail,
   isModernFeedThumbnail,
   resolveCoverDataUri,
+  resolveWorkspaceHtmlContentBaseDir,
   shouldUseScenicBackground,
+  thumbnailHasEmbeddedPhoto,
 } from './mindspace-thumbnails.mjs';
 import fs from 'node:fs/promises';
 import os from 'node:os';
@@ -163,3 +165,38 @@ test('resolveCoverDataUri rejects paths outside content base', async () => {
   });
   assert.equal(dataUri, null);
 });
+
+test('resolveWorkspaceHtmlContentBaseDir resolves nested html paths', () => {
+  assert.equal(
+    resolveWorkspaceHtmlContentBaseDir('/workspace', 'oa/report.html'),
+    path.join('/workspace', 'oa'),
+  );
+  assert.equal(resolveWorkspaceHtmlContentBaseDir('/workspace', 'page.html'), '/workspace');
+});
+
+test('ensureHtmlThumbnail refreshes cached thumbnail when cover image becomes resolvable', async () => {
+  const root = await fs.mkdtemp(path.join(os.tmpdir(), 'mindspace-thumb-refresh-'));
+  const htmlDir = path.join(root, 'oa');
+  await fs.mkdir(htmlDir, { recursive: true });
+  const png = Buffer.from(
+    'iVBORw0KGgoAAAANSUhEUgAAAAoAAAAKCAYAAACNMs+9AAAAFUlEQVR42mNk+M9Qz0AEYBxVSF+FABJADveWkH6oAAAAAElFTkSuQmCC',
+    'base64',
+  );
+  await fs.writeFile(path.join(htmlDir, 'hero.png'), png);
+  const html = `<!doctype html><html><head>
+    <title>OA 报告</title>
+    <meta name="mindspace-cover" content='{"cover":"hero.png","tag":"报告"}' />
+    </head><body></body></html>`;
+  const key = 'users/u1/pages/p1/thumbnail.svg';
+  const cached = buildFeedThumbnailSvg(extractCoverSignals(html, { title: 'OA 报告' }));
+  assert.equal(thumbnailHasEmbeddedPhoto(cached), false);
+  await fs.mkdir(path.dirname(path.join(root, key)), { recursive: true });
+  await fs.writeFile(path.join(root, key), cached, 'utf8');
+
+  const svg = await ensureHtmlThumbnail(root, key, html, {
+    title: 'OA 报告',
+    contentBaseDir: htmlDir,
+  });
+  assert.equal(thumbnailHasEmbeddedPhoto(svg), true);
+  assert.match(svg, /href="data:image\/png;base64,/);
+});
diff --git a/server.mjs b/server.mjs
index 2b799b3..a859ff0 100644
--- a/server.mjs
+++ b/server.mjs
@@ -1942,7 +1942,7 @@ api.get('/mindspace/v1/assets/:assetId/thumbnail', async (req, res) => {
   try {
     const svg = await mindSpaceAssets.renderAssetThumbnail(req.currentUser.id, req.params.assetId);
     res.set('Content-Type', 'image/svg+xml; charset=utf-8');
-    res.set('Cache-Control', 'private, max-age=300');
+    res.set('Cache-Control', 'private, no-cache');
     res.setHeader('X-Request-Id', req.requestId);
     return res.send(svg);
   } catch (error) {
@@ -2614,7 +2614,7 @@ api.get('/mindspace/v1/pages/:pageId/thumbnail', async (req, res) => {
   try {
     const svg = await mindSpacePages.renderThumbnail(req.currentUser.id, req.params.pageId);
     res.set('Content-Type', 'image/svg+xml; charset=utf-8');
-    res.set('Cache-Control', 'private, max-age=300');
+    res.set('Cache-Control', 'private, no-cache');
     res.setHeader('X-Request-Id', req.requestId);
     return res.send(svg);
   } catch (error) {
diff --git a/src/components/SpaceChatPanel.tsx b/src/components/SpaceChatPanel.tsx
index 914cca1..7843974 100644
--- a/src/components/SpaceChatPanel.tsx
+++ b/src/components/SpaceChatPanel.tsx
@@ -48,6 +48,16 @@ export function SpaceChatPanel({
     openRecharge,
     retryConnect,
   } = chat;
+  const busy = chatState === 'streaming' || chatState === 'loading' || chatState === 'connecting';
+  const memoryLoading = chatBridge ? false : mainChat.memoryLoading;
+
+  const handleNewSession = () => {
+    if (chatBridge) {
+      void chatBridge.newSession();
+      return;
+    }
+    void mainChat.newSession();
+  };
 
   useEffect(() => {
     if (!open) return;
@@ -75,6 +85,14 @@ export function SpaceChatPanel({
           </div>
         </div>
         <div className="space-chat-panel-actions">
+          <button
+            type="button"
+            className="ghost-btn space-chat-panel-new-session"
+            disabled={busy || memoryLoading}
+            onClick={handleNewSession}
+          >
+            新会话
+          </button>
           {!hideOpenFullChat ? (
             <button type="button" className="ghost-btn" onClick={onOpenFullChat}>
               打开完整聊天
diff --git a/src/hooks/usePageEditSubChat.ts b/src/hooks/usePageEditSubChat.ts
index 943e080..f66ba55 100644
--- a/src/hooks/usePageEditSubChat.ts
+++ b/src/hooks/usePageEditSubChat.ts
@@ -306,6 +306,12 @@ export function usePageEditSubChat({
     }
   }, [connectSubSession, start]);
 
+  const newSession = useCallback(async () => {
+    if (chatState === 'streaming' || chatState === 'loading' || chatState === 'connecting') return;
+    await close({ merge: false });
+    await start();
+  }, [chatState, close, start]);
+
   const startedRef = useRef(false);
 
   useEffect(() => {
@@ -335,6 +341,7 @@ export function usePageEditSubChat({
     dismissNotice,
     retryConnect,
     openRecharge: () => setNotice('余额不足，请充值后继续使用'),
+    newSession,
     close,
   };
 }
diff --git a/src/index.css b/src/index.css
index e6acab1..6c44731 100644
--- a/src/index.css
+++ b/src/index.css
@@ -6045,7 +6045,7 @@ body,
     border-radius: 24px 24px 0 0;
   }
 
-  .space-chat-panel-actions .ghost-btn {
+  .space-chat-panel-actions .ghost-btn:not(.space-chat-panel-new-session) {
     display: none;
   }
 }