Fix OA workspace cover thumbnails and add space chat new session.

Resolve mindspace-cover images from workspace directories when generating feed thumbnails, refresh stale SVGs missing embedded photos, and disable thumbnail API caching so fixes take effect immediately. Also add a new session control to the space chat panel, including on mobile.

Co-authored-by: Cursor <cursoragent@cursor.com>

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,
     });
   };