fix(mindspace): ensure thumbnail sidecars for WeChat link card og:image

Generate SVG/PNG sidecars at HTML delivery and after share-preview repair so
forwarded service-account links get a raster og:image when only meta exists.

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

mindspace-workspace-publication-delivery-service.mjs

@@ -234,6 +234,24 @@ export function createMindSpaceWorkspacePublicationDeliveryService({
           publishDir,
           thumbnailRelativePath,
         );
+      // WeChat link cards and forwards read og:image at serve time. Pages may
+      // already have share-preview meta without a raster sidecar (e.g. service
+      // account auto-repair); ensure the SVG exists before building fallbackImageUrl.
+      if (!existsSyncFn(thumbnailAbsolutePath)) {
+        try {
+          await ensureWorkspaceThumbnailFn(
+            publishDir,
+            relativePath,
+            html,
+          );
+        } catch (error) {
+          logger?.warn?.(
+            `[MindSpace] thumbnail sidecar ensure failed for ${relativePath}: ${
+              error?.message || error
+            }`,
+          );
+        }
+      }
       return {
         action: 'deliver',
         kind: 'html',

mindspace-workspace-publication-delivery-service.test.mjs

@@ -198,6 +198,32 @@ test('enforces the page delivery contract inside MindSpace', async () => {
   );
 });
 
+test('ensures a thumbnail sidecar before HTML delivery when share preview exists without one', async () => {
+  const calls = [];
+  const setup = createSetup({
+    existsSyncFn() {
+      return false;
+    },
+    async ensureWorkspaceThumbnailFn(publishDir, relativePath, html) {
+      calls.push([
+        'ensure-thumbnail',
+        publishDir,
+        relativePath,
+        html,
+      ]);
+    },
+  });
+  const result =
+    await setup.service.resolveWorkspaceRequest({
+      requestPath: '/user-1/public/page.html',
+    });
+  assert.equal(result.thumbnailName, null);
+  assert.equal(
+    calls.some(([kind]) => kind === 'ensure-thumbnail'),
+    true,
+  );
+});
+
 test('materializes and returns thumbnail binaries through the logical contract', async () => {
   const setup = createSetup({
     async resolvePublicRequestFn() {

wechat/verify/share-preview-repair.mjs

@@ -3,6 +3,7 @@ import path from 'node:path';
 import { injectBeforeDocumentClosingHead } from '../../html-document-injection.mjs';
 import { normalizeCoverMetaSuggestion, upsertMindspaceCoverMeta } from '../../mindspace-cover-meta.mjs';
 import { preparePublishedPlatformBrand } from '../../mindspace-page-tag.mjs';
+import { scheduleWorkspaceHtmlThumbnailSidecars } from '../../mindspace-workspace-thumbnails.mjs';
 import {
   artifactFileExists,
   resolveArtifactLocalPath,
@@ -126,6 +127,12 @@ export function repairArtifactSharePreview(artifact, { topic = '', publishDir =
   if (!verified.ok) {
     return { ok: false, reason: verified.reason ?? 'repair_incomplete', changes };
   }
+  if (publishDir && artifact?.relativePath) {
+    scheduleWorkspaceHtmlThumbnailSidecars(
+      publishDir,
+      String(artifact.relativePath).replace(/\\/g, '/'),
+    );
+  }
   return { ok: true, reason: null, changes };
 }