fix(plaza): delegate thumbnail regen to chatSave authority boundary

Portal chat-share routes must not resolve workspace publish dirs directly;
quick-plaza flows now call mindSpaceChatSave.ensurePreviewThumbnail instead.

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

server/portal-mindspace-chat-share-routes.mjs

@@ -3,8 +3,6 @@ import {
   quickPlazaFromChat,
   quickPlazaFromPublicHtml,
 } from '../mindspace-chat-plaza.mjs';
-import { resolveMindSpaceUserPublishDir } from '../mindspace-runtime-config.mjs';
-import { ensureWorkspaceHtmlThumbnail } from '../mindspace-workspace-thumbnails.mjs';
 
 function assertRouter(api) {
   if (
@@ -43,8 +41,6 @@ export function attachPortalMindSpaceChatShareRoutes(
     getQuickPlazaFromPublicHtmlStatusFn =
       getQuickPlazaFromPublicHtmlStatus,
     quickPlazaFromPublicHtmlFn = quickPlazaFromPublicHtml,
-    ensureWorkspaceHtmlThumbnailFn = ensureWorkspaceHtmlThumbnail,
-    resolveMindSpaceUserPublishDirFn = resolveMindSpaceUserPublishDir,
     now = Date.now,
     logger = console,
   } = {},
@@ -100,9 +96,10 @@ export function attachPortalMindSpaceChatShareRoutes(
 
   api.post('/mindspace/v1/pages/quick-plaza-from-chat', async (req, res) => {
     const pages = getMindSpacePages();
+    const chatSave = getMindSpaceChatSave();
     const publications = getMindSpacePublications();
     const plazaPosts = getPlazaPosts();
-    if (!pages || !publications || !plazaPosts) {
+    if (!pages || !chatSave || !publications || !plazaPosts) {
       return sendError(
         res,
         req,
@@ -118,7 +115,6 @@ export function attachPortalMindSpaceChatShareRoutes(
         h5Root,
         req.body,
       );
-      const publishDir = resolveMindSpaceUserPublishDirFn(h5Root, req.currentUser);
       const result = await quickPlazaFromChatFn({
         user: req.currentUser,
         bundle,
@@ -126,8 +122,7 @@ export function attachPortalMindSpaceChatShareRoutes(
         mindSpacePages: pages,
         mindSpacePublications: publications,
         plazaPosts,
-        ensureWorkspaceHtmlThumbnail: ensureWorkspaceHtmlThumbnailFn,
-        publishDir,
+        mindSpaceChatSave: chatSave,
       });
       logger.info('[quick-plaza] ok', {
         ms: now() - startedAt,
@@ -221,7 +216,6 @@ export function attachPortalMindSpaceChatShareRoutes(
             req.body?.relativePath ??
             '',
         ).trim();
-        const publishDir = resolveMindSpaceUserPublishDirFn(h5Root, req.currentUser);
         const result = await quickPlazaFromPublicHtmlFn({
           user: req.currentUser,
           relativePath,
@@ -230,8 +224,7 @@ export function attachPortalMindSpaceChatShareRoutes(
           plazaPosts,
           readWorkspaceHtml: (input) =>
             chatSave.readWorkspaceHtml(input),
-          ensureWorkspaceHtmlThumbnail: ensureWorkspaceHtmlThumbnailFn,
-          publishDir,
+          mindSpaceChatSave: chatSave,
         });
         const plazaUrl = resolvePlazaPostUrl(
           result.post.id,

server/portal-mindspace-chat-share-routes.test.mjs

@@ -1,8 +1,6 @@
 import assert from 'node:assert/strict';
 import test from 'node:test';
 import { attachPortalMindSpaceChatShareRoutes } from './portal-mindspace-chat-share-routes.mjs';
-import { resolveMindSpaceUserPublishDir } from '../mindspace-runtime-config.mjs';
-import { ensureWorkspaceHtmlThumbnail } from '../mindspace-workspace-thumbnails.mjs';
 
 function createRouterRecorder() {
   const routes = new Map();
@@ -196,8 +194,7 @@ test('quick Plaza from chat preserves dependencies, timing, result, and errors',
     mindSpacePages: dependencies.services.pages,
     mindSpacePublications: dependencies.services.publications,
     plazaPosts: dependencies.services.plazaPosts,
-    ensureWorkspaceHtmlThumbnail,
-    publishDir: resolveMindSpaceUserPublishDir('/workspace', req.currentUser),
+    mindSpaceChatSave: dependencies.services.chatSave,
   });
 
   const failureApi = createRouterRecorder();