diff --git a/src/main/engine/BlogGenerationEngine.ts b/src/main/engine/BlogGenerationEngine.ts
index f2e62bf..3209a16 100644
--- a/src/main/engine/BlogGenerationEngine.ts
+++ b/src/main/engine/BlogGenerationEngine.ts
@@ -106,6 +106,11 @@ export interface SiteValidationApplyResult {
   removedEmptyDirCount: number;
 }
 
+export interface CalendarRegenerationResult {
+  calendarPath: string;
+  changed: boolean;
+}
+
 export function resolvePublicBaseUrl(publicUrl?: string): string | null {
   const trimmed = (publicUrl || '').trim();
   if (!trimmed) {
@@ -473,6 +478,41 @@ export class BlogGenerationEngine {
     };
   }
 
+  async regenerateCalendar(
+    options: BlogGenerationOptions,
+    onProgress: (progress: number, message?: string) => void,
+  ): Promise<CalendarRegenerationResult> {
+    onProgress(0, 'Loading posts...');
+
+    const categorySettings = resolveCategorySettings(options.categoryMetadata, options.categorySettings);
+    const listExcludedCategories = Object.entries(categorySettings)
+      .filter(([, settings]) => settings.renderInLists === false)
+      .map(([category]) => category);
+
+    const { publishedListPosts } = await loadPublishedGenerationSets(this.postEngine, listExcludedCategories);
+
+    onProgress(50, 'Building calendar data...');
+
+    const calendarJson = `${JSON.stringify(buildCalendarArchiveData(publishedListPosts), null, 2)}\n`;
+    const htmlDir = path.join(options.dataDir, 'html');
+    await fs.mkdir(htmlDir, { recursive: true });
+    const calendarPath = path.join(htmlDir, 'calendar.json');
+
+    const changed = await writeFileIfHashChanged({
+      projectId: options.projectId,
+      filePath: calendarPath,
+      relativePath: 'calendar.json',
+      content: calendarJson,
+    });
+
+    onProgress(100, 'Calendar data regenerated');
+
+    return {
+      calendarPath,
+      changed,
+    };
+  }
+
   async validateSite(
     options: BlogGenerationOptions,
     onProgress: (progress: number, message?: string) => void,
@@ -748,6 +788,14 @@ export class BlogGenerationEngine {
       }
     }
 
+    if (renderedUrlCount > 0 || deletedUrlCount > 0) {
+      onProgress(90, 'Regenerating calendar data...');
+      await this.regenerateCalendar(options, (progress, message) => {
+        const mappedProgress = 90 + Math.floor((progress / 100) * 9);
+        onProgress(Math.min(99, mappedProgress), message || 'Regenerating calendar data...');
+      });
+    }
+
     onProgress(100, `Apply complete (${deletedUrlCount} deleted, ${renderedUrlCount} rendered)`);
 
     return {
diff --git a/src/main/engine/PreviewServer.ts b/src/main/engine/PreviewServer.ts
index 84f222a..e037d23 100644
--- a/src/main/engine/PreviewServer.ts
+++ b/src/main/engine/PreviewServer.ts
@@ -28,6 +28,8 @@ import {
   loadPublishedSnapshots,
   loadPublishedSnapshotsPage,
 } from './SharedSnapshotService';
+import { buildCalendarArchiveData } from './GenerationSitemapFeedService';
+import { loadPublishedGenerationSets } from './GenerationPostSnapshotService';
 
 interface ActiveProjectContext {
   projectId: string;
@@ -254,6 +256,12 @@ export class PreviewServer {
       const picoStylesheetHref = getPicoStylesheetHref(appliedTheme);
       const htmlRewriteContext = await this.buildHtmlRewriteContext();
 
+      if (pathname === '/calendar.json') {
+        const calendarJson = await this.resolveCalendarJson(context.dataDir, listExcludedCategories);
+        this.respondAsset(res, 'application/json; charset=utf-8', calendarJson);
+        return;
+      }
+
       if (pathname === '/__style-preview') {
         const stylePreviewHtml = await this.renderStylePreview(htmlRewriteContext, {
           pageTitle,
@@ -491,6 +499,21 @@ export class PreviewServer {
     }
   }
 
+  private async resolveCalendarJson(dataDir: string | undefined, listExcludedCategories: string[]): Promise<Buffer> {
+    if (dataDir) {
+      const calendarPath = path.join(dataDir, 'html', 'calendar.json');
+      try {
+        return await readFile(calendarPath);
+      } catch {
+        // fall through to dynamic generation for preview runtime
+      }
+    }
+
+    const { publishedListPosts } = await loadPublishedGenerationSets(this.postEngine, listExcludedCategories);
+    const calendarJson = `${JSON.stringify(buildCalendarArchiveData(publishedListPosts), null, 2)}\n`;
+    return Buffer.from(calendarJson, 'utf-8');
+  }
+
   private getMediaContentType(filePath: string): string {
     const extension = path.extname(filePath).toLowerCase();
     switch (extension) {
diff --git a/src/main/engine/templates/partials/styles.liquid b/src/main/engine/templates/partials/styles.liquid
index 2b39043..d742268 100644
--- a/src/main/engine/templates/partials/styles.liquid
+++ b/src/main/engine/templates/partials/styles.liquid
@@ -17,19 +17,30 @@
   .blog-menu-submenu .blog-menu-list { flex-direction: column; flex-wrap: nowrap; gap: .2rem; }
   .blog-menu-item-with-children:hover > .blog-menu-submenu,
   .blog-menu-item-with-children:focus-within > .blog-menu-submenu { display: block; }
-  .blog-menu-calendar { position: relative; display: inline-flex; align-items: center; justify-content: center; margin-left: auto; }
-  .blog-menu-calendar-button { display: inline-flex; align-items: center; justify-content: center; width: 2rem; height: 2rem; padding: 0; border: 1px solid var(--pico-muted-border-color, var(--muted-border-color)); background: var(--pico-card-background-color, var(--card-background-color)); color: var(--pico-muted-color, var(--muted-color)); border-radius: .25rem; cursor: pointer; }
-  .blog-menu-calendar-button svg { display: block; width: 1rem; height: 1rem; fill: none; stroke: currentColor; }
+  .blog-menu-calendar { position: relative; display: inline-flex; align-items: center; justify-content: center; margin-left: auto; align-self: center; }
+  .blog-menu-calendar-button { display: inline-flex; align-items: center; justify-content: center; width: auto; height: auto; padding: .2rem .1rem; border: 0; background: transparent; color: var(--pico-muted-color, var(--muted-color)); border-radius: 0; cursor: pointer; font-size: .94rem; line-height: 1.4; }
+  .blog-menu-calendar-button svg { display: block; width: .94rem; height: .94rem; fill: none; stroke: currentColor; transform: translateY(1px); }
   .blog-menu-calendar-button:hover,
-  .blog-menu-calendar-button:focus-visible { color: var(--pico-color, var(--color)); border-color: var(--pico-color, var(--color)); }
-  .blog-calendar-panel { position: absolute; top: calc(100% + .3rem); right: 0; width: min(21.5rem, 92vw); border: 1px solid var(--pico-muted-border-color, var(--muted-border-color)); background: var(--pico-card-background-color, var(--card-background-color)); padding: .55rem; z-index: 30; }
-  .blog-calendar-header { display: flex; align-items: center; justify-content: space-between; margin-bottom: .35rem; }
-  .blog-calendar-close { border: 1px solid var(--pico-muted-border-color, var(--muted-border-color)); background: transparent; color: var(--pico-muted-color, var(--muted-color)); width: 1.8rem; height: 1.8rem; border-radius: .2rem; padding: 0; cursor: pointer; }
+  .blog-menu-calendar-button:focus-visible { color: var(--pico-color, var(--color)); }
+  .blog-calendar-panel { position: absolute; top: calc(100% + .2rem); right: 0; width: min(19rem, 92vw); border: 1px solid var(--pico-muted-border-color, var(--muted-border-color)); background: var(--pico-card-background-color, var(--card-background-color)); padding: .4rem; z-index: 30; }
+  .blog-calendar-header { display: flex; align-items: center; justify-content: space-between; margin-bottom: .2rem; }
+  .blog-calendar-close { border: 1px solid var(--pico-muted-border-color, var(--muted-border-color)); background: transparent; color: var(--pico-muted-color, var(--muted-color)); width: 1.55rem; height: 1.55rem; border-radius: .2rem; padding: 0; cursor: pointer; }
   .blog-calendar-close:hover,
   .blog-calendar-close:focus-visible { color: var(--pico-color, var(--color)); border-color: var(--pico-color, var(--color)); }
-  .blog-calendar-status { margin: .45rem 0 0; color: var(--pico-muted-color, var(--muted-color)); font-size: .85rem; }
+  .blog-calendar-content { display: grid; gap: .18rem; }
+  .blog-calendar-status { margin: .2rem 0 0; color: var(--pico-muted-color, var(--muted-color)); font-size: .78rem; }
+  [data-blog-calendar-root] [data-vc=header] { margin-bottom: .2rem; }
+  [data-blog-calendar-root] [data-vc=month],
+  [data-blog-calendar-root] [data-vc=year] { padding: .15rem .25rem; }
+  [data-blog-calendar-root] [data-vc=months],
+  [data-blog-calendar-root] [data-vc=years] { row-gap: .5rem; }
+  [data-blog-calendar-root] [data-vc-months-month],
+  [data-blog-calendar-root] [data-vc-years-year] { height: 2rem; }
+  [data-blog-calendar-root] [data-vc-week=days] { margin-bottom: .25rem; }
+  [data-blog-calendar-root] [data-vc-date] { padding-top: 0; padding-bottom: 0; }
+  [data-blog-calendar-root] [data-vc-date-btn] { min-height: 1.65rem; min-width: 1.65rem; }
   [data-blog-calendar-has-posts='true'] [data-vc-date-btn] { border-color: var(--pico-primary, var(--pico-color, var(--color))); }
-  .blog-calendar-post-count { display: inline-flex; align-items: center; justify-content: center; min-width: 1.15rem; height: 1.15rem; margin-left: .22rem; border-radius: 999px; font-size: .62rem; line-height: 1; border: 1px solid var(--pico-muted-border-color, var(--muted-border-color)); color: var(--pico-color, var(--color)); }
+  .blog-calendar-post-count { display: inline-flex; align-items: center; justify-content: center; min-width: .95rem; height: .95rem; margin-left: .16rem; border-radius: 999px; font-size: .56rem; line-height: 1; border: 1px solid var(--pico-muted-border-color, var(--muted-border-color)); color: var(--pico-color, var(--color)); }
   .post { border: 1px solid var(--pico-muted-border-color, var(--muted-border-color)); padding: 1rem; background: var(--pico-card-background-color, var(--card-background-color)); min-width: 0; }
   .post pre { position: relative; overflow-x: auto; max-width: 100%; border: 1px solid var(--pico-muted-border-color, var(--muted-border-color)); border-radius: .3rem; margin: .9rem 0; padding: .85rem .9rem; background: var(--pico-code-background-color, rgba(33, 38, 45, .82)); box-sizing: border-box; }
   .post pre code { display: block; font-size: .88rem; line-height: 1.5; white-space: pre; }
diff --git a/src/main/ipc/blogHandlers.ts b/src/main/ipc/blogHandlers.ts
index 19e4ecd..713e2e2 100644
--- a/src/main/ipc/blogHandlers.ts
+++ b/src/main/ipc/blogHandlers.ts
@@ -152,6 +152,22 @@ export function registerBlogHandlers(safeHandle: SafeHandle): void {
     });
   });
 
+  safeHandle('blog:regenerateCalendar', async () => {
+    const blogGenerationEngine = getBlogGenerationEngine();
+    const baseOptions = await resolveBlogGenerationBaseOptions();
+
+    const taskTimestamp = Date.now();
+    return taskManager.runTask({
+      id: `site-calendar-regenerate-${taskTimestamp}`,
+      name: 'Regenerate Calendar',
+      execute: async (onProgress) => {
+        return blogGenerationEngine.regenerateCalendar(baseOptions, (progress, message) => {
+          onProgress(progress, message || 'Regenerating calendar...');
+        });
+      },
+    });
+  });
+
   safeHandle('blog:applyValidation', async (_event, report: SiteValidationReport) => {
     const blogGenerationEngine = getBlogGenerationEngine();
     const baseOptions = await resolveBlogGenerationBaseOptions();
diff --git a/src/main/preload.ts b/src/main/preload.ts
index 4945a2b..1a4307f 100644
--- a/src/main/preload.ts
+++ b/src/main/preload.ts
@@ -256,6 +256,7 @@ export const electronAPI: ElectronAPI = {
     generateSitemap: () => ipcRenderer.invoke('blog:generateSitemap'),
     validateSite: () => ipcRenderer.invoke('blog:validateSite'),
     applyValidation: (report: SiteValidationReport) => ipcRenderer.invoke('blog:applyValidation', report),
+    regenerateCalendar: () => ipcRenderer.invoke('blog:regenerateCalendar'),
   },
 
   menu: {
diff --git a/src/main/shared/electronApi.ts b/src/main/shared/electronApi.ts
index 12007da..dfea63f 100644
--- a/src/main/shared/electronApi.ts
+++ b/src/main/shared/electronApi.ts
@@ -427,6 +427,11 @@ export interface SiteValidationApplyResult {
   removedEmptyDirCount: number;
 }
 
+export interface CalendarRegenerationResult {
+  calendarPath: string;
+  changed: boolean;
+}
+
 export type MenuItemKind = 'page' | 'submenu' | 'category-archive' | 'home';
 
 export interface MenuItemData {
@@ -649,6 +654,7 @@ export interface ElectronAPI {
     }>;
     validateSite: () => Promise<SiteValidationReport>;
     applyValidation: (report: SiteValidationReport) => Promise<SiteValidationApplyResult>;
+    regenerateCalendar: () => Promise<CalendarRegenerationResult>;
   };
   menu: {
     get: () => Promise<MenuDocument>;
diff --git a/src/main/shared/i18n/locales/de.json b/src/main/shared/i18n/locales/de.json
index 50bf564..5f3172b 100644
--- a/src/main/shared/i18n/locales/de.json
+++ b/src/main/shared/i18n/locales/de.json
@@ -38,6 +38,7 @@
   "menu.item.metadataDiff": "Metadaten-Diff-Werkzeug",
   "menu.item.editMenu": "Blog-Menü bearbeiten",
   "menu.item.generateSitemap": "Site rendern",
+  "menu.item.regenerateCalendar": "Kalender neu erzeugen",
   "menu.item.validateSite": "Website validieren",
   "menu.item.about": "Über Blogging Desktop Server",
   "menu.item.openDocumentation": "Dokumentation öffnen",
diff --git a/src/main/shared/i18n/locales/en.json b/src/main/shared/i18n/locales/en.json
index 366a04c..a99974d 100644
--- a/src/main/shared/i18n/locales/en.json
+++ b/src/main/shared/i18n/locales/en.json
@@ -38,6 +38,7 @@
   "menu.item.metadataDiff": "Metadata Diff Tool",
   "menu.item.editMenu": "Edit Blog Menu",
   "menu.item.generateSitemap": "Render Site",
+  "menu.item.regenerateCalendar": "Regenerate Calendar",
   "menu.item.validateSite": "Validate Site",
   "menu.item.about": "About Blogging Desktop Server",
   "menu.item.openDocumentation": "Open Documentation",
diff --git a/src/main/shared/i18n/locales/es.json b/src/main/shared/i18n/locales/es.json
index 700bb74..d77db16 100644
--- a/src/main/shared/i18n/locales/es.json
+++ b/src/main/shared/i18n/locales/es.json
@@ -38,6 +38,7 @@
   "menu.item.metadataDiff": "Herramienta diff de metadatos",
   "menu.item.editMenu": "Editar menú del blog",
   "menu.item.generateSitemap": "Renderizar sitio",
+  "menu.item.regenerateCalendar": "Regenerar calendario",
   "menu.item.validateSite": "Validar sitio",
   "menu.item.about": "Acerca de Blogging Desktop Server",
   "menu.item.openDocumentation": "Abrir documentación",
diff --git a/src/main/shared/i18n/locales/fr.json b/src/main/shared/i18n/locales/fr.json
index a8a0b53..ee4a901 100644
--- a/src/main/shared/i18n/locales/fr.json
+++ b/src/main/shared/i18n/locales/fr.json
@@ -38,6 +38,7 @@
   "menu.item.metadataDiff": "Outil de diff des métadonnées",
   "menu.item.editMenu": "Modifier le menu du blog",
   "menu.item.generateSitemap": "Rendre le site",
+  "menu.item.regenerateCalendar": "Régénérer le calendrier",
   "menu.item.validateSite": "Valider le site",
   "menu.item.about": "À propos de Blogging Desktop Server",
   "menu.item.openDocumentation": "Ouvrir la documentation",
diff --git a/src/main/shared/i18n/locales/it.json b/src/main/shared/i18n/locales/it.json
index 04452ff..70a8d30 100644
--- a/src/main/shared/i18n/locales/it.json
+++ b/src/main/shared/i18n/locales/it.json
@@ -38,6 +38,7 @@
   "menu.item.metadataDiff": "Strumento diff metadati",
   "menu.item.editMenu": "Modifica menu blog",
   "menu.item.generateSitemap": "Renderizza sito",
+  "menu.item.regenerateCalendar": "Rigenera calendario",
   "menu.item.validateSite": "Valida sito",
   "menu.item.about": "Informazioni su Blogging Desktop Server",
   "menu.item.openDocumentation": "Apri documentazione",
diff --git a/src/main/shared/menuCommands.ts b/src/main/shared/menuCommands.ts
index e623d52..2f01d1d 100644
--- a/src/main/shared/menuCommands.ts
+++ b/src/main/shared/menuCommands.ts
@@ -33,6 +33,7 @@ export type AppMenuAction =
   | 'metadataDiff'
   | 'editMenu'
   | 'generateSitemap'
+  | 'regenerateCalendar'
   | 'validateSite'
   | 'openDocumentation'
   | 'about'
@@ -126,6 +127,7 @@ export const APP_MENU_GROUPS: AppMenuGroupDefinition[] = [
       { label: 'menu.item.metadataDiff', action: 'metadataDiff' },
       { label: 'menu.item.editMenu', action: 'editMenu' },
       { label: 'menu.item.generateSitemap', action: 'generateSitemap', accelerator: 'CmdOrCtrl+R' },
+      { label: 'menu.item.regenerateCalendar', action: 'regenerateCalendar' },
       { label: 'menu.item.validateSite', action: 'validateSite', accelerator: 'CmdOrCtrl+Shift+L' },
     ],
   },
@@ -160,6 +162,7 @@ export const APP_MENU_ACTION_EVENT_MAP: Partial<Record<AppMenuAction, string>> =
   metadataDiff: 'menu:metadataDiff',
   editMenu: 'menu:editMenu',
   generateSitemap: 'menu:generateSitemap',
+  regenerateCalendar: 'menu:regenerateCalendar',
   validateSite: 'menu:validateSite',
   openDocumentation: 'menu:openDocumentation',
   about: 'menu:about',
diff --git a/src/renderer/App.tsx b/src/renderer/App.tsx
index 890a7d8..beb411a 100644
--- a/src/renderer/App.tsx
+++ b/src/renderer/App.tsx
@@ -361,6 +361,17 @@ const App: React.FC = () => {
       }) || (() => {})
     );
 
+    unsubscribers.push(
+      window.electronAPI?.on('menu:regenerateCalendar', async () => {
+        try {
+          await window.electronAPI?.blog.regenerateCalendar();
+        } catch (error) {
+          console.error('Calendar regeneration failed:', error);
+          showToast.error(tr('app.calendarRegenerationFailed'));
+        }
+      }) || (() => {})
+    );
+
     unsubscribers.push(
       window.electronAPI?.on('menu:validateSite', () => {
         const validateAndOpen = async () => {
diff --git a/src/renderer/i18n/locales/de.json b/src/renderer/i18n/locales/de.json
index 45bbf15..c441ce4 100644
--- a/src/renderer/i18n/locales/de.json
+++ b/src/renderer/i18n/locales/de.json
@@ -25,6 +25,7 @@
   "app.databaseRebuildFailed": "Datenbank-Neuaufbau fehlgeschlagen",
   "app.textReindexFailed": "Text-Neuindizierung fehlgeschlagen",
   "app.sitemapGenerationFailed": "Sitemap-Erstellung fehlgeschlagen",
+  "app.calendarRegenerationFailed": "Kalender-Neuerstellung fehlgeschlagen",
   "app.previewOpenFailed": "Ausgewählte Beitragsvorschau konnte nicht geöffnet werden",
   "app.metadataDiff": "Metadaten-Diff",
   "app.importComplete": "Import abgeschlossen: {posts} Beiträge, {media} Mediendateien",
diff --git a/src/renderer/i18n/locales/en.json b/src/renderer/i18n/locales/en.json
index 3062650..9c93d31 100644
--- a/src/renderer/i18n/locales/en.json
+++ b/src/renderer/i18n/locales/en.json
@@ -25,6 +25,7 @@
   "app.databaseRebuildFailed": "Database rebuild failed",
   "app.textReindexFailed": "Text reindex failed",
   "app.sitemapGenerationFailed": "Sitemap generation failed",
+  "app.calendarRegenerationFailed": "Calendar regeneration failed",
   "app.previewOpenFailed": "Failed to open selected post preview",
   "app.metadataDiff": "Metadata Diff",
   "app.importComplete": "Import complete: {posts} posts, {media} media files",
diff --git a/src/renderer/i18n/locales/es.json b/src/renderer/i18n/locales/es.json
index 138afd8..bc2ebdc 100644
--- a/src/renderer/i18n/locales/es.json
+++ b/src/renderer/i18n/locales/es.json
@@ -25,6 +25,7 @@
   "app.databaseRebuildFailed": "La reconstrucción de la base de datos falló",
   "app.textReindexFailed": "La reindexación de texto falló",
   "app.sitemapGenerationFailed": "La generación del sitemap falló",
+  "app.calendarRegenerationFailed": "La regeneración del calendario falló",
   "app.previewOpenFailed": "No se pudo abrir la vista previa de la entrada seleccionada",
   "app.metadataDiff": "Diferencia de Metadatos",
   "app.importComplete": "Importación completada: {posts} entradas, {media} archivos multimedia",
diff --git a/src/renderer/i18n/locales/fr.json b/src/renderer/i18n/locales/fr.json
index 786d5f5..f8fab79 100644
--- a/src/renderer/i18n/locales/fr.json
+++ b/src/renderer/i18n/locales/fr.json
@@ -25,6 +25,7 @@
   "app.databaseRebuildFailed": "Échec de la reconstruction de la base de données",
   "app.textReindexFailed": "Échec de la réindexation du texte",
   "app.sitemapGenerationFailed": "Échec de la génération du sitemap",
+  "app.calendarRegenerationFailed": "Échec de la régénération du calendrier",
   "app.previewOpenFailed": "Impossible d’ouvrir l’aperçu de l’article sélectionné",
   "app.metadataDiff": "Diff Métadonnées",
   "app.importComplete": "Import terminé : {posts} articles, {media} fichiers média",
diff --git a/src/renderer/i18n/locales/it.json b/src/renderer/i18n/locales/it.json
index d5156a3..2485e50 100644
--- a/src/renderer/i18n/locales/it.json
+++ b/src/renderer/i18n/locales/it.json
@@ -25,6 +25,7 @@
   "app.databaseRebuildFailed": "Ricostruzione database non riuscita",
   "app.textReindexFailed": "Reindicizzazione testo non riuscita",
   "app.sitemapGenerationFailed": "Generazione sitemap non riuscita",
+  "app.calendarRegenerationFailed": "Rigenerazione del calendario non riuscita",
   "app.previewOpenFailed": "Impossibile aprire l’anteprima del post selezionato",
   "app.metadataDiff": "Diff Metadati",
   "app.importComplete": "Import completato: {posts} post, {media} file multimediali",
diff --git a/tests/engine/BlogGenerationEngine.test.ts b/tests/engine/BlogGenerationEngine.test.ts
index bf5ead6..92d7b5d 100644
--- a/tests/engine/BlogGenerationEngine.test.ts
+++ b/tests/engine/BlogGenerationEngine.test.ts
@@ -994,6 +994,16 @@ describe('BlogGenerationEngine', () => {
     expect(await fileExists(path.join(tempDir, 'html', 'obsolete'))).toBe(false);
     expect(await fileExists(path.join(tempDir, 'html'))).toBe(true);
     expect(await fileExists(path.join(tempDir, 'html', '2025', '01', '15', 'apply-post', 'index.html'))).toBe(true);
+
+    const calendarJsonRaw = await readFile(path.join(tempDir, 'html', 'calendar.json'), 'utf-8');
+    const calendarJson = JSON.parse(calendarJsonRaw) as {
+      years: Record<string, number>;
+      months: Record<string, number>;
+      days: Record<string, number>;
+    };
+    expect(calendarJson.years['2025']).toBe(1);
+    expect(calendarJson.months['2025-01']).toBe(1);
+    expect(calendarJson.days['2025-01-15']).toBe(1);
   });
 
   it('does not report valid pagination routes as extra html content', async () => {
diff --git a/tests/engine/PreviewServer.test.ts b/tests/engine/PreviewServer.test.ts
index 7119567..b926cc4 100644
--- a/tests/engine/PreviewServer.test.ts
+++ b/tests/engine/PreviewServer.test.ts
@@ -357,6 +357,38 @@ describe('PreviewServer', () => {
     expect(lightboxLoadingImageResponse.headers.get('content-type')).toContain('image/gif');
   });
 
+  it('serves calendar.json for preview calendar runtime', async () => {
+    tempDir = await mkdtemp(path.join(tmpdir(), 'bds-preview-calendar-'));
+    await mkdir(path.join(tempDir, 'html'), { recursive: true });
+    await writeFile(path.join(tempDir, 'html', 'calendar.json'), JSON.stringify({
+      years: { '2025': 2 },
+      months: { '2025-01': 2 },
+      days: { '2025-01-02': 1, '2025-01-03': 1 },
+    }), 'utf-8');
+
+    server = new PreviewServer({
+      postEngine: makeEngine([makePost()]),
+      settingsEngine: makeSettings(50),
+      getActiveProjectContext: async () => ({ projectId: 'default', dataDir: tempDir ?? undefined }),
+    });
+
+    await server.start(0);
+
+    const response = await fetch(`${server.getBaseUrl()}/calendar.json`);
+    expect(response.status).toBe(200);
+    expect(response.headers.get('content-type')).toContain('application/json');
+
+    const payload = await response.json() as {
+      years: Record<string, number>;
+      months: Record<string, number>;
+      days: Record<string, number>;
+    };
+
+    expect(payload.years['2025']).toBe(2);
+    expect(payload.months['2025-01']).toBe(2);
+    expect(payload.days['2025-01-03']).toBe(1);
+  });
+
   it('keeps markdown code block html minimal and includes code language metadata', async () => {
     const postWithCode = makePost({
       content: '```python\nprint("hello")\n```',
diff --git a/tests/renderer/menuCommands.test.ts b/tests/renderer/menuCommands.test.ts
index 141a5c8..a081a44 100644
--- a/tests/renderer/menuCommands.test.ts
+++ b/tests/renderer/menuCommands.test.ts
@@ -52,6 +52,17 @@ describe('Help menu documentation entry', () => {
     expect(APP_MENU_ACTION_EVENT_MAP.validateSite).toBe('menu:validateSite');
   });
 
+  it('includes Regenerate Calendar action in Blog menu', () => {
+    const blogGroup = APP_MENU_GROUPS.find((group) => group.label === 'Blog');
+
+    expect(blogGroup).toBeDefined();
+    expect(blogGroup?.items.some((item) => item.action === 'regenerateCalendar')).toBe(true);
+  });
+
+  it('maps Regenerate Calendar to a renderer menu event', () => {
+    expect(APP_MENU_ACTION_EVENT_MAP.regenerateCalendar).toBe('menu:regenerateCalendar');
+  });
+
   it('includes Edit Preferences action in Edit menu with comma shortcut', () => {
     const editGroup = APP_MENU_GROUPS.find((group) => group.label === 'Edit');
     const preferencesItem = editGroup?.items.find((item) => item.action === 'editPreferences');