feat: #61 Plugin system — backend API, sandboxed Web Worker, hooks wired to real app flow, user guide, 47+21 tests

frontend/js/viewer.js

@@ -12,6 +12,7 @@ import { DashboardStatsWidget, DashboardRecentWidget, DashboardBookmarkWidget, D
 import { openShareDialog } from './config.js';
 import { cacheViewedFile, getCachedFile } from './offline.js';
 import { t } from './i18n.js';
+import { onFileRender } from './plugins.js';
 
 // ── Multi-format export ────────────────────────────────────────────────────
 // Downloads a file export (HTML / MD bundle / ePub) via the authenticated
@@ -877,6 +878,29 @@ export function renderFile(data) {
 
   // Initialize outline/TOC for this document
   OutlineManager.init();
+
+  // Plugin hooks: onFileRender — allow plugins to transform the rendered
+  // content or append custom widgets beneath it. Async + non-blocking so a
+  // slow/failed plugin never delays the normal file render.
+  if (data.content && data.is_markdown) {
+    onFileRender(data.vault, data.content, data.path).then((fr) => {
+      if (!fr) return;
+      if (typeof fr.replace === 'string' && fr.replace !== data.content) {
+        const rendered = document.getElementById('file-rendered-content');
+        if (rendered) rendered.innerHTML = fr.replace;
+      }
+      if (Array.isArray(fr.append) && fr.append.length > 0) {
+        const out = el('div', { class: 'plugin-render-output' });
+        fr.append.forEach((html) => {
+          const w = el('div', { class: 'plugin-widget' });
+          w.innerHTML = html;
+          out.appendChild(w);
+        });
+        area.appendChild(out);
+        safeCreateIcons();
+      }
+    }).catch(() => { /* plugins must never break rendering */ });
+  }
 }