diff --git a/apps/x/PLAN-MEDIA.md b/apps/x/PLAN-MEDIA.md
new file mode 100644
index 00000000..282037d0
--- /dev/null
+++ b/apps/x/PLAN-MEDIA.md
@@ -0,0 +1,93 @@
+# Media File Rendering — Implementation Plan
+
+## Goal
+Render PDFs, images, and videos in the knowledge view, alongside the existing HTML viewer.
+
+## Foundation
+All three file types are served through a single custom `app://` protocol registered in the Electron main process. This avoids `file://` (elevated privileges in Electron) and supports byte-range streaming (needed for video seeking).
+
+---
+
+## Phase 1 — Register `app://` custom protocol
+
+### What
+Main-process protocol handler that serves any workspace-relative file with path traversal guard.
+
+### Work
+1. In `apps/main/src/main.ts`, before `app.whenReady()`:
+   - `protocol.registerSchemesAsPrivileged` for `app` with `{ standard: true, secure: true, supportFetchAPI: true, stream: true }`
+2. After `app.whenReady()`:
+   - `protocol.handle('app', ...)` — parses URL, decodes path, resolves against workspace root using the existing `resolveWorkspacePath`, returns `net.fetch(pathToFileURL(absPath))`
+   - On invalid/outside-workspace path: return 403
+
+### Test ✅
+- DevTools: `fetch('app://local/knowledge/<known-file>').then(r => r.status)` → 200
+- DevTools: `fetch('app://local/../../etc/passwd')` → 403
+- Verify response includes correct mime type for known extensions
+
+---
+
+## Phase 2 — Image renderer
+
+### What
+`ImageFileViewer` component renders supported images via `<img src="app://local/<path>">`.
+
+### Work
+1. New file `apps/renderer/src/components/image-file-viewer.tsx`
+2. Detects: `.png .jpg .jpeg .webp .gif .svg .avif .bmp .ico`
+3. Centered, object-contain layout, dark/light bg
+4. HEIC/HEIF (or any other unsupported decode failure) → fall back to "Open in system" via `shell:openPath`
+5. Loading state and error state mirroring HtmlFileViewer
+6. Wire into `App.tsx` render switch before the `<pre>` fallback
+
+### Test ✅
+- Open `.png`, `.jpg`, `.svg`, `.webp` files → renders correctly
+- Open a `.heic` file (or rename a non-image to `.png` to force decode failure) → shows fallback
+- Switch between image files rapidly → no stale image, no flicker
+
+---
+
+## Phase 3 — Video renderer
+
+### What
+`VideoFileViewer` component using native `<video>` tag.
+
+### Work
+1. New file `apps/renderer/src/components/video-file-viewer.tsx`
+2. Detects: `.mp4 .mov .webm .m4v`
+3. `<video controls src="app://local/<path>" />` — full width, max height
+4. Loading and error states
+5. Wire into `App.tsx` render switch
+
+### Test ✅
+- Open a 50MB+ MP4 → starts playing, scrubber works, can seek to middle without re-downloading
+- Verify byte-range requests in DevTools Network tab (Range header on requests)
+- Switch away mid-playback → video stops cleanly, no leaked audio
+
+---
+
+## Phase 4 — PDF renderer
+
+### What
+`PdfFileViewer` using Chromium's built-in PDFium via `<iframe src="app://local/<path>">`.
+
+### Work
+1. New file `apps/renderer/src/components/pdf-file-viewer.tsx`
+2. Detects: `.pdf`
+3. `<iframe src="app://local/<path>" className="w-full h-full" />` — Chromium auto-detects PDF mime type and uses PDFium plugin
+4. Confirm `webPreferences.plugins: true` is set on the BrowserWindow (required for PDFium to activate)
+5. Wire into `App.tsx` render switch
+
+### Test ✅
+- Open multi-page PDF → renders with native zoom/scroll/print toolbar
+- Open password-protected PDF → Chromium prompts for password (built-in)
+- Switch between PDFs → no stale content
+
+---
+
+## Out of scope for this branch
+- DOCX rendering (requires `docx-preview` library — separate PR)
+- Split-pane resizable layout
+- Audio (the existing `AudioFileCard` is reused if needed)
+- Annotation/highlighting on PDFs (would require `pdfjs-dist`)
+- Iframe persistence cache for HTML viewer (separate optimization)
diff --git a/apps/x/apps/main/src/main.ts b/apps/x/apps/main/src/main.ts
index a6d7b4e0..661f73a3 100644
--- a/apps/x/apps/main/src/main.ts
+++ b/apps/x/apps/main/src/main.ts
@@ -31,6 +31,7 @@ import { shutdown as shutdownAnalytics } from "@x/core/dist/analytics/posthog.js
 import { identifyIfSignedIn } from "@x/core/dist/analytics/identify.js";
 
 import { initConfigs } from "@x/core/dist/config/initConfigs.js";
+import { resolveWorkspacePath } from "@x/core/dist/workspace/workspace.js";
 import started from "electron-squirrel-startup";
 import { execSync, exec, execFileSync } from "node:child_process";
 import { promisify } from "node:util";
@@ -133,16 +134,29 @@ const rendererPath = app.isPackaged
   : path.join(__dirname, "../../../renderer/dist"); // Development
 console.log("rendererPath", rendererPath);
 
-// Register custom protocol for serving built renderer files in production.
-// This keeps SPA routes working when users deep link into the packaged app.
+// Register custom protocol for serving built renderer files in production
+// AND for serving local workspace files to the renderer (images, PDFs, video).
+//
+//   app://workspace/<rel-path>  → workspace file (path-traversal guarded)
+//   app://<anything-else>/...   → renderer SPA (existing behavior)
 function registerAppProtocol() {
   protocol.handle("app", (request) => {
     const url = new URL(request.url);
 
-    // url.pathname starts with "/"
-    let urlPath = url.pathname;
+    // Workspace files: app://workspace/<rel-path>
+    if (url.host === "workspace") {
+      try {
+        const relPath = decodeURIComponent(url.pathname).replace(/^\/+/, "");
+        if (!relPath) return new Response("Not Found", { status: 404 });
+        const absPath = resolveWorkspacePath(relPath);
+        return net.fetch(pathToFileURL(absPath).toString());
+      } catch {
+        return new Response("Forbidden", { status: 403 });
+      }
+    }
 
-    // If it's "/" or a SPA route (no extension), serve index.html
+    // Renderer SPA — existing logic
+    let urlPath = url.pathname;
     if (urlPath === "/" || !path.extname(urlPath)) {
       urlPath = "/index.html";
     }
@@ -161,8 +175,8 @@ protocol.registerSchemesAsPrivileged([
       supportFetchAPI: true,
       corsEnabled: true,
       allowServiceWorkers: true,
-      // optional but often helpful:
-      // stream: true,
+      // Required for byte-range requests so <video> seeking works.
+      stream: true,
     },
   },
 ]);
@@ -251,10 +265,10 @@ function createWindow() {
 }
 
 app.whenReady().then(async () => {
-  // Register custom protocol before creating window (for production builds)
-  if (app.isPackaged) {
-    registerAppProtocol();
-  }
+  // Register custom protocol before creating window.
+  // In production this serves the renderer SPA; in dev (and prod) it also
+  // serves workspace files via app://workspace/<rel-path> for media previews.
+  registerAppProtocol();
 
   // Initialize auto-updater (only in production)
   if (app.isPackaged) {
diff --git a/apps/x/apps/renderer/src/App.tsx b/apps/x/apps/renderer/src/App.tsx
index 057aacb8..9e1a5759 100644
--- a/apps/x/apps/renderer/src/App.tsx
+++ b/apps/x/apps/renderer/src/App.tsx
@@ -14,6 +14,7 @@ import { ChatMessageAttachments } from '@/components/chat-message-attachments'
 import { GraphView, type GraphEdge, type GraphNode } from '@/components/graph-view';
 import { BasesView, type BaseConfig, DEFAULT_BASE_CONFIG } from '@/components/bases-view';
 import { HtmlFileViewer } from '@/components/html-file-viewer';
+import { ImageFileViewer } from '@/components/image-file-viewer';
 import { useDebounce } from './hooks/use-debounce';
 import { SidebarContentPanel } from '@/components/sidebar-content';
 import { SuggestedTopicsView } from '@/components/suggested-topics-view';
@@ -1425,9 +1426,10 @@ function App() {
     }
     const requestId = (fileLoadRequestIdRef.current += 1)
     const pathToLoad = selectedPath
-    // HtmlFileViewer self-loads (with size check, error states, etc.)
-    // Skip the generic loader so we don't double-fetch large files.
-    if (pathToLoad.toLowerCase().endsWith('.html') || pathToLoad.toLowerCase().endsWith('.htm')) {
+    // Media viewers (HTML, image, video, PDF) self-load via app:// protocol.
+    // Skip the generic UTF-8 loader so we don't trash fileContent with binary
+    // bytes or double-fetch large files.
+    if (/\.(html?|png|jpe?g|webp|gif|svg|avif|bmp|ico|mp4|mov|webm|m4v|pdf)$/i.test(pathToLoad)) {
       setFileContent('')
       return
     }
@@ -4830,6 +4832,10 @@ function App() {
                   <div className="flex-1 min-h-0 overflow-hidden">
                     <HtmlFileViewer path={selectedPath} />
                   </div>
+                ) : selectedPath && /\.(png|jpe?g|webp|gif|svg|avif|bmp|ico)$/i.test(selectedPath) ? (
+                  <div className="flex-1 min-h-0 overflow-hidden">
+                    <ImageFileViewer path={selectedPath} />
+                  </div>
                 ) : (
                   <div className="flex-1 overflow-auto p-4">
                     <pre className="text-sm font-mono text-foreground whitespace-pre-wrap">
diff --git a/apps/x/apps/renderer/src/components/image-file-viewer.tsx b/apps/x/apps/renderer/src/components/image-file-viewer.tsx
new file mode 100644
index 00000000..e27924c3
--- /dev/null
+++ b/apps/x/apps/renderer/src/components/image-file-viewer.tsx
@@ -0,0 +1,58 @@
+import { useEffect, useState } from 'react'
+import { ExternalLinkIcon, FileImageIcon, Loader2Icon } from 'lucide-react'
+
+interface ImageFileViewerProps {
+  path: string
+}
+
+type State = 'loading' | 'loaded' | 'error'
+
+export function ImageFileViewer({ path }: ImageFileViewerProps) {
+  const [state, setState] = useState<State>('loading')
+
+  useEffect(() => {
+    setState('loading')
+  }, [path])
+
+  const src = `app://workspace/${path.split('/').map(encodeURIComponent).join('/')}`
+
+  if (state === 'error') {
+    return (
+      <div className="flex h-full w-full flex-col items-center justify-center gap-3 px-6 text-center text-muted-foreground">
+        <FileImageIcon className="size-6" />
+        <p className="text-sm font-medium text-foreground">Cannot preview this image</p>
+        <p className="max-w-md text-xs">The format may be unsupported (e.g. HEIC on Windows).</p>
+        <button
+          type="button"
+          onClick={() => {
+            void window.ipc.invoke('shell:openPath', { path })
+          }}
+          className="inline-flex items-center gap-1.5 rounded-md border border-border bg-background px-3 py-1.5 text-xs font-medium text-foreground hover:bg-accent"
+        >
+          <ExternalLinkIcon className="size-3.5" />
+          Open in system
+        </button>
+      </div>
+    )
+  }
+
+  return (
+    <div className="relative flex h-full w-full items-center justify-center bg-muted/30">
+      <img
+        key={path}
+        src={src}
+        alt={path}
+        className="max-h-full max-w-full object-contain"
+        onLoad={() => setState('loaded')}
+        onError={() => setState('error')}
+        style={state === 'loading' ? { opacity: 0 } : undefined}
+      />
+      {state === 'loading' && (
+        <div className="absolute inset-0 flex flex-col items-center justify-center gap-3 text-muted-foreground">
+          <Loader2Icon className="size-6 animate-spin" />
+          <p className="text-sm">Loading image…</p>
+        </div>
+      )}
+    </div>
+  )
+}