diff --git a/src-tauri/src/commands/workspace.rs b/src-tauri/src/commands/workspace.rs
index da5fa72..e7d222e 100644
--- a/src-tauri/src/commands/workspace.rs
+++ b/src-tauri/src/commands/workspace.rs
@@ -476,9 +476,42 @@ fn viewer_for_path(path: &Path) -> String {
         return "json".to_string();
     }
 
+    // Binary / rich formats the in-app preview can't render as UTF-8 text.
+    // The frontend treats "external" by launching the OS default app for the
+    // file (see `open_workspace_path` target "system") instead of opening the
+    // text preview panel, which would otherwise fail with a UTF-8 error.
+    if is_external_viewer_ext(&ext) {
+        return "external".to_string();
+    }
+
     "text".to_string()
 }
 
+/// Extensions whose files are opened with the OS default application rather
+/// than the in-app text preview. Kept deliberately broad across documents,
+/// archives, media, and binaries — anything a dev workspace might hold that
+/// is not UTF-8 text.
+fn is_external_viewer_ext(ext: &str) -> bool {
+    matches!(
+        ext,
+        // Documents
+        "pdf" | "doc" | "docx" | "xls" | "xlsx" | "ppt" | "pptx" | "odt" | "ods"
+            | "odp" | "rtf" | "epub"
+        // Images (no inline image preview yet — open externally)
+            | "png" | "jpg" | "jpeg" | "gif" | "webp" | "bmp" | "ico" | "tiff" | "tif" | "avif"
+        // Audio / video
+            | "mp3" | "wav" | "flac" | "ogg" | "m4a" | "aac"
+            | "mp4" | "mov" | "mkv" | "webm" | "avi" | "wmv" | "m4v"
+        // Archives
+            | "zip" | "tar" | "gz" | "tgz" | "bz2" | "xz" | "7z" | "rar" | "zst"
+        // Binaries / other
+            | "exe" | "dll" | "so" | "dylib" | "bin" | "o" | "a"
+            | "wasm" | "class" | "jar"
+            | "sqlite" | "db" | "parquet"
+            | "woff" | "woff2" | "ttf" | "otf" | "eot"
+    )
+}
+
 /// Best-effort MIME type from a file extension, used to build `data:` URIs
 /// when inlining preview resources. Falls back to `application/octet-stream`
 /// for unknown extensions — browsers still load most binary assets from a
@@ -3206,4 +3239,17 @@ mod tests {
         )));
         assert!(!is_protected_artifact_path(Path::new("images/pic.png")));
     }
+
+    #[test]
+    fn viewer_for_path_classifies_binary_as_external() {
+        use std::path::Path;
+        assert_eq!(viewer_for_path(Path::new("report.pdf")), "external");
+        assert_eq!(viewer_for_path(Path::new("photo.PNG")), "external");
+        assert_eq!(viewer_for_path(Path::new("archive.zip")), "external");
+        assert_eq!(viewer_for_path(Path::new("data.sqlite")), "external");
+        // Text/known viewers are unchanged.
+        assert_eq!(viewer_for_path(Path::new("notes.md")), "markdown");
+        assert_eq!(viewer_for_path(Path::new("main.rs")), "text");
+        assert_eq!(viewer_for_path(Path::new("data.json")), "json");
+    }
 }
diff --git a/src/components/WorkspaceFilePreviewPanel.module.css b/src/components/WorkspaceFilePreviewPanel.module.css
index 093a48b..0e2b45e 100644
--- a/src/components/WorkspaceFilePreviewPanel.module.css
+++ b/src/components/WorkspaceFilePreviewPanel.module.css
@@ -300,3 +300,18 @@
   background: var(--color-bg-elevated);
 }
 
+.openExternalButton {
+  margin-top: 12px;
+  padding: 6px 12px;
+  font-size: 12px;
+  border: 1px solid var(--color-border-light);
+  border-radius: var(--radius-sm);
+  background: var(--color-bg-elevated);
+  color: var(--color-text-primary);
+  cursor: pointer;
+}
+
+.openExternalButton:hover {
+  border-color: var(--color-primary);
+  color: var(--color-primary);
+}
diff --git a/src/components/WorkspaceFilePreviewPanel.tsx b/src/components/WorkspaceFilePreviewPanel.tsx
index 543ee7d..f006abd 100644
--- a/src/components/WorkspaceFilePreviewPanel.tsx
+++ b/src/components/WorkspaceFilePreviewPanel.tsx
@@ -305,10 +305,25 @@ const renderBody = (
   htmlBundle: string | null,
   bundling: boolean,
   onMarkdownLinkClick: (event: React.MouseEvent) => void,
+  onOpenExternal: () => void,
 ) => {
   if (!file) return null;
   if (file.error) {
-    return <div className={styles.error}>{file.error}</div>;
+    // Binary files are routed to the OS app before ever reaching the preview
+    // (viewer === 'external'), but an unrecognized binary extension can still
+    // land here and fail the UTF-8 read — offer to open it with the OS app.
+    return (
+      <div className={styles.error}>
+        <div>{file.error}</div>
+        <button
+          type="button"
+          className={styles.openExternalButton}
+          onClick={onOpenExternal}
+        >
+          Open with the system app
+        </button>
+      </div>
+    );
   }
   if (!file.content) {
     return <div className={styles.empty}>This file is empty.</div>;
@@ -525,6 +540,13 @@ export default function WorkspaceFilePreviewPanel({
     return slash === -1 ? entry.path : entry.path.slice(slash + 1);
   })();
 
+  const handleOpenExternal = () => {
+    if (!entry?.path) return;
+    openWorkspacePath(workspaceId, entry.path, 'system').catch((err) => {
+      setError(err instanceof Error ? err.message : 'Failed to open with the system app.');
+    });
+  };
+
   const handleOpenInEditor = async () => {
     if (!entry?.path) return;
     try {
@@ -789,7 +811,7 @@ export default function WorkspaceFilePreviewPanel({
         )}
         {loading && <div className={styles.empty}>Loading…</div>}
         {!loading && error && <div className={styles.error}>{error}</div>}
-        {!loading && !error && renderBody(file, htmlMode, htmlBundle, bundling, handleMarkdownLinkClick)}
+        {!loading && !error && renderBody(file, htmlMode, htmlBundle, bundling, handleMarkdownLinkClick, handleOpenExternal)}
       </div>
     </aside>
   );
diff --git a/src/pages/Workspace.tsx b/src/pages/Workspace.tsx
index e1fd8d3..777660f 100644
--- a/src/pages/Workspace.tsx
+++ b/src/pages/Workspace.tsx
@@ -2026,7 +2026,7 @@ const Workspace = () => {
   // import files picked in the native dialog (under Flatpak the
   // FileChooser portal grants access to the picked files).
   const handleOpenWorkspaceIn = useCallback(
-    async (target: 'editor' | 'terminal') => {
+    async (target: 'editor' | 'terminal' | 'system') => {
       try {
         await openWorkspacePath(workspaceId, null, target);
       } catch (err) {
@@ -2036,6 +2036,22 @@ const Workspace = () => {
     [workspaceId]
   );
 
+  // Select an artifact: binary/rich files (viewer === 'external') can't be
+  // rendered in the text preview, so launch the OS default app instead of
+  // opening a panel that would error on non-UTF-8 content.
+  const handleSelectArtifact = useCallback(
+    (entry: WorkspaceFileEntry) => {
+      if (entry.viewer === 'external') {
+        openWorkspacePath(workspaceId, entry.relativePath, 'system').catch((err) => {
+          setError(errorMessage(err, `Failed to open ${entry.name} with the system app.`));
+        });
+        return;
+      }
+      openPreviewEntry({ kind: 'artifact', entry });
+    },
+    [workspaceId, openPreviewEntry]
+  );
+
   const handleAddFiles = useCallback(async () => {
     try {
       const picked = await openFileDialog({ multiple: true, title: 'Add files to workspace' });
@@ -2153,6 +2169,27 @@ const Workspace = () => {
                         <line x1="9" y1="15" x2="15" y2="15" />
                       </svg>
                     </button>
+                    <button
+                      type="button"
+                      className={styles.workspaceDrawerIconAction}
+                      onClick={() => handleOpenWorkspaceIn('system')}
+                      title="Open the workspace folder in your file browser"
+                      aria-label="Open the workspace folder in your file browser"
+                    >
+                      <svg
+                        width="15"
+                        height="15"
+                        viewBox="0 0 24 24"
+                        fill="none"
+                        stroke="currentColor"
+                        strokeWidth="2"
+                        strokeLinecap="round"
+                        strokeLinejoin="round"
+                        aria-hidden="true"
+                      >
+                        <path d="M4 20h16a2 2 0 0 0 2-2V8a2 2 0 0 0-2-2h-7.9a2 2 0 0 1-1.69-.9L9.6 3.9A2 2 0 0 0 7.93 3H4a2 2 0 0 0-2 2v13c0 1.1.9 2 2 2Z" />
+                      </svg>
+                    </button>
                     <button
                       type="button"
                       className={styles.workspaceDrawerIconAction}
@@ -2257,7 +2294,7 @@ const Workspace = () => {
                   workspaceId={workspaceId}
                   totalCount={artifactCount}
                   latestModifiedAt={Number(snapshot?.artifactLatestModifiedAt ?? 0)}
-                  onSelect={(entry) => openPreviewEntry({ kind: 'artifact', entry })}
+                  onSelect={handleSelectArtifact}
                   onDeleted={handleArtifactDeleted}
                 />
               )}