diff --git a/public/app.js b/public/app.js
index 4675d2d..70e3cb8 100644
--- a/public/app.js
+++ b/public/app.js
@@ -993,8 +993,13 @@ function openModelDetail(modelId) {
   if (detailItems.length) {
     loadViewer(detailItems[0]);
   } else {
+    // A model that's only archives previews a file from inside once they're listed.
+    const hasArchive = model.files.some((f) => ARCHIVE_FORMATS.includes(f.format));
     document.getElementById('regenThumbBtn').style.display = 'none';
-    window.ModelViewer.render(document.getElementById('detailViewer'), '', 'none', { fallbackImage: currentDetailThumb });
+    window.ModelViewer.render(document.getElementById('detailViewer'), '', 'none', {
+      fallbackImage: currentDetailThumb,
+      message: hasArchive ? 'Opening a file from the archive…' : 'Nothing here can be previewed yet — add files below.',
+    });
   }
 }
 
@@ -1038,6 +1043,20 @@ function resolverFor(model, archiveEntries = null) {
   return (name) => byName.get(key(name)) || null;
 }
 
+// For a model with nothing to preview directly: open the most useful file
+// inside its archive — a slicer project, then other 3D files, then pictures/PDFs.
+const ENTRY_PREVIEW_ORDER = ['3mf', 'stl', 'obj', 'step', 'stp', 'fbx', '3dm', 'jpg', 'jpeg', 'png', 'webp', 'gif', 'pdf'];
+function previewFirstEntry(archiveId, entries) {
+  const rank = (e) => (ENTRY_PREVIEW_ORDER.includes(e.format) ? ENTRY_PREVIEW_ORDER.indexOf(e.format) : Infinity);
+  const best = [...entries].sort((a, b) => rank(a) - rank(b))[0];
+  if (!best || rank(best) === Infinity) {
+    window.ModelViewer.render(document.getElementById('detailViewer'), '', 'none',
+      { fallbackImage: currentDetailThumb, message: 'Nothing inside this archive can be previewed.' });
+    return;
+  }
+  openViewerItem({ kind: 'entry', id: best.id, format: best.format, name: best.path.split('/').pop(), archiveId });
+}
+
 async function loadArchiveEntries(modelId, fileId) {
   const container = () => (fileDetailModal.dataset.currentModelId === String(modelId)
     ? document.querySelector(`[data-entries-for="${fileId}"]`) : null);
@@ -1057,14 +1076,19 @@ async function loadArchiveEntries(modelId, fileId) {
     archiveEntryCache.set(fileId, data.entries);
     const { PREVIEWABLE } = window.ModelViewer;
     container().innerHTML = `<div class="entry-head">${data.entries.length} file${data.entries.length === 1 ? '' : 's'} inside</div>`
-      + data.entries.map((e) => `
+      + data.entries.map((e) => {
+        const name = e.path.split('/').pop();
+        const folder = e.path.replace(/^\.\//, '').slice(0, -name.length);
+        return `
       <div class="entry-row">
-        <span title="${escapeHtml(e.path)}">${escapeHtml(e.path.replace(/^\.\//, ''))} <em>${formatFileSize(e.size)}</em></span>
+        <span title="${escapeHtml(e.path)}">${escapeHtml(name)}${folder ? `<span class="entry-folder">${escapeHtml(folder)}</span>` : ''} <em>${formatFileSize(e.size)}</em></span>
         <span class="row-actions">
           ${PREVIEWABLE.includes(e.format) && e.format !== 'mtl' ? `<button type="button" class="link-btn" data-view-entry="${e.id}" data-archive="${fileId}">view</button>` : ''}
           <a href="/api/entries/${e.id}/raw" download>download</a>
         </span>
-      </div>`).join('');
+      </div>`;
+      }).join('');
+    if (!detailItems.length) previewFirstEntry(fileId, data.entries);
   } catch (err) {
     if (container()) container().innerHTML = `<div class="entry-head">Couldn't list this archive: ${escapeHtml(err.message)}</div>`;
   }
diff --git a/public/styles.css b/public/styles.css
index f7680f3..4058bc2 100644
--- a/public/styles.css
+++ b/public/styles.css
@@ -205,7 +205,8 @@ label { display: block; font-size: 13px; font-weight: 500; color: var(--text-mut
 .form-actions { display: flex; justify-content: flex-end; gap: 10px; margin-top: 22px; }
 
 /* ---- model detail ---- */
-.file-detail-content { display: grid; grid-template-columns: 1.1fr 1fr; gap: 26px; }
+/* minmax(0, …) keeps a long file name from widening its column and crushing the viewer */
+.file-detail-content { display: grid; grid-template-columns: minmax(0, 1.1fr) minmax(0, 1fr); gap: 26px; }
 .file-detail-preview { display: flex; flex-direction: column; gap: 10px; }
 .model-viewer { width: 100%; height: 380px; background: radial-gradient(circle at 50% 40%, #232730 0%, #131519 100%); border: 1px solid var(--border); border-radius: var(--radius); display: flex; align-items: center; justify-content: center; }
 .model-viewer canvas { display: block; border-radius: var(--radius); }
@@ -224,6 +225,7 @@ label { display: block; font-size: 13px; font-weight: 500; color: var(--text-mut
 .info-section .entry-row { display: flex; justify-content: space-between; align-items: center; gap: 10px; padding: 3px 0; font-size: 13px; color: var(--text-muted); }
 .entry-row > span:first-child { overflow: hidden; text-overflow: ellipsis; white-space: nowrap; min-width: 0; }
 .entry-row em { color: var(--text-dim); font-style: normal; font-family: var(--mono); font-size: 11px; margin-left: 4px; }
+.entry-row .entry-folder { color: var(--text-dim); margin-left: 4px; }
 .row-actions { display: flex; gap: 12px; flex-shrink: 0; align-items: center; }
 .link-btn { background: none; border: none; color: var(--accent); font: inherit; cursor: pointer; padding: 0; }
 .link-btn:hover { text-decoration: underline; }
@@ -240,7 +242,7 @@ label { display: block; font-size: 13px; font-weight: 500; color: var(--text-mut
 .swatch { width: 16px; height: 16px; border-radius: 50%; border: 1px solid rgba(255, 255, 255, 0.25); flex-shrink: 0; }
 
 .file-tabs { display: flex; flex-wrap: wrap; gap: 6px; }
-.file-tab { border: 1px solid var(--border); background: var(--surface-2); color: var(--text-muted); padding: 5px 11px; border-radius: var(--radius-sm); font-size: 12px; cursor: pointer; font-family: inherit; }
+.file-tab { border: 1px solid var(--border); background: var(--surface-2); color: var(--text-muted); padding: 5px 11px; border-radius: var(--radius-sm); font-size: 12px; cursor: pointer; font-family: inherit; max-width: 100%; overflow: hidden; text-overflow: ellipsis; white-space: nowrap; }
 .file-tab:hover { color: var(--text); }
 .file-tab.active { background: var(--accent); color: var(--accent-text); border-color: var(--accent); }
 
@@ -253,6 +255,7 @@ label { display: block; font-size: 13px; font-weight: 500; color: var(--text-mut
 .file-row { display: flex; justify-content: space-between; align-items: center; gap: 10px; padding: 7px 0; border-bottom: 1px solid var(--border); font-size: 14px; color: var(--text-muted); }
 .file-row:last-child { border-bottom: none; }
 .file-row em { color: var(--text-dim); font-style: normal; font-family: var(--mono); font-size: 12px; }
+.file-row > span:first-child { min-width: 0; overflow-wrap: anywhere; }
 
 /* ---- import / settings ---- */
 .import-status { margin-top: 14px; color: var(--text-muted); font-size: 14px; min-height: 20px; }
diff --git a/public/viewer.js b/public/viewer.js
index c4c0251..b677797 100644
--- a/public/viewer.js
+++ b/public/viewer.js
@@ -193,7 +193,7 @@ async function render(container, url, format, opts = {}) {
     return;
   }
   if (!MODEL_FORMATS.includes(format)) {
-    showFallback(container, opts.fallbackImage, `No 3D preview for .${format} files.`);
+    showFallback(container, opts.fallbackImage, opts.message || `No 3D preview for .${format} files.`);
     return;
   }