diff --git a/client/src/VersionFooter.tsx b/client/src/VersionFooter.tsx
new file mode 100644
index 0000000..594f576
--- /dev/null
+++ b/client/src/VersionFooter.tsx
@@ -0,0 +1,24 @@
+// #68: version/diagnostics display, shared by the two low-contrast
+// footers (BarPicker, Stats) and Admin's fuller diagnostics block —
+// same underlying info (build version + browser environment), different
+// presentation for a quick glance vs. a bug-triage read.
+
+export const appVersion = __APP_VERSION__;
+
+export function VersionFooter() {
+  return <p class="version-footer">wutzcalc {appVersion}</p>;
+}
+
+// Read fresh on every call rather than once at module load — screen/
+// viewport size can change (rotation, window resize) between when the
+// admin panel first mounts and when someone actually looks at this to
+// triage a report.
+export function diagLines(): string[] {
+  return [
+    `Version: ${appVersion}`,
+    `User-Agent: ${navigator.userAgent}`,
+    `Bildschirm: ${screen.width}×${screen.height} @ ${window.devicePixelRatio}x`,
+    `Viewport: ${window.innerWidth}×${window.innerHeight}`,
+    `Sprache: ${navigator.language}`,
+  ];
+}
diff --git a/client/src/admin/Admin.tsx b/client/src/admin/Admin.tsx
index e3574bd..9dea9b9 100644
--- a/client/src/admin/Admin.tsx
+++ b/client/src/admin/Admin.tsx
@@ -1,6 +1,7 @@
 import { useEffect, useRef, useState } from 'preact/hooks';
 import type { Bar, Drink } from '@wutzcalc/shared';
 import { errText, formatCents, j } from '../api';
+import { diagLines } from '../VersionFooter';
 
 // `Drink`/`Bar` come from @wutzcalc/shared — the tablet code already did
 // this, but Admin.tsx used to re-declare its own near-identical copies,
@@ -86,10 +87,25 @@ function Dashboard({ onLogout }: { onLogout: () => void }) {
       <Exports />
       <Drinks drinks={drinks} reload={reloadDrinks} />
       <Bars drinks={drinks} />
+      <Diagnose />
     </div>
   );
 }
 
+// #68: browser/build metadata for triaging a device-specific bug report
+// (e.g. "scrolling doesn't work on this one kiosk tablet") without having
+// to walk someone through DevTools over the phone.
+function Diagnose() {
+  return (
+    <>
+      <h2>Diagnose</h2>
+      <ul class="diag-list">
+        {diagLines().map(l => <li key={l}>{l}</li>)}
+      </ul>
+    </>
+  );
+}
+
 
 function Exports() {
   return (
diff --git a/client/src/stats/Stats.tsx b/client/src/stats/Stats.tsx
index 3adb6e8..d9e7483 100644
--- a/client/src/stats/Stats.tsx
+++ b/client/src/stats/Stats.tsx
@@ -1,6 +1,7 @@
 import { useEffect, useMemo, useState } from 'preact/hooks';
 import { errText, formatCents, j } from '../api';
 import { DayChart } from './DayChart';
+import { VersionFooter } from '../VersionFooter';
 
 interface Totals { bar_id: number; bar_name: string; tx_count: number; paid_cents: number; crew_count: number; pfand_returns: number }
 interface PerDrink { drink_id: number; drink_name: string; sold_qty: number }
@@ -257,6 +258,8 @@ function Dashboard({ data, isAdmin, onReset }: { data: StatsData; isAdmin: boole
           ))}
         </tbody>
       </table>
+
+      <VersionFooter />
     </div>
   );
 }
diff --git a/client/src/styles.css b/client/src/styles.css
index f8a64f8..2565ac5 100644
--- a/client/src/styles.css
+++ b/client/src/styles.css
@@ -84,6 +84,21 @@ button.danger { background: #5a2a2a; border-color: #7a3a3a; color: #fff; }
   padding: 10px 18px;
 }
 
+/* #68: version/build indicator for bug triage. margin-top: auto pins it
+   to the bottom of a flex column (.bar-picker) without disturbing that
+   column's own justify-content: center for everything above it; in a
+   plain block container (Stats.tsx's .admin) margin-top: auto has no
+   special effect, so it just falls in as the last item on the page —
+   same class works in both contexts without a variant. */
+.version-footer {
+  margin-top: auto;
+  text-align: center;
+  font-size: 12px;
+  font-weight: 600;
+  opacity: 0.35;
+  padding-top: 8px;
+}
+
 .topbar {
   display: flex;
   justify-content: space-between;
@@ -311,6 +326,20 @@ button.danger { background: #5a2a2a; border-color: #7a3a3a; color: #fff; }
 }
 .admin .row { display: flex; gap: 8px; align-items: center; margin-bottom: 8px; flex-wrap: wrap; }
 .admin .muted { opacity: 0.6; }
+/* #68: readable-but-secondary — not as dim as .muted, this is meant to
+   actually be read for bug triage, just not competing with the primary
+   admin content above it. break-all because navigator.userAgent runs
+   long and would otherwise overflow .admin's max-width. */
+.diag-list {
+  list-style: none;
+  margin: 0;
+  padding: 0;
+  font-size: 13px;
+  font-family: ui-monospace, 'SF Mono', Menlo, Consolas, monospace;
+  opacity: 0.8;
+  word-break: break-all;
+}
+.diag-list li { padding: 3px 0; }
 .admin .login { max-width: 320px; margin: 80px auto; display: flex; flex-direction: column; gap: 12px; }
 .admin .chart {
   background: var(--surface);
diff --git a/client/src/tablet/BarPicker.tsx b/client/src/tablet/BarPicker.tsx
index fd81400..d2d4c83 100644
--- a/client/src/tablet/BarPicker.tsx
+++ b/client/src/tablet/BarPicker.tsx
@@ -1,6 +1,7 @@
 import { useState } from 'preact/hooks';
 import type { Bar } from '@wutzcalc/shared';
 import { getTheme, setTheme } from '../api';
+import { VersionFooter } from '../VersionFooter';
 
 interface Props {
   bars: Bar[] | null;
@@ -35,6 +36,7 @@ export function BarPicker({ bars, onPick }: Props) {
       <button class="theme-toggle" onClick={toggleTheme}>
         {theme === 'dark' ? '☀ Heller Modus' : '🌙 Dunkler Modus'}
       </button>
+      <VersionFooter />
     </div>
   );
 }
diff --git a/client/src/vite-env.d.ts b/client/src/vite-env.d.ts
new file mode 100644
index 0000000..57c1af3
--- /dev/null
+++ b/client/src/vite-env.d.ts
@@ -0,0 +1,5 @@
+/// <reference types="vite/client" />
+
+// Injected by vite.config.ts's `define` — the short git commit sha the
+// bundle was built from, or 'dev' if `.git` wasn't available at build time.
+declare const __APP_VERSION__: string;
diff --git a/client/vite.config.ts b/client/vite.config.ts
index 8590f10..c8e32c3 100644
--- a/client/vite.config.ts
+++ b/client/vite.config.ts
@@ -2,6 +2,7 @@ import { defineConfig } from 'vite';
 import preact from '@preact/preset-vite';
 import legacy from '@vitejs/plugin-legacy';
 import { resolve } from 'node:path';
+import { execSync } from 'node:child_process';
 
 // The dev-server proxy target — same default (3000) as the server's own
 // `process.env.PORT ?? 3000` in server/src/index.ts. Override with
@@ -10,7 +11,23 @@ import { resolve } from 'node:path';
 //   WUTZ_SERVER_PORT=4000 pnpm dev:client
 const serverTarget = `http://localhost:${process.env.WUTZ_SERVER_PORT ?? 3000}`;
 
+// #68: baked into the bundle at build time so the client can show "which
+// build is this" for bug triage without a server round-trip. Deploys run
+// `pnpm build` from a git checkout (see deploy/wutzcalc.service), but this
+// stays defensive against a tarball/CI-artifact deploy with no `.git` —
+// falls back to 'dev' rather than failing the build.
+function appVersion(): string {
+  try {
+    return execSync('git rev-parse --short HEAD', { cwd: __dirname }).toString().trim();
+  } catch {
+    return 'dev';
+  }
+}
+
 export default defineConfig({
+  define: {
+    __APP_VERSION__: JSON.stringify(appVersion()),
+  },
   plugins: [
     preact(),
     legacy({