diff --git a/frontend/src/__tests__/examples-led-resistor.test.ts b/frontend/src/__tests__/examples-led-resistor.test.ts
new file mode 100644
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+++ b/frontend/src/__tests__/examples-led-resistor.test.ts
@@ -0,0 +1,93 @@
+/**
+ * Every gallery LED must have a resistor in its path.
+ *
+ * The electrical model is honest: a LED straight across a 3.3 V or 5 V pin
+ * asks for an absurd current, the runtime burns it out and it stays dark
+ * for the rest of the run — while the sketch happily prints "LED ON". That
+ * is the worst kind of broken example, because nothing looks like an
+ * error. Twenty-four of them shipped that way (mostly Pico, and every RGB
+ * example, which needs one resistor PER CHANNEL) before this guard existed.
+ *
+ * The check walks the wiring graph rather than the LED's immediate
+ * neighbour: a resistor protects from the anode side, from the cathode
+ * side, and from the far side of a transistor or relay contact.
+ */
+import { describe, it, expect } from 'vitest';
+import { exampleProjects } from '../data/examples';
+
+const LED_TYPES = new Set(['wokwi-led', 'wokwi-rgb-led']);
+/** Anything that limits current well enough to save the LED. */
+const LIMITER_TYPES = [
+  'wokwi-resistor',
+  'wokwi-resistor-us',
+  'wokwi-potentiometer',
+  'wokwi-slide-potentiometer',
+  'wokwi-ntc-temperature-sensor',
+  'wokwi-photoresistor-sensor',
+];
+
+interface Comp {
+  type?: string;
+  id?: string;
+}
+interface Wire {
+  start?: { componentId?: string };
+  end?: { componentId?: string };
+}
+
+function isLimiter(type: string | undefined): boolean {
+  return !!type && LIMITER_TYPES.some((t) => type.startsWith(t));
+}
+
+/** LEDs with no current limiter anywhere on their side of the circuit. */
+function unprotectedLeds(example: {
+  components?: Comp[];
+  wires?: Wire[];
+}): string[] {
+  const comps = new Map<string, string>();
+  for (const c of example.components ?? []) {
+    if (c?.id) comps.set(c.id, c.type ?? '');
+  }
+  const leds = [...comps.entries()]
+    .filter(([, type]) => LED_TYPES.has(type))
+    .map(([id]) => id);
+  if (!leds.length) return [];
+
+  const adj = new Map<string, string[]>();
+  for (const w of example.wires ?? []) {
+    const a = w?.start?.componentId;
+    const b = w?.end?.componentId;
+    if (!a || !b) continue;
+    adj.set(a, [...(adj.get(a) ?? []), b]);
+    adj.set(b, [...(adj.get(b) ?? []), a]);
+  }
+
+  return leds.filter((led) => {
+    const seen = new Set([led]);
+    const queue = [...(adj.get(led) ?? [])];
+    while (queue.length) {
+      const node = queue.shift()!;
+      if (seen.has(node)) continue;
+      seen.add(node);
+      const type = comps.get(node);
+      if (isLimiter(type)) return false; // protected
+      // An unknown id is the board itself (a supply rail) and another LED
+      // is not protection either: neither continues the search.
+      if (type === undefined || LED_TYPES.has(type)) continue;
+      queue.push(...(adj.get(node) ?? []));
+    }
+    return true;
+  });
+}
+
+describe('gallery examples — LED current limiting', () => {
+  it('no example drives a LED straight off a pin', () => {
+    const offenders: string[] = [];
+    for (const ex of exampleProjects) {
+      for (const led of unprotectedLeds(ex as never)) {
+        offenders.push(`${ex.id}: ${led}`);
+      }
+    }
+    expect(offenders, 'LEDs without a series resistor').toEqual([]);
+  });
+});