diff --git a/frontend/src/components/DynamicComponent.tsx b/frontend/src/components/DynamicComponent.tsx
index 19d0952f..7c6e8e3c 100644
--- a/frontend/src/components/DynamicComponent.tsx
+++ b/frontend/src/components/DynamicComponent.tsx
@@ -369,11 +369,29 @@ export const DynamicComponent: React.FC<DynamicComponentProps> = ({
       // Helper to find Arduino pin connected to a component pin.
       // Traces through electrically-transparent passive components so that a
       // circuit like  LED-cathode → resistor → GND  returns -1 (GND) instead
-      // of null. Delegates to the module-level `traceDetailed` (shared with
-      // getPinResolver).
-      const getArduinoPin = (componentPinName: string): number | null => {
+      // of null. Delegates to the module-level `traceDetailed`.
+      //
+      // Two call shapes are supported because this same function is passed
+      // BOTH to PartSimulationRegistry handlers (which call it as
+      // `getArduinoPin(componentPinName)`) AND to `createDefaultPinResolver`
+      // as a `PinTracer` (which calls it as `tracePin(componentId,
+      // componentPinName)`). When the second arg is present we treat the
+      // first as a componentId override; otherwise we use the closure-
+      // captured component id. The previous single-arg signature silently
+      // matched the PinTracer 2-arg call as `(componentId, undefined)` —
+      // traceDetailed then looked up a pin literally named "rgb-led-1" on
+      // component "rgb-led-1", got null, and the PinResolver reported
+      // FLOATING forever (the canonical "wokwi-rgb-led never lights up
+      // even though SPICE is driving R/G/B" symptom).
+      const getArduinoPin = (
+        componentIdOrPin: string,
+        maybePinName?: string,
+      ): number | null => {
         const state = useSimulatorStore.getState();
-        return traceDetailed(state, id, componentPinName, 0).arduinoPin;
+        const componentId = maybePinName !== undefined ? componentIdOrPin : id;
+        const componentPinName =
+          maybePinName !== undefined ? maybePinName : componentIdOrPin;
+        return traceDetailed(state, componentId, componentPinName, 0).arduinoPin;
       };
 
       // PinResolver factory — Phase 0 of the mixed-mode simulator project
diff --git a/scripts/visual-led-test.mjs b/scripts/visual-led-test.mjs
index 7987d8ad..f2e84ed8 100644
--- a/scripts/visual-led-test.mjs
+++ b/scripts/visual-led-test.mjs
@@ -48,7 +48,11 @@ const DEFAULT_SUITE = [
     expectGradient: true,
     note: 'Brightness must hit 3+ distinct non-zero values (smooth fade)' },
   { slug: 'rgb-led', label: 'RGB 3-PWM driven', simulateMs: 12000,
-    leafCheck: 'pwmActive' },
+    leafCheck: 'rgbLed',
+    note: 'wokwi-rgb-led ledRed/Green/Blue MUST cycle — catches PinTracer signature bug' },
+  { slug: 'uno-7segment', label: '7-segment counter', simulateMs: 8000,
+    leafCheck: 'sevenSegment',
+    note: 'wokwi-7segment.values MUST hit ≥4 distinct digit patterns — catches the PinResolver-floating bug for any handler that subscribes per pin' },
 ];
 
 // ── CDP plumbing ──────────────────────────────────────────────────────────
@@ -181,6 +185,57 @@ async function runOne(cdp, ex) {
     return result;
   }
 
+  if (ex.leafCheck === 'rgbLed') {
+    // wokwi-rgb-led exposes ledRed/Green/Blue (0-255). Visual correctness
+    // requires each channel to take ≥2 distinct values during the cycle.
+    // Without that, the SPICE side may be driving the pins but the visual
+    // is stuck (the canonical PinTracer-signature bug).
+    const rgbSamples = await cdp.eval(`
+      (async () => {
+        const out = [];
+        for (let i = 0; i < 16; i++) {
+          const el = document.querySelector('wokwi-rgb-led');
+          out.push({ R: el?.ledRed ?? null, G: el?.ledGreen ?? null, B: el?.ledBlue ?? null });
+          await new Promise(r => setTimeout(r, 400));
+        }
+        return out;
+      })()
+    `, { awaitPromise: true });
+    if (!rgbSamples || rgbSamples[0].R === null) {
+      result.fail = 'no wokwi-rgb-led element found';
+      return result;
+    }
+    const rs = new Set(rgbSamples.map(s => s.R));
+    const gs = new Set(rgbSamples.map(s => s.G));
+    const bs = new Set(rgbSamples.map(s => s.B));
+    result.distinctR = rs.size; result.distinctG = gs.size; result.distinctB = bs.size;
+    if (rs.size < 2 || gs.size < 2 || bs.size < 2) {
+      result.fail = `RGB channel(s) stuck — distinct R=${rs.size} G=${gs.size} B=${bs.size} (each MUST be ≥2)`;
+    }
+    return result;
+  }
+
+  if (ex.leafCheck === 'sevenSegment') {
+    // wokwi-7segment exposes `values` (length-8 array, segments a..g + dp).
+    // A working counter must hit ≥4 distinct patterns during the run.
+    const patterns = await cdp.eval(`
+      (async () => {
+        const out = new Set();
+        for (let i = 0; i < 12; i++) {
+          const el = document.querySelector('wokwi-7segment');
+          if (el?.values) out.add(Array.from(el.values).join(','));
+          await new Promise(r => setTimeout(r, 500));
+        }
+        return [...out];
+      })()
+    `, { awaitPromise: true });
+    result.distinctPatterns = patterns?.length ?? 0;
+    if (!patterns || patterns.length < 4) {
+      result.fail = `7-seg only ${patterns?.length ?? 0} distinct pattern(s) — display stuck or not driving segments`;
+    }
+    return result;
+  }
+
   // Standard LED assertions.
   if (samples[0].leds.length === 0) {
     // No wokwi-led on canvas — only validate SPICE pin activity.
@@ -271,7 +326,11 @@ async function main() {
         failed++;
       } else {
         let detail;
-        if (r.outputPinCount != null && r.maxBrightness == null) {
+        if (r.distinctR != null) {
+          detail = `RGB channels distinct R=${r.distinctR} G=${r.distinctG} B=${r.distinctB}`;
+        } else if (r.distinctPatterns != null) {
+          detail = `7-seg patterns=${r.distinctPatterns}`;
+        } else if (r.outputPinCount != null && r.maxBrightness == null) {
           detail = `no canvas LED, ${r.outputPinCount} pin(s) driven`;
         } else if (r.outputPinCount != null) {
           detail = `${r.outputPinCount} pin(s) driven, max=${r.maxBrightness} min=${r.minBrightness}`;