diff --git a/frontend/src/__tests__/component-to-spice.test.ts b/frontend/src/__tests__/component-to-spice.test.ts
index d0e6351a..1f0b37c1 100644
--- a/frontend/src/__tests__/component-to-spice.test.ts
+++ b/frontend/src/__tests__/component-to-spice.test.ts
@@ -222,9 +222,18 @@ describe('PASSIVE_PRESETS — preset variants share their base mapper', () => {
   });
 });
 
+// Mappers whose output depends on live runtime state rather than the static
+// component (pins + properties) a fixture can describe. `custom-chip` emits its
+// SPICE sources from getChipDrivenPins(comp.id) — the chip's currently-driven
+// output pins — so a static fixture always yields null. It is exercised by the
+// chip-bus integration tests instead, not this catalog harness.
+const RUNTIME_STATE_MAPPERS = new Set(['custom-chip']);
+
 describe('componentToSpice — catalog completeness', () => {
   it('every mapped metadataId has a test fixture', () => {
-    const missing = mappedMetadataIds().filter((id) => !MINIMAL_FIXTURES[id]);
+    const missing = mappedMetadataIds().filter(
+      (id) => !MINIMAL_FIXTURES[id] && !RUNTIME_STATE_MAPPERS.has(id),
+    );
     expect(missing, `Missing fixtures for: ${missing.join(', ')}`).toEqual([]);
   });