diff --git a/demo/benchmark_large_house.mjs b/demo/benchmark_large_house.mjs
index ba7dc3c1..9c329fe0 100644
--- a/demo/benchmark_large_house.mjs
+++ b/demo/benchmark_large_house.mjs
@@ -175,6 +175,13 @@ try {
       const loadLongTasks = startLongTaskWindow();
       const loadStarted = performance.now();
       host.replaceChildren(card);
+      if (requiresIsometric) {
+        if (typeof card._onLabsSnapshot !== 'function')
+          throw new Error('large-house-isometric-v1 candidate has no Labs fixture hook');
+        // The product flag expires at 1.65.0. Performance keeps exercising
+        // the dormant renderer without changing the public registry contract.
+        card._onLabsSnapshot({ active: Object.freeze(['iso']), space: '' });
+      }
       card.hass = hassFor(fixture.states);
       window.__hpAssertCardContract(card, cardContract);
       if (requiresIsometric && (typeof card._setProjection !== 'function'
diff --git a/demo/performance/README.md b/demo/performance/README.md
index 1729ef8a..d3c0fd6a 100644
--- a/demo/performance/README.md
+++ b/demo/performance/README.md
@@ -4,10 +4,11 @@
 fixture. The fixture has 60 rooms, 200 devices, 100 openings, 60 partitions,
 40 columns and 500 decor objects on three floors.
 
-Issue #89 adds `large-house-isometric-v1` through the same runner. It enables
-`hp-labs=iso`, selects iso per fixture space, measures the View toggle and
-records the capped `isoGeometry` cache. A comparison SHA predating #89 remains
-flat while reporting the same profile. The dedicated
+Issue #89 adds `large-house-isometric-v1` through the same runner. Because the
+product flag expires at 1.65.0, the runner injects an explicit test-only Labs
+snapshot, selects iso per fixture space, measures the View toggle and records
+the capped `isoGeometry` cache. A comparison SHA predating #89 remains flat
+while reporting the same profile. The dedicated
 `budgets-large-house-isometric.json` applies the reviewed 20% relative allowance
 plus absolute noise/ceiling checks. Only the exact-SHA Linux workflow is gate
 evidence; a local report is diagnostic.
diff --git a/demo/performance/card-contract.mjs b/demo/performance/card-contract.mjs
index 03c918ba..40c1c270 100644
--- a/demo/performance/card-contract.mjs
+++ b/demo/performance/card-contract.mjs
@@ -40,8 +40,10 @@ export const LARGE_HOUSE_CARD_CONTRACT = Object.freeze({
     '_tool',
   ]),
   // A comparison SHA before #89 is intentionally flat; the isometric runner
-  // checks these two members only when the target source tree supports Stage 1.
-  optionalFields: Object.freeze(['_isoGeometryCache', '_planSnapGeometryCache', '_setProjection']),
+  // checks these members only when the target source tree supports Stage 1.
+  optionalFields: Object.freeze([
+    '_isoGeometryCache', '_onLabsSnapshot', '_planSnapGeometryCache', '_setProjection',
+  ]),
   fieldTypes: Object.freeze({
     _booting: 'boolean',
     _cleanFloorCache: 'map',
@@ -50,6 +52,7 @@ export const LARGE_HOUSE_CARD_CONTRACT = Object.freeze({
     _gridPitch: 'number',
     _loadOk: 'boolean',
     _model: 'array',
+    _onLabsSnapshot: 'function',
     _path: 'array',
     _isoGeometryCache: 'map',
     _planSnapGeometryCache: 'object',
diff --git a/demo/smoke_isometric_contract.mjs b/demo/smoke_isometric_contract.mjs
index bcdcbe02..d5bfc03f 100644
--- a/demo/smoke_isometric_contract.mjs
+++ b/demo/smoke_isometric_contract.mjs
@@ -13,6 +13,12 @@ const out = await page.evaluate(async () => {
   const enable = async () => {
     history.replaceState(null, '', '#space=f1&hp-labs=iso');
     dispatchEvent(new HashChangeEvent('hashchange'));
+    if (typeof card._onLabsSnapshot !== 'function') throw new Error('missing Labs fixture hook');
+    const active = Object.freeze(['iso']);
+    // The product flag expires at 1.65.0. Keep this renderer/lifecycle smoke
+    // explicit without extending the public Labs registry contract.
+    card._onLabsSnapshot({ active, space: '' });
+    window.__hpLabs = active;
     await card.updateComplete;
     await frame();
   };
diff --git a/demo/smoke_isometric_live_touch.mjs b/demo/smoke_isometric_live_touch.mjs
index 5435249a..f09a538d 100644
--- a/demo/smoke_isometric_live_touch.mjs
+++ b/demo/smoke_isometric_live_touch.mjs
@@ -11,6 +11,12 @@ const out = await page.evaluate(async () => {
   const frame = () => new Promise((done) => requestAnimationFrame(() => requestAnimationFrame(done)));
   history.replaceState(null, '', '?hp-labs=iso#space=f1');
   dispatchEvent(new HashChangeEvent('hashchange'));
+  if (typeof original._onLabsSnapshot !== 'function') throw new Error('missing Labs fixture hook');
+  const testOnlyIso = Object.freeze(['iso']);
+  // The product registry remains expired; this direct snapshot exercises the
+  // dormant Stage 2 renderer and is removed by the real -iso path below.
+  original._onLabsSnapshot({ active: testOnlyIso, space: '' });
+  window.__hpLabs = testOnlyIso;
   await original.updateComplete;
   const configSpace = original._serverCfg.spaces.find((space) => space.id === 'f1');
   configSpace.settings = {
@@ -293,6 +299,7 @@ const out = await page.evaluate(async () => {
     const card = document.createElement('houseplan-card');
     card.setConfig({ type: 'custom:houseplan-card', kiosk });
     host.replaceChildren(card);
+    card._onLabsSnapshot({ active: Object.freeze(['iso']), space: '' });
     card.hass = window.__mkHass();
     const started = performance.now();
     while ((!card._loadOk || card._booting) && performance.now() - started < 9000) await wait(30);
diff --git a/demo/smoke_split_corner_wall.mjs b/demo/smoke_split_corner_wall.mjs
index 8f5992e5..84e99131 100644
--- a/demo/smoke_split_corner_wall.mjs
+++ b/demo/smoke_split_corner_wall.mjs
@@ -112,6 +112,8 @@ const res = await page.evaluate(async () => {
 
   history.replaceState(null, '', `?hp-labs=iso#space=${encodeURIComponent(c._space)}`);
   dispatchEvent(new HashChangeEvent('hashchange'));
+  if (typeof c._onLabsSnapshot !== 'function') throw new Error('missing Labs fixture hook');
+  c._onLabsSnapshot({ active: Object.freeze(['iso']), space: '' });
   await c.updateComplete;
   c._setProjection('iso');
   await update();
diff --git a/demo/smoke_wall_junctions.mjs b/demo/smoke_wall_junctions.mjs
index 3fa84d98..bce10e32 100644
--- a/demo/smoke_wall_junctions.mjs
+++ b/demo/smoke_wall_junctions.mjs
@@ -120,6 +120,8 @@ const out = await page.evaluate(async () => {
 
   history.replaceState(null, '', '?hp-labs=iso#space=junctions');
   dispatchEvent(new HashChangeEvent('hashchange'));
+  if (typeof card._onLabsSnapshot !== 'function') throw new Error('missing Labs fixture hook');
+  card._onLabsSnapshot({ active: Object.freeze(['iso']), space: '' });
   await card.updateComplete;
   card._setProjection('iso');
   await update();