fix: keep SVG compositor stable during pinch (#579)

Issue: #579
User-Visible: yes

scripts/mutation-registry.mjs

@@ -8024,6 +8024,30 @@ const MUTANT_DEFINITIONS = [
       replace: '',
     }],
   },
+  {
+    id: 'live-pinch-compositor-demoted-on-budget-refresh',
+    guard: 'node --test --test-name-pattern="#579" test/live-viewport.test.mjs',
+    because: '#579: a budgeted viewBox refresh must re-anchor the picture without removing '
+      + 'the scene transform, will-change or overflow. Demoting and promoting the SVG during '
+      + 'an active pinch produces white or transparent frames in HA Companion WebView',
+    patches: [{
+      file: 'src/live-viewport.ts',
+      find: '  const keepSceneLayer = options.keepSceneLayer === true;',
+      replace: '  const keepSceneLayer = false; // mutant: demote at every identity refresh',
+    }],
+  },
+  {
+    id: 'live-pinch-compositor-demoted-on-active-lit-commit',
+    guard: 'node demo/smoke_live_pan_coverage.mjs',
+    because: '#579: a full Lit update can land before the fingers are released. It may '
+      + 're-anchor viewBox, but it must preserve the same promoted scene lifecycle until the '
+      + 'terminal commit or the WebView flashes between compositor ownership paths',
+    patches: [{
+      file: 'src/live-interaction-runtime.ts',
+      find: '    commitHouseplanViewport(this.host, this.active());',
+      replace: '    commitHouseplanViewport(this.host);',
+    }],
+  },
   {
     id: 'live-pan-rewrites-viewbox-every-frame',
     guard: 'node demo/smoke_live_pan_viewbox.mjs',

scripts/smoke-links.mjs

@@ -27,6 +27,15 @@
 
 /** @type {SmokeLink[]} */
 export const SMOKE_LINKS = [
+  {
+    symbols: [
+      'commitHouseplanViewport', 'isIdentityLiveLayerProjection', 'paintLiveViewport',
+    ],
+    smokes: ['smoke_live_pan_coverage.mjs'],
+    because: '#579: the production-bundle witness observes promotion through budgeted viewBox '
+      + 'refreshes and active Lit commits via scene style attributes; it intentionally does not '
+      + 'call the viewport helpers whose compositor lifecycle it guards',
+  },
   {
     symbols: ['_renderDevice', '_renderOpenings'],
     smokes: ['smoke_space_switch_transitions.mjs'],