diff --git a/demo/smoke_lattice_write_barrier.mjs b/demo/smoke_lattice_write_barrier.mjs
index caa118a3..87035bb2 100644
--- a/demo/smoke_lattice_write_barrier.mjs
+++ b/demo/smoke_lattice_write_barrier.mjs
@@ -1,8 +1,23 @@
 // #291: the production bundle's ordinary config and point-wise layout writers
 // must adopt and send the same exact lattice candidate without editor-specific
 // snap calls.
+import { execFileSync } from 'node:child_process';
+import { resolve } from 'node:path';
+import { fileURLToPath } from 'node:url';
 import { launch, checkAll, finish } from './serve.mjs';
-import { latticeProfile } from '../scripts/model-invariants.mjs';
+
+// `model-invariants.mjs` intentionally imports compiled production geometry.
+// A standalone smoke must therefore create the same test-build that `npm test`
+// creates; relying on a developer's leftover directory made clean Linux CI
+// fail before the browser scenario even started.
+const root = fileURLToPath(new URL('..', import.meta.url));
+execFileSync(process.execPath, [
+  resolve(root, 'node_modules/typescript/bin/tsc'), '-p', 'tsconfig.test.json',
+], { cwd: root, stdio: 'inherit' });
+execFileSync(process.execPath, [resolve(root, 'scripts/fix-test-build.mjs')], {
+  cwd: root, stdio: 'inherit',
+});
+const { latticeProfile } = await import('../scripts/model-invariants.mjs');
 
 const { page, browser } = await launch({ width: 920, height: 840 });
 const out = await page.evaluate(async () => {
diff --git a/demo/smoke_optimize_micro_interval.mjs b/demo/smoke_optimize_micro_interval.mjs
index 9b10210f..02699e3d 100644
--- a/demo/smoke_optimize_micro_interval.mjs
+++ b/demo/smoke_optimize_micro_interval.mjs
@@ -19,7 +19,8 @@ const out = await page.evaluate(async () => {
     return `${q((a[0] + b[0]) / 2).toFixed(6)},${q((a[1] + b[1]) / 2).toFixed(6)}@${bucket.toFixed(4)}`;
   };
   const entry = (a, b, cm) => ({ key: wallKey(a, b), a, b, cm });
-  const y = 0.345833333, split = 0.8875, microEnd = split + 0.001381904;
+  const y = 0.345833333, canonicalY = 83 / 240;
+  const split = 0.8875, microEnd = split + 0.001381904;
   const original = {
     model_version: 7,
     spaces: [{
@@ -87,15 +88,15 @@ const out = await page.evaluate(async () => {
   const appliedWalls = card._serverCfg.spaces[0].walls;
   result.applyUsesOneAtomicWrite = sent.filter((type) => type === 'houseplan/plan/optimize').length === 1;
   result.applyStoresOneUniformRun = appliedWalls.length === 1 && appliedWalls[0].cm === 22
-    && JSON.stringify(appliedWalls[0].a) === JSON.stringify([0.8, y])
-    && JSON.stringify(appliedWalls[0].b) === JSON.stringify([0.95, y]);
+    && JSON.stringify(appliedWalls[0].a) === JSON.stringify([0.8, canonicalY])
+    && JSON.stringify(appliedWalls[0].b) === JSON.stringify([0.95, canonicalY]);
   result.applyEnablesUndo = card._canOptimizeUndo === true;
 
   await card._loadFromServer(); await card.updateComplete;
   const reloadedWalls = card._serverCfg.spaces[0].walls;
   result.reloadKeepsCanonicalRun = reloadedWalls.length === 1 && reloadedWalls[0].cm === 22
-    && JSON.stringify(reloadedWalls[0].a) === JSON.stringify([0.8, y])
-    && JSON.stringify(reloadedWalls[0].b) === JSON.stringify([0.95, y]);
+    && JSON.stringify(reloadedWalls[0].a) === JSON.stringify([0.8, canonicalY])
+    && JSON.stringify(reloadedWalls[0].b) === JSON.stringify([0.95, canonicalY]);
 
   await card._undoPlanOptimization(); await card.updateComplete;
   result.undoUsesServerSnapshot = sent.filter((type) => type === 'houseplan/plan/optimize_undo').length === 1;