diff --git a/web/src/app/pattern-lab/HardwareModal.test.tsx b/web/src/app/pattern-lab/HardwareModal.test.tsx
index 87f2d192d..54a974d15 100644
--- a/web/src/app/pattern-lab/HardwareModal.test.tsx
+++ b/web/src/app/pattern-lab/HardwareModal.test.tsx
@@ -311,6 +311,41 @@ describe("HardwareModal", () => {
     expect(screen.queryByText(/Not translated/)).toBeNull();
   });
 
+  // With one layer showing, the community gets that layer. The prompt used to
+  // take the layer picked in Layers even when it was hidden or at 0%, so the
+  // board got a pattern nobody could see in the preview.
+  it.each([
+    ["hidden", (id: string) => useLabStore.getState().setLayerVisible(id, false)],
+    ["at 0%", (id: string) => useLabStore.getState().setLayerOpacity(id, 0)],
+  ])("translates the layer that shows when the picked one is %s", async (_, hide) => {
+    const lab = useLabStore.getState();
+    const starter = lab.layers[0].id;
+    lab.addCodeLayerFromCode("export function draw(display) { display.setPixel(1, 1, 0, 255, 0); } // shown", "Shown");
+    useLabStore.getState().addCodeLayerFromCode("export function draw(display) { display.setPixel(2, 2, 0, 0, 255); } // hidden", "Hidden");
+    useLabStore.getState().removeLayer(starter);
+    const picked = useLabStore.getState().activeLayerId;
+    expect(useLabStore.getState().layers.find((layer) => layer.id === picked)?.name).toBe("Hidden");
+    hide(picked);
+    const writeText = vi.fn<(text: string) => Promise<void>>(() => Promise.resolve());
+    Object.defineProperty(navigator, "clipboard", { configurable: true, value: { writeText } });
+    try {
+      render(<Lab />);
+      fireEvent.click(screen.getByText("Copy the conversion prompt"));
+      expect(await screen.findByText("Copied ✓")).toBeTruthy();
+      const prompt = String(writeText.mock.calls[0][0]);
+      expect(prompt).toContain("// shown");
+      expect(prompt).not.toContain("// hidden");
+
+      // The build carries the shown layer's name too.
+      pasteHeaderAndContinue();
+      fireEvent.click(screen.getByText("↗ Apply to my Patternflow"));
+      const request = vi.mocked(fetch).mock.calls.find(([url]) => String(url).endsWith("/api/community/builds"));
+      expect(JSON.parse(String(request?.[1]?.body)).patterns[0].label).toBe("Shown");
+    } finally {
+      delete (navigator as { clipboard?: unknown }).clipboard;
+    }
+  });
+
   it("a code layer under a text layer is the one to translate before Next", () => {
     useLabStore.getState().addTextLayer();
     render(<Lab />);
diff --git a/web/src/app/pattern-lab/HardwareModal.tsx b/web/src/app/pattern-lab/HardwareModal.tsx
index bb080ff5b..6a8116b9b 100644
--- a/web/src/app/pattern-lab/HardwareModal.tsx
+++ b/web/src/app/pattern-lab/HardwareModal.tsx
@@ -13,10 +13,10 @@ import {
 } from "@/lib/lab/hExport";
 import { buildCppPrompt } from "@/lib/lab/cppPrompt";
 import { currentPerformanceJson } from "@/lib/lab/director/publish";
-import { needsFlatten } from "@/lib/lab/flatten";
+import { loneCodeLayer } from "@/lib/lab/flatten";
 import { labPatternName, useLabStore } from "@/lib/lab/store";
 import { activeTextEffect } from "@/lib/lab/textEffects";
-import { isCodeLayer, isTextLayer } from "@/lib/lab/types";
+import { isTextLayer } from "@/lib/lab/types";
 import styles from "./PatternLab.module.css";
 import local from "./HardwareModal.module.css";
 
@@ -48,7 +48,6 @@ export default function HardwareModal({
   const knobs = useLabStore((state) => state.knobs);
   const ranges = useLabStore((state) => state.ranges);
   const knobLabels = useLabStore((state) => state.knobLabels);
-  const activeLayerId = useLabStore((state) => state.activeLayerId);
   const forkOf = useLabStore((state) => state.forkOf);
 
   // Seeded from the lab's pattern name so the .h NAME, the .pfm slug and the
@@ -64,11 +63,12 @@ export default function HardwareModal({
   const [publishPerfJson, setPublishPerfJson] = useState<string | null>(null);
 
   // One visible code layer is the simple case: a single prompt and a single
-  // paste. Anything else goes through the scaffold.
-  const codeLayers = layers.filter(isCodeLayer);
-  // Same test the export path uses (masks count; a lone pixel layer is a
-  // stack, not a pattern with an empty prompt).
-  const stacked = needsFlatten(layers);
+  // paste. Anything else goes through the scaffold. Same test the export path
+  // uses (masks count; a lone pixel layer is a stack, not a pattern with an
+  // empty prompt), and the same layer: the one showing, whichever is picked
+  // in Layers. A hidden pick used to go into the prompt in its place.
+  const lone = loneCodeLayer(layers);
+  const stacked = lone === null;
 
   const exportData = useMemo(
     () => buildHExport({ name, matrix, layers, knobs, ranges, knobLabels }),
@@ -76,20 +76,18 @@ export default function HardwareModal({
   );
 
   const singlePrompt = useMemo(() => {
-    const active = layers.find((layer) => layer.id === activeLayerId);
-    const focus = isCodeLayer(active) ? active : codeLayers[0];
-    if (!focus) return "";
+    if (!lone) return "";
     return buildCppPrompt({
-      code: focus.code,
+      code: lone.code,
       matrix,
       knobs,
       ranges,
       knobLabels,
-      ramp: focus.ramp,
-      recolor: focus.recolor,
+      ramp: lone.ramp,
+      recolor: lone.recolor,
       name,
     });
-  }, [layers, activeLayerId, codeLayers, matrix, knobs, ranges, knobLabels, name]);
+  }, [lone, matrix, knobs, ranges, knobLabels, name]);
 
   // A chat answer pasted whole used to go into the .h with the model's words
   // and the ``` fence, and the header test below passed it.
@@ -157,7 +155,7 @@ export default function HardwareModal({
     URL.revokeObjectURL(url);
   };
 
-  const label = stacked ? name : codeLayers[0]?.name ?? "Pattern";
+  const label = lone?.name ?? name;
 
   // Only a press on this backdrop itself closes. Send and Publish open inside
   // it, so a press on their backdrop bubbles up here too, and the header
diff --git a/web/src/app/pattern-lab/PatternLabClient.tsx b/web/src/app/pattern-lab/PatternLabClient.tsx
index b141ee5da..3e3454dbb 100644
--- a/web/src/app/pattern-lab/PatternLabClient.tsx
+++ b/web/src/app/pattern-lab/PatternLabClient.tsx
@@ -32,13 +32,12 @@ import {
 import { withKnobsAnnotation } from "@/lib/lab/annotations";
 import { currentPerformanceJson } from "@/lib/lab/director/publish";
 import { onEditorReveal } from "@/lib/lab/editorReveal";
-import { flattenLayers, needsFlatten } from "@/lib/lab/flatten";
+import { flattenLayers, loneCodeLayer } from "@/lib/lab/flatten";
 import { readStorage, removeStorage, writeStorage, type LabStorageKey } from "@/lib/lab/persist";
 import { LAYOUT_NARROW_STORAGE, LAYOUT_STORAGE, dropRetiredPanels, layoutViewCount } from "@/lib/lab/serialize";
 import { listSessions, type SessionMeta } from "@/lib/lab/sessions";
 import { buildStackAnnotation, stripStackAnnotation } from "@/lib/lab/stackShare";
 import { flushLabProject, saveLabProjectNow, useLabStore } from "@/lib/lab/store";
-import type { CodeLayer } from "@/lib/lab/types";
 import HardwareModal from "./HardwareModal";
 import { openIncomingPattern } from "./openIncomingPattern";
 import {
@@ -84,7 +83,8 @@ function premultiplyHex(hex: string, alpha: number): string {
 
 async function buildExportCode(): Promise<string> {
   const state = useLabStore.getState();
-  if (needsFlatten(state.layers)) {
+  const layer = loneCodeLayer(state.layers);
+  if (!layer) {
     const flat = flattenLayers(state.layers, state.matrix, {
       labels: state.knobLabels,
       ranges: state.ranges,
@@ -113,9 +113,6 @@ async function buildExportCode(): Promise<string> {
     const withStack = stackLine ? `${flat}\n\n${stackLine}\n` : flat;
     return withStack.length <= CODE_MAX ? withStack : flat;
   }
-  const layer = state.layers.find(
-    (entry) => entry.visible && entry.opacity > 0 && entry.type === "code",
-  ) as CodeLayer;
   // A layer that arrived from a shared composition may still carry that
   // composition's @stack line; published as-is it would reopen as the
   // original author's layers rather than this pattern.
diff --git a/web/src/lib/lab/flatten.ts b/web/src/lib/lab/flatten.ts
index a64a44dd4..50451bc81 100644
--- a/web/src/lib/lab/flatten.ts
+++ b/web/src/lib/lab/flatten.ts
@@ -172,13 +172,23 @@ function __fxDraw(L) {
   }
 }`;
 
-/** Does this composition even need flattening, or is it a single plain pattern? */
-export function needsFlatten(layers: Layer[]): boolean {
+/**
+ * The code layer a single plain pattern is made of: the one layer left
+ * showing. Null when the composition is a stack. The community upload and
+ * To hardware both take this layer, so the board gets what was published.
+ */
+export function loneCodeLayer(layers: Layer[]): CodeLayer | null {
   const visible = layers.filter(
     (layer) => layer.visible && (layer.role === "mask" || layer.opacity > 0),
   );
-  if (visible.length !== 1) return true;
-  return visible[0].type !== "code" || visible[0].role === "mask";
+  if (visible.length !== 1) return null;
+  const [layer] = visible;
+  return layer.type === "code" && layer.role !== "mask" ? layer : null;
+}
+
+/** Does this composition even need flattening, or is it a single plain pattern? */
+export function needsFlatten(layers: Layer[]): boolean {
+  return loneCodeLayer(layers) === null;
 }
 
 export function flattenLayers(