diff --git a/flow-state/HOWTO-variety.md b/flow-state/HOWTO-variety.md
index 4f3a224..4a69f7f 100644
--- a/flow-state/HOWTO-variety.md
+++ b/flow-state/HOWTO-variety.md
@@ -213,6 +213,10 @@ sample size is not a difference.
 
 Two more traps, both of which have bitten:
 
+- **A score of exactly 0.000 is a dead shader, not a boring scene.** The gallery
+  now says so outright — the row goes purple and carries the luminance and
+  variance — but the underlying trap is general: a broken render produces the
+  most boring possible numbers rather than an error.
 - **A permanently-zero block looks like a property of your scene.** The gallery
   built four of the descriptor's five blocks for weeks; `motion` came back 0.000
   for every scene and depressed every score by a fifth. If a block is identical
diff --git a/flow-state/gallery.html b/flow-state/gallery.html
index ec61e19..f24bec6 100644
--- a/flow-state/gallery.html
+++ b/flow-state/gallery.html
@@ -43,6 +43,7 @@
     .row.flat { border-color: #ef4444; }
     .row.thin { border-color: #eab308; }
     .row.good { border-color: #22c55e; }
+    .row.broken { border-color: #a855f7; background: #150e1c; }
     .head { display: flex; align-items: baseline; gap: 12px; margin-bottom: 6px; flex-wrap: wrap; }
     .name { font-size: 14px; color: #e6eaf2; }
     .fam { color: #6b7280; }
@@ -112,7 +113,7 @@ let contexts = [];
 
 // Graded against the bar rather than against taste: below it is a failure, and
 // the band just above it is where a scene is passing by too little to trust.
-const grade = (v) => (v < MIN_VARIETY ? 'flat' : v < MIN_VARIETY * 2 ? 'thin' : 'good');
+const grade = (v, err) => (err ? 'broken' : v < MIN_VARIETY ? 'flat' : v < MIN_VARIETY * 2 ? 'thin' : 'good');
 
 function draw() {
     const mode = sortSel.value;
@@ -134,7 +135,7 @@ function draw() {
             out.appendChild(cut);
         }
         const el = document.createElement('div');
-        el.className = `row ${grade(row.variety)}`;
+        el.className = `row ${grade(row.variety, row.error)}`;
         const blocks = Object.entries(row.byBlock || {})
             .map(([k, v]) => `${k} ${v.toFixed(3)}`).join(' · ');
         el.innerHTML = `
@@ -169,8 +170,10 @@ function draw() {
 sortSel.addEventListener('change', draw);
 
 function summarise(built) {
-    const flat = rows.filter((r) => r.variety < MIN_VARIETY).length;
+    const flat = rows.filter((r) => r.variety < MIN_VARIETY && !r.error).length;
+    const broken = rows.filter((r) => r.error).length;
     return `${rows.length} scenes · ${flat} below the ${MIN_VARIETY} bar` +
+        (broken ? ` · ${broken} BROKEN` : '') +
         (built ? ` · built ${new Date(built).toLocaleString()}` : '');
 }
 
diff --git a/flow-state/src/checks/gallery.js b/flow-state/src/checks/gallery.js
index e3ace7d..9d6e08e 100644
--- a/flow-state/src/checks/gallery.js
+++ b/flow-state/src/checks/gallery.js
@@ -24,6 +24,7 @@ import { songBank } from '../audio/songbank.js';
 import { generateLook } from '../look/LookGenerator.js';
 import { describeIdentity } from '../look/Identity.js';
 import { frameDescriptor, motionDescriptor } from './variety/descriptors.js';
+import { frameLuminance, frameVariance } from '../engine/hash.js';
 import { descriptorDistance, STRUCTURAL } from './variety/signature.js';
 
 const THUMB = { width: 256, height: 144 };
@@ -140,7 +141,24 @@ export function renderScene(engine, module, contexts) {
     }
     for (const b of Object.keys(byBlock)) byBlock[b] /= pairs || 1;
 
-    return { thumbs, variety: pairs ? total / pairs : 0, byBlock };
+    // A dead shader scores zero on every block, which is indistinguishable from
+    // a very boring scene if you only read the number — and it happened: the
+    // subject helpers were declared above the ink they call, the whole preamble
+    // failed to compile, and every scene rendered black while the gallery
+    // reported a variety of exactly 0.000. Say which it is.
+    const lum = frameLuminance(thumbs[0]);
+    const variance = frameVariance(thumbs[0]);
+    const dead = lum < 0.002 || variance < 0.001;
+
+    return {
+        thumbs,
+        variety: pairs ? total / pairs : 0,
+        byBlock,
+        error: dead
+            ? `renders nothing — luminance ${lum.toFixed(4)}, variance ${variance.toFixed(4)}. ` +
+              'A failed shader compile scores 0.000 on every block; check the console for GLSL errors.'
+            : undefined,
+    };
 }
 
 /**