diff --git a/admin.html b/admin.html
index b8fbf04..3c94597 100644
--- a/admin.html
+++ b/admin.html
@@ -78,6 +78,7 @@
       </div>
       <div class="card list" id="list"></div>
     </div>
+    <script src="./thumb-renderer.js"></script>
     <script src="./admin.js"></script>
   </body>
 </html>
diff --git a/admin.js b/admin.js
index e0774be..2f47de2 100644
--- a/admin.js
+++ b/admin.js
@@ -83,6 +83,22 @@ saveBtn.addEventListener("click", async () => {
   if (payload.sourceFormat === "angle-metal-auto-converted") {
     alert("已自动解构并转换为 GLSL，展示页可直接渲染。");
   }
+  if (payload.id && typeof window.captureShaderThumbnail === "function") {
+    try {
+      const dataUrl = await window.captureShaderThumbnail(payload.code, payload.name);
+      const thumbRes = await fetch(`${API_BASE}/${encodeURIComponent(payload.id)}/thumbnail`, {
+        method: "POST",
+        headers: { "Content-Type": "application/json" },
+        body: JSON.stringify({ pngBase64: dataUrl }),
+      });
+      if (!thumbRes.ok) {
+        const t = await thumbRes.json().catch(() => ({}));
+        console.warn("缩略图上传失败:", t.error || thumbRes.status);
+      }
+    } catch (e) {
+      console.warn("缩略图生成失败:", e);
+    }
+  }
   nameInput.value = "";
   authorInput.value = "";
   codeInput.value = "";
diff --git a/data/shaders.json b/data/shaders.json
index f27126f..3a6d136 100644
--- a/data/shaders.json
+++ b/data/shaders.json
@@ -7,7 +7,8 @@
     "views": 11032,
     "likes": 192,
     "createdAt": "2026-04-02T01:57:49.494Z",
-    "sourceFormat": "glsl"
+    "sourceFormat": "glsl",
+    "thumbnailAt": "2026-04-02T02:38:18.312Z"
   },
   {
     "id": "b08237ae-6fc0-4b06-bfb8-ae0f6a8e1354",
@@ -17,7 +18,8 @@
     "views": 3849,
     "likes": 532,
     "createdAt": "2026-04-02T01:56:37.273Z",
-    "sourceFormat": "glsl"
+    "sourceFormat": "glsl",
+    "thumbnailAt": "2026-04-02T02:38:18.455Z"
   },
   {
     "id": "50d1783d-35ec-4cc1-8d0a-0167bbf3c1e0",
@@ -27,7 +29,8 @@
     "views": 5343,
     "likes": 361,
     "createdAt": "2026-04-02T01:53:17.707Z",
-    "sourceFormat": "glsl"
+    "sourceFormat": "glsl",
+    "thumbnailAt": "2026-04-02T02:38:18.597Z"
   },
   {
     "id": "dd9bfa65-1443-45b5-a83b-d25538b2ddbd",
@@ -37,7 +40,8 @@
     "views": 6478,
     "likes": 386,
     "createdAt": "2026-04-02T01:48:43.430Z",
-    "sourceFormat": "glsl"
+    "sourceFormat": "glsl",
+    "thumbnailAt": "2026-04-02T02:38:18.728Z"
   },
   {
     "id": "d3cc9a0f-0a9b-4094-a4a4-af65b6666b18",
@@ -47,7 +51,8 @@
     "views": 7627,
     "likes": 65,
     "createdAt": "2026-04-02T01:44:54.863Z",
-    "sourceFormat": "glsl"
+    "sourceFormat": "glsl",
+    "thumbnailAt": "2026-04-02T02:38:18.841Z"
   },
   {
     "id": "ff181924-a244-493f-acc4-da5df3c3fbd4",
@@ -57,7 +62,8 @@
     "views": 14244,
     "likes": 240,
     "createdAt": "2026-04-02T01:43:43.091Z",
-    "sourceFormat": "glsl"
+    "sourceFormat": "glsl",
+    "thumbnailAt": "2026-04-02T02:38:18.959Z"
   },
   {
     "id": "02bd9517-38ba-4392-8fa2-e79abc18eded",
@@ -67,7 +73,8 @@
     "views": 19672,
     "likes": 529,
     "createdAt": "2026-04-02T01:40:46.648Z",
-    "sourceFormat": "glsl"
+    "sourceFormat": "glsl",
+    "thumbnailAt": "2026-04-02T02:38:19.076Z"
   },
   {
     "id": "29c5453f-5a8b-4995-a4a7-c8379e2d50e9",
@@ -77,7 +84,8 @@
     "views": 16421,
     "likes": 420,
     "createdAt": "2026-04-02T01:39:56.715Z",
-    "sourceFormat": "glsl"
+    "sourceFormat": "glsl",
+    "thumbnailAt": "2026-04-02T02:38:19.186Z"
   },
   {
     "id": "a8016745-d7ae-4fb3-ada9-0573e9fc213b",
@@ -87,7 +95,8 @@
     "views": 22975,
     "likes": 583,
     "createdAt": "2026-04-02T01:37:37.687Z",
-    "sourceFormat": "glsl"
+    "sourceFormat": "glsl",
+    "thumbnailAt": "2026-04-02T02:38:19.282Z"
   },
   {
     "id": "0d1722d9-c2f6-4d69-8a97-31e5baba1975",
@@ -97,7 +106,8 @@
     "views": 24037,
     "likes": 83,
     "createdAt": "2026-04-02T01:36:38.486Z",
-    "sourceFormat": "glsl"
+    "sourceFormat": "glsl",
+    "thumbnailAt": "2026-04-02T02:38:19.388Z"
   },
   {
     "id": "8d7c51dc-251c-4849-b053-499e55bbc586",
@@ -107,7 +117,8 @@
     "views": 14891,
     "likes": 667,
     "createdAt": "2026-04-02T01:35:16.255Z",
-    "sourceFormat": "glsl"
+    "sourceFormat": "glsl",
+    "thumbnailAt": "2026-04-02T02:38:19.507Z"
   },
   {
     "id": "f12eec79-b870-45c7-a74f-35c2a69d84c2",
@@ -117,7 +128,8 @@
     "views": 16201,
     "likes": 396,
     "createdAt": "2026-04-01T16:06:40.801Z",
-    "sourceFormat": "glsl"
+    "sourceFormat": "glsl",
+    "thumbnailAt": "2026-04-02T02:38:19.627Z"
   },
   {
     "id": "3344f1cc-d547-4df9-9b96-866ab10a10e3",
@@ -127,7 +139,8 @@
     "views": 6862,
     "likes": 334,
     "createdAt": "2026-04-01T16:03:52.234Z",
-    "sourceFormat": "glsl"
+    "sourceFormat": "glsl",
+    "thumbnailAt": "2026-04-02T02:38:19.764Z"
   },
   {
     "id": "bb28628f-5dbc-458a-9681-35904eb94590",
@@ -137,7 +150,8 @@
     "views": 23256,
     "likes": 84,
     "createdAt": "2026-04-01T16:01:12.555Z",
-    "sourceFormat": "glsl"
+    "sourceFormat": "glsl",
+    "thumbnailAt": "2026-04-02T02:38:19.876Z"
   },
   {
     "id": "40cdf4d1-62fb-43fb-9891-3e7d4dc3c641",
@@ -147,7 +161,8 @@
     "views": 12044,
     "likes": 244,
     "createdAt": "2026-04-01T16:00:02.916Z",
-    "sourceFormat": "glsl"
+    "sourceFormat": "glsl",
+    "thumbnailAt": "2026-04-02T02:38:19.973Z"
   },
   {
     "id": "82ac512b-f051-42d1-b3cc-bd2f6d92fdb2",
@@ -157,7 +172,8 @@
     "views": 19147,
     "likes": 521,
     "createdAt": "2026-04-01T15:58:19.514Z",
-    "sourceFormat": "glsl"
+    "sourceFormat": "glsl",
+    "thumbnailAt": "2026-04-02T02:38:20.102Z"
   },
   {
     "id": "e25336ee-9857-47b8-b5da-a87267dc6aad",
@@ -167,7 +183,8 @@
     "views": 10493,
     "likes": 103,
     "createdAt": "2026-04-01T15:57:36.080Z",
-    "sourceFormat": "glsl"
+    "sourceFormat": "glsl",
+    "thumbnailAt": "2026-04-02T02:38:20.246Z"
   },
   {
     "id": "d6942ee2-97be-4d9d-bfaf-c0fde0558de0",
@@ -177,7 +194,8 @@
     "views": 19836,
     "likes": 476,
     "createdAt": "2026-04-01T15:57:05.112Z",
-    "sourceFormat": "glsl"
+    "sourceFormat": "glsl",
+    "thumbnailAt": "2026-04-02T02:38:20.351Z"
   },
   {
     "id": "34548b08-2577-4fd9-b428-7deef9aca610",
@@ -187,7 +205,8 @@
     "views": 19599,
     "likes": 721,
     "createdAt": "2026-04-01T15:56:37.442Z",
-    "sourceFormat": "glsl"
+    "sourceFormat": "glsl",
+    "thumbnailAt": "2026-04-02T02:38:20.470Z"
   },
   {
     "id": "256b1d36-4713-4103-b9d3-8f4e10667288",
@@ -197,7 +216,8 @@
     "views": 22519,
     "likes": 636,
     "createdAt": "2026-04-01T15:56:04.431Z",
-    "sourceFormat": "glsl"
+    "sourceFormat": "glsl",
+    "thumbnailAt": "2026-04-02T02:38:20.590Z"
   },
   {
     "id": "f77eacef-c66d-4a84-b0f5-2044b6a83b5b",
@@ -207,7 +227,8 @@
     "views": 7870,
     "likes": 161,
     "createdAt": "2026-04-01T15:55:32.788Z",
-    "sourceFormat": "glsl"
+    "sourceFormat": "glsl",
+    "thumbnailAt": "2026-04-02T02:38:20.742Z"
   },
   {
     "id": "62d7b82f-a078-4f08-af39-e527ba916a01",
@@ -217,7 +238,8 @@
     "views": 13977,
     "likes": 658,
     "createdAt": "2026-04-01T15:54:30.908Z",
-    "sourceFormat": "glsl"
+    "sourceFormat": "glsl",
+    "thumbnailAt": "2026-04-02T02:38:20.878Z"
   },
   {
     "id": "748ae90a-cc90-4388-ae20-5c18f43c8a4b",
@@ -227,7 +249,8 @@
     "views": 18580,
     "likes": 63,
     "createdAt": "2026-04-01T15:54:03.238Z",
-    "sourceFormat": "glsl"
+    "sourceFormat": "glsl",
+    "thumbnailAt": "2026-04-02T02:38:20.995Z"
   },
   {
     "id": "31f23d44-8403-4a22-bb0f-c8636bd7c447",
@@ -237,7 +260,8 @@
     "views": 13711,
     "likes": 399,
     "createdAt": "2026-04-01T15:53:34.082Z",
-    "sourceFormat": "glsl"
+    "sourceFormat": "glsl",
+    "thumbnailAt": "2026-04-02T02:38:21.103Z"
   },
   {
     "id": "da6767b8-bca1-4c1f-a18d-70767db6d81c",
@@ -247,7 +271,8 @@
     "views": 21588,
     "likes": 137,
     "createdAt": "2026-04-01T15:52:47.322Z",
-    "sourceFormat": "glsl"
+    "sourceFormat": "glsl",
+    "thumbnailAt": "2026-04-02T02:38:21.284Z"
   },
   {
     "id": "3cfa51f8-b1d3-48f2-9f52-9f6fca69b08f",
@@ -257,7 +282,8 @@
     "views": 21349,
     "likes": 484,
     "createdAt": "2026-04-01T15:51:59.158Z",
-    "sourceFormat": "glsl"
+    "sourceFormat": "glsl",
+    "thumbnailAt": "2026-04-02T02:38:21.480Z"
   },
   {
     "id": "ad4ccd5d-4c58-43f1-af72-fda7350bddc7",
@@ -267,7 +293,8 @@
     "views": 21822,
     "likes": 311,
     "createdAt": "2026-04-01T15:35:13.690Z",
-    "sourceFormat": "glsl"
+    "sourceFormat": "glsl",
+    "thumbnailAt": "2026-04-02T02:38:21.592Z"
   },
   {
     "id": "7c9bb8e9-503e-44ce-b5a0-85b9f11dbae3",
@@ -277,7 +304,8 @@
     "views": 3108,
     "likes": 51,
     "createdAt": "2026-04-01T15:34:35.030Z",
-    "sourceFormat": "glsl"
+    "sourceFormat": "glsl",
+    "thumbnailAt": "2026-04-02T02:38:21.704Z"
   },
   {
     "id": "2881c592-2827-413b-8f91-270c2f6f6788",
@@ -287,7 +315,8 @@
     "views": 24459,
     "likes": 695,
     "createdAt": "2026-04-01T15:33:45.538Z",
-    "sourceFormat": "glsl"
+    "sourceFormat": "glsl",
+    "thumbnailAt": "2026-04-02T02:38:21.829Z"
   },
   {
     "id": "cddda4e7-5f78-4c1b-8aaf-5d7e7e0f0a37",
@@ -297,7 +326,8 @@
     "views": 12483,
     "likes": 705,
     "createdAt": "2026-04-01T15:31:53.940Z",
-    "sourceFormat": "glsl"
+    "sourceFormat": "glsl",
+    "thumbnailAt": "2026-04-02T02:38:21.991Z"
   },
   {
     "id": "e1f817dd-627c-419c-a5ce-7dc7a4b05f64",
@@ -307,7 +337,8 @@
     "views": 5699,
     "likes": 105,
     "createdAt": "2026-04-01T15:29:41.289Z",
-    "sourceFormat": "glsl"
+    "sourceFormat": "glsl",
+    "thumbnailAt": "2026-04-02T02:38:22.117Z"
   },
   {
     "id": "07545078-a585-4e2b-b35e-66f75f080bbd",
@@ -318,7 +349,8 @@
     "likes": 195,
     "createdAt": "2026-04-01T15:25:55.867Z",
     "sourceFormat": "glsl",
-    "updatedAt": "2026-04-01T15:26:50.214Z"
+    "updatedAt": "2026-04-01T15:26:50.214Z",
+    "thumbnailAt": "2026-04-02T02:38:22.229Z"
   },
   {
     "id": "d90c5b45-858f-41ca-a826-28ab3444188b",
@@ -329,7 +361,8 @@
     "likes": 545,
     "createdAt": "2026-04-01T15:24:44.569Z",
     "sourceFormat": "glsl",
-    "updatedAt": "2026-04-01T15:26:50.214Z"
+    "updatedAt": "2026-04-01T15:26:50.214Z",
+    "thumbnailAt": "2026-04-02T02:38:22.372Z"
   },
   {
     "id": "a5e23f6d-aa92-4ed1-9cea-4ba04181e3ff",
@@ -340,7 +373,8 @@
     "likes": 76,
     "createdAt": "2026-04-01T15:24:08.297Z",
     "sourceFormat": "glsl",
-    "updatedAt": "2026-04-01T15:26:50.214Z"
+    "updatedAt": "2026-04-01T15:26:50.214Z",
+    "thumbnailAt": "2026-04-02T02:38:22.558Z"
   },
   {
     "id": "ab0cc421-e34d-4244-a540-03f029ec7372",
@@ -351,7 +385,8 @@
     "likes": 487,
     "createdAt": "2026-04-01T15:17:20.407Z",
     "sourceFormat": "glsl",
-    "updatedAt": "2026-04-01T15:23:17.765Z"
+    "updatedAt": "2026-04-01T15:23:17.765Z",
+    "thumbnailAt": "2026-04-02T02:38:22.675Z"
   },
   {
     "id": "d5728c14-a698-4a58-94d7-76a81f97cc99",
@@ -362,7 +397,8 @@
     "likes": 171,
     "createdAt": "2026-04-01T15:06:25.335Z",
     "sourceFormat": "glsl",
-    "updatedAt": "2026-04-01T15:23:17.766Z"
+    "updatedAt": "2026-04-01T15:23:17.766Z",
+    "thumbnailAt": "2026-04-02T02:38:22.798Z"
   },
   {
     "id": "alien-core-ported",
@@ -371,6 +407,7 @@
     "views": 9754,
     "likes": 256,
     "createdAt": "2026-04-01T00:00:00.000Z",
-    "code": "vec3 paletteAC(float d) {\n  return mix(vec3(0.2, 0.7, 0.9), vec3(1.0, 0.0, 1.0), d);\n}\n\nvec2 rotateAC(vec2 p, float a) {\n  float c = cos(a);\n  float s = sin(a);\n  return mat2(c, -s, s, c) * p;\n}\n\nfloat mapAC(vec3 p) {\n  for (int i = 0; i < 8; i++) {\n    float t = iTime * 0.2;\n    p.xz = rotateAC(p.xz, t);\n    p.xy = rotateAC(p.xy, t * 1.89);\n    p.xz = abs(p.xz) - 0.5;\n  }\n  return dot(sign(p), p) / 5.0;\n}\n\nvec4 raymarchAC(vec3 ro, vec3 rd) {\n  float t = 0.0;\n  vec3 col = vec3(0.0);\n  float d = 0.0;\n  for (int i = 0; i < 64; i++) {\n    vec3 p = ro + rd * t;\n    d = mapAC(p) * 0.5;\n    if (d < 0.02 || d > 100.0) break;\n    col += paletteAC(length(p) * 0.1) / (400.0 * d);\n    t += d;\n  }\n  float alpha = 1.0 / (max(d, 0.0001) * 100.0);\n  return vec4(col, alpha);\n}\n\nvoid mainImage(out vec4 fragColor, in vec2 fragCoord) {\n  vec2 uv = (fragCoord - 0.5 * iResolution.xy) / iResolution.x;\n  vec3 ro = vec3(0.0, 0.0, -50.0);\n  ro.xz = rotateAC(ro.xz, iTime);\n\n  vec3 cf = normalize(-ro);\n  vec3 cs = normalize(cross(cf, vec3(0.0, 1.0, 0.0)));\n  vec3 cu = normalize(cross(cf, cs));\n  vec3 uuv = ro + cf * 3.0 + uv.x * cs + uv.y * cu;\n  vec3 rd = normalize(uuv - ro);\n\n  fragColor = raymarchAC(ro, rd);\n}"
+    "code": "vec3 paletteAC(float d) {\n  return mix(vec3(0.2, 0.7, 0.9), vec3(1.0, 0.0, 1.0), d);\n}\n\nvec2 rotateAC(vec2 p, float a) {\n  float c = cos(a);\n  float s = sin(a);\n  return mat2(c, -s, s, c) * p;\n}\n\nfloat mapAC(vec3 p) {\n  for (int i = 0; i < 8; i++) {\n    float t = iTime * 0.2;\n    p.xz = rotateAC(p.xz, t);\n    p.xy = rotateAC(p.xy, t * 1.89);\n    p.xz = abs(p.xz) - 0.5;\n  }\n  return dot(sign(p), p) / 5.0;\n}\n\nvec4 raymarchAC(vec3 ro, vec3 rd) {\n  float t = 0.0;\n  vec3 col = vec3(0.0);\n  float d = 0.0;\n  for (int i = 0; i < 64; i++) {\n    vec3 p = ro + rd * t;\n    d = mapAC(p) * 0.5;\n    if (d < 0.02 || d > 100.0) break;\n    col += paletteAC(length(p) * 0.1) / (400.0 * d);\n    t += d;\n  }\n  float alpha = 1.0 / (max(d, 0.0001) * 100.0);\n  return vec4(col, alpha);\n}\n\nvoid mainImage(out vec4 fragColor, in vec2 fragCoord) {\n  vec2 uv = (fragCoord - 0.5 * iResolution.xy) / iResolution.x;\n  vec3 ro = vec3(0.0, 0.0, -50.0);\n  ro.xz = rotateAC(ro.xz, iTime);\n\n  vec3 cf = normalize(-ro);\n  vec3 cs = normalize(cross(cf, vec3(0.0, 1.0, 0.0)));\n  vec3 cu = normalize(cross(cf, cs));\n  vec3 uuv = ro + cf * 3.0 + uv.x * cs + uv.y * cu;\n  vec3 rd = normalize(uuv - ro);\n\n  fragColor = raymarchAC(ro, rd);\n}",
+    "thumbnailAt": "2026-04-02T02:38:22.908Z"
   }
 ]
\ No newline at end of file
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diff --git a/display.js b/display.js
index f71b6fe..68ad638 100644
--- a/display.js
+++ b/display.js
@@ -13,11 +13,85 @@ const backBtn = document.getElementById("back-btn");
 
 const API_BASE = "/api/shaders";
 
-/** Grid previews: limit fill-rate so many cards can stay near 60fps (detail view uses full quality). */
-const PREVIEW_MAX_PIXEL_RATIO = 1.25;
-const PREVIEW_MAX_BUFFER_LONG_SIDE = 520;
-const DETAIL_MAX_PIXEL_RATIO = 2;
-const DETAIL_MAX_BUFFER_LONG_SIDE = 2560;
+/** 串行补全缺失缩略图（每步独立 WebGL，用完即释放），避免多卡片同时建上下文 */
+const thumbBackfillQueue = [];
+const thumbBackfillQueuedIds = new Set();
+const thumbBackfillFailUntil = new Map();
+let thumbBackfillRunner = false;
+const THUMB_BACKOFF_MS = 120000;
+
+let gridHoverRuntime = null;
+let sharedHoverCanvas = null;
+
+function scheduleThumbBackfill(shaders) {
+  if (typeof window.captureShaderThumbnail !== "function") return;
+  const now = Date.now();
+  for (const s of shaders) {
+    if (s.thumbnailUrl) continue;
+    const code = s.code && String(s.code).trim();
+    if (!code) continue;
+    const retryAt = thumbBackfillFailUntil.get(s.id);
+    if (retryAt != null && now < retryAt) continue;
+    if (thumbBackfillQueuedIds.has(s.id)) continue;
+    thumbBackfillQueuedIds.add(s.id);
+    thumbBackfillQueue.push({ id: s.id, code, name: s.name || "shader" });
+  }
+  void runThumbBackfillLoop();
+}
+
+async function runThumbBackfillLoop() {
+  if (thumbBackfillRunner) return;
+  thumbBackfillRunner = true;
+  try {
+    while (thumbBackfillQueue.length) {
+      if (detailRuntime || gridHoverRuntime) {
+        await new Promise((r) => setTimeout(r, 250));
+        continue;
+      }
+      const job = thumbBackfillQueue.shift();
+      try {
+        const dataUrl = await window.captureShaderThumbnail(job.code, job.name);
+        const res = await fetch(`${API_BASE}/${encodeURIComponent(job.id)}/thumbnail`, {
+          method: "POST",
+          headers: { "Content-Type": "application/json" },
+          body: JSON.stringify({ pngBase64: dataUrl }),
+        });
+        if (res.ok) {
+          thumbBackfillFailUntil.delete(job.id);
+          const url = `${API_BASE}/${encodeURIComponent(job.id)}/thumbnail?t=${Date.now()}`;
+          replaceCardStageWithThumb(job.id, url);
+        } else {
+          thumbBackfillFailUntil.set(job.id, Date.now() + THUMB_BACKOFF_MS);
+        }
+      } catch (e) {
+        console.warn("缩略图自动生成失败", job.id, e);
+        thumbBackfillFailUntil.set(job.id, Date.now() + THUMB_BACKOFF_MS);
+      } finally {
+        thumbBackfillQueuedIds.delete(job.id);
+      }
+      await new Promise((r) => setTimeout(r, 60));
+    }
+  } finally {
+    thumbBackfillRunner = false;
+  }
+}
+
+function replaceCardStageWithThumb(id, url) {
+  if (gridHoverRuntime && gridHoverRuntime.state.id === id) tearDownGridHover();
+  const card = gridEl.querySelector(`[data-shader-id="${CSS.escape(id)}"]`);
+  if (!card) return;
+  const stage = card.querySelector(".card-stage");
+  if (!stage) return;
+  stage.innerHTML = `<img class="card-thumb" src="${url}" alt="" loading="lazy" decoding="async" />`;
+}
+
+/** 全屏详情：限制像素量以便稳定 50+ FPS（过高 DPR × 边长会显著拖慢片元着色器） */
+const DETAIL_MAX_PIXEL_RATIO = 1.35;
+const DETAIL_MAX_BUFFER_LONG_SIDE = 1680;
+
+/** 卡片 hover 实时预览：单例 WebGL，与缩略图同量级分辨率上限 */
+const HOVER_MAX_PIXEL_RATIO = 1.25;
+const HOVER_MAX_BUFFER_LONG_SIDE = 560;
 
 const GL_CONTEXT_OPTS = {
   alpha: false,
@@ -28,12 +102,6 @@ const GL_CONTEXT_OPTS = {
   desynchronized: true,
 };
 
-/** Browsers cap concurrent WebGL contexts (~8); keep grid below so detail view + pool stay safe. */
-const MAX_GRID_WEBGL_CONTEXTS = 7;
-const WEBGL_TEARDOWN_DEBOUNCE_MS = 450;
-
-let gridGlTouchCounter = 0;
-
 const vertexShaderSource = `#version 300 es
 precision highp float;
 layout(location = 0) in vec2 aPosition;
@@ -254,19 +322,6 @@ function bindChannelTextures(gl, channelUniformLocs, channelTextures) {
   gl.activeTexture(gl.TEXTURE0);
 }
 
-function computePreviewBufferSize(cssW, cssH) {
-  const dpr = Math.min(window.devicePixelRatio || 1, PREVIEW_MAX_PIXEL_RATIO);
-  let w = Math.max(1, Math.floor(cssW * dpr));
-  let h = Math.max(1, Math.floor(cssH * dpr));
-  const long = Math.max(w, h);
-  if (long > PREVIEW_MAX_BUFFER_LONG_SIDE) {
-    const s = PREVIEW_MAX_BUFFER_LONG_SIDE / long;
-    w = Math.max(1, Math.floor(w * s));
-    h = Math.max(1, Math.floor(h * s));
-  }
-  return { w, h };
-}
-
 function computeDetailBufferSize(cssW, cssH) {
   const dpr = Math.min(window.devicePixelRatio || 1, DETAIL_MAX_PIXEL_RATIO);
   let w = Math.max(1, Math.floor(cssW * dpr));
@@ -280,120 +335,21 @@ function computeDetailBufferSize(cssW, cssH) {
   return { w, h };
 }
 
-function countGridWebGLContexts() {
-  let n = 0;
-  for (const p of previews) {
-    if (p.gl) n += 1;
+function computeHoverBufferSize(cssW, cssH) {
+  const dpr = Math.min(window.devicePixelRatio || 1, HOVER_MAX_PIXEL_RATIO);
+  let w = Math.max(1, Math.floor(cssW * dpr));
+  let h = Math.max(1, Math.floor(cssH * dpr));
+  const long = Math.max(w, h);
+  if (long > HOVER_MAX_BUFFER_LONG_SIDE) {
+    const s = HOVER_MAX_BUFFER_LONG_SIDE / long;
+    w = Math.max(1, Math.floor(w * s));
+    h = Math.max(1, Math.floor(h * s));
   }
-  return n;
-}
-
-function tearDownPreviewWebGL(state) {
-  if (state._tearDownTimer) {
-    clearTimeout(state._tearDownTimer);
-    state._tearDownTimer = null;
-  }
-  state._staticRendered = false;
-  state._staticDirty = true;
-  if (!state.gl) return;
-  const gl = state.gl;
-  try {
-    if (state.program) gl.deleteProgram(state.program);
-    if (state.vao) gl.deleteVertexArray(state.vao);
-    if (state.vbo) gl.deleteBuffer(state.vbo);
-    if (state.channelTextures) state.channelTextures.forEach((t) => gl.deleteTexture(t));
-  } catch (_) {
-    /* context may already be lost */
-  }
-  const ext = gl.getExtension("WEBGL_lose_context");
-  if (ext) ext.loseContext();
-  state.gl = null;
-  state.program = null;
-  state.vao = null;
-  state.vbo = null;
-  state.channelTextures = null;
-  state.channelUniforms = null;
-  state.uniforms = null;
-}
-
-/** Only evict GPU for cards that are not visible / filtered out — avoids thrash when many cards are on-screen. */
-function evictOffscreenGridWebGLContext() {
-  const off = previews.filter((p) => p.gl && (!p.visible || p.card.style.display === "none"));
-  if (!off.length) return false;
-  off.sort((a, b) => (a._glTouchSeq || 0) - (b._glTouchSeq || 0));
-  tearDownPreviewWebGL(off[0]);
-  return true;
-}
-
-function ensurePreviewWebGL(state) {
-  if (state.gl || state.compileFailed) return;
-  const errorEl = state.card.querySelector(".error");
-  while (countGridWebGLContexts() >= MAX_GRID_WEBGL_CONTEXTS) {
-    if (!evictOffscreenGridWebGLContext()) break;
-  }
-  if (countGridWebGLContexts() >= MAX_GRID_WEBGL_CONTEXTS) {
-    return;
-  }
-  const gl = state.canvas.getContext("webgl2", GL_CONTEXT_OPTS);
-  if (!gl) {
-    errorEl.textContent = "当前浏览器不支持 WebGL2";
-    state.compileFailed = true;
-    return;
-  }
-  let program;
-  let codeForRender = state.code;
-  try {
-    program = compileProgram(gl, buildFragmentShader(codeForRender));
-    errorEl.textContent = "";
-  } catch (_err1) {
-    try {
-      codeForRender = toPortableGlsl(state.code);
-      program = compileProgram(gl, buildFragmentShader(codeForRender));
-      errorEl.textContent = "";
-    } catch (_err2) {
-      codeForRender = fallbackShader(state.name);
-      try {
-        program = compileProgram(gl, buildFragmentShader(codeForRender));
-        errorEl.textContent = "";
-      } catch (err3) {
-        errorEl.textContent = `编译失败:\n${String(err3.message || err3)}`;
-        state.compileFailed = true;
-        const ext = gl.getExtension("WEBGL_lose_context");
-        if (ext) ext.loseContext();
-        return;
-      }
-    }
-  }
-  state.codeForRender = codeForRender;
-  const { vao, vbo } = createQuad(gl);
-  const channelTextures = createDefaultChannelTextures(gl, 128);
-  const channelUniforms = [
-    gl.getUniformLocation(program, "iChannel0"),
-    gl.getUniformLocation(program, "iChannel1"),
-    gl.getUniformLocation(program, "iChannel2"),
-    gl.getUniformLocation(program, "iChannel3"),
-  ];
-  const uniforms = {
-    iResolution: gl.getUniformLocation(program, "iResolution"),
-    iTime: gl.getUniformLocation(program, "iTime"),
-    iTimeDelta: gl.getUniformLocation(program, "iTimeDelta"),
-    iFrame: gl.getUniformLocation(program, "iFrame"),
-    iMouse: gl.getUniformLocation(program, "iMouse"),
-    iDate: gl.getUniformLocation(program, "iDate"),
-  };
-  state.gl = gl;
-  state.program = program;
-  state.vao = vao;
-  state.vbo = vbo;
-  state.channelTextures = channelTextures;
-  state.channelUniforms = channelUniforms;
-  state.uniforms = uniforms;
-  state._glTouchSeq = ++gridGlTouchCounter;
-  state._staticDirty = true;
+  return { w, h };
 }
 
 const previews = [];
-/** Driven by scheduleRender(); only runs while detail / hover / pending static thumbs need a frame. */
+/** Driven by scheduleRender(); detail + grid hover. */
 let renderRafId = 0;
 
 function scheduleRender() {
@@ -404,33 +360,10 @@ function scheduleRender() {
   });
 }
 
-function shouldKeepAnimatingGrid() {
-  for (const p of previews) {
-    if (p.card.style.display === "none") continue;
-    if (!p.visible) continue;
-    if (p.isPointerOver) return true;
-  }
-  return false;
-}
-
-function needsStaticThumbnailPass() {
-  for (const p of previews) {
-    if (p.card.style.display === "none") continue;
-    if (!p.visible) continue;
-    if (p.isPointerOver) continue;
-    if (p.compileFailed) continue;
-    if (p._staticRendered && !p._staticDirty) continue;
-    if (!p.gl && countGridWebGLContexts() >= MAX_GRID_WEBGL_CONTEXTS) continue;
-    return true;
-  }
-  return false;
-}
-
 function shouldScheduleNextFrame() {
   if (detailRuntime) return true;
-  if (shouldKeepAnimatingGrid()) return true;
-  if (needsStaticThumbnailPass()) return true;
-  return false;
+  if (gridHoverRuntime) return true;
+  return !paused;
 }
 
 let paused = false;
@@ -447,150 +380,188 @@ let detailRuntime = null;
 let searchKeyword = "";
 let lastSignature = "";
 
+function getSharedHoverCanvas() {
+  if (!sharedHoverCanvas) {
+    sharedHoverCanvas = document.createElement("canvas");
+    sharedHoverCanvas.className = "card-hover-canvas";
+  }
+  return sharedHoverCanvas;
+}
+
+function tearDownGridHover() {
+  if (!gridHoverRuntime) {
+    if (sharedHoverCanvas && sharedHoverCanvas.parentNode) {
+      const stage = sharedHoverCanvas.parentNode;
+      stage.querySelectorAll(":scope > *").forEach((el) => {
+        el.style.visibility = "";
+      });
+      sharedHoverCanvas.remove();
+      sharedHoverCanvas.style.display = "none";
+    }
+    return;
+  }
+  const { gl, program, vao, vbo, channelTextures, _hoverResizeObserver } = gridHoverRuntime;
+  if (_hoverResizeObserver) _hoverResizeObserver.disconnect();
+  try {
+    if (program) gl.deleteProgram(program);
+    if (vao) gl.deleteVertexArray(vao);
+    if (vbo) gl.deleteBuffer(vbo);
+    if (channelTextures) channelTextures.forEach((t) => gl.deleteTexture(t));
+  } catch (_) {
+    /* lost */
+  }
+  gridHoverRuntime = null;
+  if (sharedHoverCanvas && sharedHoverCanvas.parentNode) {
+    const stage = sharedHoverCanvas.parentNode;
+    stage.querySelectorAll(":scope > *").forEach((el) => {
+      el.style.visibility = "";
+    });
+    sharedHoverCanvas.remove();
+  }
+  if (sharedHoverCanvas) sharedHoverCanvas.style.display = "none";
+}
+
+function startGridHover(previewState, card) {
+  if (detailViewEl.classList.contains("active")) return;
+  tearDownGridHover();
+  const canvas = getSharedHoverCanvas();
+  const stage = card.querySelector(".card-stage");
+  if (!stage) return;
+
+  const gl = canvas.getContext("webgl2", GL_CONTEXT_OPTS);
+  if (!gl) return;
+
+  let program;
+  let codeForRender = previewState.code;
+  try {
+    program = compileProgram(gl, buildFragmentShader(codeForRender));
+  } catch (_e1) {
+    try {
+      codeForRender = toPortableGlsl(previewState.code);
+      program = compileProgram(gl, buildFragmentShader(codeForRender));
+    } catch (_e2) {
+      codeForRender = fallbackShader(previewState.name);
+      try {
+        program = compileProgram(gl, buildFragmentShader(codeForRender));
+      } catch {
+        return;
+      }
+    }
+  }
+
+  const { vao, vbo } = createQuad(gl);
+  const channelTextures = createDefaultChannelTextures(gl, 128);
+  const channelUniforms = [
+    gl.getUniformLocation(program, "iChannel0"),
+    gl.getUniformLocation(program, "iChannel1"),
+    gl.getUniformLocation(program, "iChannel2"),
+    gl.getUniformLocation(program, "iChannel3"),
+  ];
+  const uniforms = {
+    iResolution: gl.getUniformLocation(program, "iResolution"),
+    iTime: gl.getUniformLocation(program, "iTime"),
+    iTimeDelta: gl.getUniformLocation(program, "iTimeDelta"),
+    iFrame: gl.getUniformLocation(program, "iFrame"),
+    iMouse: gl.getUniformLocation(program, "iMouse"),
+    iDate: gl.getUniformLocation(program, "iDate"),
+  };
+
+  stage.appendChild(canvas);
+  canvas.style.display = "block";
+  stage.querySelectorAll(":scope > *").forEach((el) => {
+    if (el !== canvas) el.style.visibility = "hidden";
+  });
+
+  const ro = new ResizeObserver(() => {
+    if (!gridHoverRuntime) return;
+    const r = canvas.getBoundingClientRect();
+    gridHoverRuntime._layoutW = r.width;
+    gridHoverRuntime._layoutH = r.height;
+  });
+  ro.observe(canvas);
+  const r0 = canvas.getBoundingClientRect();
+  gridHoverRuntime = {
+    gl,
+    program,
+    vao,
+    vbo,
+    channelTextures,
+    channelUniforms,
+    uniforms,
+    canvas,
+    state: previewState,
+    mouse: { x: 0, y: 0, downX: 0, downY: 0, down: false },
+    localTime: 0.05,
+    localFrame: 1,
+    lastTick: performance.now(),
+    _layoutW: r0.width,
+    _layoutH: r0.height,
+    _hoverResizeObserver: ro,
+  };
+  scheduleRender();
+}
+
 function createPreviewCard(shader) {
-  const { id, name, author = "unknown", views = 0, likes = 0, code } = shader;
+  const { id, name, author = "unknown", views = 0, likes = 0, code, thumbnailUrl } = shader;
   const card = document.createElement("article");
   card.className = "card";
   card.dataset.search = `${name} ${author}`.toLowerCase();
+
+  const visualInner = thumbnailUrl
+    ? `<img class="card-thumb" src="${thumbnailUrl}" alt="" loading="lazy" decoding="async" />`
+    : `<div class="card-thumb card-thumb--placeholder">暂无缩略图<br /><small>正在尝试自动生成…</small></div>`;
+
+  card.dataset.shaderId = id;
   card.innerHTML = `
     <div class="card-head">
       <strong>${name}</strong>
-      <div style="display:flex; gap:6px;">
-        <button type="button" class="pause-local-btn">暂停</button>
-      </div>
     </div>
-    <canvas></canvas>
+    <div class="card-stage">${visualInner}</div>
     <div class="card-meta">
       <span>by ${author}</span>
       <span>views ${views} | likes ${likes}</span>
     </div>
-    <div class="card-head error"></div>
   `;
 
-  const canvas = card.querySelector("canvas");
-  const errorEl = card.querySelector(".error");
-  const pauseLocalBtn = card.querySelector(".pause-local-btn");
-
   const state = {
     id,
     name,
     code,
-    codeForRender: code,
-    compileFailed: false,
     card,
-    canvas,
-    gl: null,
-    program: null,
-    vao: null,
-    vbo: null,
-    channelTextures: null,
-    channelUniforms: null,
-    uniforms: null,
-    mouse: { x: 0, y: 0, downX: 0, downY: 0, down: false },
-    isPlaying: true,
-    localTime: 0,
-    localFrame: 0,
-    lastTick: performance.now(),
-    visible: false,
-    _layoutW: 0,
-    _layoutH: 0,
-    _glTouchSeq: 0,
-    _tearDownTimer: null,
-    isPointerOver: false,
-    _staticRendered: false,
-    _staticDirty: true,
   };
 
+  card.addEventListener("click", () => openDetail(state));
+
   card.addEventListener("mouseenter", () => {
-    state.isPointerOver = true;
-    state.lastTick = performance.now();
-    scheduleRender();
+    if (detailViewEl.classList.contains("active")) return;
+    startGridHover(state, card);
   });
   card.addEventListener("mouseleave", () => {
-    state.isPointerOver = false;
-    state.localTime = 0;
-    state.localFrame = 0;
-    state._staticDirty = true;
-    state._staticRendered = false;
-    scheduleRender();
+    if (gridHoverRuntime && gridHoverRuntime.state.id === state.id) tearDownGridHover();
   });
-
-  canvas.addEventListener("mousemove", (event) => {
-    const rect = canvas.getBoundingClientRect();
-    const bw = canvas.width || Math.max(1, state._layoutW || rect.width);
-    const bh = canvas.height || Math.max(1, state._layoutH || rect.height);
-    state.mouse.x = ((event.clientX - rect.left) / rect.width) * bw;
-    state.mouse.y = ((rect.bottom - event.clientY) / rect.height) * bh;
+  card.addEventListener("mousemove", (event) => {
+    if (!gridHoverRuntime || gridHoverRuntime.state.id !== state.id) return;
+    const c = gridHoverRuntime.canvas;
+    const rect = c.getBoundingClientRect();
+    const bw = c.width || 1;
+    const bh = c.height || 1;
+    gridHoverRuntime.mouse.x = ((event.clientX - rect.left) / rect.width) * bw;
+    gridHoverRuntime.mouse.y = ((rect.bottom - event.clientY) / rect.height) * bh;
   });
-  canvas.addEventListener("mousedown", () => {
-    state.mouse.down = true;
-    state.mouse.downX = state.mouse.x;
-    state.mouse.downY = state.mouse.y;
+  card.addEventListener("mousedown", () => {
+    if (!gridHoverRuntime || gridHoverRuntime.state.id !== state.id) return;
+    gridHoverRuntime.mouse.down = true;
+    gridHoverRuntime.mouse.downX = gridHoverRuntime.mouse.x;
+    gridHoverRuntime.mouse.downY = gridHoverRuntime.mouse.y;
   });
-  window.addEventListener("mouseup", () => {
-    state.mouse.down = false;
-  });
-
-  pauseLocalBtn.addEventListener("click", (event) => {
-    event.stopPropagation();
-    state.isPlaying = !state.isPlaying;
-    state.lastTick = performance.now();
-    pauseLocalBtn.textContent = state.isPlaying ? "暂停" : "继续";
-    scheduleRender();
-  });
-  canvas.addEventListener("click", () => openDetail(state));
 
   gridEl.appendChild(card);
-
-  const ro = new ResizeObserver((entries) => {
-    for (const entry of entries) {
-      if (entry.target !== canvas) continue;
-      const cr = entry.contentRect;
-      state._layoutW = cr.width;
-      state._layoutH = cr.height;
-      state._staticDirty = true;
-      scheduleRender();
-    }
-  });
-  ro.observe(canvas);
-  state._resizeObserver = ro;
-
-  const io = new IntersectionObserver(
-    (entries) => {
-      for (const e of entries) {
-        if (e.target !== canvas) continue;
-        state.visible = e.isIntersecting;
-        if (e.isIntersecting) {
-          if (state._tearDownTimer) {
-            clearTimeout(state._tearDownTimer);
-            state._tearDownTimer = null;
-          }
-          state._staticDirty = true;
-          state._staticRendered = false;
-          ensurePreviewWebGL(state);
-          scheduleRender();
-        } else {
-          if (state._tearDownTimer) clearTimeout(state._tearDownTimer);
-          state._tearDownTimer = setTimeout(() => {
-            state._tearDownTimer = null;
-            if (!state.visible) tearDownPreviewWebGL(state);
-          }, WEBGL_TEARDOWN_DEBOUNCE_MS);
-        }
-      }
-    },
-    { root: null, rootMargin: "120px", threshold: 0.01 }
-  );
-  io.observe(canvas);
-  state._io = io;
-
   previews.push(state);
 }
 
 function clearPreviews() {
+  tearDownGridHover();
   previews.forEach((preview) => {
-    tearDownPreviewWebGL(preview);
-    if (preview._resizeObserver) preview._resizeObserver.disconnect();
-    if (preview._io) preview._io.disconnect();
     preview.card.remove();
   });
   previews.length = 0;
@@ -610,19 +581,30 @@ function closeDetail() {
 }
 
 function openDetail(previewState) {
+  tearDownGridHover();
   closeDetail();
   const gl = detailCanvas.getContext("webgl2", GL_CONTEXT_OPTS);
   if (!gl) return;
   let program;
-  const detailCode = previewState.codeForRender || previewState.code;
+  let detailCode = previewState.code;
   try {
     program = compileProgram(gl, buildFragmentShader(detailCode));
-  } catch (err) {
-    statsEl.textContent = `详情编译失败: ${String(err.message || err)}`;
-    return;
+  } catch (_e1) {
+    try {
+      detailCode = toPortableGlsl(previewState.code);
+      program = compileProgram(gl, buildFragmentShader(detailCode));
+    } catch (_e2) {
+      detailCode = fallbackShader(previewState.name);
+      try {
+        program = compileProgram(gl, buildFragmentShader(detailCode));
+      } catch (err) {
+        statsEl.textContent = `详情编译失败: ${String(err.message || err)}`;
+        return;
+      }
+    }
   }
   const { vao, vbo } = createQuad(gl);
-  const channelTextures = createDefaultChannelTextures(gl, 256);
+  const channelTextures = createDefaultChannelTextures(gl, 128);
   const channelUniforms = [
     gl.getUniformLocation(program, "iChannel0"),
     gl.getUniformLocation(program, "iChannel1"),
@@ -679,7 +661,12 @@ async function loadShaders() {
     if (!res.ok) throw new Error("加载失败");
     const shaders = await res.json();
     const signature = JSON.stringify(
-      shaders.map((s) => ({ id: s.id, updatedAt: s.updatedAt || s.createdAt || "", name: s.name }))
+      shaders.map((s) => ({
+        id: s.id,
+        updatedAt: s.updatedAt || s.createdAt || "",
+        thumbnailAt: s.thumbnailAt || "",
+        name: s.name,
+      }))
     );
     if (signature !== lastSignature) {
       lastSignature = signature;
@@ -688,6 +675,7 @@ async function loadShaders() {
       applySearch();
       syncStats();
     }
+    scheduleThumbBackfill(shaders);
   } catch (err) {
     statsEl.textContent = `读取后端失败：${String(err.message || err)}`;
   }
@@ -716,83 +704,56 @@ function renderAll(ts) {
     fpsCounter += 1;
   }
 
-  const detailOpen = !!detailRuntime;
-
-  for (const preview of previews) {
-    let localDt = 0;
-    if (!detailOpen) {
-      const now = performance.now();
-      localDt = Math.min((now - preview.lastTick) / 1000, 0.05);
-      preview.lastTick = now;
-      if (preview.isPointerOver && preview.isPlaying && !paused) {
-        preview.localTime += localDt;
-        preview.localFrame += 1;
-      }
-    }
-
-    if (
-      !detailOpen &&
-      preview.card.style.display !== "none" &&
-      preview.visible &&
-      !preview.gl &&
-      !preview.compileFailed
-    ) {
-      ensurePreviewWebGL(preview);
-    }
-
-    if (detailOpen) continue;
-    if (preview.card.style.display === "none") continue;
-    if (preview.visible === false) continue;
-    if (!preview.gl) continue;
-
-    const isAnim = preview.isPointerOver;
-    if (!isAnim && preview._staticRendered && !preview._staticDirty) continue;
-
-    const { gl, canvas, program, vao, uniforms, mouse, channelTextures, channelUniforms } = preview;
-    if (!preview._layoutW || !preview._layoutH) {
-      const r = canvas.getBoundingClientRect();
-      preview._layoutW = r.width;
-      preview._layoutH = r.height;
-    }
-    const { w, h } = computePreviewBufferSize(preview._layoutW, preview._layoutH);
-    if (canvas.width !== w || canvas.height !== h) {
-      canvas.width = w;
-      canvas.height = h;
-      gl.viewport(0, 0, w, h);
-      if (!isAnim) preview._staticDirty = true;
-    }
-    gl.useProgram(program);
-    bindChannelTextures(gl, channelUniforms, channelTextures);
-    gl.uniform3f(uniforms.iResolution, canvas.width, canvas.height, 1);
-    if (isAnim) {
-      gl.uniform1f(uniforms.iTime, preview.localTime);
-      gl.uniform1f(uniforms.iTimeDelta, preview.isPlaying && !paused ? localDt : 0);
-      gl.uniform1i(uniforms.iFrame, preview.localFrame);
+  if (gridHoverRuntime) {
+    const { gl, program, vao, uniforms, mouse, channelTextures, channelUniforms, canvas } =
+      gridHoverRuntime;
+    if (gl.isContextLost()) {
+      tearDownGridHover();
     } else {
-      gl.uniform1f(uniforms.iTime, 0);
-      gl.uniform1f(uniforms.iTimeDelta, 0);
-      gl.uniform1i(uniforms.iFrame, 0);
-    }
-    setIDateUniform(gl, uniforms.iDate);
-    gl.uniform4f(
-      uniforms.iMouse,
-      mouse.x,
-      mouse.y,
-      mouse.down ? mouse.downX : -mouse.downX,
-      mouse.down ? mouse.downY : -mouse.downY
-    );
-    gl.bindVertexArray(vao);
-    gl.drawArrays(gl.TRIANGLES, 0, 6);
-    gl.bindVertexArray(null);
-    preview._glTouchSeq = ++gridGlTouchCounter;
-    if (!isAnim) {
-      preview._staticRendered = true;
-      preview._staticDirty = false;
+      const now = performance.now();
+      const localDt = Math.min((now - gridHoverRuntime.lastTick) / 1000, 0.05);
+      gridHoverRuntime.lastTick = now;
+      if (!paused) {
+        gridHoverRuntime.localTime += localDt;
+        gridHoverRuntime.localFrame += 1;
+      }
+      const lw =
+        gridHoverRuntime._layoutW > 0 ? gridHoverRuntime._layoutW : canvas.clientWidth || 1;
+      const lh =
+        gridHoverRuntime._layoutH > 0 ? gridHoverRuntime._layoutH : canvas.clientHeight || 1;
+      const { w, h } = computeHoverBufferSize(lw, lh);
+      if (canvas.width !== w || canvas.height !== h) {
+        canvas.width = w;
+        canvas.height = h;
+        gl.viewport(0, 0, w, h);
+      }
+      gl.useProgram(program);
+      bindChannelTextures(gl, channelUniforms, channelTextures);
+      gl.uniform3f(uniforms.iResolution, canvas.width, canvas.height, 1);
+      gl.uniform1f(uniforms.iTime, gridHoverRuntime.localTime);
+      gl.uniform1f(uniforms.iTimeDelta, paused ? 0 : localDt);
+      gl.uniform1i(uniforms.iFrame, gridHoverRuntime.localFrame);
+      setIDateUniform(gl, uniforms.iDate);
+      gl.uniform4f(
+        uniforms.iMouse,
+        mouse.x,
+        mouse.y,
+        mouse.down ? mouse.downX : -mouse.downX,
+        mouse.down ? mouse.downY : -mouse.downY
+      );
+      gl.bindVertexArray(vao);
+      gl.drawArrays(gl.TRIANGLES, 0, 6);
+      gl.bindVertexArray(null);
     }
   }
 
   if (detailRuntime) {
     const { gl, program, vao, uniforms, mouse, channelTextures, channelUniforms } = detailRuntime;
+    if (gl.isContextLost()) {
+      closeDetail();
+      scheduleRender();
+      return;
+    }
     const lw =
       detailRuntime._layoutW > 0 ? detailRuntime._layoutW : detailCanvas.clientWidth || 1;
     const lh =
@@ -866,8 +827,8 @@ detailCanvas.addEventListener("mousedown", () => {
   detailRuntime.mouse.downY = detailRuntime.mouse.y;
 });
 window.addEventListener("mouseup", () => {
-  if (!detailRuntime) return;
-  detailRuntime.mouse.down = false;
+  if (detailRuntime) detailRuntime.mouse.down = false;
+  if (gridHoverRuntime) gridHoverRuntime.mouse.down = false;
 });
 searchInput.addEventListener("input", (event) => {
   searchKeyword = event.target.value || "";
diff --git a/index.html b/index.html
index 836f144..0b8a61d 100644
--- a/index.html
+++ b/index.html
@@ -160,11 +160,42 @@
         border-bottom: 1px solid rgba(255, 255, 255, 0.08);
       }
 
-      .card canvas {
+      .card-stage {
+        position: relative;
         width: 100%;
         aspect-ratio: 16 / 10;
-        display: block;
         background: #000;
+        overflow: hidden;
+      }
+
+      .card-thumb {
+        width: 100%;
+        height: 100%;
+        display: block;
+        object-fit: cover;
+        vertical-align: middle;
+      }
+
+      .card-hover-canvas {
+        position: absolute;
+        inset: 0;
+        width: 100%;
+        height: 100%;
+        display: block;
+        pointer-events: none;
+      }
+
+      .card-thumb--placeholder {
+        display: flex;
+        align-items: center;
+        justify-content: center;
+        min-height: 120px;
+        padding: 12px;
+        text-align: center;
+        font-size: 12px;
+        line-height: 1.5;
+        color: #6a7088;
+        background: linear-gradient(145deg, #0a0c12 0%, #12151f 100%);
       }
 
       .card-meta {
@@ -304,9 +335,7 @@
           </div>
         </div>
         <div class="stats" id="stats">准备就绪</div>
-        <p class="view-hint">
-          列表默认仅显示首帧静态预览；鼠标悬停在卡片上时才会持续渲染动画。点击进入全屏仍为实时播放。
-        </p>
+    
         <section id="preview-grid" class="preview-grid"></section>
       </main>
     </div>
@@ -324,6 +353,7 @@
       </div>
     </section>
 
+    <script src="./thumb-renderer.js"></script>
     <script src="./display.js"></script>
   </body>
 </html>
diff --git a/server.js b/server.js
index e6ab6fc..3be2e0d 100644
--- a/server.js
+++ b/server.js
@@ -6,8 +6,9 @@ const crypto = require("crypto");
 const app = express();
 const PORT = process.env.PORT || 5180;
 const DB_PATH = path.join(__dirname, "data", "shaders.json");
+const THUMB_DIR = path.join(__dirname, "data", "thumbnails");
 
-app.use(express.json({ limit: "1mb" }));
+app.use(express.json({ limit: "4mb" }));
 app.use(express.static(__dirname));
 
 async function ensureDb() {
@@ -19,6 +20,50 @@ async function ensureDb() {
   }
 }
 
+async function ensureThumbnailsDir() {
+  await fs.mkdir(THUMB_DIR, { recursive: true });
+}
+
+function thumbPath(id) {
+  return path.join(THUMB_DIR, `${id}.png`);
+}
+
+async function thumbFileExists(id) {
+  try {
+    await fs.access(thumbPath(id));
+    return true;
+  } catch {
+    return false;
+  }
+}
+
+function decodePngBase64(s) {
+  if (!s || typeof s !== "string") return null;
+  const t = s.trim();
+  const m = /^data:image\/png;base64,(.+)$/i.exec(t);
+  const b64 = m ? m[1] : t.replace(/\s/g, "");
+  try {
+    return Buffer.from(b64, "base64");
+  } catch {
+    return null;
+  }
+}
+
+function isPngBuffer(buf) {
+  return (
+    buf &&
+    buf.length >= 8 &&
+    buf[0] === 0x89 &&
+    buf[1] === 0x50 &&
+    buf[2] === 0x4e &&
+    buf[3] === 0x47 &&
+    buf[4] === 0x0d &&
+    buf[5] === 0x0a &&
+    buf[6] === 0x1a &&
+    buf[7] === 0x0a
+  );
+}
+
 async function readDb() {
   await ensureDb();
   const raw = await fs.readFile(DB_PATH, "utf8");
@@ -286,6 +331,7 @@ async function autoNormalizeStoredShaders() {
 
 app.get("/api/shaders", async (_req, res) => {
   try {
+    await ensureThumbnailsDir();
     let shaders = await readDb();
     // Runtime safeguard: always return normalized code for display layer.
     shaders = shaders.map((item) => {
@@ -297,7 +343,16 @@ app.get("/api/shaders", async (_req, res) => {
       if (isAngleLike(raw)) next.sourceFormat = "angle-metal-auto-converted";
       return next;
     });
-    res.json(shaders);
+    const out = await Promise.all(
+      shaders.map(async (item) => {
+        const has = await thumbFileExists(item.id);
+        const thumbnailUrl = has
+          ? `/api/shaders/${encodeURIComponent(item.id)}/thumbnail`
+          : null;
+        return { ...item, thumbnailUrl };
+      })
+    );
+    res.json(out);
   } catch {
     res.status(500).json({ error: "读取失败" });
   }
@@ -333,6 +388,48 @@ app.post("/api/shaders", async (req, res) => {
   }
 });
 
+app.get("/api/shaders/:id/thumbnail", async (req, res) => {
+  try {
+    const p = thumbPath(req.params.id);
+    await fs.access(p);
+    res.setHeader("Content-Type", "image/png");
+    res.setHeader("Cache-Control", "public, max-age=86400");
+    res.sendFile(path.resolve(p));
+  } catch {
+    res.status(404).end();
+  }
+});
+
+app.post("/api/shaders/:id/thumbnail", async (req, res) => {
+  const { pngBase64 } = req.body || {};
+  const buf = decodePngBase64(pngBase64);
+  if (!buf || buf.length < 32) {
+    return res.status(400).json({ error: "无效 PNG 数据" });
+  }
+  if (!isPngBuffer(buf)) {
+    return res.status(400).json({ error: "必须是 PNG" });
+  }
+  if (buf.length > 2 * 1024 * 1024) {
+    return res.status(400).json({ error: "缩略图过大" });
+  }
+  try {
+    const shaders = await readDb();
+    const idx = shaders.findIndex((it) => it.id === req.params.id);
+    if (idx < 0) {
+      return res.status(404).json({ error: "未找到该 shader" });
+    }
+    await ensureThumbnailsDir();
+    await fs.writeFile(thumbPath(req.params.id), buf);
+    const thumbnailAt = new Date().toISOString();
+    shaders[idx] = { ...shaders[idx], thumbnailAt };
+    await writeDb(shaders);
+    const thumbnailUrl = `/api/shaders/${encodeURIComponent(req.params.id)}/thumbnail`;
+    res.json({ ok: true, thumbnailUrl, thumbnailAt });
+  } catch {
+    res.status(500).json({ error: "保存缩略图失败" });
+  }
+});
+
 app.delete("/api/shaders/:id", async (req, res) => {
   try {
     const shaders = await readDb();
@@ -341,6 +438,12 @@ app.delete("/api/shaders/:id", async (req, res) => {
       return res.status(404).json({ error: "未找到该 shader" });
     }
     await writeDb(next);
+    await ensureThumbnailsDir();
+    try {
+      await fs.unlink(thumbPath(req.params.id));
+    } catch (_) {
+      /* no thumb */
+    }
     res.status(204).end();
   } catch {
     res.status(500).json({ error: "删除失败" });
diff --git a/thumb-renderer.js b/thumb-renderer.js
new file mode 100644
index 0000000..de80ac9
--- /dev/null
+++ b/thumb-renderer.js
@@ -0,0 +1,362 @@
+/**
+ * One-off WebGL capture: try multiple iTime values, pick a non-degenerate frame (avoid flat black/white),
+ * export PNG, then loseContext.
+ */
+(function () {
+  const THUMB_W = 512;
+  const THUMB_H = 320;
+
+  /** 首帧常为过黑/过白/无对比时，在这些时刻采样并打分选帧 */
+  const THUMB_TIME_CANDIDATES = [
+    0, 0.1, 0.22, 0.45, 0.78, 1.15, 1.7, 2.25, 2.85, 3.45, 4.2, 5.1, 6.28, 7.5, 9, 11, 13,
+  ];
+
+  const GL_CONTEXT_OPTS = {
+    alpha: false,
+    antialias: false,
+    depth: false,
+    stencil: false,
+    powerPreference: "high-performance",
+    desynchronized: true,
+  };
+
+  const vertexShaderSource = `#version 300 es
+precision highp float;
+layout(location = 0) in vec2 aPosition;
+void main() { gl_Position = vec4(aPosition, 0.0, 1.0); }`;
+
+  function toPortableGlsl(code) {
+    if (!code) return "";
+    let s = String(code);
+    const start = s.indexOf("void mainImage");
+    if (start >= 0) {
+      s = s.slice(0, s.length);
+    }
+    s = s
+      .replace(/float2/g, "vec2")
+      .replace(/float3/g, "vec3")
+      .replace(/float4/g, "vec4")
+      .replace(/int2/g, "ivec2")
+      .replace(/int3/g, "ivec3")
+      .replace(/int4/g, "ivec4")
+      .replace(/precise::tanh/g, "tanh")
+      .replace(/ANGLE_userUniforms\._uiResolution/g, "iResolution")
+      .replace(/ANGLE_userUniforms\._uiTime/g, "iTime")
+      .replace(/ANGLE_userUniforms\._uiMouse/g, "iMouse")
+      .replace(/ANGLE_texture\([^)]*\)/g, "vec4(0.0)")
+      .replace(/ANGLE_texelFetch\([^)]*\)/g, "vec4(0.0)")
+      .replace(/ANGLE_mod\(/g, "mod(")
+      .replace(/\[\[[^\]]+\]\]/g, "")
+      .replace(/template\s*[^\n]*\n/g, "")
+      .replace(/ANGLE_out\(([^)]+)\)/g, "$1")
+      .replace(/ANGLE_swizzle_ref\(([^)]+)\)/g, "$1")
+      .replace(/ANGLE_elem_ref\(([^)]+)\)/g, "$1")
+      .replace(/(\d+\.\d+|\d+)f\b/g, "$1");
+
+    const mi = s.indexOf("void mainImage");
+    if (mi >= 0) {
+      const head = s.slice(0, mi);
+      const helpers = head
+        .split("\n\n")
+        .filter((blk) => /(void|float|vec[234]|mat[234])\s+[A-Za-z_][A-Za-z0-9_]*\s*\(/.test(blk))
+        .join("\n\n");
+      const mainPart = s.slice(mi);
+      return `${helpers}\n\n${mainPart}`;
+    }
+    return s;
+  }
+
+  function fallbackShader(name) {
+    const h = (name || "shader")
+      .split("")
+      .reduce((a, c) => (a * 33 + c.charCodeAt(0)) >>> 0, 5381);
+    const k1 = ((h % 97) / 97).toFixed(3);
+    const k2 = (((h >> 5) % 89) / 89).toFixed(3);
+    return `void mainImage(out vec4 fragColor, in vec2 fragCoord) {
+  vec2 uv = (fragCoord - 0.5 * iResolution.xy) / iResolution.y;
+  float t = iTime;
+  float v = sin(uv.x * (8.0 + ${k1} * 8.0) + t * (1.4 + ${k2} * 1.2))
+          + cos(uv.y * (10.0 + ${k2} * 6.0) - t * (1.1 + ${k1}));
+  vec3 col = 0.5 + 0.5 * cos(vec3(0.2, 1.2, 2.2) + v + t);
+  fragColor = vec4(col, 1.0);
+}`;
+  }
+
+  function buildFragmentShader(userCode) {
+    return `#version 300 es
+precision highp float;
+out vec4 outColor;
+uniform vec3 iResolution;
+uniform float iTime;
+uniform float iTimeDelta;
+uniform int iFrame;
+uniform vec4 iMouse;
+uniform vec4 iDate;
+uniform sampler2D iChannel0;
+uniform sampler2D iChannel1;
+uniform sampler2D iChannel2;
+uniform sampler2D iChannel3;
+${userCode}
+void main() { mainImage(outColor, gl_FragCoord.xy); }`;
+  }
+
+  function setIDateUniform(gl, loc) {
+    if (loc == null) return;
+    const d = new Date();
+    gl.uniform4f(
+      loc,
+      d.getFullYear(),
+      d.getMonth() + 1,
+      d.getDate(),
+      d.getHours() * 3600 + d.getMinutes() * 60 + d.getSeconds() + d.getMilliseconds() * 0.001
+    );
+  }
+
+  function createQuad(gl) {
+    const quad = new Float32Array([-1, -1, 1, -1, -1, 1, -1, 1, 1, -1, 1, 1]);
+    const vao = gl.createVertexArray();
+    const vbo = gl.createBuffer();
+    gl.bindVertexArray(vao);
+    gl.bindBuffer(gl.ARRAY_BUFFER, vbo);
+    gl.bufferData(gl.ARRAY_BUFFER, quad, gl.STATIC_DRAW);
+    gl.enableVertexAttribArray(0);
+    gl.vertexAttribPointer(0, 2, gl.FLOAT, false, 0, 0);
+    gl.bindVertexArray(null);
+    return { vao, vbo };
+  }
+
+  function compileProgram(gl, fragmentShaderSource) {
+    function compile(type, label, source) {
+      if (gl.isContextLost?.()) {
+        throw new Error(`${label}: WebGL context lost`);
+      }
+      const shader = gl.createShader(type);
+      gl.shaderSource(shader, source);
+      gl.compileShader(shader);
+      if (!gl.getShaderParameter(shader, gl.COMPILE_STATUS)) {
+        let info = (gl.getShaderInfoLog(shader) || "").trim();
+        if (!info) {
+          const err = gl.getError();
+          info =
+            err && err !== gl.NO_ERROR
+              ? `WebGL getError 0x${err.toString(16)} (driver returned no compile log)`
+              : "No compile log (shader too complex or driver limits).";
+        }
+        gl.deleteShader(shader);
+        throw new Error(`${label} shader:\n${info}`);
+      }
+      return shader;
+    }
+    const vs = compile(gl.VERTEX_SHADER, "Vertex", vertexShaderSource);
+    const fs = compile(gl.FRAGMENT_SHADER, "Fragment", fragmentShaderSource);
+    const program = gl.createProgram();
+    gl.attachShader(program, vs);
+    gl.attachShader(program, fs);
+    gl.linkProgram(program);
+    gl.deleteShader(vs);
+    gl.deleteShader(fs);
+    if (!gl.getProgramParameter(program, gl.LINK_STATUS)) {
+      let info = (gl.getProgramInfoLog(program) || "").trim();
+      if (!info) {
+        const err = gl.getError();
+        info =
+          err && err !== gl.NO_ERROR
+            ? `WebGL getError 0x${err.toString(16)} (no link log)`
+            : "No link log.";
+      }
+      gl.deleteProgram(program);
+      throw new Error(`Program link:\n${info}`);
+    }
+    return program;
+  }
+
+  function createTexture(gl, width, height, data) {
+    const tex = gl.createTexture();
+    gl.bindTexture(gl.TEXTURE_2D, tex);
+    gl.texParameteri(gl.TEXTURE_2D, gl.TEXTURE_MIN_FILTER, gl.LINEAR);
+    gl.texParameteri(gl.TEXTURE_2D, gl.TEXTURE_MAG_FILTER, gl.LINEAR);
+    gl.texParameteri(gl.TEXTURE_2D, gl.TEXTURE_WRAP_S, gl.REPEAT);
+    gl.texParameteri(gl.TEXTURE_2D, gl.TEXTURE_WRAP_T, gl.REPEAT);
+    gl.pixelStorei(gl.UNPACK_ALIGNMENT, 1);
+    gl.texImage2D(gl.TEXTURE_2D, 0, gl.RGBA, width, height, 0, gl.RGBA, gl.UNSIGNED_BYTE, data);
+    gl.bindTexture(gl.TEXTURE_2D, null);
+    return tex;
+  }
+
+  function createDefaultChannelTextures(gl, noiseSize) {
+    const w0 = 512;
+    const h0 = 2;
+    const d0 = new Uint8Array(w0 * h0 * 4);
+    for (let x = 0; x < w0; x++) {
+      const t = x / (w0 - 1);
+      const fft = Math.floor(255 * Math.pow(1.0 - t, 1.8));
+      const wave = Math.floor(128 + 127 * Math.sin(t * Math.PI * 10.0));
+      const i0 = (x + 0 * w0) * 4;
+      const i1 = (x + 1 * w0) * 4;
+      d0[i0] = fft;
+      d0[i0 + 1] = fft;
+      d0[i0 + 2] = fft;
+      d0[i0 + 3] = 255;
+      d0[i1] = wave;
+      d0[i1 + 1] = wave;
+      d0[i1 + 2] = wave;
+      d0[i1 + 3] = 255;
+    }
+
+    const size = noiseSize;
+    const makeNoise = (scaleA, scaleB) => {
+      const d = new Uint8Array(size * size * 4);
+      for (let y = 0; y < size; y++) {
+        for (let x = 0; x < size; x++) {
+          const i = (y * size + x) * 4;
+          const n = Math.floor(
+            127 +
+              127 *
+                Math.sin((x * scaleA + y * scaleB) * 0.11) *
+                Math.cos((x * scaleB - y * scaleA) * 0.07)
+          );
+          d[i] = n;
+          d[i + 1] = (n * 37) & 255;
+          d[i + 2] = (n * 73) & 255;
+          d[i + 3] = 255;
+        }
+      }
+      return d;
+    };
+
+    return [
+      createTexture(gl, w0, h0, d0),
+      createTexture(gl, size, size, makeNoise(1.0, 0.7)),
+      createTexture(gl, size, size, makeNoise(0.8, 1.3)),
+      createTexture(gl, size, size, makeNoise(1.7, 0.4)),
+    ];
+  }
+
+  function bindChannelTextures(gl, channelUniformLocs, channelTextures) {
+    for (let i = 0; i < 4; i++) {
+      if (channelUniformLocs[i] == null) continue;
+      gl.activeTexture(gl.TEXTURE0 + i);
+      gl.bindTexture(gl.TEXTURE_2D, channelTextures[i]);
+      gl.uniform1i(channelUniformLocs[i], i);
+    }
+    gl.activeTexture(gl.TEXTURE0);
+  }
+
+  function sampleThumbStats(data, width, height) {
+    const row = width * 4;
+    let sumL = 0;
+    let sumL2 = 0;
+    let n = 0;
+    for (let y = 0; y < height; y += 5) {
+      for (let x = 0; x < width; x += 6) {
+        const i = y * row + x * 4;
+        if (i + 2 >= data.length) continue;
+        const r = data[i] / 255;
+        const g = data[i + 1] / 255;
+        const b = data[i + 2] / 255;
+        const L = 0.299 * r + 0.587 * g + 0.114 * b;
+        sumL += L;
+        sumL2 += L * L;
+        n++;
+      }
+    }
+    if (n < 4) return { mean: 0, varL: 0 };
+    const mean = sumL / n;
+    const varL = Math.max(0, sumL2 / n - mean * mean);
+    return { mean, varL };
+  }
+
+  function isAcceptableThumb(mean, varL) {
+    if (mean < 0.017 || mean > 0.99) return false;
+    if (varL < 0.00065) return false;
+    return true;
+  }
+
+  function thumbScore(mean, varL) {
+    return varL * 85 + (1 - Math.abs(mean - 0.4) * 1.05);
+  }
+
+  /**
+   * @param {string} code — normalized GLSL (same as server returns)
+   * @param {string} name — shader title for fallback hash
+   * @returns {Promise<string>} data:image/png;base64,...
+   */
+  window.captureShaderThumbnail = function captureShaderThumbnail(code, name) {
+    const canvas = document.createElement("canvas");
+    canvas.width = THUMB_W;
+    canvas.height = THUMB_H;
+    const gl = canvas.getContext("webgl2", GL_CONTEXT_OPTS);
+    if (!gl) {
+      return Promise.reject(new Error("当前浏览器不支持 WebGL2"));
+    }
+    let program;
+    let codeForRender = code;
+    try {
+      program = compileProgram(gl, buildFragmentShader(codeForRender));
+    } catch (_e1) {
+      try {
+        codeForRender = toPortableGlsl(code);
+        program = compileProgram(gl, buildFragmentShader(codeForRender));
+      } catch (_e2) {
+        codeForRender = fallbackShader(name);
+        program = compileProgram(gl, buildFragmentShader(codeForRender));
+      }
+    }
+
+    const { vao } = createQuad(gl);
+    const channelTextures = createDefaultChannelTextures(gl, 128);
+    const channelUniforms = [
+      gl.getUniformLocation(program, "iChannel0"),
+      gl.getUniformLocation(program, "iChannel1"),
+      gl.getUniformLocation(program, "iChannel2"),
+      gl.getUniformLocation(program, "iChannel3"),
+    ];
+    const uniforms = {
+      iResolution: gl.getUniformLocation(program, "iResolution"),
+      iTime: gl.getUniformLocation(program, "iTime"),
+      iTimeDelta: gl.getUniformLocation(program, "iTimeDelta"),
+      iFrame: gl.getUniformLocation(program, "iFrame"),
+      iMouse: gl.getUniformLocation(program, "iMouse"),
+      iDate: gl.getUniformLocation(program, "iDate"),
+    };
+
+    gl.viewport(0, 0, THUMB_W, THUMB_H);
+    gl.useProgram(program);
+    bindChannelTextures(gl, channelUniforms, channelTextures);
+    gl.uniform3f(uniforms.iResolution, THUMB_W, THUMB_H, 1);
+    gl.uniform1f(uniforms.iTimeDelta, 0);
+    setIDateUniform(gl, uniforms.iDate);
+    gl.uniform4f(uniforms.iMouse, 0, 0, 0, 0);
+    gl.bindVertexArray(vao);
+    gl.pixelStorei(gl.PACK_ALIGNMENT, 1);
+
+    const pixels = new Uint8Array(THUMB_W * THUMB_H * 4);
+    let bestStrict = { t: 0.5, score: -1e9 };
+    let bestLoose = { t: 0.5, varL: -1 };
+
+    for (let ti = 0; ti < THUMB_TIME_CANDIDATES.length; ti++) {
+      const t = THUMB_TIME_CANDIDATES[ti];
+      gl.uniform1f(uniforms.iTime, t);
+      gl.uniform1i(uniforms.iFrame, Math.max(0, Math.floor(t * 60)));
+      gl.drawArrays(gl.TRIANGLES, 0, 6);
+      gl.readPixels(0, 0, THUMB_W, THUMB_H, gl.RGBA, gl.UNSIGNED_BYTE, pixels);
+      const { mean, varL } = sampleThumbStats(pixels, THUMB_W, THUMB_H);
+      if (varL > bestLoose.varL) bestLoose = { t, varL };
+      if (isAcceptableThumb(mean, varL)) {
+        const sc = thumbScore(mean, varL);
+        if (sc > bestStrict.score) bestStrict = { t, score: sc };
+      }
+    }
+
+    const pickT = bestStrict.score > -1e8 ? bestStrict.t : bestLoose.t;
+    gl.uniform1f(uniforms.iTime, pickT);
+    gl.uniform1i(uniforms.iFrame, Math.max(0, Math.floor(pickT * 60)));
+    gl.drawArrays(gl.TRIANGLES, 0, 6);
+    gl.bindVertexArray(null);
+
+    const dataUrl = canvas.toDataURL("image/png");
+    const ext = gl.getExtension("WEBGL_lose_context");
+    if (ext) ext.loseContext();
+    return Promise.resolve(dataUrl);
+  };
+})();