diff --git a/docs/checklist-manual-testing.md b/docs/checklist-manual-testing.md
index 8c8db06..27ade45 100644
--- a/docs/checklist-manual-testing.md
+++ b/docs/checklist-manual-testing.md
@@ -12,6 +12,9 @@
 
 ## A. Краевые PNG-файлы
 
+> Фикстуры для этого раздела генерируются скриптом: `pnpm generate:fixtures` →
+> `tests/fixtures/manual-edge-cases/`.
+
 - [ ] Огромное изображение (мегапиксели) — загрузка не висит, прогресс есть.
 - [ ] PNG 1×1 — инструменты не падают (проверено авто: flip-png, см. suite).
 - [ ] PNG с полупрозрачностью/чётким альфа-краёв (чёрно-белая шахматка) —
@@ -23,6 +26,31 @@
 - [ ] PNG с битой CRCh / 16-bit — как ведут себя анализаторы (ориентация,
       размер, прозрачность).
 
+### Файлы (`tests/fixtures/manual-edge-cases/`)
+
+| Файл                     | Описание                                                     |
+| ------------------------ | ------------------------------------------------------------ |
+| `1x1.png`                | Минимальное изображение 1×1, сплошной красный                |
+| `1x1-transparent.png`    | 1×1, полностью прозрачный (alpha=0)                          |
+| `2x2-extreme.png`        | 2×2: чёрный, белый, полупрозрачный красный, прозрачный синий |
+| `1024x1024-checker.png`  | 1024×1024, шахматка ≈1 мегапиксель                           |
+| `1920x1080-gradient.png` | 1920×1080, градиент ≈2 мегапикселя                           |
+| `alpha-checkerboard.png` | 64×64, чёрно-белая шахматка с чередующейся альфой            |
+| `alpha-gradient.png`     | 128×64, альфа-градиент 0→255 по ширине                       |
+| `sparse-alpha.png`       | 100×100, 10% пикселей с alpha=0                              |
+| `all-black-opaque.png`   | 64×64, сплошной чёрный                                       |
+| `all-white-opaque.png`   | 64×64, сплошной белый                                        |
+| `all-transparent.png`    | 64×64, полностью прозрачное                                  |
+| `palette-4colors.png`    | 32×32, палитровый 4 цвета (RGBW)                             |
+| `palette-256.png`        | 64×64, палитровый полная палитра 256 цветов                  |
+| `16bit-subtle.png`       | 32×32, 16-bit RGBA, тонкий градиент                          |
+| `noise-pattern.png`      | 100×100, шумовая текстура                                    |
+| `1x4000-strip.png`       | 1×4000, длинная вертикальная полоса                          |
+| `4000x1-strip.png`       | 4000×1, широкая горизонтальная полоса                        |
+| `corrupt-bad-crc.png`    | 4×4, повреждённый CRC в IDAT                                 |
+| `truncated.png`          | Обрезанный файл (только PNG-заголовок + часть IHDR)          |
+| `fake-png.txt`           | Текстовый файл «.png» — не-PNG                               |
+
 ## B. Края параметров
 
 - [ ] Экстремальные значения слайдеров (0 и max) в blur/sharpen/pixelate — не
diff --git a/package.json b/package.json
index 901e5bf..9462b3f 100644
--- a/package.json
+++ b/package.json
@@ -9,7 +9,8 @@
     "build": "pnpm --dir web build",
     "format": "pnpm format:docs && pnpm --dir web format",
     "format:docs": "prettier --write docs --log-level warn",
-    "check:docs": "prettier --check docs"
+    "check:docs": "prettier --check docs",
+    "generate:fixtures": "node tests/fixtures/manual-edge-cases/generate.mjs"
   },
   "keywords": [],
   "author": "Ku6epXBOCTuK",
diff --git a/tests/fixtures/manual-edge-cases/1024x1024-checker.png b/tests/fixtures/manual-edge-cases/1024x1024-checker.png
new file mode 100644
index 0000000..7377e3c
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diff --git a/tests/fixtures/manual-edge-cases/16bit-subtle.png b/tests/fixtures/manual-edge-cases/16bit-subtle.png
new file mode 100644
index 0000000..237e2dc
Binary files /dev/null and b/tests/fixtures/manual-edge-cases/16bit-subtle.png differ
diff --git a/tests/fixtures/manual-edge-cases/1920x1080-gradient.png b/tests/fixtures/manual-edge-cases/1920x1080-gradient.png
new file mode 100644
index 0000000..8e5c67b
Binary files /dev/null and b/tests/fixtures/manual-edge-cases/1920x1080-gradient.png differ
diff --git a/tests/fixtures/manual-edge-cases/1x1-transparent.png b/tests/fixtures/manual-edge-cases/1x1-transparent.png
new file mode 100644
index 0000000..35a340b
Binary files /dev/null and b/tests/fixtures/manual-edge-cases/1x1-transparent.png differ
diff --git a/tests/fixtures/manual-edge-cases/1x1.png b/tests/fixtures/manual-edge-cases/1x1.png
new file mode 100644
index 0000000..cf5d589
Binary files /dev/null and b/tests/fixtures/manual-edge-cases/1x1.png differ
diff --git a/tests/fixtures/manual-edge-cases/1x4000-strip.png b/tests/fixtures/manual-edge-cases/1x4000-strip.png
new file mode 100644
index 0000000..71bc5f5
Binary files /dev/null and b/tests/fixtures/manual-edge-cases/1x4000-strip.png differ
diff --git a/tests/fixtures/manual-edge-cases/2x2-extreme.png b/tests/fixtures/manual-edge-cases/2x2-extreme.png
new file mode 100644
index 0000000..fce1969
Binary files /dev/null and b/tests/fixtures/manual-edge-cases/2x2-extreme.png differ
diff --git a/tests/fixtures/manual-edge-cases/4000x1-strip.png b/tests/fixtures/manual-edge-cases/4000x1-strip.png
new file mode 100644
index 0000000..ee2dd6e
Binary files /dev/null and b/tests/fixtures/manual-edge-cases/4000x1-strip.png differ
diff --git a/tests/fixtures/manual-edge-cases/all-black-opaque.png b/tests/fixtures/manual-edge-cases/all-black-opaque.png
new file mode 100644
index 0000000..2d0b013
Binary files /dev/null and b/tests/fixtures/manual-edge-cases/all-black-opaque.png differ
diff --git a/tests/fixtures/manual-edge-cases/all-transparent.png b/tests/fixtures/manual-edge-cases/all-transparent.png
new file mode 100644
index 0000000..0858c19
Binary files /dev/null and b/tests/fixtures/manual-edge-cases/all-transparent.png differ
diff --git a/tests/fixtures/manual-edge-cases/all-white-opaque.png b/tests/fixtures/manual-edge-cases/all-white-opaque.png
new file mode 100644
index 0000000..5400ae8
Binary files /dev/null and b/tests/fixtures/manual-edge-cases/all-white-opaque.png differ
diff --git a/tests/fixtures/manual-edge-cases/alpha-checkerboard.png b/tests/fixtures/manual-edge-cases/alpha-checkerboard.png
new file mode 100644
index 0000000..31e7c4d
Binary files /dev/null and b/tests/fixtures/manual-edge-cases/alpha-checkerboard.png differ
diff --git a/tests/fixtures/manual-edge-cases/alpha-gradient.png b/tests/fixtures/manual-edge-cases/alpha-gradient.png
new file mode 100644
index 0000000..1ea28da
Binary files /dev/null and b/tests/fixtures/manual-edge-cases/alpha-gradient.png differ
diff --git a/tests/fixtures/manual-edge-cases/corrupt-bad-crc.png b/tests/fixtures/manual-edge-cases/corrupt-bad-crc.png
new file mode 100644
index 0000000..6ff7570
Binary files /dev/null and b/tests/fixtures/manual-edge-cases/corrupt-bad-crc.png differ
diff --git a/tests/fixtures/manual-edge-cases/fake-png.txt b/tests/fixtures/manual-edge-cases/fake-png.txt
new file mode 100644
index 0000000..003e76d
--- /dev/null
+++ b/tests/fixtures/manual-edge-cases/fake-png.txt
@@ -0,0 +1 @@
+this is definitely not a png file
\ No newline at end of file
diff --git a/tests/fixtures/manual-edge-cases/generate.mjs b/tests/fixtures/manual-edge-cases/generate.mjs
new file mode 100644
index 0000000..3e0b2db
--- /dev/null
+++ b/tests/fixtures/manual-edge-cases/generate.mjs
@@ -0,0 +1,329 @@
+import { deflateSync } from "node:zlib";
+import { writeFileSync, mkdirSync } from "node:fs";
+import { join, dirname } from "node:path";
+import { fileURLToPath } from "node:url";
+
+const __dirname = dirname(fileURLToPath(import.meta.url));
+
+const CRC_TABLE = (() => {
+  const table = new Uint32Array(256);
+  for (let n = 0; n < 256; n++) {
+    let c = n;
+    for (let k = 0; k < 8; k++) c = c & 1 ? 0xedb88320 ^ (c >>> 1) : c >>> 1;
+    table[n] = c >>> 0;
+  }
+  return table;
+})();
+
+function crc32(data) {
+  let c = 0xffffffff;
+  for (let i = 0; i < data.length; i++)
+    c = CRC_TABLE[(c ^ data[i]) & 0xff] ^ (c >>> 8);
+  return (c ^ 0xffffffff) >>> 0;
+}
+
+function chunk(type, data) {
+  const out = Buffer.alloc(8 + data.length + 4);
+  out.writeUInt32BE(data.length, 0);
+  out.write(type, 4, "ascii");
+  data.copy(out, 8);
+  out.writeUInt32BE(crc32(out.subarray(4, 8 + data.length)), 8 + data.length);
+  return out;
+}
+
+function makePng(width, height, pixelAt) {
+  const sig = Buffer.from([137, 80, 78, 71, 13, 10, 26, 10]);
+  const ihdr = Buffer.alloc(13);
+  ihdr.writeUInt32BE(width, 0);
+  ihdr.writeUInt32BE(height, 4);
+  ihdr[8] = 8; // bit depth
+  ihdr[9] = 6; // color type RGBA
+  ihdr[10] = 0; // compression
+  ihdr[11] = 0; // filter
+  ihdr[12] = 0; // interlace
+  const stride = width * 4 + 1;
+  const raw = Buffer.alloc(height * stride);
+  for (let y = 0; y < height; y++) {
+    raw[y * stride] = 0; // filter: none
+    for (let x = 0; x < width; x++) {
+      const [r, g, b, a] = pixelAt(x, y);
+      const p = y * stride + 1 + x * 4;
+      raw[p] = r;
+      raw[p + 1] = g;
+      raw[p + 2] = b;
+      raw[p + 3] = a;
+    }
+  }
+  return Buffer.concat([
+    sig,
+    chunk("IHDR", ihdr),
+    chunk("IDAT", deflateSync(raw)),
+    chunk("IEND", Buffer.alloc(0)),
+  ]);
+}
+
+function makePalettePng(width, height, palette, pixelAt) {
+  const sig = Buffer.from([137, 80, 78, 71, 13, 10, 26, 10]);
+  const ihdr = Buffer.alloc(13);
+  ihdr.writeUInt32BE(width, 0);
+  ihdr.writeUInt32BE(height, 4);
+  ihdr[8] = 8; // bit depth
+  ihdr[9] = 3; // color type: indexed
+  ihdr[10] = 0;
+  ihdr[11] = 0;
+  ihdr[12] = 0;
+
+  // PLTE: palette entries (R,G,B × count), padded to multiple of 3
+  const plteData = Buffer.alloc(256 * 3);
+  for (let i = 0; i < palette.length && i < 256; i++) {
+    plteData[i * 3] = palette[i][0];
+    plteData[i * 3 + 1] = palette[i][1];
+    plteData[i * 3 + 2] = palette[i][2];
+  }
+
+  // Raw image data: 1 byte per pixel (index)
+  const stride = width + 1;
+  const raw = Buffer.alloc(height * stride);
+  for (let y = 0; y < height; y++) {
+    raw[y * stride] = 0;
+    for (let x = 0; x < width; x++) {
+      raw[y * stride + 1 + x] = pixelAt(x, y);
+    }
+  }
+
+  return Buffer.concat([
+    sig,
+    chunk("IHDR", ihdr),
+    chunk("PLTE", plteData),
+    chunk("IDAT", deflateSync(raw)),
+    chunk("IEND", Buffer.alloc(0)),
+  ]);
+}
+
+function make16bitPng(width, height, pixelAt) {
+  const sig = Buffer.from([137, 80, 78, 71, 13, 10, 26, 10]);
+  const ihdr = Buffer.alloc(13);
+  ihdr.writeUInt32BE(width, 0);
+  ihdr.writeUInt32BE(height, 4);
+  ihdr[8] = 16; // bit depth
+  ihdr[9] = 6; // color type RGBA
+  ihdr[10] = 0;
+  ihdr[11] = 0;
+  ihdr[12] = 0;
+
+  const stride = width * 8 + 1;
+  const raw = Buffer.alloc(height * stride);
+  for (let y = 0; y < height; y++) {
+    raw[y * stride] = 0;
+    for (let x = 0; x < width; x++) {
+      const [r, g, b, a] = pixelAt(x, y);
+      const p = y * stride + 1 + x * 8;
+      raw.writeUInt16BE(r, p);
+      raw.writeUInt16BE(g, p + 2);
+      raw.writeUInt16BE(b, p + 4);
+      raw.writeUInt16BE(a, p + 6);
+    }
+  }
+
+  return Buffer.concat([
+    sig,
+    chunk("IHDR", ihdr),
+    chunk("IDAT", deflateSync(raw)),
+    chunk("IEND", Buffer.alloc(0)),
+  ]);
+}
+
+function makeCorruptPng() {
+  const sig = Buffer.from([137, 80, 78, 71, 13, 10, 26, 10]);
+  const ihdr = Buffer.alloc(13);
+  ihdr.writeUInt32BE(4, 0);
+  ihdr.writeUInt32BE(4, 4);
+  ihdr[8] = 8;
+  ihdr[9] = 2; // RGB
+  ihdr[10] = 0;
+  ihdr[11] = 0;
+  ihdr[12] = 0;
+
+  const stride = 4 * 3 + 1;
+  const raw = Buffer.alloc(4 * stride);
+  for (let y = 0; y < 4; y++) {
+    raw[y * stride] = 0;
+    for (let x = 0; x < 4; x++) {
+      const p = y * stride + 1 + x * 3;
+      raw[p] = 255;
+      raw[p + 1] = 0;
+      raw[p + 2] = 0;
+    }
+  }
+
+  const idat = chunk("IDAT", deflateSync(raw));
+  // Corrupt CRC: flip a byte in the CRC field
+  idat[idat.length - 1] ^= 0xff;
+
+  return Buffer.concat([sig, chunk("IHDR", ihdr), idat, chunk("IEND", Buffer.alloc(0))]);
+}
+
+function makeTruncatedPng() {
+  return Buffer.from([137, 80, 78, 71, 13, 10, 26, 10, 0, 0, 0, 13, 73, 72, 68, 82]);
+}
+
+const outDir = join(__dirname);
+
+// 1. PNG 1×1
+writeFileSync(join(outDir, "1x1.png"), makePng(1, 1, () => [255, 0, 0, 255]));
+
+// 2. PNG 1×1 fully transparent
+writeFileSync(
+  join(outDir, "1x1-transparent.png"),
+  makePng(1, 1, () => [0, 0, 0, 0]),
+);
+
+// 3. Large 1024×1024 checkerboard (≈1 megapixel RGBA)
+writeFileSync(
+  join(outDir, "1024x1024-checker.png"),
+  makePng(1024, 1024, (x, y) =>
+    x % 2 === y % 2 ? [255, 0, 0, 255] : [255, 255, 255, 255],
+  ),
+);
+
+// 4. 1920×1080 gradient (≈2 megapixels, tests larger displays)
+writeFileSync(
+  join(outDir, "1920x1080-gradient.png"),
+  makePng(1920, 1080, (x, y) => [
+    Math.floor((x / 1920) * 255),
+    Math.floor((y / 1080) * 255),
+    128,
+    255,
+  ]),
+);
+
+// 5. Transparency checkerboard (black/white with alpha pattern)
+writeFileSync(
+  join(outDir, "alpha-checkerboard.png"),
+  makePng(64, 64, (x, y) => {
+    const alpha = (x + y) % 3 === 0 ? 0 : 255;
+    const base = (x % 2 === y % 2) ? 0 : 255;
+    return [base, base, base, alpha];
+  }),
+);
+
+// 6. Palette / indexed-color PNG (4 colors: red, green, blue, white)
+const palette = [
+  [255, 0, 0],
+  [0, 255, 0],
+  [0, 0, 255],
+  [255, 255, 255],
+];
+writeFileSync(
+  join(outDir, "palette-4colors.png"),
+  makePalettePng(32, 32, palette, (x, y) => {
+    const idx = (Math.floor(x / 8) + Math.floor(y / 8)) % palette.length;
+    return idx;
+  }),
+);
+
+// 7. Palette with many colors (256-color full palette)
+const fullPalette = Array.from({ length: 256 }, (_, i) => [
+  i,
+  (i * 3) % 256,
+  (i * 7) % 256,
+]);
+writeFileSync(
+  join(outDir, "palette-256.png"),
+  makePalettePng(64, 64, fullPalette, (x, y) => (x + y * 64) % 256),
+);
+
+// 8. 16-bit RGBA PNG (subtle gradient to test high bit depth)
+writeFileSync(
+  join(outDir, "16bit-subtle.png"),
+  make16bitPng(32, 32, (x, y) => [
+    Math.floor((x / 32) * 65535),
+    Math.floor((y / 32) * 65535),
+    32768,
+    65535,
+  ]),
+);
+
+// 9. Corrupt PNG (bad CRC in IDAT)
+writeFileSync(join(outDir, "corrupt-bad-crc.png"), makeCorruptPng());
+
+// 10. Truncated PNG (only header, no data)
+writeFileSync(join(outDir, "truncated.png"), makeTruncatedPng());
+
+// 11. Non-PNG file disguised as PNG
+writeFileSync(
+  join(outDir, "fake-png.txt"),
+  Buffer.from("this is definitely not a png file"),
+);
+
+// 12. All-black fully opaque
+writeFileSync(
+  join(outDir, "all-black-opaque.png"),
+  makePng(64, 64, () => [0, 0, 0, 255]),
+);
+
+// 13. All-white fully opaque
+writeFileSync(
+  join(outDir, "all-white-opaque.png"),
+  makePng(64, 64, () => [255, 255, 255, 255]),
+);
+
+// 14. All-transparent
+writeFileSync(
+  join(outDir, "all-transparent.png"),
+  makePng(64, 64, () => [0, 0, 0, 0]),
+);
+
+// 15. Semi-transparent gradient (alpha 0→255 across width)
+writeFileSync(
+  join(outDir, "alpha-gradient.png"),
+  makePng(128, 64, (x, y) => [
+    0,
+    100,
+    255,
+    Math.floor((x / 128) * 255),
+  ]),
+);
+
+// 16. Noise pattern (random-ish pixels)
+writeFileSync(
+  join(outDir, "noise-pattern.png"),
+  makePng(100, 100, (x, y) => {
+    const v = ((x * 7919 + y * 104729) % 256);
+    return [v, (v * 3) % 256, (v * 7) % 256, 255];
+  }),
+);
+
+// 17. Minimal size: 2×2 with extreme colors
+writeFileSync(
+  join(outDir, "2x2-extreme.png"),
+  makePng(2, 2, (x, y) => {
+    if (x === 0 && y === 0) return [0, 0, 0, 255];
+    if (x === 1 && y === 0) return [255, 255, 255, 255];
+    if (x === 0 && y === 1) return [255, 0, 0, 128];
+    return [0, 0, 255, 0];
+  }),
+);
+
+// 18. Long strip (1×4000) — tests scroll / vertical tools
+writeFileSync(
+  join(outDir, "1x4000-strip.png"),
+  makePng(1, 4000, (x, y) => [y % 256, (y * 2) % 256, (y * 3) % 256, 255]),
+);
+
+// 19. Wide strip (4000×1) — tests horizontal handling
+writeFileSync(
+  join(outDir, "4000x1-strip.png"),
+  makePng(4000, 1, (x, y) => [x % 256, (x * 2) % 256, (x * 3) % 256, 255]),
+);
+
+// 20. PNG with very high alpha variance (sparse transparency)
+writeFileSync(
+  join(outDir, "sparse-alpha.png"),
+  makePng(100, 100, (x, y) => {
+    const sparse = ((x * 31 + y * 17) % 100) < 10;
+    return [sparse ? 0 : 100, sparse ? 0 : 200, 255, sparse ? 0 : 255];
+  }),
+);
+
+console.log("Generated 20 edge case PNG files in:", outDir);
diff --git a/tests/fixtures/manual-edge-cases/noise-pattern.png b/tests/fixtures/manual-edge-cases/noise-pattern.png
new file mode 100644
index 0000000..9ffbe24
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diff --git a/tests/fixtures/manual-edge-cases/palette-256.png b/tests/fixtures/manual-edge-cases/palette-256.png
new file mode 100644
index 0000000..92ae1ac
Binary files /dev/null and b/tests/fixtures/manual-edge-cases/palette-256.png differ
diff --git a/tests/fixtures/manual-edge-cases/palette-4colors.png b/tests/fixtures/manual-edge-cases/palette-4colors.png
new file mode 100644
index 0000000..2396aff
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diff --git a/tests/fixtures/manual-edge-cases/sparse-alpha.png b/tests/fixtures/manual-edge-cases/sparse-alpha.png
new file mode 100644
index 0000000..5d07093
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diff --git a/tests/fixtures/manual-edge-cases/truncated.png b/tests/fixtures/manual-edge-cases/truncated.png
new file mode 100644
index 0000000..029ace0
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