diff --git a/apps/api/src/lib/format-decoders.ts b/apps/api/src/lib/format-decoders.ts
index 91c05f00..333aa085 100644
--- a/apps/api/src/lib/format-decoders.ts
+++ b/apps/api/src/lib/format-decoders.ts
@@ -24,6 +24,9 @@ const CLI_DECODED_FORMATS = new Set([
   "dds",
   "cur",
   "dpx",
+  "ppm",
+  "pgm",
+  "pbm",
   "fits",
 ]);
 
@@ -78,6 +81,11 @@ export async function decodeToSharpCompat(
       return decodeFits(buffer);
     case "qoi":
       return decodeQoi(buffer);
+    case "ppm":
+    case "pgm":
+    case "pbm":
+      return decodeNetpbm(buffer, format);
+      return decodeQoi(buffer);
     default:
       return buffer;
   }
@@ -452,3 +460,27 @@ async function decodeQoi(buffer: Buffer): Promise<Buffer> {
     .png()
     .toBuffer();
 }
+
+// ── Netpbm (PPM/PGM/PBM) decoder ──
+
+async function decodeNetpbm(buffer: Buffer, format: string): Promise<Buffer> {
+  try {
+    return await sharp(buffer).png().toBuffer();
+  } catch {
+    const cmd = await findMagickCmd();
+    const id = randomUUID();
+    const ext = format === "pgm" ? "pgm" : format === "pbm" ? "pbm" : "ppm";
+    const inputPath = join(tmpdir(), `netpbm-in-${id}.${ext}`);
+    const outputPath = join(tmpdir(), `netpbm-out-${id}.png`);
+    try {
+      await writeFile(inputPath, buffer);
+      await execFileAsync(cmd, magickArgs(cmd, [inputPath, `png:${outputPath}`]), {
+        timeout: 120_000,
+      });
+      return await readFile(outputPath);
+    } finally {
+      await rm(inputPath, { force: true }).catch(() => {});
+      await rm(outputPath, { force: true }).catch(() => {});
+    }
+  }
+}
diff --git a/tests/fixtures/formats/sample.qoi b/tests/fixtures/formats/sample.qoi
new file mode 100644
index 00000000..6605fb53
Binary files /dev/null and b/tests/fixtures/formats/sample.qoi differ
diff --git a/tests/integration/format-matrix.test.ts b/tests/integration/format-matrix.test.ts
index 0cc00b30..8ec2f96c 100644
--- a/tests/integration/format-matrix.test.ts
+++ b/tests/integration/format-matrix.test.ts
@@ -207,7 +207,7 @@ const FORMAT_SAMPLES: FormatSample[] = [
     name: "PPM",
     file: "sample.ppm",
     mime: "image/x-portable-pixmap",
-    needsCliDecoder: false,
+    needsCliDecoder: true,
     needsHeifDecoder: false,
     mayFailValidation: false,
   },
@@ -215,7 +215,7 @@ const FORMAT_SAMPLES: FormatSample[] = [
     name: "PGM",
     file: "sample.pgm",
     mime: "image/x-portable-graymap",
-    needsCliDecoder: false,
+    needsCliDecoder: true,
     needsHeifDecoder: false,
     mayFailValidation: false,
   },
@@ -223,7 +223,7 @@ const FORMAT_SAMPLES: FormatSample[] = [
     name: "PBM",
     file: "sample.pbm",
     mime: "image/x-portable-bitmap",
-    needsCliDecoder: false,
+    needsCliDecoder: true,
     needsHeifDecoder: false,
     mayFailValidation: false,
   },
@@ -267,6 +267,14 @@ const FORMAT_SAMPLES: FormatSample[] = [
     needsHeifDecoder: false,
     mayFailValidation: false,
   },
+  {
+    name: "QOI",
+    file: "sample.qoi",
+    mime: "image/x-qoi",
+    needsCliDecoder: true,
+    needsHeifDecoder: false,
+    mayFailValidation: false,
+  },
 ];
 
 // ---------------------------------------------------------------------------