fix(validate): only recommend 512x512 icon size when the icon isn't already 512x512

src/node/validate.ts

@@ -13,6 +13,8 @@ import {
 import { getManifestVersionFromRawData } from "../shared/manifestVersionResolve.js";
 import { getAllFilesWithCount, readMcpbIgnorePatterns } from "./files.js";
 
+const RECOMMENDED_ICON_SIZE = 512;
+
 /**
  * Check if a buffer contains a valid PNG file signature
  */
@@ -31,6 +33,33 @@ function isPNG(buffer: Buffer): boolean {
   );
 }
 
+/**
+ * Read the pixel dimensions of a PNG from its IHDR chunk.
+ *
+ * The IHDR chunk is required by the spec to be the first chunk and to
+ * immediately follow the 8-byte signature: a 4-byte length, the "IHDR" type,
+ * then the 4-byte big-endian width and height. Returns null if the buffer is
+ * too short or the IHDR chunk is not where the spec requires it to be.
+ */
+function getPNGDimensions(
+  buffer: Buffer,
+): { width: number; height: number } | null {
+  // 8 (signature) + 4 (length) + 4 (type) + 4 (width) + 4 (height) = 24
+  if (buffer.length < 24) {
+    return null;
+  }
+
+  // Bytes 12-15 must spell "IHDR" for the width/height offsets to be valid.
+  if (buffer.toString("ascii", 12, 16) !== "IHDR") {
+    return null;
+  }
+
+  return {
+    width: buffer.readUInt32BE(16),
+    height: buffer.readUInt32BE(20),
+  };
+}
+
 /**
  * Validate icon field in manifest
  * @param iconPath - The icon path from manifest.json
@@ -89,10 +118,19 @@ function validateIcon(
             `Icon file must be PNG format. The file at "${iconPath}" does not appear to be a valid PNG file.`,
           );
         } else {
-          // File exists and is a valid PNG - add recommendation
-          warnings.push(
-            "Icon validation passed. Recommended size is 512×512 pixels for best display in Claude Desktop.",
-          );
+          // File exists and is a valid PNG. Only recommend a different size
+          // when the icon is not already at the recommended dimensions.
+          const dimensions = getPNGDimensions(buffer);
+          if (
+            dimensions &&
+            (dimensions.width !== RECOMMENDED_ICON_SIZE ||
+              dimensions.height !== RECOMMENDED_ICON_SIZE)
+          ) {
+            warnings.push(
+              `Icon is ${dimensions.width}×${dimensions.height} pixels. ` +
+                `Recommended size is ${RECOMMENDED_ICON_SIZE}×${RECOMMENDED_ICON_SIZE} pixels for best display in Claude Desktop.`,
+            );
+          }
         }
       } catch (error) {
         errors.push(

test/icon-validation.test.ts

@@ -87,6 +87,61 @@ describe("Icon Validation", () => {
     ]);
     fs.writeFileSync(join(testFixturesDir, "valid-icon.png"), validPngBuffer);
 
+    // Create a valid PNG file declaring the recommended 512x512 dimensions.
+    // Only the signature and the IHDR width/height are read by validation, so
+    // a minimal chunk layout is enough to exercise the size check.
+    const recommendedSizePngBuffer = Buffer.from([
+      0x89,
+      0x50,
+      0x4e,
+      0x47,
+      0x0d,
+      0x0a,
+      0x1a,
+      0x0a, // PNG signature
+      0x00,
+      0x00,
+      0x00,
+      0x0d,
+      0x49,
+      0x48,
+      0x44,
+      0x52, // IHDR chunk
+      0x00,
+      0x00,
+      0x02,
+      0x00,
+      0x00,
+      0x00,
+      0x02,
+      0x00, // 512x512 dimensions
+      0x08,
+      0x06,
+      0x00,
+      0x00,
+      0x00,
+      0x1f,
+      0x15,
+      0xc4,
+      0x89, // IHDR data + CRC
+      0x00,
+      0x00,
+      0x00,
+      0x00,
+      0x49,
+      0x45,
+      0x4e,
+      0x44, // IEND chunk
+      0xae,
+      0x42,
+      0x60,
+      0x82,
+    ]);
+    fs.writeFileSync(
+      join(testFixturesDir, "recommended-size-icon.png"),
+      recommendedSizePngBuffer,
+    );
+
     // Create an invalid (non-PNG) file
     fs.writeFileSync(
       join(testFixturesDir, "invalid-icon.jpg"),
@@ -102,6 +157,10 @@ describe("Icon Validation", () => {
       icon: "valid-icon.png",
     });
 
+    createTestManifest("recommended-size-icon.json", {
+      icon: "recommended-size-icon.png",
+    });
+
     createTestManifest("invalid-remote-url.json", {
       icon: "https://example.com/icon.png",
     });
@@ -161,14 +220,28 @@ describe("Icon Validation", () => {
   }
 
   describe("Valid icon configurations", () => {
-    it("should pass validation with a valid local PNG icon", () => {
+    it("should recommend the standard size for a PNG that is not 512x512", () => {
       const manifestPath = join(testFixturesDir, "valid-local-icon.json");
       const result = execSync(`node ${cliPath} validate ${manifestPath}`, {
         encoding: "utf-8",
       });
 
       expect(result).toContain("Manifest schema validation passes!");
-      expect(result).toContain("Icon validation passed");
+      expect(result).toContain("Icon validation warnings");
+      expect(result).toContain("Icon is 1×1 pixels");
+      expect(result).toContain("Recommended size is 512×512 pixels");
+      expect(result).not.toContain("ERROR");
+    });
+
+    it("should not recommend a size when the PNG is already 512x512", () => {
+      const manifestPath = join(testFixturesDir, "recommended-size-icon.json");
+      const result = execSync(`node ${cliPath} validate ${manifestPath}`, {
+        encoding: "utf-8",
+      });
+
+      expect(result).toContain("Manifest schema validation passes!");
+      expect(result).not.toContain("Recommended size");
+      expect(result).not.toContain("ERROR");
     });
 
     it("should pass validation when no icon is specified", () => {
@@ -326,7 +399,7 @@ describe("Icon Validation", () => {
       });
 
       expect(result).toContain("Manifest schema validation passes!");
-      expect(result).toContain("Icon validation passed");
+      expect(result).not.toContain("ERROR");
     });
   });
 });