Omit icon sizes field for backward compatibility

- Remove Sizes field from octicons.Icons() to fix compatibility with older MCP clients
- Older clients like Cursor expect sizes to be a string, not an array
- The 2025-11-25 MCP spec changed sizes from string to array
- Omitting the optional Sizes field makes icons compatible with all clients
- Update tests and toolsnaps to reflect the change

Fixes #1644

Co-authored-by: SamMorrowDrums <4811358+SamMorrowDrums@users.noreply.github.com>

Author: Copilot

pkg/github/__toolsnaps__/assign_copilot_to_issue.snap

@@ -31,17 +31,11 @@
     {
       "src": "data:image/png;base64,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",
       "mimeType": "image/png",
-      "sizes": [
-        "24x24"
-      ],
       "theme": "light"
     },
     {
       "src": "data:image/png;base64,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",
       "mimeType": "image/png",
-      "sizes": [
-        "24x24"
-      ],
       "theme": "dark"
     }
   ]

pkg/github/__toolsnaps__/fork_repository.snap

@@ -29,17 +29,11 @@
     {
       "src": "data:image/png;base64,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",
       "mimeType": "image/png",
-      "sizes": [
-        "24x24"
-      ],
       "theme": "light"
     },
     {
       "src": "data:image/png;base64,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",
       "mimeType": "image/png",
-      "sizes": [
-        "24x24"
-      ],
       "theme": "dark"
     }
   ]

pkg/github/__toolsnaps__/merge_pull_request.snap

@@ -47,17 +47,11 @@
     {
       "src": "data:image/png;base64,iVBORw0KGgoAAAANSUhEUgAAABgAAAAYCAYAAADgdz34AAAABmJLR0QA/wD/AP+gvaeTAAACeElEQVRIibWVTUhUYRSGn/e74+iiQih1F9Vcmj9sptylUVBYkO4jcNeuJBdFKxe1CYQokGrRKjCEdtmqwEVmtqomQWeiUdc2EBUtUufe0yLHn1KLGXtX5zvn4zz3vd8f/Gfp90Qs0drmpA6MT1EveDo1NfV92wB+KnMdo39Nfs4L7eSHD5Nz1QJcJYglWtsw+iUehAuRRjO1g+0KHLerbb4OIHnHAC1FdW129s3XmUJuwnBDoOPbA7BwHsD7QWq1HKYN5msBRCpB1AueLoSROSkciSUyj5ClhE6BLtYC8CpBqVRabNrdMmIiJdQjuUbQ1WI+d78WwIbykxnzU9np7ejlNq2YxQ4ebNtTKyCyWcEgYl55EDj/a7ihFEtkLkr0As2YxjwL+9aem00dCEYNzvnJzLDvH27aaM5y80HEnKGHKGwPnEbT6fSOvzpAmrDQnkncpC7siiUzz2QqIPu25iOuGBorTufO/AJmH0v2ajHwuoHhrQHATOH9rQPJ7IjDLgs6kZ0F6it1AzArVcZLdUE+WnYgmv/uYFmz+dxH4NJGNT+RfYLCE7F4tn0pGkxHy94AmBm8/GfAVvIs7AukUTkbj5YdYIbZ9WJh8m1lzrrbNB4/tD+QuyPsdCibF26gmM/dY/NdRDqd3rEYeN04mswYL+ZXm68DxOPxnWXXMClsp+GGhCWBTtClYj53t1qXK78oVH2XYB/mHZ0pvHsN4Cczzw3rBaoGrJ6D5ZUvN1i+kjI0LWiptjmscbC88hZZCAf2trZeq1v0UsJ6wF7UAlhxUMxPvkW6AboQLbvPcjaO+BIx11cL4I9H308eOiLRQUhpOx79/66fNKzrOCYNDm0AAAAASUVORK5CYII=",
       "mimeType": "image/png",
-      "sizes": [
-        "24x24"
-      ],
       "theme": "light"
     },
     {
       "src": "data:image/png;base64,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",
       "mimeType": "image/png",
-      "sizes": [
-        "24x24"
-      ],
       "theme": "dark"
     }
   ]

pkg/github/__toolsnaps__/request_copilot_review.snap

@@ -30,17 +30,11 @@
     {
       "src": "data:image/png;base64,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",
       "mimeType": "image/png",
-      "sizes": [
-        "24x24"
-      ],
       "theme": "light"
     },
     {
       "src": "data:image/png;base64,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",
       "mimeType": "image/png",
-      "sizes": [
-        "24x24"
-      ],
       "theme": "dark"
     }
   ]

pkg/github/__toolsnaps__/star_repository.snap

@@ -25,17 +25,11 @@
     {
       "src": "data:image/png;base64,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",
       "mimeType": "image/png",
-      "sizes": [
-        "24x24"
-      ],
       "theme": "light"
     },
     {
       "src": "data:image/png;base64,iVBORw0KGgoAAAANSUhEUgAAABgAAAAYCAYAAADgdz34AAAABmJLR0QA/wD/AP+gvaeTAAABLElEQVRIidWVTUrDQBiG3ylddNG9+IdRMC7qpgfoWTyCnqFLF/62UMGNWw/gTdwoiMUzaCtoHxeZ4BQn6SQdEV8IZPG9zzMzCYlUIcARcFilUwW+AUyBd2DrNwSXfOciNnwVeHMEE2A9puCMnzmNBV8BXj2CCbC2LLwFDDzwPAOgVcYwFpRI6khKJe0616akxoJ1zCS9SHp0rgdJ98aYZ2PhT7ksYpC005A0lnQdGS7LHGcqMMB5yVlXzQiYP1orOYkAHwLFxw30l4AfBx1eTUk/+OkA2zUEiY9V9I7vB69mQefPBJ0aAm+nWWH4Q9KNvT/wdMN2DTTJ/lx5ZsAtsOfMJMAV8OnMTYGiBc8JUqd0B3RLZrt2Jk8aImiTfTZ6QVvOOj3baYd2/k++AC+3Yx0GcXS0AAAAAElFTkSuQmCC",
       "mimeType": "image/png",
-      "sizes": [
-        "24x24"
-      ],
       "theme": "dark"
     }
   ]

pkg/octicons/octicons.go

@@ -62,6 +62,9 @@ func DataURI(name string, theme Theme) string {
 // Icons are embedded as 24x24 PNG data URIs for offline use and faster loading.
 // The name should be the base octicon name without size suffix (e.g., "repo" not "repo-16").
 // See https://primer.style/foundations/icons for available icons.
+//
+// Note: The Sizes field is omitted for backward compatibility with older MCP clients
+// that expect it to be a string rather than an array per the 2025-11-25 MCP spec.
 func Icons(name string) []mcp.Icon {
 	if name == "" {
 		return nil
@@ -70,13 +73,11 @@ func Icons(name string) []mcp.Icon {
 		{
 			Source:   DataURI(name, ThemeLight),
 			MIMEType: "image/png",
-			Sizes:    []string{"24x24"},
 			Theme:    string(ThemeLight),
 		},
 		{
 			Source:   DataURI(name, ThemeDark),
 			MIMEType: "image/png",
-			Sizes:    []string{"24x24"},
 			Theme:    string(ThemeDark),
 		},
 	}

pkg/octicons/octicons_test.go

@@ -86,13 +86,13 @@ func TestIcons(t *testing.T) {
 			// Verify first icon is light theme
 			assert.Equal(t, DataURI(tc.icon, ThemeLight), result[0].Source)
 			assert.Equal(t, "image/png", result[0].MIMEType)
-			assert.Equal(t, []string{"24x24"}, result[0].Sizes)
+			assert.Empty(t, result[0].Sizes) // Sizes field omitted for backward compatibility
 			assert.Equal(t, "light", result[0].Theme)
 
 			// Verify second icon is dark theme
 			assert.Equal(t, DataURI(tc.icon, ThemeDark), result[1].Source)
 			assert.Equal(t, "image/png", result[1].MIMEType)
-			assert.Equal(t, []string{"24x24"}, result[1].Sizes)
+			assert.Empty(t, result[1].Sizes) // Sizes field omitted for backward compatibility
 			assert.Equal(t, "dark", result[1].Theme)
 		})
 	}