fix(repos): return a resource link for files over 1 MB in get_file_contents (#3419)

The Contents API returns files over 1 MB with an empty content field and encoding "none". Since the symlink read checks, get_file_contents tried to decode that content and failed with "unsupported content encoding: none" before reaching the large-file branch. Treat that response as content not available so the tool returns the resource link again.

Co-authored-by: Iryna Kulakova <52420926+IrynaKulakova@users.noreply.github.com>

Author: jayhemnani9910

pkg/github/repositories_helper.go

@@ -214,7 +214,8 @@ func inspectRepositoryFile(ctx context.Context, client *github.Client, owner, re
 }
 
 func repositoryContentBytes(file *github.RepositoryContent) ([]byte, bool, error) {
-	if file.Content == nil {
+	// Files over 1 MB come back with encoding "none" and no content.
+	if file.Content == nil || file.GetEncoding() == "none" {
 		return []byte{}, file.GetType() != "symlink" && file.GetSize() == 0, nil
 	}
 	content, err := file.GetContent()

pkg/github/repositories_test.go

@@ -795,6 +795,22 @@ func Test_GetFileContents_ContentlessRequestCounts(t *testing.T) {
 		require.True(t, ok)
 	})
 
+	t.Run("large file with encoding none", func(t *testing.T) {
+		result, requests := runRepositoryReadFixture(t, repositoryReadFixture{
+			contents: &github.RepositoryContent{
+				Type: new("file"), Path: new("large.bin"), SHA: new(fileSHA), Size: new(largeSize),
+				Content: new(""), Encoding: new("none"),
+			},
+			trees: map[string]*github.Tree{commitSHA: {Entries: []*github.TreeEntry{
+				{Path: new("large.bin"), Mode: new("100644"), Type: new("blob"), SHA: new(fileSHA)},
+			}}},
+		}, args("large.bin"))
+		require.False(t, result.IsError)
+		assert.Equal(t, 2, requests)
+		_, ok := result.Content[1].(*mcp.ResourceLink)
+		require.True(t, ok)
+	})
+
 	t.Run("internal large link uses exact-path tree descent", func(t *testing.T) {
 		target := "../target.bin"
 		linkSHA := gitBlobSHA([]byte(target))