fix(raw): escape path segments when building raw content URLs

pkg/github/repository_resource_test.go

@@ -118,6 +118,49 @@ func TestRepositoryResourceContentsDecodesUTF8Path(t *testing.T) {
 	require.Equal(t, "package x", result.Contents[0].Text)
 }
 
+func TestRepositoryResourceContentsPercentInFileName(t *testing.T) {
+	tests := []struct {
+		name     string
+		uri      string
+		wantPath string
+	}{
+		{
+			name:     "literal percent sign",
+			uri:      "repo://owner/repo/contents/docs/100%25.txt",
+			wantPath: "/owner/repo/HEAD/docs/100%.txt",
+		},
+		{
+			name:     "file name that looks like a percent escape",
+			uri:      "repo://owner/repo/contents/%2541.txt",
+			wantPath: "/owner/repo/HEAD/%41.txt",
+		},
+	}
+
+	for _, tc := range tests {
+		t.Run(tc.name, func(t *testing.T) {
+			base, _ := url.Parse("https://raw.example.com/")
+			var gotPath string
+			client := mustNewGHClient(t, MockHTTPClientWithHandlers(map[string]http.HandlerFunc{
+				GetRawReposContentsByOwnerByRepoByPath: func(w http.ResponseWriter, r *http.Request) {
+					gotPath = r.URL.Path
+					w.Header().Set("Content-Type", "text/plain")
+					_, err := w.Write([]byte("file body"))
+					require.NoError(t, err)
+				},
+			}))
+			rawClient, err := raw.NewClient(client, base)
+			require.NoError(t, err)
+			ctx := ContextWithDeps(context.Background(), BaseDeps{Client: client, RawClient: rawClient})
+			handler := RepositoryResourceContentsHandler(repositoryResourceContentURITemplate)
+
+			result, err := handler(ctx, &mcp.ReadResourceRequest{Params: &mcp.ReadResourceParams{URI: tc.uri}})
+			require.NoError(t, err)
+			require.Equal(t, "file body", result.Contents[0].Text)
+			require.Equal(t, tc.wantPath, gotPath)
+		})
+	}
+}
+
 func Test_repositoryResourceContents(t *testing.T) {
 	base, _ := url.Parse("https://raw.example.com/")
 	tests := []struct {

pkg/raw/raw.go

@@ -92,7 +92,7 @@ func (c *Client) refURL(owner, repo, ref, path string) (string, error) {
 	if err := rejectPathTraversal(owner, repo, ref, path); err != nil {
 		return "", err
 	}
-	return c.url.JoinPath(owner, repo, ref, path).String(), nil
+	return c.url.JoinPath(escapePathSegments(owner, repo, ref, path)...).String(), nil
 }
 
 func (c *Client) URLFromOpts(opts *ContentOpts, owner, repo, path string) (string, error) {
@@ -110,7 +110,26 @@ func (c *Client) commitURL(owner, repo, sha, path string) (string, error) {
 	if err := rejectPathTraversal(owner, repo, sha, path); err != nil {
 		return "", err
 	}
-	return c.url.JoinPath(owner, repo, sha, path).String(), nil
+	return c.url.JoinPath(escapePathSegments(owner, repo, sha, path)...).String(), nil
+}
+
+// escapePathSegments percent-encodes every "/"-separated segment of the given
+// components. The components are decoded text (for example a file path taken
+// from a repo:// resource URI), but url.URL.JoinPath treats its arguments as
+// already escaped: a literal "%41" would be decoded again (fetching "A"), and
+// an invalid escape such as "100%.txt" makes JoinPath silently fall back to
+// the base URL. Escaping each segment keeps the file name exactly as given
+// while preserving "/" as the path separator.
+func escapePathSegments(components ...string) []string {
+	escaped := make([]string, 0, len(components))
+	for _, component := range components {
+		segments := strings.Split(component, "/")
+		for i, segment := range segments {
+			segments[i] = url.PathEscape(segment)
+		}
+		escaped = append(escaped, strings.Join(segments, "/"))
+	}
+	return escaped
 }
 
 type ContentOpts struct {

pkg/raw/raw_test.go

@@ -285,10 +285,34 @@ func TestUrlFromOpts(t *testing.T) {
 			wantErr: true,
 		},
 		{
-			name:  "benign percent-encoded filename allowed",
+			name:  "literal percent-escape-like filename kept as typed",
 			opts:  nil,
 			owner: "octocat", repo: "hello", path: "%2ehidden",
-			want: "https://raw.example.com/octocat/hello/HEAD/%2ehidden",
+			want: "https://raw.example.com/octocat/hello/HEAD/%252ehidden",
+		},
+		{
+			name:  "filename with literal percent sign",
+			opts:  nil,
+			owner: "octocat", repo: "hello", path: "docs/100%.txt",
+			want: "https://raw.example.com/octocat/hello/HEAD/docs/100%25.txt",
+		},
+		{
+			name:  "filename that looks like a percent escape is not decoded",
+			opts:  nil,
+			owner: "octocat", repo: "hello", path: "%41.txt",
+			want: "https://raw.example.com/octocat/hello/HEAD/%2541.txt",
+		},
+		{
+			name:  "percent sign in ref with sha path",
+			opts:  &ContentOpts{SHA: "abc123"},
+			owner: "octocat", repo: "hello", path: "50%off/file.txt",
+			want: "https://raw.example.com/octocat/hello/abc123/50%25off/file.txt",
+		},
+		{
+			name:  "space hash question mark and unicode are escaped",
+			opts:  &ContentOpts{Ref: "refs/heads/feature/分支"},
+			owner: "octocat", repo: "hello", path: "a b/#c?.md",
+			want: "https://raw.example.com/octocat/hello/refs/heads/feature/%E5%88%86%E6%94%AF/a%20b/%23c%3F.md",
 		},
 	}