Fix documentation URL preprocessing to recognize directories with dots.

app/lib/frontend/handlers/documentation.dart

@@ -124,7 +124,7 @@ DocFilePath? parseRequestUri(Uri uri) {
   final relativeSegments =
       uri.pathSegments.skip(3).where((s) => s.isNotEmpty).toList();
   var pathSegments = relativeSegments;
-  if (relativeSegments.isEmpty || !relativeSegments.last.contains('.')) {
+  if (_expandToIndexHtml(relativeSegments)) {
     pathSegments = [...relativeSegments, 'index.html'];
   }
   final path = p.normalize(p.joinAll(pathSegments));
@@ -143,6 +143,32 @@ DocFilePath? parseRequestUri(Uri uri) {
   return DocFilePath(package, version, path);
 }
 
+const _nonExpandedExtensions = {
+  '.html',
+  '.json',
+  '.gz',
+  '.png',
+  '.svg',
+};
+// NOTE: This is a best-effort detection on the segments.
+//       Instead, we should rather check if the file (or the updated path)
+//       is in the generated output, and base the decision on the file list.
+//       However, with the current serving code it is costly, we need to refactor it.
+// TODO: Use blob index to decide how the relative path should be handled
+bool _expandToIndexHtml(List<String> segments) {
+  if (segments.isEmpty) {
+    return true;
+  }
+  if (!segments.last.contains('.')) {
+    return true;
+  }
+  if (segments.first.contains('static-assets')) {
+    return false;
+  }
+  final ext = p.extension(segments.last);
+  return !_nonExpandedExtensions.contains(ext);
+}
+
 bool _isValidVersion(String version) {
   if (version.trim().isEmpty) return false;
   if (version == 'latest') return true;

app/test/frontend/handlers/documentation_test.dart

@@ -78,6 +78,18 @@ void main() {
       testUri(
           '/documentation/pkg/1.0.0/A%20_0.html', 'pkg', '1.0.0', 'A _0.html');
     });
+
+    test('library with dots are recognized', () {
+      testUri('/documentation/pkg/latest/a.b.c', 'pkg', 'latest',
+          'a.b.c/index.html');
+      testUri('/documentation/pkg/latest/a.b.c/', 'pkg', 'latest',
+          'a.b.c/index.html');
+    });
+
+    test('static assets are left as-is', () {
+      testUri('/documentation/pkg/latest/static-assets/search.svg', 'pkg',
+          'latest', 'static-assets/search.svg');
+    });
   });
 
   group('dartdoc handlers', () {
@@ -110,6 +122,9 @@ void main() {
       await expectRedirectResponse(
           await issueGet('/documentation/oxygen/1.0.0/abc'),
           '/documentation/oxygen/1.0.0/abc/');
+      await expectRedirectResponse(
+          await issueGet('/documentation/oxygen/1.0.0/abc.def'),
+          '/documentation/oxygen/1.0.0/abc.def/');
       await expectRedirectResponse(
           await issueGet('/documentation/oxygen/latest/abc/def'),
           '/documentation/oxygen/latest/abc/def/');