Name matches at the beginning of search.

app/lib/frontend/handlers/listing.dart

@@ -81,8 +81,7 @@ Future<shelf.Response> _packagesHandlerHtmlCore(shelf.Request request) async {
   );
   final int totalCount = searchResult.totalCount;
   final errorMessage = searchResult.errorMessage;
-  final statusCode =
-      searchResult.statusCode ?? (errorMessage == null ? 200 : 500);
+  final statusCode = searchResult.statusCode;
   if (errorMessage != null && statusCode >= 500) {
     _logger.severe('[pub-search-not-working] ${searchResult.errorMessage}');
   }
@@ -93,7 +92,6 @@ Future<shelf.Response> _packagesHandlerHtmlCore(shelf.Request request) async {
       searchResult,
       links,
       searchForm: searchForm,
-      messageFromBackend: searchResult.errorMessage,
       openSections: openSections,
     ),
     status: statusCode,

app/lib/frontend/templates/listing.dart

@@ -5,9 +5,11 @@
 import 'dart:math';
 
 import 'package:_pub_shared/search/search_form.dart';
+import 'package:collection/collection.dart';
 
 import '../../package/search_adapter.dart';
 import '../../search/search_service.dart';
+import '../../shared/urls.dart' as urls;
 import '../dom/dom.dart' as d;
 
 import '_consts.dart';
@@ -35,7 +37,6 @@ String renderPkgIndexPage(
   SearchResultPage searchResultPage,
   PageLinks links, {
   required SearchForm searchForm,
-  String? messageFromBackend,
   Set<String>? openSections,
 }) {
   final topPackages = getSdkDict(null).topSdkPackages;
@@ -47,8 +48,9 @@ String renderPkgIndexPage(
       searchForm: searchForm,
       totalCount: searchResultPage.totalCount,
       title: topPackages,
-      messageFromBackend: messageFromBackend,
+      messageFromBackend: searchResultPage.errorMessage,
     ),
+    nameMatches: _nameMatches(searchForm, searchResultPage.nameMatches),
     packageList: packageList(searchResultPage),
     pagination: searchResultPage.hasHit ? paginationNode(links) : null,
     openSections: openSections,
@@ -121,3 +123,24 @@ class PageLinks {
     return min(fromSymmetry, max(currentPage!, fromCount));
   }
 }
+
+d.Node? _nameMatches(SearchForm form, List<String>? matches) {
+  if (matches == null || matches.isEmpty) {
+    return null;
+  }
+  final singular = matches.length == 1;
+  final isExactNameMatch = singular && form.parsedQuery.text == matches.single;
+  final nameMatchLabel = isExactNameMatch
+      ? 'Exact package name match: '
+      : 'Matching package ${singular ? 'name' : 'names'}: ';
+
+  return d.p(children: [
+    d.b(text: nameMatchLabel),
+    ...matches.expandIndexed((i, name) {
+      return [
+        if (i > 0) d.text(', '),
+        d.code(child: d.a(href: urls.pkgPageUrl(name), text: name)),
+      ];
+    }),
+  ]);
+}

app/lib/frontend/templates/views/pkg/index.dart

@@ -13,12 +13,14 @@ import '../../../static_files.dart';
 d.Node packageListingNode({
   required SearchForm searchForm,
   required d.Node listingInfo,
+  required d.Node? nameMatches,
   required d.Node packageList,
   required d.Node? pagination,
   required Set<String>? openSections,
 }) {
   final innerContent = d.fragment([
     listingInfo,
+    if (nameMatches != null) nameMatches,
     packageList,
     if (pagination != null) pagination,
     d.markdown('Check our help page for details on '

app/lib/package/search_adapter.dart

@@ -42,11 +42,12 @@ class SearchAdapter {
     return SearchResultPage(
       form,
       result.totalCount,
+      nameMatches: result.nameMatches,
       sdkLibraryHits: result.sdkLibraryHits,
       packageHits:
           result.packageHits.map((h) => views[h.package]).nonNulls.toList(),
       errorMessage: result.errorMessage,
-      statusCode: result.statusCode,
+      statusCode: result.statusCode ?? 200,
     );
   }
 
@@ -84,8 +85,10 @@ class SearchAdapter {
   Future<PackageSearchResult> _fallbackSearch(SearchForm form) async {
     // Some search queries must not be served with the fallback search.
     if (form.parsedQuery.tagsPredicate.isNotEmpty) {
-      return PackageSearchResult.empty(
-          errorMessage: 'Search is temporarily unavailable.');
+      return PackageSearchResult.error(
+        errorMessage: 'Search is temporarily unavailable.',
+        statusCode: 503,
+      );
     }
 
     final names = await nameTracker
@@ -108,11 +111,13 @@ class SearchAdapter {
     packageHits =
         packageHits.skip(form.offset).take(form.pageSize ?? 10).toList();
     return PackageSearchResult(
-        timestamp: clock.now().toUtc(),
-        packageHits: packageHits,
-        totalCount: totalCount,
-        errorMessage:
-            'Search is temporarily impaired, filtering and ranking may be incorrect.');
+      timestamp: clock.now().toUtc(),
+      packageHits: packageHits,
+      totalCount: totalCount,
+      errorMessage:
+          'Search is temporarily impaired, filtering and ranking may be incorrect.',
+      statusCode: 503,
+    );
   }
 
   Future<Map<String, PackageView>> _getPackageViewsFromHits(
@@ -137,6 +142,11 @@ class SearchResultPage {
   /// The total number of results available for the search.
   final int totalCount;
 
+  /// Package names that are exact name matches or close to (e.g. names that
+  /// would be considered as blocker for publishing).
+  final List<String>? nameMatches;
+
+  /// The hits from the SDK libraries.
   final List<SdkLibraryHit> sdkLibraryHits;
 
   /// The current list of packages on the page.
@@ -146,24 +156,20 @@ class SearchResultPage {
   /// the query was not processed entirely.
   final String? errorMessage;
 
-  /// The non-200 status code that will be used to render the [errorMessage].
-  final int? statusCode;
+  /// The code that will be used to render the page.
+  final int statusCode;
 
   SearchResultPage(
     this.form,
     this.totalCount, {
+    this.nameMatches,
     List<SdkLibraryHit>? sdkLibraryHits,
     List<PackageView>? packageHits,
     this.errorMessage,
-    this.statusCode,
+    this.statusCode = 200,
   })  : sdkLibraryHits = sdkLibraryHits ?? <SdkLibraryHit>[],
         packageHits = packageHits ?? <PackageView>[];
 
-  SearchResultPage.empty(this.form, {this.errorMessage, this.statusCode})
-      : totalCount = 0,
-        sdkLibraryHits = <SdkLibraryHit>[],
-        packageHits = [];
-
   bool get hasNoHit => sdkLibraryHits.isEmpty && packageHits.isEmpty;
   bool get hasHit => !hasNoHit;
 }

app/lib/search/mem_index.dart

@@ -147,6 +147,7 @@ class InMemoryPackageIndex {
       packages.removeWhere((x) => !keys.contains(x));
     }
 
+    List<String>? nameMatches;
     late List<PackageHit> packageHits;
     switch (query.effectiveOrder ?? SearchOrder.top) {
       case SearchOrder.top:
@@ -162,12 +163,10 @@ class InMemoryPackageIndex {
             .map((key, value) => value * _adjustedOverallScores[key]!);
         // If the search hits have an exact name match, we move it to the front of the result list.
         final parsedQueryText = query.parsedQuery.text;
-        final priorityPackageName =
-            packages.contains(parsedQueryText ?? '') ? parsedQueryText : null;
-        packageHits = _rankWithValues(
-          overallScore.getValues(),
-          priorityPackageName: priorityPackageName,
-        );
+        if (parsedQueryText != null && _packages.containsKey(parsedQueryText)) {
+          nameMatches = <String>[parsedQueryText];
+        }
+        packageHits = _rankWithValues(overallScore.getValues());
         break;
       case SearchOrder.text:
         final score = textResults?.pkgScore ?? Score.empty();
@@ -209,6 +208,7 @@ class InMemoryPackageIndex {
     return PackageSearchResult(
       timestamp: clock.now().toUtc(),
       totalCount: totalCount,
+      nameMatches: nameMatches,
       packageHits: packageHits,
     );
   }
@@ -333,16 +333,11 @@ class InMemoryPackageIndex {
     return null;
   }
 
-  List<PackageHit> _rankWithValues(
-    Map<String, double> values, {
-    String? priorityPackageName,
-  }) {
+  List<PackageHit> _rankWithValues(Map<String, double> values) {
     final list = values.entries
         .map((e) => PackageHit(package: e.key, score: e.value))
         .toList();
     list.sort((a, b) {
-      if (a.package == priorityPackageName) return -1;
-      if (b.package == priorityPackageName) return 1;
       final int scoreCompare = -a.score!.compareTo(b.score!);
       if (scoreCompare != 0) return scoreCompare;
       // if two packages got the same score, order by last updated

app/lib/search/result_combiner.dart

@@ -48,10 +48,7 @@ class SearchResultCombiner {
       sdkLibraryHits.sort((a, b) => -a.score.compareTo(b.score));
     }
 
-    return PackageSearchResult(
-      timestamp: primaryResult.timestamp,
-      totalCount: primaryResult.totalCount,
-      packageHits: primaryResult.packageHits,
+    return primaryResult.change(
       sdkLibraryHits: sdkLibraryHits.take(3).toList(),
     );
   }

app/lib/search/search_client.dart

@@ -52,7 +52,7 @@ class SearchClient {
     // check validity first
     final validity = query.evaluateValidity();
     if (validity.isRejected) {
-      return PackageSearchResult.empty(
+      return PackageSearchResult.error(
         errorMessage: 'Search query rejected. ${validity.rejectReason}',
         statusCode: 400,
       );
@@ -87,8 +87,10 @@ class SearchClient {
         }
       }
       if (response == null) {
-        return PackageSearchResult.empty(
-            errorMessage: 'Search is temporarily unavailable.');
+        return PackageSearchResult.error(
+          errorMessage: 'Search is temporarily unavailable.',
+          statusCode: 503,
+        );
       }
       if (response.statusCode == 200) {
         return PackageSearchResult.fromJson(
@@ -97,12 +99,16 @@ class SearchClient {
       }
       // Search request before the service initialization completed.
       if (response.statusCode == searchIndexNotReadyCode) {
-        return PackageSearchResult.empty(
-            errorMessage: 'Search is temporarily unavailable.');
+        return PackageSearchResult.error(
+          errorMessage: 'Search is temporarily unavailable.',
+          statusCode: 503,
+        );
       }
       // There has been a generic issue with the service.
-      return PackageSearchResult.empty(
-          errorMessage: 'Service returned status code ${response.statusCode}.');
+      return PackageSearchResult.error(
+        errorMessage: 'Service returned status code ${response.statusCode}.',
+        statusCode: response.statusCode,
+      );
     }
 
     if (sourceIp != null) {

app/lib/search/search_service.dart

@@ -303,8 +303,12 @@ class QueryValidity {
 
 @JsonSerializable(includeIfNull: false, explicitToJson: true)
 class PackageSearchResult {
-  final DateTime? timestamp;
+  final DateTime timestamp;
   final int totalCount;
+
+  /// Package names that are exact name matches or close to (e.g. names that
+  /// would be considered as blocker for publishing).
+  final List<String>? nameMatches;
   final List<SdkLibraryHit> sdkLibraryHits;
   final List<PackageHit> packageHits;
 
@@ -317,32 +321,46 @@ class PackageSearchResult {
   PackageSearchResult({
     required this.timestamp,
     required this.totalCount,
+    this.nameMatches,
     List<SdkLibraryHit>? sdkLibraryHits,
     List<PackageHit>? packageHits,
     this.errorMessage,
-    this.statusCode,
-  })  : sdkLibraryHits = sdkLibraryHits ?? <SdkLibraryHit>[],
-        packageHits = packageHits ?? <PackageHit>[];
-
-  PackageSearchResult.empty({this.errorMessage, this.statusCode})
-      : timestamp = clock.now().toUtc(),
+    int? statusCode,
+  })  : packageHits = packageHits ?? <PackageHit>[],
+        sdkLibraryHits = sdkLibraryHits ?? <SdkLibraryHit>[],
+        statusCode = statusCode;
+
+  PackageSearchResult.error({
+    required this.errorMessage,
+    required this.statusCode,
+  })  : timestamp = clock.now().toUtc(),
         totalCount = 0,
+        nameMatches = null,
         sdkLibraryHits = <SdkLibraryHit>[],
         packageHits = <PackageHit>[];
 
-  factory PackageSearchResult.fromJson(Map<String, dynamic> json) {
-    return _$PackageSearchResultFromJson({
-      // TODO: remove fallback in the next release
-      'errorMessage': json['message'],
-      ...json,
-    });
-  }
+  factory PackageSearchResult.fromJson(Map<String, dynamic> json) =>
+      _$PackageSearchResultFromJson(json);
 
-  Duration get age => clock.now().difference(timestamp!);
+  Duration get age => clock.now().difference(timestamp);
 
   Map<String, dynamic> toJson() => _$PackageSearchResultToJson(this);
 
   bool get isEmpty => packageHits.isEmpty && sdkLibraryHits.isEmpty;
+
+  PackageSearchResult change({
+    List<SdkLibraryHit>? sdkLibraryHits,
+  }) {
+    return PackageSearchResult(
+      timestamp: timestamp,
+      totalCount: totalCount,
+      nameMatches: nameMatches,
+      sdkLibraryHits: sdkLibraryHits ?? this.sdkLibraryHits,
+      packageHits: packageHits,
+      errorMessage: errorMessage,
+      statusCode: statusCode,
+    );
+  }
 }
 
 @JsonSerializable(includeIfNull: false, explicitToJson: true)