feat(merge_requests): select and confirm suggestion batches (#593)

* feat(merge_requests): select and confirm suggestion batches

Review every selected patch and freshly inspect all selected discussions before one batch write; require complete read-only recovery after uncertain confirmation while preserving drafts and session isolation.

Signed-off-by: sjungwon03 <sjungwon03@gmail.com>

* docs(parity): link batch suggestion UI PR

Link the complete batch UI slice and retain multiline review as the remaining parity follow-up.

Signed-off-by: sjungwon03 <sjungwon03@gmail.com>

---------

Signed-off-by: sjungwon03 <sjungwon03@gmail.com>

Author: sjungwon03

apps/labfox/lib/features/comments/data/comments_repository.dart

@@ -35,6 +35,14 @@ class CommentsRepository {
     String? commitMessage,
   }) => _client.suggestions.apply(suggestionId, commitMessage: commitMessage);
 
+  Future<List<Suggestion>> applySuggestions({
+    required List<int> suggestionIds,
+    String? commitMessage,
+  }) => _client.suggestions.applyBatch(
+    suggestionIds,
+    commitMessage: commitMessage,
+  );
+
   Future<Note> replyToDiscussion({
     required int projectId,
     required int iid,

apps/labfox/lib/features/comments/data/suggestion_application.dart

@@ -1,5 +1,11 @@
 import 'package:gitlab_models/gitlab_models.dart';
 
+typedef SuggestionTarget = ({
+  String discussionId,
+  Note note,
+  Suggestion suggestion,
+});
+
 /// Patch eligibility is not a permission check: GitLab enforces write access.
 bool canApplySuggestion(Note note, Suggestion suggestion) =>
     !note.isSystem &&
@@ -53,3 +59,37 @@ bool confirmsAppliedSuggestion(Suggestion returned, Suggestion expected) =>
     (returned.fromContent == null ||
         returned.fromContent == expected.fromContent) &&
     (returned.toContent == null || returned.toContent == expected.toContent);
+
+List<SuggestionTarget> applicableSuggestionTargets(List<Discussion> groups) {
+  final counts = <int, int>{};
+  for (final group in groups) {
+    for (final note in group.notes) {
+      for (final suggestion in note.suggestions ?? <Suggestion>[]) {
+        counts.update(suggestion.id, (v) => v + 1, ifAbsent: () => 1);
+      }
+    }
+  }
+  return List<SuggestionTarget>.unmodifiable([
+    for (final group in groups)
+      for (final note in group.notes)
+        for (final suggestion in note.suggestions ?? <Suggestion>[])
+          if (counts[suggestion.id] == 1 &&
+              canApplySuggestion(note, suggestion))
+            (discussionId: group.id, note: note, suggestion: suggestion),
+  ]);
+}
+
+bool containsApplicableSuggestionTargets(
+  List<Discussion> groups,
+  List<SuggestionTarget> targets,
+) =>
+    targets.length >= 2 &&
+    targets.map((t) => t.suggestion.id).toSet().length == targets.length &&
+    targets.every(
+      (t) => containsApplicableSuggestion(
+        groups,
+        discussionId: t.discussionId,
+        note: t.note,
+        suggestion: t.suggestion,
+      ),
+    );

apps/labfox/lib/features/merge_requests/presentation/controllers/mr_discussions_controller.dart

@@ -214,12 +214,96 @@ class MrDiscussionsController
     }
   }
 
+  bool _currentSuggestions(List<SuggestionTarget> targets) =>
+      !state.isLoading &&
+      !state.hasError &&
+      state.hasValue &&
+      containsApplicableSuggestionTargets(state.value!.items, targets);
+
+  /// Confirms all selected patches before one batch; never applies a subset.
+  Future<bool> applySuggestions(
+    List<SuggestionTarget> selection, {
+    String? commitMessage,
+    bool Function()? isCurrent,
+  }) async {
+    final targets = List<SuggestionTarget>.unmodifiable(selection);
+    if (_posting ||
+        _loadingMore ||
+        !_currentSuggestions(targets) ||
+        isCurrent?.call() == false) {
+      return false;
+    }
+    final generation = _generation;
+    _posting = true;
+    bool current() => generation == _generation && isCurrent?.call() != false;
+    try {
+      final repo = await _repository();
+      if (!current()) return false;
+      if (repo == null) {
+        throw const GitLabAuthException('No authenticated account.');
+      }
+      if (!_currentSuggestions(targets)) return false;
+      final fresh = await _readDiscussions(
+        repo,
+        targets.map((t) => t.discussionId).toSet().toList(),
+        current,
+      );
+      if (!current() || fresh == null) return false;
+      if (!_currentSuggestions(targets) ||
+          !containsApplicableSuggestionTargets(fresh, targets)) {
+        throw const GitLabConflictException(
+          'Suggestions changed. Reload before applying.',
+        );
+      }
+      final returned = await repo.applySuggestions(
+        suggestionIds: targets.map((t) => t.suggestion.id).toList(),
+        commitMessage: commitMessage,
+      );
+      if (!current()) return false;
+      final byId = {for (final s in returned) s.id: s};
+      if (returned.length != targets.length ||
+          byId.length != targets.length ||
+          !targets.every(
+            (t) =>
+                byId[t.suggestion.id] != null &&
+                confirmsAppliedSuggestion(byId[t.suggestion.id]!, t.suggestion),
+          )) {
+        throw const GitLabServerException(
+          'Unconfirmed suggestion batch application.',
+        );
+      }
+      ref.invalidate(mergeRequestControllerProvider(arg));
+      ref.invalidate(mrReviewSnapshotControllerProvider(arg));
+      ref.invalidateSelf();
+      return true;
+    } catch (_) {
+      if (!current()) return false;
+      rethrow;
+    } finally {
+      if (generation == _generation) _posting = false;
+    }
+  }
+
   /// Explicit read-only recovery never retries an application automatically.
   Future<Discussion?> inspectDiscussion(
     String discussionId, {
     bool Function()? isCurrent,
+  }) async =>
+      (await inspectDiscussions([discussionId], isCurrent: isCurrent))?.single;
+
+  /// Stages every selected thread before replacing any loaded cache entry.
+  Future<List<Discussion>?> inspectDiscussions(
+    List<String> discussionIds, {
+    bool Function()? isCurrent,
   }) async {
-    if (_posting || _loadingMore || isCurrent?.call() == false) return null;
+    final ids = List<String>.unmodifiable(discussionIds);
+    if (_posting ||
+        _loadingMore ||
+        isCurrent?.call() == false ||
+        ids.isEmpty ||
+        ids.toSet().length != ids.length) {
+      return null;
+    }
     final generation = _generation;
     _posting = true;
     bool current() => generation == _generation && isCurrent?.call() != false;
@@ -229,21 +313,15 @@ class MrDiscussionsController
       if (repo == null) {
         throw const GitLabAuthException('No authenticated account.');
       }
-      final fresh = await repo.discussion(
-        projectId: arg.projectId,
-        iid: arg.iid,
-        discussionId: discussionId,
-      );
-      if (!current()) return null;
-      if (fresh.id != discussionId) {
-        throw const GitLabServerException('Invalid discussion response.');
-      }
+      final fresh = await _readDiscussions(repo, ids, current);
+      if (!current() || fresh == null) return null;
       final page = state.valueOrNull;
       if (page != null && !state.isLoading && !state.hasError) {
+        final byId = {for (final g in fresh) g.id: g};
         state = AsyncData(
           Paginated(
             items: List<Discussion>.unmodifiable(
-              page.items.map((g) => g.id == discussionId ? fresh : g),
+              page.items.map((g) => byId[g.id] ?? g),
             ),
             nextPage: page.nextPage,
             total: page.total,
@@ -260,6 +338,28 @@ class MrDiscussionsController
     }
   }
 
+  Future<List<Discussion>?> _readDiscussions(
+    CommentsRepository repo,
+    List<String> ids,
+    bool Function() isCurrent,
+  ) async {
+    final result = <Discussion>[];
+    for (final id in ids) {
+      if (!isCurrent()) return null;
+      final fresh = await repo.discussion(
+        projectId: arg.projectId,
+        iid: arg.iid,
+        discussionId: id,
+      );
+      if (!isCurrent()) return null;
+      if (fresh.id != id) {
+        throw const GitLabServerException('Invalid discussion response.');
+      }
+      result.add(fresh);
+    }
+    return List<Discussion>.unmodifiable(result);
+  }
+
   Future<bool> _post(
     String body, {
     String? discussionId,

apps/labfox/lib/features/merge_requests/presentation/widgets/mr_discussion_thread.dart

@@ -14,6 +14,7 @@ import '../controllers/merge_requests_controllers.dart';
 import '../controllers/mr_discussions_controller.dart';
 import 'mr_discussion_position_context.dart';
 import 'mr_suggestion_apply_dialog.dart';
+import 'mr_suggestion_batch_apply_dialog.dart';
 import 'mr_suggestion_preview.dart';
 
 /// Grouped MR replies with explicit pagination and the shared note composer.
@@ -202,6 +203,49 @@ class _ConversationState extends ConsumerState<_Conversation> {
     }
   }
 
+  Future<void> _applyBatch(List<SuggestionTarget> targets) async {
+    if (_applicationId != null ||
+        _topPosting ||
+        _replyId != null ||
+        _resolutionId != null ||
+        widget.discussions.isLoading ||
+        widget.discussions.hasError) {
+      return;
+    }
+    final session = ref.read(commentsRepositoryProvider);
+    final view = ValueNotifier(true);
+    _applicationView = view;
+    setState(() => _applicationId = 0);
+    try {
+      final applied = await showDialog<bool>(
+        context: context,
+        barrierDismissible: false,
+        builder: (_) => MrSuggestionBatchApplyDialog(
+          resource: widget.arg,
+          targets: targets,
+          session: session,
+          isCurrent: () => mounted,
+          viewActive: view,
+        ),
+      );
+      if (mounted &&
+          applied == true &&
+          ref.read(commentsRepositoryProvider) == session) {
+        ScaffoldMessenger.of(context).showSnackBar(
+          SnackBar(
+            content: Text(
+              AppLocalizations.of(context).mrSuggestionsApplySuccess,
+            ),
+          ),
+        );
+      }
+    } finally {
+      _applicationView = null;
+      view.dispose();
+      if (mounted) setState(() => _applicationId = null);
+    }
+  }
+
   @override
   Widget build(BuildContext context) {
     final l10n = AppLocalizations.of(context);
@@ -248,12 +292,29 @@ class _ConversationState extends ConsumerState<_Conversation> {
               }
             }
           }
+          final targets = applicableSuggestionTargets(page.items);
           final groups = page.items
               .where((group) => group.notes.any((note) => !note.isSystem))
               .toList();
           return Column(
             crossAxisAlignment: CrossAxisAlignment.stretch,
             children: [
+              if (targets.length >= 2)
+                Align(
+                  alignment: AlignmentDirectional.centerStart,
+                  child: TextButton(
+                    key: const ValueKey('mr-suggestions-batch-open'),
+                    onPressed:
+                        canPost &&
+                            _applicationId == null &&
+                            !_topPosting &&
+                            _replyId == null &&
+                            _resolutionId == null
+                        ? () => _applyBatch(targets)
+                        : null,
+                    child: Text(l10n.mrSuggestionsBatchButton),
+                  ),
+                ),
               if (groups.isEmpty)
                 Text(
                   page.hasMore ? l10n.mrDiscussionsPartial : l10n.commentsEmpty,