fix(provider): count same-file reads for notifier-field-unread

Found by dogfooding on nuwayze: `pipe check` reported

  _AgentHubController is consumed in the UI but 8 of its public
  member(s) are read by name nowhere outside the class ...

for a private ChangeNotifier whose widget, declared in the same file
(lib/screens/settings/agent_hub_screen.dart), renders every one of
those getters (`controller.authorizations`, `controller.hasLoadError`,
...).

The rule claims "outside the class" but discounted the notifier's
whole file: member reads were collected per file and the file that
declares the notifier was skipped. A private controller can only be
rendered from its own library, so that exclusion hid exactly the reads
that matter.

Member reads are now kept per scope: reads inside a ChangeNotifier
class body go under `memberUseScope(file, Class)`, everything else
under the file. The rule discounts only the notifier's own scope, so a
widget in the same file, or in a `part` of the library, counts as a
reader, while a notifier reading itself (`this.x`, `other.x`) still
does not. The model JSON keeps its shape (a map of name sets); only
the keys gained the class scope.

Tests (test/field_unread_scope_test.dart, a generated project): a
same-file widget read and a part-file read are not reported; a member
read nowhere and a member read only inside its own class are.

On nuwayze-w3 the finding is gone and nothing else moves: 65 findings
with the current release, 64 with this change, the only difference
being _AgentHubController. 221 tests pass.

lib/src/dart_provider_facts.dart

@@ -373,22 +373,49 @@ class _ReadCallCollector extends RecursiveAstVisitor<void> {
   }
 }
 
-/// Collects member reads (`x.someGetter`, `x.someField`) per file, so a public
+/// Collects member reads (`x.someGetter`, `x.someField`) per scope, so a public
 /// notifier getter that nothing reads can be identified as dead state.
+///
+/// Reads inside a `ChangeNotifier` class body are kept under that class's own
+/// scope ([memberUseScope]) and everything else under the file, so the rule can
+/// discount a notifier reading itself without discounting the widget declared
+/// next to it in the same file.
 class _MemberUseCollector extends RecursiveAstVisitor<void> {
-  _MemberUseCollector(this.uses);
+  _MemberUseCollector(this.relativePath, this.uses);
 
-  final Set<String> uses;
+  final String relativePath;
+  final Map<String, Set<String>> uses;
+  String? _notifier;
+
+  Set<String> get _scope => uses.putIfAbsent(
+    _notifier == null ? relativePath : memberUseScope(relativePath, _notifier!),
+    () => <String>{},
+  );
+
+  @override
+  void visitClassDeclaration(ClassDeclaration node) {
+    if (!_NotifierCollector._isChangeNotifier(node)) {
+      super.visitClassDeclaration(node);
+      return;
+    }
+    final outer = _notifier;
+    _notifier = node.namePart.typeName.lexeme;
+    try {
+      super.visitClassDeclaration(node);
+    } finally {
+      _notifier = outer;
+    }
+  }
 
   @override
   void visitPropertyAccess(PropertyAccess node) {
-    uses.add(node.propertyName.name);
+    _scope.add(node.propertyName.name);
     super.visitPropertyAccess(node);
   }
 
   @override
   void visitPrefixedIdentifier(PrefixedIdentifier node) {
-    uses.add(node.identifier.name);
+    _scope.add(node.identifier.name);
     super.visitPrefixedIdentifier(node);
   }
 }
@@ -532,9 +559,9 @@ NotifierModel collectNotifierModel(
     unit.accept(
       _ProviderDeclarationCollector(relative, lineInfo, declarations),
     );
-    final uses = <String>{};
+    final uses = <String, Set<String>>{relative: <String>{}};
-    unit.accept(_MemberUseCollector(uses));
+    unit.accept(_MemberUseCollector(relative, uses));
-    memberUses[relative] = uses;
+    memberUses.addAll(uses);
     unit.accept(_ReadInBuildCollector(relative, lineInfo, reads));
     unit.accept(_ProviderInBuildCollector(relative, lineInfo, createdInBuild));
   }

lib/src/facts.dart

@@ -353,6 +353,11 @@ class ProviderCreation {
   };
 }
 
+/// The [NotifierModel.memberUses] key for reads inside [notifier]'s own class
+/// body in [file]. A file key ends in `.dart`, so the two never collide, and a
+/// class name is unique within its library.
+String memberUseScope(String file, String notifier) => '$file#$notifier';
+
 /// Everything the notifier/provider rules judge.
 class NotifierModel {
   NotifierModel({
@@ -397,7 +402,11 @@ class NotifierModel {
   final Map<String, List<String>> consumedBy;
   final List<ProviderDeclaration> declarations;
 
-  /// Project-relative file -> member names read in it.
+  /// Scope -> member names read in it. A scope is a project-relative file for
+  /// reads outside any notifier class, or [memberUseScope] for reads inside
+  /// one, so a notifier's reads of itself can be told apart from reads by the
+  /// rest of its file (a private controller and the widget that renders it
+  /// usually share one).
   final Map<String, Set<String>> memberUses;
   final List<NonSubscribingRead> nonSubscribingReads;
   final List<ProvidersCreatedInBuild> createdInBuild;

lib/src/provider_rules.dart

@@ -121,10 +121,14 @@ String runProviderRules({
   if (wantFieldUnread) {
     for (final notifier in notifiers) {
       if ((consumedBy[notifier.name] ?? const <String>[]).isEmpty) continue;
+      // Only the class's own body is discounted. Excluding its whole file
+      // reported a private controller whose widget, in the same file, renders
+      // every one of its getters.
+      final ownScope = memberUseScope(notifier.file, notifier.name);
       final unread = <String>[];
       for (final member in notifier.apiMembers) {
         final read = memberUses.entries
-            .where((entry) => entry.key != notifier.file)
+            .where((entry) => entry.key != ownScope)
             .any((entry) => entry.value.contains(member));
         if (!read) unread.add(member);
       }

test/field_unread_scope_test.dart

@@ -0,0 +1,205 @@
+import 'dart:io';
+
+import 'package:pipe/pipe.dart';
+import 'package:test/test.dart';
+
+/// notifier-field-unread discounts reads inside the notifier's own class body,
+/// and nothing else. It used to discount the notifier's whole file, so a
+/// private controller rendered by the widget declared next to it was reported
+/// as unread (nuwayze's `_AgentHubController`, eight getters, all rendered).
+///
+/// Each case uses member names no other case reads, because a read is matched
+/// by name anywhere in the scan.
+const Map<String, String> _files = {
+  'lib/support.dart': '''
+class ChangeNotifier {
+  void notifyListeners() {}
+}
+
+class BuildContext {
+  T watch<T>() => throw UnimplementedError();
+}
+''',
+  // A private controller and the widget that renders it, in one file.
+  'lib/same_file.dart': '''
+import 'support.dart';
+
+class _SameFileController extends ChangeNotifier {
+  int _sameCount = 0;
+  String? _sameLoadError;
+
+  int get sameCount => _sameCount;
+  String? get sameLoadError => _sameLoadError;
+
+  void refresh() {
+    _sameCount++;
+    notifyListeners();
+  }
+}
+
+class SameFileView {
+  String build(BuildContext context) {
+    final controller = context.watch<_SameFileController>();
+    return '\${controller.sameCount} \${controller.sameLoadError}';
+  }
+}
+''',
+  // A controller whose only reader is a part of its library.
+  'lib/part_host.dart': '''
+import 'support.dart';
+
+part 'part_host_view.dart';
+
+class PartController extends ChangeNotifier {
+  int _partTotal = 0;
+
+  int get partTotal => _partTotal;
+  String get partStatus => 'ok';
+
+  void bump() {
+    _partTotal++;
+    notifyListeners();
+  }
+}
+''',
+  'lib/part_host_view.dart': '''
+part of 'part_host.dart';
+
+class PartView {
+  String build(BuildContext context) {
+    final controller = context.watch<PartController>();
+    return '\${controller.partTotal} \${controller.partStatus}';
+  }
+}
+''',
+  // `unreadHiddenCount` is read nowhere, though its sibling is rendered next
+  // door: the true positive the same-file fix must keep.
+  'lib/unread.dart': '''
+import 'support.dart';
+
+class UnreadController extends ChangeNotifier {
+  int _unreadShown = 0;
+  int _unreadHiddenCount = 0;
+
+  int get unreadShown => _unreadShown;
+  int get unreadHiddenCount => _unreadHiddenCount;
+
+  void bump() {
+    _unreadShown++;
+    _unreadHiddenCount++;
+    notifyListeners();
+  }
+}
+
+class UnreadView {
+  String build(BuildContext context) =>
+      '\${context.watch<UnreadController>().unreadShown}';
+}
+''',
+  // `selfErrorMessage` is read only by the class itself, which is not a
+  // render.
+  'lib/self_read.dart': '''
+import 'support.dart';
+
+class SelfReadController extends ChangeNotifier {
+  String? _selfErrorMessage;
+
+  String get selfLabel => 'label';
+  String? get selfErrorMessage => _selfErrorMessage;
+
+  // ignore: unnecessary_this
+  String describe() => 'error: \${this.selfErrorMessage}';
+
+  bool sameErrorAs(SelfReadController other) =>
+      other.selfErrorMessage == _selfErrorMessage;
+
+  void fail(String message) {
+    _selfErrorMessage = message;
+    notifyListeners();
+  }
+}
+
+class SelfReadView {
+  String build(BuildContext context) =>
+      context.watch<SelfReadController>().selfLabel;
+}
+''',
+};
+
+String _project() {
+  final root = Directory.systemTemp.createTempSync('pipe-field-unread');
+  File('${root.path}/pubspec.yaml').writeAsStringSync('''
+name: field_unread
+publish_to: none
+environment:
+  sdk: ^3.0.0
+''');
+  File('${root.path}/.dart_tool/package_config.json')
+    ..createSync(recursive: true)
+    ..writeAsStringSync('''
+{
+  "configVersion": 2,
+  "packages": [
+    {
+      "name": "field_unread",
+      "rootUri": "../",
+      "packageUri": "lib/",
+      "languageVersion": "3.0"
+    }
+  ]
+}
+''');
+  for (final entry in _files.entries) {
+    File('${root.path}/${entry.key}')
+      ..createSync(recursive: true)
+      ..writeAsStringSync(entry.value);
+  }
+  return root.path;
+}
+
+void main() {
+  late String root;
+  late ProjectAnalysis analysis;
+  late Map<String, List<Object?>> unreadByOwner;
+
+  setUpAll(() async {
+    root = _project();
+    analysis = await analyzeProject(
+      await loadProject(root),
+      concurrency: 1,
+      enabledRules: {ruleNotifierFieldUnread},
+    );
+    unreadByOwner = {
+      for (final finding in analysis.report.findings)
+        if (finding.rule == ruleNotifierFieldUnread)
+          finding.data['owner']! as String: finding.data['members']! as List,
+    };
+  });
+
+  tearDownAll(() async {
+    await analysis.dispose();
+    Directory(root).deleteSync(recursive: true);
+  });
+
+  test('the scan resolved every file', () {
+    // Otherwise a missing finding below could be an analysis failure.
+    expect(analysis.report.coverage!.resolved, _files.length);
+    expect(analysis.report.notes.join('\n'), isNot(contains('unresolved')));
+  });
+
+  test('reads by a widget in the notifier\'s own file count', () {
+    expect(unreadByOwner, isNot(contains('_SameFileController')));
+  });
+
+  test('reads in a part of the notifier\'s library count', () {
+    expect(unreadByOwner, isNot(contains('PartController')));
+  });
+
+  test('a member read nowhere is still reported', () {
+    expect(unreadByOwner['UnreadController'], ['unreadHiddenCount']);
+  });
+
+  test('a member read only inside its own class is still reported', () {
+    expect(unreadByOwner['SelfReadController'], ['selfErrorMessage']);
+  });
+}