fix(guide): scope "nothing references it" to the directories scanned

The brief said "nothing outside the bloc references it" and, under
--policy remove, that removing a dead handler "is safe even without product
context", while the scan defaults to --dir lib. The dead-handler finding
itself was scoped in f0fc57e; these three statements were not. A handler
dispatched only from test/ still read as safe to delete.

The decision line and the dead-handler section now say "nothing under <dirs>"
and tell the reader to rule out unscanned directories (rerun with --dir)
before wiring or removing; the remove-policy remediation in rules.dart says
the same. buildGuidance takes the scanned directories, which the guide
command passes from the project.

lib/src/cli.dart

@@ -740,6 +740,7 @@ class GuideCommand extends Command<int> {
         flow: analysis.flow,
         report: analysis.report,
         policy: _readPolicy(results),
+        scannedDirectories: project.directories,
         budgetChars: readPositiveInt(results, 'budget', fallback: 6000),
         maxFindings: readPositiveInt(results, 'max-findings', fallback: 12),
       );

lib/src/guide.dart

@@ -220,7 +220,10 @@ String? _groupLabel(Finding finding) {
 /// Turn a finding into the concrete decision the reader has to make. Without
 /// this, "render it or delete it" is not actionable: the reader cannot tell
 /// whether the whole feature is unwired.
-String? _decisionLine(Finding finding, FixPolicy policy) {
+///
+/// [scope] names the scanned directories: "nothing references it" is only ever
+/// established for them.
+String? _decisionLine(Finding finding, FixPolicy policy, String scope) {
   if (finding.rule != ruleEmittedNotRendered) return null;
   final observed = finding.data['unionObservedInUi'] == true;
   final sites = finding.data['unionRenderSites'];
@@ -236,12 +239,14 @@ String? _decisionLine(Finding finding, FixPolicy policy) {
   }
   if (owners.isEmpty) {
     return policy == FixPolicy.wireUp
-        ? 'wire it up: nothing outside the bloc references it either, so the '
-              'feature is unwired end to end - mount it in a screen and render '
-              'its states. Removing it needs explicit approval.'
-        : 'no UI renders this state type and nothing outside the bloc '
-              'references it, so nothing is wired up: this is safe to delete '
-              'unless the feature is still to come.';
+        ? 'wire it up: nothing under $scope outside the bloc references it '
+              'either, so the feature looks unwired end to end - mount it in a '
+              'screen and render its states. Removing it needs explicit '
+              'approval.'
+        : 'no UI renders this state type and nothing under $scope outside the '
+              'bloc references it, so nothing scanned wires it up: this is safe '
+              'to delete once no unscanned directory uses it and the feature is '
+              'not still to come.';
   }
   final shown = owners.take(3).join(', ');
   final suffix = owners.length > 3 ? ', +${owners.length - 3} more' : '';
@@ -255,7 +260,12 @@ String? _decisionLine(Finding finding, FixPolicy policy) {
             'it.';
 }
 
-String _groupBlock(List<Finding> group, int index, FixPolicy policy) {
+String _groupBlock(
+  List<Finding> group,
+  int index,
+  FixPolicy policy,
+  String scope,
+) {
   final head = group.first;
   final buffer = StringBuffer();
   final label = _groupLabel(head);
@@ -307,7 +317,7 @@ String _groupBlock(List<Finding> group, int index, FixPolicy policy) {
   if (parts.isNotEmpty) {
     buffer.writeln('   where: ${parts.join(' | ')}');
   }
-  final decision = _decisionLine(head, policy);
+  final decision = _decisionLine(head, policy, scope);
   if (decision != null) buffer.writeln('   decision: $decision');
   // Evidence quotes the analysed repository, which is untrusted input. It is
   // labelled as data and fenced so nothing in it can close its own quotation.
@@ -326,7 +336,9 @@ Guidance buildGuidance({
   int budgetChars = 6000,
   int maxFindings = 12,
   FixPolicy policy = FixPolicy.wireUp,
+  List<String> scannedDirectories = const ['lib'],
 }) {
+  final scope = scannedDirectories.join(', ');
   final ranked = rankFindings(report.newFindings);
   final summary = <String, Object?>{
     'root': root,
@@ -426,7 +438,7 @@ Guidance buildGuidance({
   for (var i = 0; i < groups.length; i++) {
     final block = selected.length >= maxFindings
         ? null
-        : _groupBlock(groups[i], selected.length + 1, policy);
+        : _groupBlock(groups[i], selected.length + 1, policy, scope);
     if (block == null ||
         runningLength + block.length + noteReserve > budgetChars) {
       // Stop at the first entry that does not fit. Skipping it and packing the
@@ -479,8 +491,9 @@ Guidance buildGuidance({
       );
   }
 
-  // Certain edits: a dead handler can be removed without product context, so
-  // surface those anchors even when they did not fit the ranked entries above.
+  // Dead handlers: once the scan's scope is confirmed, removing one needs no
+  // product context, so surface those anchors even when they did not fit the
+  // ranked entries above.
   final dead = report.newFindings
       .where((f) => f.rule == ruleDeadHandler)
       .toList();
@@ -500,11 +513,14 @@ Guidance buildGuidance({
       )
       ..writeln(
         policy == FixPolicy.wireUp
-            ? 'Nothing dispatches these, so the handler is unreachable. Wire it '
-                  'up by adding the control that dispatches the event; removing '
-                  'the handler needs explicit approval: $anchors'
-            : 'Nothing dispatches these, so removing the `on<...>` registration '
-                  'is safe even without product context: $anchors',
+            ? 'Nothing under $scope dispatches these, so the handler is '
+                  'unreachable from there. Check that no unscanned directory '
+                  'dispatches them (rerun with --dir), then wire it up by adding '
+                  'the control that dispatches the event; removing the handler '
+                  'needs explicit approval: $anchors'
+            : 'Nothing under $scope dispatches these. Once no unscanned '
+                  'directory does either (rerun with --dir), removing the '
+                  '`on<...>` registration needs no product context: $anchors',
       );
     if (buffer.length + section.length < budgetChars) buffer.write(section);
   }

lib/src/rules.dart

@@ -715,7 +715,10 @@ FindingReport runChecks({
                         'approval. Before wiring, check the event is not simply '
                         'dispatched from a directory that was not scanned (add it '
                         'with --dir): test-only handlers are not missing features.'
-                  : 'Remove the dead handler, or dispatch $event from the UI.',
+                  : 'Remove the dead handler once nothing outside '
+                        '${project.directories.join(', ')} dispatches $event '
+                        '(widen the scan with --dir to check), or dispatch '
+                        '$event from the UI.',
               data: {'union': union.name, 'owner': union.owner, 'event': event},
             ),
           );

test/policy_test.dart

@@ -104,4 +104,20 @@ void main() {
     expect(ruleFixFor(FixPolicy.wireUp).keys, containsAll(allRules));
     expect(ruleFixFor(FixPolicy.remove).keys, containsAll(allRules));
   });
+
+  test('removal claims are scoped to the scanned directories', () {
+    // The scan defaults to --dir lib, so "nothing outside the bloc references
+    // it" and "safe even without product context" claimed more than was
+    // checked: a handler dispatched only from test/ read as safe to delete.
+    for (final policy in FixPolicy.values) {
+      final brief = briefWith(policy);
+      expect(brief, contains('nothing under lib'), reason: '$policy');
+      expect(brief, isNot(contains('without product context')));
+      expect(brief, isNot(contains('nothing outside the bloc')));
+    }
+    final dead = reportWith(
+      FixPolicy.remove,
+    ).findings.firstWhere((finding) => finding.rule == ruleDeadHandler);
+    expect(dead.remediation, contains('nothing outside lib'));
+  });
 }