make conversation card actions keyboard-reachable

The copy button and custom message actions only rendered on hover, so
they were unreachable by keyboard or assistive tech. Keep them in the
tree always — revealed via opacity on hover OR focus — and route each
through ClideTappable (Tab traversal + Enter/Space activation) with a
Semantics button label and onTap so AT can discover and invoke them.
alwaysIncludeSemantics keeps them in the semantics tree while hidden.

T-174.

Co-Authored-By: Claude <noreply@anthropic.com>

test/builtin/claude/conversation_card_test.dart

@@ -29,6 +29,32 @@ void main() {
     await tester.pump();
   }
 
+  // Returns the Opacity wrapping the action bar (the Opacity that reveals/hides
+  // the action buttons on hover or focus).
+  Opacity actionBarOpacity(WidgetTester tester) {
+    // The action bar Opacity is a direct child of the header Row — pick the
+    // first Opacity that is an ancestor of the 'copy' Semantics (or any action
+    // label), which is the one whose value toggles on hover/focus.
+    return tester.widgetList<Opacity>(find.byType(Opacity)).first;
+  }
+
+  testWidgets('copy button is always in the tree (Opacity 0 before hover)', (tester) async {
+    await tester.pumpWidget(harness(
+      f,
+      const ConversationCard(
+        accent: Color(0xFFFFFFFF),
+        label: 'you',
+        copyText: 'the raw message',
+        body: Text('the raw message', textDirection: TextDirection.ltr),
+      ),
+    ));
+    await tester.pump();
+
+    // The text widget is in the tree (always), but the Opacity hides it.
+    expect(find.text('copy'), findsOneWidget);
+    expect(actionBarOpacity(tester).opacity, 0.0);
+  });
+
   testWidgets('copy button (on hover) writes the copyText to the clipboard', (tester) async {
     await tester.pumpWidget(harness(
       f,
@@ -40,10 +66,9 @@ void main() {
       ),
     ));
     await tester.pump();
-    expect(find.text('copy'), findsNothing); // hidden until hover
 
     await hoverCard(tester);
-    expect(find.text('copy'), findsOneWidget);
+    expect(actionBarOpacity(tester).opacity, 1.0);
 
     await tester.tap(find.text('copy'));
     // writePlain awaits the clipboard channel; let the real async settle.
@@ -51,6 +76,63 @@ void main() {
     expect(f.services.clipboard.readAs<String>(), 'the raw message');
   });
 
+  testWidgets('copy button: keyboard focus + ActivateIntent writes to clipboard without hovering', (tester) async {
+    // T-174: actions must be keyboard-reachable even when the card is not hovered.
+    await tester.pumpWidget(harness(
+      f,
+      const ConversationCard(
+        accent: Color(0xFFFFFFFF),
+        label: 'you',
+        copyText: 'keyboard written',
+        body: Text('keyboard written', textDirection: TextDirection.ltr),
+      ),
+    ));
+    await tester.pump();
+
+    // Locate the ClideTappable whose FocusNode we want: the one wrapping the
+    // 'copy' label. We drive focus programmatically via the node embedded in
+    // the widget — find the Focus descendent nearest to the 'copy' text.
+    final copyTextFinder = find.text('copy');
+    expect(copyTextFinder, findsOneWidget);
+
+    // Walk up to find the Focus that ClideTappable installed, then request focus.
+    final focusWidget = tester.widget<Focus>(
+      find.ancestor(of: copyTextFinder, matching: find.byType(Focus)).first,
+    );
+    focusWidget.focusNode!.requestFocus();
+    await tester.pump(); // focus resolves; the focus listener calls setState
+    await tester.pump(); // the scheduled rebuild paints the lifted opacity
+
+    expect(focusWidget.focusNode!.hasFocus, isTrue, reason: 'copy action should accept keyboard focus');
+
+    // With focus, the action bar opacity should lift to 1.0.
+    expect(actionBarOpacity(tester).opacity, 1.0);
+
+    // Invoke via ActivateIntent (what Enter/Space dispatches from the keymap).
+    Actions.invoke(focusWidget.focusNode!.context!, const ActivateIntent());
+    await tester.runAsync(() => Future<void>.delayed(const Duration(milliseconds: 20)));
+
+    expect(f.services.clipboard.readAs<String>(), 'keyboard written');
+  });
+
+  testWidgets('copy button carries a Semantics button label', (tester) async {
+    final handle = tester.ensureSemantics();
+    await tester.pumpWidget(harness(
+      f,
+      const ConversationCard(
+        accent: Color(0xFFFFFFFF),
+        label: 'you',
+        copyText: 'msg',
+        body: Text('msg', textDirection: TextDirection.ltr),
+      ),
+    ));
+    await tester.pump();
+    // Semantics label 'copy' must be present even before hover, so AT can
+    // discover the button without the user mousing over first.
+    expect(find.bySemanticsLabel('copy'), findsOneWidget);
+    handle.dispose();
+  });
+
   testWidgets('collapsible card hides its body until expanded', (tester) async {
     await tester.pumpWidget(harness(
       f,
@@ -87,6 +169,23 @@ void main() {
     expect(find.bySemanticsLabel('Collapse'), findsNothing);
   });
 
+  testWidgets('custom actions are always in the tree (Opacity 0 before hover)', (tester) async {
+    await tester.pumpWidget(harness(
+      f,
+      ConversationCard(
+        accent: const Color(0xFFFFFFFF),
+        label: 'claude',
+        body: const Text('body', textDirection: TextDirection.ltr),
+        actions: [MessageAction(label: 'fork', onInvoke: () {})],
+      ),
+    ));
+    await tester.pump();
+
+    // 'fork' is in the tree (always), but the Opacity hides it.
+    expect(find.text('fork'), findsOneWidget);
+    expect(actionBarOpacity(tester).opacity, 0.0);
+  });
+
   testWidgets('custom actions appear on hover and invoke', (tester) async {
     var forked = false;
     await tester.pumpWidget(harness(
@@ -99,9 +198,9 @@ void main() {
       ),
     ));
     await tester.pump();
-    expect(find.text('fork'), findsNothing);
 
     await hoverCard(tester);
+    expect(actionBarOpacity(tester).opacity, 1.0);
     await tester.tap(find.text('fork'));
     await tester.pump();
     expect(forked, isTrue);