claude: live-tail terminal sub-card in expanded Bash cards (T-325, UI)

Wire the detection + follower core into the Bash tool card. A Bash card
with a follow intent (`tail -f …`) gains a "live tail" segment below the
result: an embedded read-only TerminalView fed by FileTailFollower on the
file the command follows, resolved against the open workspace.

Lazy lifecycle for free: the collapser builds its children only when
expanded (clide_collapser_card.dart), so _BashLiveTail starts the follower
in didChangeDependencies on expand and stops it in dispose on collapse —
no follower runs until the card is expanded. No resolvable file-backed
source → a muted "no independent source to follow" note, never an empty
terminal. The workspace root comes from kernel.project.current, so no new
plumbing through the conversation widget tree.

Tests: a tail Bash card surfaces the segment (+ the muted note when no
project/source); an ordinary `ls` card gets no segment; the segment only
builds on expand.

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

CHANGELOG.md

@@ -16,6 +16,19 @@ heading, and (b) bumping `pubspec.yaml` `version:` in the same commit.
 
 ## [Unreleased]
 
+### Added
+
+- **Live tail inside expanded Bash activity cards.** Expanding a Bash card whose
+  command follows a file (`tail -f …`, `tail -n N …`) now shows a live, scrolling
+  terminal of that file below the result, so you can watch progress on a
+  long-running tail instead of waiting for the final block. clide can't see
+  Claude's running process, so it opens its OWN read-only follower on the same
+  file — never re-running or intercepting the command — connected lazily only
+  while the card is expanded and torn down on collapse. A command with no
+  independent file-backed source (a pipe into `tail`, a path outside the repo)
+  shows a muted "no independent source to follow" note rather than an empty
+  terminal. (T-325)
+
 ### Changed
 
 - **Each spawned subagent gets its own collapsing activity card.** A fan-out of

lib/builtin/claude/src/conversation_view.dart

@@ -14,8 +14,10 @@ import 'dart:convert';
 import 'dart:io';
 
 import 'package:clide/builtin/claude/src/activity_cluster.dart';
+import 'package:clide/builtin/claude/src/bash_tail_source.dart';
 import 'package:clide/builtin/claude/src/conversation_card.dart';
 import 'package:clide/builtin/claude/src/conversation_controller.dart';
+import 'package:clide/builtin/claude/src/file_tail_follower.dart';
 import 'package:clide/builtin/claude/src/image_thumbnail.dart';
 import 'package:clide/builtin/claude/src/prompt_card.dart';
 import 'package:clide/builtin/claude/src/transcript_reader.dart';
@@ -23,6 +25,7 @@ import 'package:clide/kernel/src/facade.dart';
 import 'package:clide/kernel/src/syntax/language_map.dart';
 import 'package:clide/kernel/src/theme/controller.dart';
 import 'package:clide/kernel/src/theme/tokens.dart';
+import 'package:clide/src/terminal/terminal.dart';
 import 'package:clide/widgets/widgets.dart';
 import 'package:flutter/widgets.dart';
 
@@ -423,6 +426,64 @@ void _openFile(BuildContext context, String path, int? line) {
   unawaited(ClideKernel.of(context).ipc.request('editor.open', args: {'path': path, 'line': ?line}));
 }
 
+/// A live, read-only tail of the file a Bash command follows (T-325).
+///
+/// Mounts when the Bash card is EXPANDED — the collapser builds its children
+/// lazily (clide_collapser_card.dart), so initialising here and tearing down in
+/// [dispose] gives the "connect on expand, disconnect on collapse" lifecycle
+/// for free. Resolves the followed file from the command against the open
+/// workspace; when there's no independent file-backed source (a pipe into
+/// `tail`, a path outside the repo) it shows a muted note instead of an empty
+/// terminal.
+class _BashLiveTail extends StatefulWidget {
+  const _BashLiveTail({required this.command});
+
+  final String command;
+
+  @override
+  State<_BashLiveTail> createState() => _BashLiveTailState();
+}
+
+class _BashLiveTailState extends State<_BashLiveTail> {
+  Terminal? _terminal;
+  FileTailFollower? _follower;
+  bool _resolved = false;
+
+  @override
+  void didChangeDependencies() {
+    super.didChangeDependencies();
+    if (_resolved) return; // resolve once — InheritedWidget access needs context
+    _resolved = true;
+    final root = ClideKernel.of(context).project.current;
+    final source = root == null ? null : detectBashTailSource(widget.command, workspaceRoot: root);
+    if (source == null) return; // no file-backed source → muted note in build
+    final term = Terminal(maxLines: 1000);
+    _terminal = term;
+    _follower = FileTailFollower(source, onData: (bytes) => term.write(utf8.decode(bytes, allowMalformed: true)));
+    unawaited(_follower!.start());
+  }
+
+  @override
+  void dispose() {
+    _follower?.stop();
+    super.dispose();
+  }
+
+  @override
+  Widget build(BuildContext context) {
+    final term = _terminal;
+    if (term == null) {
+      return ClideText('no independent source to follow', muted: true, fontSize: clideFontMeta);
+    }
+    return SizedBox(
+      height: 160,
+      child: ClipRect(
+        child: ClidePtyView(terminal: term, label: 'live tail', fontSize: clideFontMeta),
+      ),
+    );
+  }
+}
+
 /// One conversation item, rendered by kind.
 class _ConversationTurn extends StatelessWidget {
   const _ConversationTurn({
@@ -694,6 +755,14 @@ class _ConversationTurn extends StatelessWidget {
           label: 'result',
           child: ClideCodeBlock(source: result.content, language: _resultLanguage(t)),
         ),
+      // T-325: a Bash card that follows a file (`tail -f …`) gets a live,
+      // scrolling tail of that file below the result — connected lazily, only
+      // while the card is expanded (the collapser builds segments on expand).
+      if (t.name == 'Bash' && t.input['command'] is String && bashHasTailIntent(t.input['command'] as String))
+        CardSegment(
+          label: 'live tail',
+          child: _BashLiveTail(command: t.input['command'] as String),
+        ),
     ];
 
     // A resolved permission-prompted call is tinted green if approved / red if

test/builtin/claude/conversation_view_test.dart

@@ -818,6 +818,29 @@ void main() {
       expect(copied, contains('question text'));
       expect(copied, contains('answer text'));
     });
+
+    testWidgets('a tail Bash card shows a live-tail segment; no workspace source → muted note (T-325)', (tester) async {
+      await pumpWith(tester, [
+        AssistantToolUse(uuid: 'b1', timestamp: _t, isSidechain: false, toolUseId: 'tb', name: 'Bash', input: const {'command': 'tail -f app.log'}),
+      ]);
+      // Collapsed by default — the segment only builds (and connects) on expand.
+      expect(find.text('live tail'), findsNothing);
+      await tester.tap(find.bySemanticsLabel('Bash, 1 step, collapsed'));
+      await tester.pumpAndSettle();
+      expect(find.text('live tail'), findsOneWidget); // segment surfaced for a tail command
+      // No project open in the fixture → no resolvable source → the muted note,
+      // never a broken/empty terminal.
+      expect(find.text('no independent source to follow'), findsOneWidget);
+    });
+
+    testWidgets('an ordinary Bash card has no live-tail segment (T-325)', (tester) async {
+      await pumpWith(tester, [
+        AssistantToolUse(uuid: 'b2', timestamp: _t, isSidechain: false, toolUseId: 'tb2', name: 'Bash', input: const {'command': 'ls -la'}),
+      ]);
+      await tester.tap(find.bySemanticsLabel('Bash, 1 step, collapsed'));
+      await tester.pumpAndSettle();
+      expect(find.text('live tail'), findsNothing); // no tail intent → no segment
+    });
   });
 
   group('ClaudeBanner', () {