seed resumed Claude session from the transcript tail

claude --resume keeps the model's prior context but emits no past
turns over stream-json, so the pane was visually empty until the
user sent a new prompt. The orchestrator now reads the last 256 KB
of the on-disk transcript JSONL when SpawnSpec.resume is true and
seeds the ConversationController with the parsed items before the
stream subscription starts. Best-effort: missing or unreadable file
just falls back to the previous empty-pane behaviour.

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

lib/builtin/claude/src/claude_pane.dart

@@ -184,6 +184,7 @@ class _ClaudePaneState extends State<ClaudePane> {
         sessionId: _sessionId!,
         cwd: repoRoot,
         resume: resume,
+        transcriptPath: resume ? transcriptFile : null,
       ));
     } catch (e) {
       if (mounted) setState(() => _error = 'Could not start claude: $e');

lib/builtin/claude/src/conversation_controller.dart

@@ -15,13 +15,18 @@ import 'package:clide/kernel/src/events/message_bus.dart';
 import 'package:flutter/foundation.dart';
 
 class ConversationController extends ChangeNotifier {
-  /// Listens to [stream] and accumulates items. [onDispose] is invoked
-  /// from [dispose] — wire it to the reader's `dispose` so cancelling
-  /// the view tears down the underlying tail.
+  /// Listens to [stream] and accumulates items. [seed] pre-populates the
+  /// item list synchronously before subscribing — used when resuming a
+  /// session (D-77), where `claude --resume` doesn't replay prior turns
+  /// over stream-json so the pane would otherwise start empty. [onDispose]
+  /// is invoked from [dispose] — wire it to the reader's `dispose` so
+  /// cancelling the view tears down the underlying tail.
   ConversationController({
     required Stream<ConversationItem> stream,
+    Iterable<ConversationItem>? seed,
     Future<void> Function()? onDispose,
   }) : _onDispose = onDispose {
+    if (seed != null) _items.addAll(seed);
     _sub = stream.listen(_onItem);
   }
 

lib/builtin/claude/src/session_orchestrator.dart

@@ -12,13 +12,22 @@
 library;
 
 import 'dart:async';
+import 'dart:convert';
+import 'dart:io';
 
 import 'package:clide/builtin/claude/src/conversation_controller.dart';
 import 'package:clide/builtin/claude/src/session_naming.dart';
 import 'package:clide/builtin/claude/src/stream_json_session.dart';
 import 'package:clide/builtin/claude/src/team_broker.dart';
+import 'package:clide/builtin/claude/src/transcript_reader.dart';
 import 'package:flutter/foundation.dart';
 
+/// Max bytes of recent transcript to replay into the [ConversationController]
+/// when resuming a session — `claude --resume` carries Claude's context but
+/// emits no past turns over stream-json, so the pane would start empty
+/// without this hydration. Matches [TranscriptReader]'s initial-tail size.
+const _resumeTailBytes = 256 * 1024;
+
 /// Creates the subprocess for a session — production uses
 /// [ClaudeStreamJsonProcess.start]; tests inject a fake.
 typedef ProcessFactory = Future<StreamJsonProcess> Function({
@@ -36,6 +45,7 @@ class SpawnSpec {
     required this.sessionId,
     required this.cwd,
     this.resume = false,
+    this.transcriptPath,
     this.env,
     this.visible = true,
     this.team = false,
@@ -49,6 +59,11 @@ class SpawnSpec {
 
   /// Resume an existing session (`--resume`) vs create one (`--session-id`).
   final bool resume;
+
+  /// Transcript JSONL to replay into the conversation when [resume] is true.
+  /// Optional — without it, a resumed session still works but its pane starts
+  /// empty until the user sends a new prompt.
+  final String? transcriptPath;
   final Map<String, String>? env;
   final bool visible;
 
@@ -142,7 +157,8 @@ class ClaudeSessionOrchestrator extends ChangeNotifier {
       env: spec.env,
     );
     final session = StreamJsonSession(proc, mcpServers: mcpServers)..start();
-    final conversation = ConversationController(stream: session.items, onDispose: session.dispose);
+    final seed = spec.resume && spec.transcriptPath != null ? await _readTranscriptTail(spec.transcriptPath!) : null;
+    final conversation = ConversationController(stream: session.items, seed: seed, onDispose: session.dispose);
     final managed = ManagedSession(
       id: spec.id,
       role: spec.role,
@@ -178,6 +194,32 @@ class ClaudeSessionOrchestrator extends ChangeNotifier {
     notifyListeners();
   }
 
+  /// Read up to [_resumeTailBytes] from the end of [path] and parse it into
+  /// items to seed the conversation. Best-effort: a missing/unreadable file
+  /// returns null and the pane resumes empty, same as before this fix.
+  Future<List<ConversationItem>?> _readTranscriptTail(String path) async {
+    try {
+      final f = File(path);
+      if (!await f.exists()) return null;
+      final length = await f.length();
+      final start = length > _resumeTailBytes ? length - _resumeTailBytes : 0;
+      final raf = await f.open();
+      try {
+        await raf.setPosition(start);
+        final bytes = await raf.read(length - start);
+        final text = utf8.decode(bytes, allowMalformed: true);
+        // Started mid-file → drop the partial first line so we never feed
+        // half a JSON record to the parser.
+        final chunk = start == 0 ? text : text.substring(text.indexOf('\n') + 1);
+        return parseTranscriptChunk(chunk).items;
+      } finally {
+        await raf.close();
+      }
+    } catch (_) {
+      return null;
+    }
+  }
+
   /// The team-awareness preamble injected via `--append-system-prompt` (T-170).
   static String _teamSystemPrompt(String name, String role) => 'You are part of a clide-managed agent team. Your name is "$name" and your role is "$role". '
       'Coordinate with teammates using the clide-team MCP tools: '