Updater v1 --upgrade + roadmap as flat backlog

Updater: watch-together --upgrade checks updates/manifest.json,
downloads the tarball, verifies sha256, applies over the live
install (extract-temp + delete-first move-over; rename-safe on
Linux while running). Zero Flutter imports, 7 tests incl.
stub-server flows. Version stamped via --dart-define=APP_VERSION
in package script. Warns (never silently jumps) on proto mismatch.
Roadmap: phases retired as tracker (history in git log), now flat
Built/Backlog/Epics/Deferred; Jellyfin next feature, transcode
never; updater expansion stays an epic. Endpoint publishing
(manifest + release tarball) is user-owned.

apps/desktop/test/updater_test.dart

@@ -0,0 +1,173 @@
+import 'dart:convert';
+import 'dart:io';
+
+import 'package:archive/archive.dart';
+import 'package:crypto/crypto.dart';
+import 'package:flutter_test/flutter_test.dart';
+import 'package:watch_together/src/update/updater.dart';
+
+void main() {
+  test('version compare', () {
+    expect(isNewerVersion('0.1.0', '0.1.1'), isTrue);
+    expect(isNewerVersion('0.1.0', '0.2.0'), isTrue);
+    expect(isNewerVersion('0.1.0', '1.0.0'), isTrue);
+    expect(isNewerVersion('0.0.0-dev', '0.1.0'), isTrue);
+    expect(isNewerVersion('0.1.0', '0.1.0'), isFalse);
+    expect(isNewerVersion('0.2.0', '0.1.9'), isFalse);
+  });
+
+  test('manifest rejects missing fields', () {
+    expect(() => UpdateManifest.fromJson({}), throwsFormatException);
+    expect(
+        () => UpdateManifest.fromJson({
+              'version': '0.2.0',
+              'protocol': 4,
+              'url': 'https://x/y.tar.gz',
+            }),
+        throwsFormatException);
+  });
+
+  test('findInstallRoot honors bundle layout', () async {
+    final tmp = await Directory.systemTemp.createTemp('wt-root-test');
+    try {
+      final root = Directory('${tmp.path}/root');
+      await Directory('${root.path}/data').create(recursive: true);
+      await Directory('${root.path}/lib').create(recursive: true);
+      final exe = File('${root.path}/watch_together')..createSync();
+      expect(findInstallRoot(exe.path)?.path, root.path);
+      expect(findInstallRoot('${tmp.path}/stray-binary'), isNull);
+    } finally {
+      await tmp.delete(recursive: true);
+    }
+  });
+
+  group('upgrade flow', () {
+    late HttpServer server;
+    late Directory work;
+    late List<int> tarball;
+    late String tarSha;
+    var tarHits = 0;
+
+    setUp(() async {
+      tarHits = 0;
+      work = await Directory.systemTemp.createTemp('wt-up-test');
+      final archive = Archive();
+      final v2 = utf8.encode('binary-v2');
+      archive.addFile(ArchiveFile('watch_together', v2.length, v2));
+      final cfg = utf8.encode('fresh-config');
+      archive.addFile(ArchiveFile('data/fresh.cfg', cfg.length, cfg));
+      tarball = GZipEncoder().encode(TarEncoder().encode(archive));
+      tarSha = sha256.convert(tarball).toString();
+      server = await HttpServer.bind(InternetAddress.loopbackIPv4, 0);
+      server.listen((req) async {
+        if (req.uri.path == '/manifest.json') {
+          final manifest = {
+            'version': '0.2.0',
+            'protocol': 4,
+            'url':
+                'http://127.0.0.1:${server.port}/watch-together-0.2.0.tar.gz',
+            'sha256': tarSha,
+            'notes': 'test build',
+          };
+          req.response
+            ..statusCode = 200
+            ..write(jsonEncode(manifest));
+        } else if (req.uri.path == '/watch-together-0.2.0.tar.gz') {
+          tarHits++;
+          req.response
+            ..statusCode = 200
+            ..add(tarball);
+        } else {
+          req.response.statusCode = 404;
+        }
+        await req.response.close();
+      });
+    });
+
+    tearDown(() async {
+      await server.close(force: true);
+      if (await work.exists()) {
+        await work.delete(recursive: true);
+      }
+    });
+
+    Future<Directory> fakeRoot() async {
+      final root = Directory('${work.path}/root');
+      await Directory('${root.path}/data').create(recursive: true);
+      await Directory('${root.path}/lib').create(recursive: true);
+      await File('${root.path}/watch_together')
+          .writeAsString('binary-v1', flush: true);
+      return root;
+    }
+
+    String manifestUrl() =>
+        'http://127.0.0.1:${server.port}/manifest.json';
+
+    test('downloads, verifies and applies', () async {
+      final root = await fakeRoot();
+      final rc = await runUpgrade(
+          currentVersion: '0.1.0',
+          manifestUrl: manifestUrl(),
+          installRoot: root);
+      expect(rc, 0);
+      expect(tarHits, 1);
+      expect(await File('${root.path}/watch_together').readAsString(),
+          'binary-v2');
+      expect(await File('${root.path}/data/fresh.cfg').readAsString(),
+          'fresh-config');
+    });
+
+    test('up to date downloads nothing', () async {
+      final root = await fakeRoot();
+      final rc = await runUpgrade(
+          currentVersion: '0.2.0',
+          manifestUrl: manifestUrl(),
+          installRoot: root);
+      expect(rc, 0);
+      expect(tarHits, 0);
+      expect(await File('${root.path}/watch_together').readAsString(),
+          'binary-v1');
+    });
+
+    test('bad hash aborts, install untouched', () async {
+      await server.close(force: true);
+      server = await HttpServer.bind(InternetAddress.loopbackIPv4, 0);
+      server.listen((req) async {
+        if (req.uri.path == '/manifest.json') {
+          req.response
+            ..statusCode = 200
+            ..write(jsonEncode({
+              'version': '0.2.0',
+              'protocol': 4,
+              'url':
+                  'http://127.0.0.1:${server.port}/watch-together-0.2.0.tar.gz',
+              'sha256': '0' * 64,
+              'notes': '',
+            }));
+        } else {
+          tarHits++;
+          req.response
+            ..statusCode = 200
+            ..add(tarball);
+        }
+        await req.response.close();
+      });
+      final root = await fakeRoot();
+      final rc = await runUpgrade(
+          currentVersion: '0.1.0',
+          manifestUrl: manifestUrl(),
+          installRoot: root);
+      expect(rc, 1);
+      expect(await File('${root.path}/watch_together').readAsString(),
+          'binary-v1');
+    });
+
+    test('unknown layout asks for manual update', () async {
+      final rc = await runUpgrade(
+          currentVersion: '0.1.0',
+          manifestUrl: manifestUrl(),
+          executablePath: '${work.path}/stray-binary');
+      expect(rc, 2);
+    });
+  });
+}