feat(block2): messaging UI — private 1:1 chat (NIP-17)

- MessagesCubit: 1:1 conversation over MessageTransport. Filters the shared
  inbox to the peer; tags our own sends with our pubkey (NIP-17 wraps don't come
  back to the sender) so the UI can align bubbles; degrades gracefully offline.
- ChatScreen (mockup 10): message bubbles (mine right / peer left) + a composer;
  opens a session lazily, shows 'set up sharing' when there's no relay.
- Entry point: a 'Message' button on each offer card (hidden on your own
  listings) → /chat/:pubkey.
- Routing + i18n en/es/pt.

Tests: 5 cubit (send/receive/order/filter/offline) + chat offline + market, green.

apps/app_seeds/lib/app.dart

@@ -17,6 +17,7 @@ import 'state/inventory_cubit.dart';
 import 'state/variety_detail_cubit.dart';
 import 'ui/about_screen.dart';
 import 'ui/auto_backup_gate.dart';
+import 'ui/chat_screen.dart';
 import 'ui/home_screen.dart';
 import 'ui/intro_screen.dart';
 import 'ui/inventory_list_screen.dart';
@@ -98,6 +99,15 @@ class TaneApp extends StatelessWidget {
               outbox: outbox,
             ),
           ),
+        if (social != null && socialSettings != null)
+          GoRoute(
+            path: '/chat/:pubkey',
+            builder: (context, state) => ChatScreen(
+              social: social,
+              settings: socialSettings,
+              peerPubkey: state.pathParameters['pubkey']!,
+            ),
+          ),
         GoRoute(
           path: '/intro',
           builder: (context, state) => IntroScreen(

apps/app_seeds/lib/i18n/en.i18n.json

@@ -342,6 +342,7 @@
     "searching": "Looking around your area…",
     "empty": "No seeds shared near you yet",
     "near": "Near you",
+    "contact": "Message",
     "configTitle": "Sharing setup",
     "setupIntro": "Sharing with people nearby is optional. To turn it on, set your rough area and join a community you trust — a seed network or collective that runs a shared meeting point for passing messages. No company in the middle.",
     "areaLabel": "Your area",
@@ -358,5 +359,12 @@
     "useLocation": "Use my approximate location",
     "locationFailed": "Couldn't get your location",
     "queued": "Saved — we'll share these when you're connected"
+  },
+  "chat": {
+    "title": "Chat",
+    "hint": "Write a message…",
+    "send": "Send",
+    "empty": "No messages yet — say hello",
+    "offline": "Set up sharing to send messages"
   }
 }

apps/app_seeds/lib/i18n/es.i18n.json

@@ -342,6 +342,7 @@
     "searching": "Buscando por tu zona…",
     "empty": "Aún no hay semillas compartidas cerca de ti",
     "near": "Cerca de ti",
+    "contact": "Mensaje",
     "configTitle": "Configuración de compartir",
     "setupIntro": "Compartir con gente cercana es opcional. Para activarlo, indica tu zona aproximada y únete a una comunidad de confianza — una red de semillas o un colectivo que mantiene un punto de encuentro compartido para pasar mensajes. Sin ninguna empresa en medio.",
     "areaLabel": "Tu zona",
@@ -358,5 +359,12 @@
     "useLocation": "Usar mi ubicación aproximada",
     "locationFailed": "No se pudo obtener tu ubicación",
     "queued": "Guardado — las compartiremos cuando tengas conexión"
+  },
+  "chat": {
+    "title": "Chat",
+    "hint": "Escribe un mensaje…",
+    "send": "Enviar",
+    "empty": "Aún no hay mensajes — saluda",
+    "offline": "Configura el compartir para enviar mensajes"
   }
 }

apps/app_seeds/lib/i18n/pt.i18n.json

@@ -338,6 +338,7 @@
     "searching": "A procurar pela tua zona…",
     "empty": "Ainda não há sementes partilhadas perto de ti",
     "near": "Perto de ti",
+    "contact": "Mensagem",
     "configTitle": "Configuração de partilha",
     "setupIntro": "Partilhar com pessoas por perto é opcional. Para ativar, indica a tua zona aproximada e junta-te a uma comunidade de confiança — uma rede de sementes ou um coletivo que mantém um ponto de encontro partilhado para passar mensagens. Sem nenhuma empresa no meio.",
     "areaLabel": "A tua zona",
@@ -354,5 +355,12 @@
     "useLocation": "Usar a minha localização aproximada",
     "locationFailed": "Não foi possível obter a tua localização",
     "queued": "Guardado — vamos partilhá-las quando tiveres ligação"
+  },
+  "chat": {
+    "title": "Conversa",
+    "hint": "Escreve uma mensagem…",
+    "send": "Enviar",
+    "empty": "Ainda não há mensagens — diz olá",
+    "offline": "Configura a partilha para enviar mensagens"
   }
 }

apps/app_seeds/lib/i18n/strings.g.dart

@@ -4,9 +4,9 @@
 /// To regenerate, run: `dart run slang`
 ///
 /// Locales: 3
-/// Strings: 956 (318 per locale)
+/// Strings: 974 (324 per locale)
 ///
-/// Built on 2026-07-10 at 08:49 UTC
+/// Built on 2026-07-10 at 08:58 UTC
 
 // coverage:ignore-file
 // ignore_for_file: type=lint, unused_import

apps/app_seeds/lib/i18n/strings_en.g.dart

@@ -70,6 +70,7 @@ class Translations with BaseTranslations<AppLocale, Translations> {
 	late final Translations$desiccant$en desiccant = Translations$desiccant$en.internal(_root);
 	late final Translations$unit$en unit = Translations$unit$en.internal(_root);
 	late final Translations$market$en market = Translations$market$en.internal(_root);
+	late final Translations$chat$en chat = Translations$chat$en.internal(_root);
 }
 
 // Path: app
@@ -1085,6 +1086,9 @@ class Translations$market$en {
 	/// en: 'Near you'
 	String get near => 'Near you';
 
+	/// en: 'Message'
+	String get contact => 'Message';
+
 	/// en: 'Sharing setup'
 	String get configTitle => 'Sharing setup';
 
@@ -1134,6 +1138,30 @@ class Translations$market$en {
 	String get queued => 'Saved — we\'ll share these when you\'re connected';
 }
 
+// Path: chat
+class Translations$chat$en {
+	Translations$chat$en.internal(this._root);
+
+	final Translations _root; // ignore: unused_field
+
+	// Translations
+
+	/// en: 'Chat'
+	String get title => 'Chat';
+
+	/// en: 'Write a message…'
+	String get hint => 'Write a message…';
+
+	/// en: 'Send'
+	String get send => 'Send';
+
+	/// en: 'No messages yet — say hello'
+	String get empty => 'No messages yet — say hello';
+
+	/// en: 'Set up sharing to send messages'
+	String get offline => 'Set up sharing to send messages';
+}
+
 // Path: intro.slides
 class Translations$intro$slides$en {
 	Translations$intro$slides$en.internal(this._root);
@@ -1895,6 +1923,7 @@ extension on Translations {
 			'market.searching' => 'Looking around your area…',
 			'market.empty' => 'No seeds shared near you yet',
 			'market.near' => 'Near you',
+			'market.contact' => 'Message',
 			'market.configTitle' => 'Sharing setup',
 			'market.setupIntro' => 'Sharing with people nearby is optional. To turn it on, set your rough area and join a community you trust — a seed network or collective that runs a shared meeting point for passing messages. No company in the middle.',
 			'market.areaLabel' => 'Your area',
@@ -1911,6 +1940,11 @@ extension on Translations {
 			'market.useLocation' => 'Use my approximate location',
 			'market.locationFailed' => 'Couldn\'t get your location',
 			'market.queued' => 'Saved — we\'ll share these when you\'re connected',
+			'chat.title' => 'Chat',
+			'chat.hint' => 'Write a message…',
+			'chat.send' => 'Send',
+			'chat.empty' => 'No messages yet — say hello',
+			'chat.offline' => 'Set up sharing to send messages',
 			_ => null,
 		};
 	}

apps/app_seeds/lib/i18n/strings_es.g.dart

@@ -69,6 +69,7 @@ class TranslationsEs extends Translations with BaseTranslations<AppLocale, Trans
 	@override late final _Translations$desiccant$es desiccant = _Translations$desiccant$es._(_root);
 	@override late final _Translations$unit$es unit = _Translations$unit$es._(_root);
 	@override late final _Translations$market$es market = _Translations$market$es._(_root);
+	@override late final _Translations$chat$es chat = _Translations$chat$es._(_root);
 }
 
 // Path: app
@@ -612,6 +613,7 @@ class _Translations$market$es extends Translations$market$en {
 	@override String get searching => 'Buscando por tu zona…';
 	@override String get empty => 'Aún no hay semillas compartidas cerca de ti';
 	@override String get near => 'Cerca de ti';
+	@override String get contact => 'Mensaje';
 	@override String get configTitle => 'Configuración de compartir';
 	@override String get setupIntro => 'Compartir con gente cercana es opcional. Para activarlo, indica tu zona aproximada y únete a una comunidad de confianza — una red de semillas o un colectivo que mantiene un punto de encuentro compartido para pasar mensajes. Sin ninguna empresa en medio.';
 	@override String get areaLabel => 'Tu zona';
@@ -630,6 +632,20 @@ class _Translations$market$es extends Translations$market$en {
 	@override String get queued => 'Guardado — las compartiremos cuando tengas conexión';
 }
 
+// Path: chat
+class _Translations$chat$es extends Translations$chat$en {
+	_Translations$chat$es._(TranslationsEs root) : this._root = root, super.internal(root);
+
+	final TranslationsEs _root; // ignore: unused_field
+
+	// Translations
+	@override String get title => 'Chat';
+	@override String get hint => 'Escribe un mensaje…';
+	@override String get send => 'Enviar';
+	@override String get empty => 'Aún no hay mensajes — saluda';
+	@override String get offline => 'Configura el compartir para enviar mensajes';
+}
+
 // Path: intro.slides
 class _Translations$intro$slides$es extends Translations$intro$slides$en {
 	_Translations$intro$slides$es._(TranslationsEs root) : this._root = root, super.internal(root);
@@ -1275,6 +1291,7 @@ extension on TranslationsEs {
 			'market.searching' => 'Buscando por tu zona…',
 			'market.empty' => 'Aún no hay semillas compartidas cerca de ti',
 			'market.near' => 'Cerca de ti',
+			'market.contact' => 'Mensaje',
 			'market.configTitle' => 'Configuración de compartir',
 			'market.setupIntro' => 'Compartir con gente cercana es opcional. Para activarlo, indica tu zona aproximada y únete a una comunidad de confianza — una red de semillas o un colectivo que mantiene un punto de encuentro compartido para pasar mensajes. Sin ninguna empresa en medio.',
 			'market.areaLabel' => 'Tu zona',
@@ -1291,6 +1308,11 @@ extension on TranslationsEs {
 			'market.useLocation' => 'Usar mi ubicación aproximada',
 			'market.locationFailed' => 'No se pudo obtener tu ubicación',
 			'market.queued' => 'Guardado — las compartiremos cuando tengas conexión',
+			'chat.title' => 'Chat',
+			'chat.hint' => 'Escribe un mensaje…',
+			'chat.send' => 'Enviar',
+			'chat.empty' => 'Aún no hay mensajes — saluda',
+			'chat.offline' => 'Configura el compartir para enviar mensajes',
 			_ => null,
 		};
 	}

apps/app_seeds/lib/i18n/strings_pt.g.dart

@@ -69,6 +69,7 @@ class TranslationsPt extends Translations with BaseTranslations<AppLocale, Trans
 	@override late final _Translations$desiccant$pt desiccant = _Translations$desiccant$pt._(_root);
 	@override late final _Translations$unit$pt unit = _Translations$unit$pt._(_root);
 	@override late final _Translations$market$pt market = _Translations$market$pt._(_root);
+	@override late final _Translations$chat$pt chat = _Translations$chat$pt._(_root);
 }
 
 // Path: app
@@ -608,6 +609,7 @@ class _Translations$market$pt extends Translations$market$en {
 	@override String get searching => 'A procurar pela tua zona…';
 	@override String get empty => 'Ainda não há sementes partilhadas perto de ti';
 	@override String get near => 'Perto de ti';
+	@override String get contact => 'Mensagem';
 	@override String get configTitle => 'Configuração de partilha';
 	@override String get setupIntro => 'Partilhar com pessoas por perto é opcional. Para ativar, indica a tua zona aproximada e junta-te a uma comunidade de confiança — uma rede de sementes ou um coletivo que mantém um ponto de encontro partilhado para passar mensagens. Sem nenhuma empresa no meio.';
 	@override String get areaLabel => 'A tua zona';
@@ -626,6 +628,20 @@ class _Translations$market$pt extends Translations$market$en {
 	@override String get queued => 'Guardado — vamos partilhá-las quando tiveres ligação';
 }
 
+// Path: chat
+class _Translations$chat$pt extends Translations$chat$en {
+	_Translations$chat$pt._(TranslationsPt root) : this._root = root, super.internal(root);
+
+	final TranslationsPt _root; // ignore: unused_field
+
+	// Translations
+	@override String get title => 'Conversa';
+	@override String get hint => 'Escreve uma mensagem…';
+	@override String get send => 'Enviar';
+	@override String get empty => 'Ainda não há mensagens — diz olá';
+	@override String get offline => 'Configura a partilha para enviar mensagens';
+}
+
 // Path: intro.slides
 class _Translations$intro$slides$pt extends Translations$intro$slides$en {
 	_Translations$intro$slides$pt._(TranslationsPt root) : this._root = root, super.internal(root);
@@ -1267,6 +1283,7 @@ extension on TranslationsPt {
 			'market.searching' => 'A procurar pela tua zona…',
 			'market.empty' => 'Ainda não há sementes partilhadas perto de ti',
 			'market.near' => 'Perto de ti',
+			'market.contact' => 'Mensagem',
 			'market.configTitle' => 'Configuração de partilha',
 			'market.setupIntro' => 'Partilhar com pessoas por perto é opcional. Para ativar, indica a tua zona aproximada e junta-te a uma comunidade de confiança — uma rede de sementes ou um coletivo que mantém um ponto de encontro partilhado para passar mensagens. Sem nenhuma empresa no meio.',
 			'market.areaLabel' => 'A tua zona',
@@ -1283,6 +1300,11 @@ extension on TranslationsPt {
 			'market.useLocation' => 'Usar a minha localização aproximada',
 			'market.locationFailed' => 'Não foi possível obter a tua localização',
 			'market.queued' => 'Guardado — vamos partilhá-las quando tiveres ligação',
+			'chat.title' => 'Conversa',
+			'chat.hint' => 'Escreve uma mensagem…',
+			'chat.send' => 'Enviar',
+			'chat.empty' => 'Ainda não há mensagens — diz olá',
+			'chat.offline' => 'Configura a partilha para enviar mensagens',
 			_ => null,
 		};
 	}

apps/app_seeds/lib/state/messages_cubit.dart

@@ -0,0 +1,133 @@
+import 'dart:async';
+
+import 'package:commons_core/commons_core.dart';
+import 'package:equatable/equatable.dart';
+import 'package:flutter_bloc/flutter_bloc.dart';
+
+import '../services/social_service.dart';
+import '../services/social_settings.dart';
+
+/// A 1:1 conversation with one peer. Holds the running message list plus send
+/// status. Transport-agnostic — depends on [MessageTransport], not the relay.
+class ChatState extends Equatable {
+  const ChatState({
+    this.messages = const [],
+    this.sending = false,
+    this.error,
+  });
+
+  /// Messages in this conversation, oldest first. Incoming ones arrive from the
+  /// inbox; our own are appended optimistically on send (NIP-17 wraps don't come
+  /// back to the sender).
+  final List<PrivateMessage> messages;
+  final bool sending;
+  final String? error;
+
+  ChatState copyWith({
+    List<PrivateMessage>? messages,
+    bool? sending,
+    String? Function()? error,
+  }) =>
+      ChatState(
+        messages: messages ?? this.messages,
+        sending: sending ?? this.sending,
+        error: error != null ? error() : this.error,
+      );
+
+  @override
+  List<Object?> get props => [messages, sending, error];
+}
+
+/// Drives a 1:1 chat over a [MessageTransport]. Filters the shared inbox to
+/// [peerPubkey], and tags our own sent messages with [selfPubkey] so the UI can
+/// tell the two sides apart. Degrades gracefully when offline (null transport).
+class MessagesCubit extends Cubit<ChatState> {
+  MessagesCubit(
+    this._transport, {
+    required this.peerPubkey,
+    required this.selfPubkey,
+    Future<void> Function()? onDispose,
+  })  : _onDispose = onDispose,
+        super(const ChatState());
+
+  final MessageTransport? _transport;
+  final String peerPubkey;
+  final String selfPubkey;
+  final Future<void> Function()? _onDispose;
+  StreamSubscription<PrivateMessage>? _sub;
+
+  bool get isOnline => _transport != null;
+
+  /// Subscribes to incoming messages from [peerPubkey].
+  void start() {
+    final transport = _transport;
+    if (transport == null) return;
+    _sub = transport.inbox().listen(
+      (message) {
+        if (message.fromPubkey != peerPubkey) return; // another conversation
+        emit(state.copyWith(messages: [...state.messages, message]));
+      },
+      onError: (Object e) => emit(state.copyWith(error: () => '$e')),
+    );
+  }
+
+  /// Sends [text] to the peer and appends it optimistically.
+  Future<void> send(String text) async {
+    final transport = _transport;
+    final trimmed = text.trim();
+    if (transport == null || trimmed.isEmpty) return;
+    emit(state.copyWith(sending: true, error: () => null));
+    try {
+      await transport.send(toPubkey: peerPubkey, text: trimmed);
+      emit(state.copyWith(
+        sending: false,
+        messages: [
+          ...state.messages,
+          PrivateMessage(
+            fromPubkey: selfPubkey,
+            text: trimmed,
+            at: DateTime.now(),
+          ),
+        ],
+      ));
+    } catch (e) {
+      emit(state.copyWith(sending: false, error: () => '$e'));
+    }
+  }
+
+  /// Whether [message] was sent by us (for right-aligned bubbles).
+  bool isMine(PrivateMessage message) => message.fromPubkey == selfPubkey;
+
+  @override
+  Future<void> close() async {
+    await _sub?.cancel();
+    await _onDispose?.call();
+    return super.close();
+  }
+}
+
+/// Opens a [MessagesCubit] wired to the social layer for a chat with
+/// [peerPubkey], or an offline one that degrades gracefully.
+Future<MessagesCubit> createMessagesCubit(
+  SocialService social,
+  SocialSettings settings, {
+  required String peerPubkey,
+}) async {
+  final relays = await settings.relayUrls();
+  if (relays.isEmpty) {
+    return MessagesCubit(null,
+        peerPubkey: peerPubkey, selfPubkey: social.publicKeyHex);
+  }
+  try {
+    final session = await social.openSession(relays);
+    return MessagesCubit(
+      session.messages,
+      peerPubkey: peerPubkey,
+      selfPubkey: social.publicKeyHex,
+      onDispose: session.close,
+    );
+  } catch (_) {
+    return MessagesCubit(null,
+        peerPubkey: peerPubkey, selfPubkey: social.publicKeyHex);
+  }
+}

apps/app_seeds/lib/ui/chat_screen.dart

@@ -0,0 +1,216 @@
+import 'package:flutter/material.dart';
+import 'package:flutter_bloc/flutter_bloc.dart';
+
+import '../i18n/strings.g.dart';
+import '../services/social_service.dart';
+import '../services/social_settings.dart';
+import '../state/messages_cubit.dart';
+import 'theme.dart';
+
+/// A 1:1 encrypted chat with one peer (redesign screen 10). Private and
+/// metadata-hiding (NIP-17) under the hood; local-first, so it degrades to a
+/// "set up sharing" note when there's no relay.
+class ChatScreen extends StatefulWidget {
+  const ChatScreen({
+    required this.social,
+    required this.settings,
+    required this.peerPubkey,
+    super.key,
+  });
+
+  final SocialService social;
+  final SocialSettings settings;
+  final String peerPubkey;
+
+  @override
+  State<ChatScreen> createState() => _ChatScreenState();
+}
+
+class _ChatScreenState extends State<ChatScreen> {
+  MessagesCubit? _cubit;
+  bool _loading = true;
+  final _input = TextEditingController();
+
+  @override
+  void initState() {
+    super.initState();
+    _init();
+  }
+
+  Future<void> _init() async {
+    final cubit = await createMessagesCubit(
+      widget.social,
+      widget.settings,
+      peerPubkey: widget.peerPubkey,
+    );
+    if (!mounted) {
+      await cubit.close();
+      return;
+    }
+    cubit.start();
+    setState(() {
+      _cubit = cubit;
+      _loading = false;
+    });
+  }
+
+  Future<void> _send() async {
+    final cubit = _cubit;
+    if (cubit == null || _input.text.trim().isEmpty) return;
+    final text = _input.text;
+    _input.clear();
+    await cubit.send(text);
+  }
+
+  @override
+  void dispose() {
+    _cubit?.close();
+    _input.dispose();
+    super.dispose();
+  }
+
+  @override
+  Widget build(BuildContext context) {
+    final t = context.t;
+    final cubit = _cubit;
+    return Scaffold(
+      appBar: AppBar(title: Text(t.chat.title)),
+      body: _loading || cubit == null
+          ? const Center(child: CircularProgressIndicator())
+          : BlocProvider.value(
+              value: cubit,
+              child: _ChatBody(controller: _input, onSend: _send),
+            ),
+    );
+  }
+}
+
+class _ChatBody extends StatelessWidget {
+  const _ChatBody({required this.controller, required this.onSend});
+
+  final TextEditingController controller;
+  final Future<void> Function() onSend;
+
+  @override
+  Widget build(BuildContext context) {
+    final t = context.t;
+    final cubit = context.read<MessagesCubit>();
+    if (!cubit.isOnline) {
+      return Center(
+        child: Padding(
+          padding: const EdgeInsets.all(32),
+          child: Text(
+            t.chat.offline,
+            textAlign: TextAlign.center,
+            style: const TextStyle(color: seedMuted, fontSize: 15),
+          ),
+        ),
+      );
+    }
+    return Column(
+      children: [
+        Expanded(
+          child: BlocBuilder<MessagesCubit, ChatState>(
+            builder: (context, state) {
+              if (state.messages.isEmpty) {
+                return Center(
+                  child: Text(t.chat.empty,
+                      style: const TextStyle(color: seedMuted)),
+                );
+              }
+              return ListView.builder(
+                padding: const EdgeInsets.all(12),
+                itemCount: state.messages.length,
+                itemBuilder: (context, i) {
+                  final m = state.messages[i];
+                  return _Bubble(text: m.text, mine: cubit.isMine(m));
+                },
+              );
+            },
+          ),
+        ),
+        _Composer(controller: controller, onSend: onSend),
+      ],
+    );
+  }
+}
+
+class _Bubble extends StatelessWidget {
+  const _Bubble({required this.text, required this.mine});
+
+  final String text;
+  final bool mine;
+
+  @override
+  Widget build(BuildContext context) {
+    return Align(
+      alignment: mine ? AlignmentDirectional.centerEnd : AlignmentDirectional.centerStart,
+      child: Container(
+        margin: const EdgeInsets.symmetric(vertical: 4),
+        padding: const EdgeInsets.symmetric(horizontal: 14, vertical: 10),
+        constraints: BoxConstraints(
+          maxWidth: MediaQuery.of(context).size.width * 0.75,
+        ),
+        decoration: BoxDecoration(
+          color: mine ? seedGreen : seedPrimaryContainer,
+          borderRadius: BorderRadius.circular(16),
+        ),
+        child: Text(
+          text,
+          style: TextStyle(
+            color: mine ? Colors.white : seedOnSurface,
+            fontSize: 15,
+          ),
+        ),
+      ),
+    );
+  }
+}
+
+class _Composer extends StatelessWidget {
+  const _Composer({required this.controller, required this.onSend});
+
+  final TextEditingController controller;
+  final Future<void> Function() onSend;
+
+  @override
+  Widget build(BuildContext context) {
+    final t = context.t;
+    return SafeArea(
+      top: false,
+      child: Padding(
+        padding: const EdgeInsets.fromLTRB(12, 6, 12, 12),
+        child: Row(
+          children: [
+            Expanded(
+              child: TextField(
+                key: const Key('chat.input'),
+                controller: controller,
+                textInputAction: TextInputAction.send,
+                onSubmitted: (_) => onSend(),
+                decoration: InputDecoration(
+                  hintText: t.chat.hint,
+                  filled: true,
+                  fillColor: seedField,
+                  border: OutlineInputBorder(
+                    borderRadius: BorderRadius.circular(24),
+                    borderSide: BorderSide.none,
+                  ),
+                  contentPadding:
+                      const EdgeInsets.symmetric(horizontal: 18, vertical: 10),
+                ),
+              ),
+            ),
+            const SizedBox(width: 8),
+            IconButton.filled(
+              key: const Key('chat.send'),
+              icon: const Icon(Icons.send),
+              tooltip: t.chat.send,
+              onPressed: onSend,
+            ),
+          ],
+        ),
+      ),
+    );
+  }
+}

apps/app_seeds/lib/ui/market_screen.dart

@@ -1,6 +1,7 @@
 import 'package:commons_core/commons_core.dart';
 import 'package:flutter/material.dart';
 import 'package:flutter_bloc/flutter_bloc.dart';
+import 'package:go_router/go_router.dart';
 
 import '../data/variety_repository.dart';
 import '../i18n/strings.g.dart';
@@ -166,17 +167,27 @@ class _MarketScreenState extends State<MarketScreen> {
           ? const Center(child: CircularProgressIndicator())
           : BlocProvider.value(
               value: cubit,
-              child: MarketBody(onConfigure: _openConfig),
+              child: MarketBody(
+                onConfigure: _openConfig,
+                selfPubkey: widget.social.publicKeyHex,
+              ),
             ),
     );
   }
 }
 
 class MarketBody extends StatelessWidget {
-  const MarketBody({required this.onConfigure, super.key});
+  const MarketBody({
+    required this.onConfigure,
+    this.selfPubkey,
+    super.key,
+  });
 
   final VoidCallback onConfigure;
 
+  /// This user's own pubkey, so we don't offer to message our own listings.
+  final String? selfPubkey;
+
   @override
   Widget build(BuildContext context) {
     final t = context.t;
@@ -215,7 +226,15 @@ class MarketBody extends StatelessWidget {
           padding: const EdgeInsets.all(16),
           itemCount: state.offers.length,
           separatorBuilder: (_, _) => const SizedBox(height: 12),
-          itemBuilder: (context, i) => _OfferCard(offer: state.offers[i]),
+          itemBuilder: (context, i) {
+            final o = state.offers[i];
+            return _OfferCard(
+              offer: o,
+              onContact: o.authorPubkeyHex == selfPubkey
+                  ? null
+                  : () => context.go('/chat/${o.authorPubkeyHex}'),
+            );
+          },
         );
       },
     );
@@ -225,10 +244,13 @@ class MarketBody extends StatelessWidget {
 /// One discovered offer. Human words for the reciprocity mode; coarse "near you"
 /// instead of any precise location; price only when it's a sale.
 class _OfferCard extends StatelessWidget {
-  const _OfferCard({required this.offer});
+  const _OfferCard({required this.offer, this.onContact});
 
   final Offer offer;
 
+  /// Opens a private chat with the author; null for our own listings.
+  final VoidCallback? onContact;
+
   @override
   Widget build(BuildContext context) {
     final t = context.t;
@@ -263,8 +285,8 @@ class _OfferCard extends StatelessWidget {
               const Icon(Icons.place_outlined, size: 15, color: seedMuted),
               const SizedBox(width: 4),
               Text(t.market.near, style: const TextStyle(color: seedMuted, fontSize: 13)),
-              if (offer.type == OfferType.sale && offer.priceAmount != null) ...[
               const Spacer(),
+              if (offer.type == OfferType.sale && offer.priceAmount != null)
                 Text(
                   '${offer.priceAmount} ${offer.priceCurrency ?? ''}'.trim(),
                   style: const TextStyle(
@@ -272,7 +294,12 @@ class _OfferCard extends StatelessWidget {
                     fontWeight: FontWeight.w600,
                   ),
                 ),
-              ],
+              if (onContact != null)
+                TextButton.icon(
+                  onPressed: onContact,
+                  icon: const Icon(Icons.chat_bubble_outline, size: 16),
+                  label: Text(t.market.contact),
+                ),
             ],
           ),
         ],

apps/app_seeds/test/state/messages_cubit_test.dart

@@ -0,0 +1,90 @@
+import 'dart:async';
+
+import 'package:commons_core/commons_core.dart';
+import 'package:flutter_test/flutter_test.dart';
+import 'package:tane/state/messages_cubit.dart';
+
+/// In-memory [MessageTransport]: records sends, lets a test push inbox messages.
+class FakeMessageTransport implements MessageTransport {
+  final List<({String to, String text})> sent = [];
+  final StreamController<PrivateMessage> _inbox =
+      StreamController<PrivateMessage>.broadcast();
+
+  void receive(PrivateMessage message) => _inbox.add(message);
+
+  @override
+  Future<void> send({required String toPubkey, required String text}) async =>
+      sent.add((to: toPubkey, text: text));
+
+  @override
+  Stream<PrivateMessage> inbox() => _inbox.stream;
+
+  @override
+  Future<void> close() async => _inbox.close();
+}
+
+void main() {
+  const peer = 'aa';
+  const me = 'bb';
+
+  PrivateMessage msg(String from, String text) =>
+      PrivateMessage(fromPubkey: from, text: text, at: DateTime(2026));
+
+  test('receives messages from the peer only', () async {
+    final transport = FakeMessageTransport();
+    final cubit =
+        MessagesCubit(transport, peerPubkey: peer, selfPubkey: me)..start();
+
+    transport.receive(msg(peer, 'hola'));
+    transport.receive(msg('cc', 'not for this chat')); // other conversation
+    await pumpEventQueue();
+
+    expect(cubit.state.messages, hasLength(1));
+    expect(cubit.state.messages.single.text, 'hola');
+    expect(cubit.isMine(cubit.state.messages.single), isFalse);
+    await cubit.close();
+  });
+
+  test('send delivers to the peer and appends our own message', () async {
+    final transport = FakeMessageTransport();
+    final cubit = MessagesCubit(transport, peerPubkey: peer, selfPubkey: me);
+
+    await cubit.send('  ¿cambiamos?  ');
+    expect(transport.sent, [(to: peer, text: '¿cambiamos?')]);
+    expect(cubit.state.messages, hasLength(1));
+    expect(cubit.isMine(cubit.state.messages.single), isTrue);
+    expect(cubit.state.sending, isFalse);
+    await cubit.close();
+  });
+
+  test('a full exchange keeps order and sides', () async {
+    final transport = FakeMessageTransport();
+    final cubit =
+        MessagesCubit(transport, peerPubkey: peer, selfPubkey: me)..start();
+
+    await cubit.send('hi');
+    transport.receive(msg(peer, 'hello'));
+    await pumpEventQueue();
+
+    expect(cubit.state.messages.map((m) => m.text), ['hi', 'hello']);
+    expect(cubit.state.messages.map(cubit.isMine), [true, false]);
+    await cubit.close();
+  });
+
+  test('empty/whitespace text is not sent', () async {
+    final transport = FakeMessageTransport();
+    final cubit = MessagesCubit(transport, peerPubkey: peer, selfPubkey: me);
+    await cubit.send('   ');
+    expect(transport.sent, isEmpty);
+    expect(cubit.state.messages, isEmpty);
+    await cubit.close();
+  });
+
+  test('offline (no transport) never throws', () async {
+    final cubit = MessagesCubit(null, peerPubkey: peer, selfPubkey: me)..start();
+    expect(cubit.isOnline, isFalse);
+    await cubit.send('hi');
+    expect(cubit.state.messages, isEmpty);
+    await cubit.close();
+  });
+}

apps/app_seeds/test/ui/chat_screen_test.dart

@@ -0,0 +1,40 @@
+import 'package:flutter/material.dart';
+import 'package:flutter_localizations/flutter_localizations.dart';
+import 'package:flutter_test/flutter_test.dart';
+import 'package:tane/i18n/strings.g.dart';
+import 'package:tane/services/social_service.dart';
+import 'package:tane/services/social_settings.dart';
+import 'package:tane/ui/chat_screen.dart';
+
+import '../support/test_support.dart';
+
+void main() {
+  testWidgets('with no relay configured, chat shows the offline note',
+      (tester) async {
+    final social = await SocialService.fromRootSeedHex('00' * 32);
+    final settings = SocialSettings(InMemorySecretStore());
+    LocaleSettings.setLocaleSync(AppLocale.en);
+
+    await tester.pumpWidget(
+      TranslationProvider(
+        child: MaterialApp(
+          locale: AppLocale.en.flutterLocale,
+          supportedLocales: AppLocaleUtils.supportedLocales,
+          localizationsDelegates: const [
+            GlobalMaterialLocalizations.delegate,
+            GlobalWidgetsLocalizations.delegate,
+            GlobalCupertinoLocalizations.delegate,
+          ],
+          home: ChatScreen(
+            social: social,
+            settings: settings,
+            peerPubkey: 'ab' * 32,
+          ),
+        ),
+      ),
+    );
+    await tester.pumpAndSettle();
+
+    expect(find.text('Set up sharing to send messages'), findsOneWidget);
+  });
+}