fix(cli,gateway): surface title errors from /new <name>

The contributor's PR silently swallowed ValueError from
SessionDB.set_session_title() with bare except Exception: pass.
Users typing /new <title> with an already-in-use title got an
untitled session and no feedback.

Changes:
- cli.py: catch ValueError from both sanitize_title() and
  set_session_title(); print the error and mark the session
  untitled in the banner (never echo the rejected title back).
- gateway/run.py: append a warning note to the reset reply on
  title rejection; reflect the accepted title in the header.
- Add regression tests for the duplicate-title path in CLI and
  gateway.

Also map exx@example.com -> @exxmen in scripts/release.py.

tests/cli/test_cli_new_session.py

@@ -238,3 +238,40 @@ def test_new_session_with_title(capsys):
 
     captured = capsys.readouterr()
     assert "My Test Session" in captured.out
+
+
+def test_new_session_with_duplicate_title_surfaces_error(capsys):
+    """new_session(title=...) handles ValueError from a duplicate-title conflict.
+
+    The session is still created; the title assignment fails; the success banner
+    must not claim the rejected title as the session name.
+    """
+    cli = _make_cli()
+    cli._session_db = MagicMock()
+    cli._session_db.set_session_title.side_effect = ValueError(
+        "Title 'Dup' is already in use by session abc-123"
+    )
+    cli.agent = _FakeAgent("old_session_id", datetime.now())
+    cli.conversation_history = []
+
+    # Capture warnings printed via cli._cprint. After importlib.reload(),
+    # the method's __globals__ dict is the one from the live module — patch
+    # the exact dict the method will read.
+    warnings: list[str] = []
+    method_globals = cli.new_session.__globals__
+    original = method_globals["_cprint"]
+    method_globals["_cprint"] = lambda msg: warnings.append(msg)
+    try:
+        cli.new_session(title="Dup")
+    finally:
+        method_globals["_cprint"] = original
+
+    cli._session_db.set_session_title.assert_called_once()
+    joined = "\n".join(warnings)
+    assert "already in use" in joined
+    assert "session started untitled" in joined
+
+    # The success banner must NOT claim the rejected title as the session name.
+    captured = capsys.readouterr()
+    assert "New session started: Dup" not in captured.out
+    assert "New session started!" in captured.out

tests/gateway/test_title_command.py

@@ -274,6 +274,71 @@ class TestResetCommandWithTitle:
         runner._session_db.set_session_title.assert_called_once_with(
             "sess-new", "Custom Name"
         )
+        # Header reflects the applied title
+        assert "Custom Name" in str(result)
+
+    @pytest.mark.asyncio
+    async def test_reset_command_duplicate_title_surfaces_warning(self):
+        """/new <title> with an already-in-use title returns a warning in the reply."""
+        from datetime import datetime
+
+        from gateway.run import GatewayRunner
+        from gateway.session import SessionEntry, SessionSource, build_session_key
+
+        runner = object.__new__(GatewayRunner)
+        runner.config = GatewayConfig(
+            platforms={Platform.TELEGRAM: PlatformConfig(enabled=True, token="***")}
+        )
+        adapter = MagicMock()
+        adapter.send = AsyncMock()
+        runner.adapters = {Platform.TELEGRAM: adapter}
+        runner._voice_mode = {}
+        runner.hooks = SimpleNamespace(emit=AsyncMock(), loaded_hooks=False)
+        runner._session_model_overrides = {}
+        runner._pending_model_notes = {}
+        runner._background_tasks = set()
+
+        source = SessionSource(
+            platform=Platform.TELEGRAM,
+            user_id="12345",
+            chat_id="67890",
+            user_name="testuser",
+        )
+        session_key = build_session_key(source)
+        new_session_entry = SessionEntry(
+            session_key=session_key,
+            session_id="sess-new",
+            created_at=datetime.now(),
+            updated_at=datetime.now(),
+            platform=Platform.TELEGRAM,
+            chat_type="dm",
+        )
+        runner.session_store = MagicMock()
+        runner.session_store.get_or_create_session.return_value = new_session_entry
+        runner.session_store.reset_session.return_value = new_session_entry
+        runner.session_store._entries = {session_key: new_session_entry}
+        runner.session_store._generate_session_key.return_value = session_key
+        runner._running_agents = {}
+        runner._pending_messages = {}
+        runner._pending_approvals = {}
+        runner._session_db = MagicMock()
+        runner._session_db.set_session_title.side_effect = ValueError(
+            "Title 'Dup' is already in use by session abc-123"
+        )
+        runner._agent_cache = {}
+        runner._agent_cache_lock = None
+        runner._is_user_authorized = lambda _source: True
+        runner._format_session_info = lambda: ""
+
+        event = _make_event(text="/new Dup")
+        result = await runner._handle_reset_command(event)
+
+        runner._session_db.set_session_title.assert_called_once()
+        reply = str(result)
+        assert "already in use" in reply
+        assert "session started untitled" in reply
+        # Header must NOT claim the rejected title as the session name
+        assert "New session started: Dup" not in reply
 
 
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