fix(cli): make /new, /reset, and /clear start real fresh sessions

Create a new session DB row when starting fresh from the CLI, reset the
agent DB flush cursor and todo state, and update session timing/session ID
bookkeeping so follow-up logging stays correct.

Also update slash-command descriptions and add regression tests for /new,
/reset, and /clear.

Supersedes PR #899.
Closes #641.

tests/test_cli_new_session.py

@@ -0,0 +1,139 @@
+"""Regression tests for CLI fresh-session commands."""
+
+from __future__ import annotations
+
+import importlib
+import os
+import sys
+from datetime import timedelta
+from unittest.mock import MagicMock, patch
+
+from hermes_state import SessionDB
+from tools.todo_tool import TodoStore
+
+
+class _FakeAgent:
+    def __init__(self, session_id: str, session_start):
+        self.session_id = session_id
+        self.session_start = session_start
+        self.model = "anthropic/claude-opus-4.6"
+        self._last_flushed_db_idx = 7
+        self._todo_store = TodoStore()
+        self._todo_store.write(
+            [{"id": "t1", "content": "unfinished task", "status": "in_progress"}]
+        )
+        self.flush_memories = MagicMock()
+        self._invalidate_system_prompt = MagicMock()
+
+
+def _make_cli(env_overrides=None, config_overrides=None, **kwargs):
+    """Create a HermesCLI instance with minimal mocking."""
+    _clean_config = {
+        "model": {
+            "default": "anthropic/claude-opus-4.6",
+            "base_url": "https://openrouter.ai/api/v1",
+            "provider": "auto",
+        },
+        "display": {"compact": False, "tool_progress": "all"},
+        "agent": {},
+        "terminal": {"env_type": "local"},
+    }
+    if config_overrides:
+        _clean_config.update(config_overrides)
+    clean_env = {"LLM_MODEL": "", "HERMES_MAX_ITERATIONS": ""}
+    if env_overrides:
+        clean_env.update(env_overrides)
+    prompt_toolkit_stubs = {
+        "prompt_toolkit": MagicMock(),
+        "prompt_toolkit.history": MagicMock(),
+        "prompt_toolkit.styles": MagicMock(),
+        "prompt_toolkit.patch_stdout": MagicMock(),
+        "prompt_toolkit.application": MagicMock(),
+        "prompt_toolkit.layout": MagicMock(),
+        "prompt_toolkit.layout.processors": MagicMock(),
+        "prompt_toolkit.filters": MagicMock(),
+        "prompt_toolkit.layout.dimension": MagicMock(),
+        "prompt_toolkit.layout.menus": MagicMock(),
+        "prompt_toolkit.widgets": MagicMock(),
+        "prompt_toolkit.key_binding": MagicMock(),
+        "prompt_toolkit.completion": MagicMock(),
+        "prompt_toolkit.formatted_text": MagicMock(),
+    }
+    with patch.dict(sys.modules, prompt_toolkit_stubs), patch.dict(
+        "os.environ", clean_env, clear=False
+    ):
+        import cli as _cli_mod
+
+        _cli_mod = importlib.reload(_cli_mod)
+        with patch.object(_cli_mod, "get_tool_definitions", return_value=[]), patch.dict(
+            _cli_mod.__dict__, {"CLI_CONFIG": _clean_config}
+        ):
+            return _cli_mod.HermesCLI(**kwargs)
+
+
+def _prepare_cli_with_active_session(tmp_path):
+    cli = _make_cli()
+    cli._session_db = SessionDB(db_path=tmp_path / "state.db")
+    cli._session_db.create_session(session_id=cli.session_id, source="cli", model=cli.model)
+
+    cli.agent = _FakeAgent(cli.session_id, cli.session_start)
+    cli.conversation_history = [{"role": "user", "content": "hello"}]
+
+    old_session_start = cli.session_start - timedelta(seconds=1)
+    cli.session_start = old_session_start
+    cli.agent.session_start = old_session_start
+    return cli
+
+
+def test_new_command_creates_real_fresh_session_and_resets_agent_state(tmp_path):
+    cli = _prepare_cli_with_active_session(tmp_path)
+    old_session_id = cli.session_id
+    old_session_start = cli.session_start
+
+    cli.process_command("/new")
+
+    assert cli.session_id != old_session_id
+
+    old_session = cli._session_db.get_session(old_session_id)
+    assert old_session is not None
+    assert old_session["end_reason"] == "new_session"
+
+    new_session = cli._session_db.get_session(cli.session_id)
+    assert new_session is not None
+
+    cli._session_db.append_message(cli.session_id, role="user", content="next turn")
+
+    assert cli.agent.session_id == cli.session_id
+    assert cli.agent._last_flushed_db_idx == 0
+    assert cli.agent._todo_store.read() == []
+    assert cli.session_start > old_session_start
+    assert cli.agent.session_start == cli.session_start
+    cli.agent.flush_memories.assert_called_once_with([{"role": "user", "content": "hello"}])
+    cli.agent._invalidate_system_prompt.assert_called_once()
+
+
+def test_reset_command_is_alias_for_new_session(tmp_path):
+    cli = _prepare_cli_with_active_session(tmp_path)
+    old_session_id = cli.session_id
+
+    cli.process_command("/reset")
+
+    assert cli.session_id != old_session_id
+    assert cli._session_db.get_session(old_session_id)["end_reason"] == "new_session"
+    assert cli._session_db.get_session(cli.session_id) is not None
+
+
+def test_clear_command_starts_new_session_before_redrawing(tmp_path):
+    cli = _prepare_cli_with_active_session(tmp_path)
+    cli.console = MagicMock()
+    cli.show_banner = MagicMock()
+
+    old_session_id = cli.session_id
+    cli.process_command("/clear")
+
+    assert cli.session_id != old_session_id
+    assert cli._session_db.get_session(old_session_id)["end_reason"] == "new_session"
+    assert cli._session_db.get_session(cli.session_id) is not None
+    cli.console.clear.assert_called_once()
+    cli.show_banner.assert_called_once()
+    assert cli.conversation_history == []