Method save

src/agent/session.py:49–79

Save session to disk including a cost block. Ch03 round-2 (R2.1): the ``cost`` key matches the schema read by ``src/services/cost_restore.py:restore_cost_state_for_session`` so a save → load round-trip restores bootstrap counters (`total_cost_usd`, durations, lines a

(self)

    updated_at: str = field(default_factory=lambda: datetime.now().isoformat())

    def save(self):
        """Save session to disk including a cost block.

        Ch03 round-2 (R2.1): the ``cost`` key matches the schema read by
        ``src/services/cost_restore.py:restore_cost_state_for_session``
        so a save → load round-trip restores bootstrap counters
        (`total_cost_usd`, durations, lines added/removed, per-model
        usage). Previously this method emitted no cost block; the
        restore reader hit defaults of 0 unconditionally.
        """
        session_dir = Path.home() / ".clawcodex" / "sessions"
        session_dir.mkdir(parents=True, exist_ok=True)

        session_file = session_dir / f"{self.session_id}.json"

        cost_block = _snapshot_cost_block()

        session_data = {
            "session_id": self.session_id,
            "provider": self.provider,
            "model": self.model,
            "conversation": self.conversation.to_dict(),
            "created_at": self.created_at,
            "updated_at": datetime.now().isoformat(),
            "cost": cost_block,
        }

        with open(session_file, 'w') as f:
            json.dump(session_data, f, indent=2)

        self.updated_at = datetime.now().isoformat()

    @classmethod
    def load(cls, session_id: str) -> Optional['Session']: