**Error:**
```
TypeError: LettaAgentV2.__init__() got an unexpected keyword argument 'conversation_id'
```
**Trace:** https://letta.grafana.net/goto/afbk4da3fuxhcf?orgId=stacks-1189126
**Problem:**
The `POST /v1/conversations/{conversation_id}/compact` endpoint was failing
because `LettaAgentV3` inherits from `LettaAgentV2` without overriding
`__init__`, so passing `conversation_id` to the constructor failed.
**Fix:**
1. Add `__init__` to `LettaAgentV3` that accepts optional `conversation_id`
2. Remove redundant `conversation_id` param from `_checkpoint_messages` -
use `self.conversation_id` consistently instead
3. Clean up internal callers that were passing `conversation_id=self.conversation_id`
Backward compatible - existing code creating `LettaAgentV3(agent_state, actor)`
still works since `conversation_id` defaults to `None`.
👾 Generated with [Letta Code](https://letta.com)
Co-authored-by: Letta <noreply@letta.com>
372c8dcc85