Earendil Works released an experimental durable agent harness for its pi toolkit. It commits conversations, model turns, tool calls and state to storage before display. A restarted process resumes work from the last stored checkpoint. It supports SQLite or JSONL storage backends. Conversations can be forked and extended with custom tools and system prompts. Built-in tools include read, write, edit and bash. Each tool call runs as a durable task with replay safety controls. The API is marked experimental and may change without notice.