# K1 chat-thread durable state 0.2.0
`DurableThread` is the concrete one-consumer synchronous state owner for K1 Chat Thread Main Actor. It combines canonical conversation transitions, authorization binding, persistence checkpoints, recovery, restart, and `llm_done` durability while leaving async channels, Codex Turn/Steer effects, WebSearch tasks, model-input observation, stage-reply ordering, and the final search-aware authorization release decision with the session actor.
Provider stages persist Agent Response, explicit Agent Message, and Tool Call boxes before effects. Prepared provider input contains only the external prefix plus the synthetic unpersisted open Agent Response header. A successful provider effect must still be followed by `commit_steer`; preparing or validating never advances the submitted frontier.
Recovery uses Chat Thread Recovery 0.2.0 and Persistence 0.6.0. The package changes no persistence format, provider protocol, HTTP API, migration, daemon composition, authorization policy, or public Main Actor contract.