Describe the bug
The in-memory hosting \SessionStore.get()\ returns the stored mutable \AgentSession\ instance directly. Multiple runs that restore the same continuation ID therefore share one live session object, so concurrent \previous_response_id\ branches can mutate each other and older response IDs do not remain independent continuation points.
Expected behavior
Each successful session read should return an independent working copy. Response-keyed continuations should be able to branch concurrently into new response IDs. Stable \conversation_id\ values should be documented as mutable heads that require app-owned single-writer coordination. Concurrent workflow hosts should use fresh workflow instances because one \Workflow\ instance permits one active run.
Describe the bug
The in-memory hosting \SessionStore.get()\ returns the stored mutable \AgentSession\ instance directly. Multiple runs that restore the same continuation ID therefore share one live session object, so concurrent \previous_response_id\ branches can mutate each other and older response IDs do not remain independent continuation points.
Expected behavior
Each successful session read should return an independent working copy. Response-keyed continuations should be able to branch concurrently into new response IDs. Stable \conversation_id\ values should be documented as mutable heads that require app-owned single-writer coordination. Concurrent workflow hosts should use fresh workflow instances because one \Workflow\ instance permits one active run.