SessionFormatError 未完成的工具调用

undohaven restore --to <snapshot-id> --scope sessions。讨论 #8517 记录了 SessionFormatError：step/end 留下未完成的工具调用，前面还有 reading 'prepare' 的崩溃。用更早的会话快照恢复。

undohaven restore --to <snapshot-id> --scope sessions. Discussion #8517 records SessionFormatError: step/end leaves unresolved tool call, after Cannot read properties of undefined (reading 'prepare'). The log is then dropped from the workspace list. Restore an earlier session snapshot.