What
A new schema describes a checkpoint 'chain': an array of entries, each with a generation number, worktree commit, sha256 hash, size, and a via field, validated so generation numbers strictly increase. The restore-state schema now carries an optional chain field, a new chained boolean, and a new readsResultEcho flag, alongside the existing attached and seedless flags.
Why
This lets Claude Code track and verify a sequence of checkpoint generations with hashes, giving restore operations a way to confirm the integrity and lineage of a chain of checkpoints.
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The writer flagged doubt
The finding does not say what readsResultEcho does or how the chain is used during an actual restore.