What changed
Orca 0.5.19 adds per-turn content-addressed file checkpoints, dry-run previews, journaled restore with rollback and pruning, conversation or summary rewind modes, a workspace-drift guard, typed rewind events and cumulative token and cost accounting.
Why it matters
Agent rollback becomes an inspectable operation rather than an informal request to undo work. File pre-images, previewable plans and durable rewind events give operators a concrete recovery and audit path after a bad turn.
What to do
Pin 0.5.19 in a disposable repository, commit the baseline, preview a file-and-conversation rewind, interrupt one restore to exercise rollback, and verify the journal, retained checkpoints, usage totals and final Git diff before enabling it on valuable work.
Caveat
The release and tests are maintainer evidence, not an independent data-integrity audit. Rewind is stateful and can overwrite later edits; checkpoints retain file content, and the default 100-checkpoint policy still needs local storage, privacy and recovery testing.