You'll notice
Useful2 Signal3
You cannot rewind past a turn that received an event delivered from outside the session.
What's wrong with this entry?
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What
The check that decides whether a turn can be rewound now rejects any range that includes a delivered external-event record, on top of the existing refusal for entries that came from outside the session.
Evidence
range contains a delivered poll-event record
Strings lifted out of the shipped bundle, so the claim above can be checked against them.