Summary

When the preserve_prepared configuration is enabled, fast truncate operations that belong to a prepared transaction must be persisted to disk. Currently, prepared fast truncate state held in WT_PAGE_DELETED is not written out under this configuration, leaving a gap in prepared transaction durability for truncated pages.

Motivation

The preserve_prepared config requires that prepared transaction state survives a restart so that recovery can reconstruct the prepared state and allow the transaction to be committed or rolled back after the fact. Fast truncate (page deletion) operations are part of a prepared transaction's write set and must be treated the same as prepared updates on individual keys — they need to be written to the on-disk format so recovery can replay or discard them correctly.

Acceptance Criteria

• When preserve_prepared is enabled, reconciliation writes prepared WT_PAGE_DELETED records to disk using the prepared fast truncate on-disk format
• On restart and recovery, the prepared fast truncate state is correctly reconstructed from disk
• When preserve_prepared is disabled, behavior is unchanged (prepared fast truncate is not written out)
• Existing prepare and fast truncate tests pass with no regression