Illustrative example. The dates and amounts below are provided for practice.
An older backup has two dates and one plan. The current browser has three dates and two plans. Restoring the old file will replace the collection, so the extra current items need protection first.
Keep the current snapshot
Choose All dates and export JSON before attempting recovery. All dates includes unlinked plans as well as dated records. Store this new copy separately from the older file.
For a concrete date check, let the older backup contain a one-time August 14, 2027 event and the current record contain August 24. The intended correction is ten elapsed days earlier.
Validate, then replace
Choose the older file and use Validate and Restore. Review the counts and confirm only if replacement is intended. Search for the restored date and reopen the plan afterward.
Malformed JSON, unsupported versions, duplicate IDs, unknown fields, and files over 5 MiB are rejected. A failed validation does not partially overwrite records. Valid replacement covers both IndexedDB stores in one transaction.
This is replacement rather than automatic merging. If only one record needs correction and the right value is known, editing that card can preserve newer work more directly.