Currently, importing a CSV file for a manual account replaces the entire transaction history rather than appending to it. Users who regularly download and import new transactions (e.g. weekly) lose all existing history and any manually-edited categories each time they import.

The request is for a true append/merge mode for CSV imports that:
– Adds only new transactions from the imported CSV
– Deduplicates against transactions already present on the account
– Preserves existing transaction history that has no match in the CSV
– Preserves manually-edited categories and customizations on existing transactions

An explicit “Append only – skip duplicates” option at the “Tell us which transactions to prioritize” step would address this. This is especially important for users whose bank or credit card has no live connection available in Piere and who rely entirely on CSV imports to keep their history up to date.