“Everything is in” can be a dangerously ambiguous migration report. It might mean that files appeared in a folder, that rows reached a database or that the resulting balances agree with the original ledger. The supplied conversation repeatedly asks for complete collection and the remaining partner ledgers. I read those requests as a need for several explicit completion boundaries, rather than one success flag. The useful question is what evidence supports each boundary.
A downloaded row is not necessarily a new transaction
One transaction can appear in a document list, a product detail export and a partner ledger. Three files containing a row each do not establish three separate transactions. The unit of preservation differs from the unit of business data. Files should be retained individually, while the migration interprets whether each row represents a document, a detail line, a balance or another view of an existing event. Adding every exported row to the same total would create a convincing but incorrect result.
The relationship I care about joins a source file, its row, its original identifiers and the interpreted record. Overwriting a source with a newly tidied file makes that relationship difficult to explain later. Content hashes and sizes help distinguish different files sharing a name and identical copies carrying different names. A matching hash establishes byte identity for the compared files; it does not establish that the business interpretation, accounting scope or completeness of collection is correct.
Preserve files and verify loading as separate operations
The archived audit describes checks of received-file hashes, expected row counts and database relationships. Those are useful forms of evidence. They do not prove that the external system supplied all available material. A date filter might have excluded older entries. An export condition might have remained active. A requested ledger might not have finished downloading. All received files can be intact while the collection remains incomplete.
I would therefore keep separate states for requested, received, hash checked, interpreted, loaded and reconciled. A failed download must not become an empty ledger, and an unrecognized row must not disappear silently. Missing input and input that cannot yet be interpreted require different follow-up work. Recording the distinction also lets another operator resume the job without guessing what the previous operator meant by a completed line in a checklist.
Reconciliation must ask an independent question
If the importing code calculates a total and the checking code merely reads that same total back, a shared error may pass unnoticed. The preserved report records independent aggregation and source-row comparisons, alongside an explicit limit on collection completeness. I would retain that limit in a handover. It tells the operator which conclusion the checks support and which conclusion still needs evidence. Removing it would make the report more confident and less useful.
For another project, compare a selected partner's opening balance, movements during a defined period and closing balance. Do not assume historical balances can always be reconstructed from the exported transaction totals alone. Opening values, adjustments and effective dates can differ. When a difference appears, record its scope and definition before changing anything. The source should not be rewritten merely to make a new system's number agree with an expectation.
A migration must survive interruption
Large collections stop and resume. A useful checkpoint records the files already received, outstanding requests and identifiers of loaded records. Repeatedly receiving the same filename should not automatically create another business event. Nor should the latest progress number imply that every earlier record received meaningful review. Completion needs to point to identifiable artifacts and checks, not just the final line printed by a script.
For this article I inspected the supplied archive structure, selected migration implementation and dated reconciliation reports. Original business files and the external ledger were excluded, and I did not query the operating ERP. The historical collection limits therefore remain historical limits; writing about them does not resolve them. When commissioning a migration, ask for the received scope, the loaded scope, the compared scope and the remaining differences as separate statements. That gives both the maker and the business a practical way to agree on what finished actually means.