Ingest a BAI2 bank statement file and load balances and transactions into an internal cash-position ledger

Verified steps

1. Retrieve the BAI2 file via SFTP or bank portal download; confirm it begins with a Type-01 File Header record containing sender/receiver routing identifiers and a file creation date-time
2. Parse each record type in order: 01 File Header, 02 Group Header, 03 Account Identifier and Summary (captures account number, currency, and opening/closing ledger and available balances using three-digit BAI type codes), 16 Transaction Detail (captures amount, text, and bank reference), 49 Account Trailer, 98 Group Trailer, 99 File Trailer — validate that control totals in trailers match summed transaction amounts
3. Map each three-digit BAI transaction code (e.g., codes in the 100-series for credits, 400-series for debits) to your internal GL account and transaction category; maintain a code-to-category lookup table because banks extend the standard with proprietary codes
4. Upsert balance records keyed on account number plus value date; write each transaction detail row as an immutable ledger entry with the bank reference as an idempotency key to prevent duplicates on re-ingestion
5. Emit a reconciliation summary comparing the BAI closing ledger balance against the sum of your internal ledger entries for the same account and date; flag any delta for manual review
6. Schedule the ingest job after the bank's prior-day file delivery window (typically early morning) and retry with exponential backoff if the file has not yet arrived