Paginate the discrepancy export during a large close
A synthetic close with 250,000 discrepancies exhausts API memory because the export loads every row. Finance also receives spreadsheet formulas when a reference begins with an equals sign.
- Focused work estimate
- 3h + prerequisites
- Priority in the scenario
- Medium
- Engineering practice
- Streaming · Pagination · CSV safety · Performance measurement
Estimated field mix
- Performance engineering40%
- Backend40%
- Security20%
Field percentages are editorial estimates of the ticket's engineering focus. They total 100%; they are not measured time, proficiency scores, or ownership evidence.
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Project context
A fictional subscription service invoices in USD and EUR. Finance currently compares a payment-provider CSV with database exports; late refunds and retried imports make the monthly close unreliable. Work on synthetic ledger entries only.
Setup prerequisites
- REST APIs
- SQL transactions
- Integer money representation
Preceding work
Complete these dependencies, or supply their agreed outputs before taking this ticket.
- BILL-101 · Reject ambiguous settlement amounts before import
- BILL-102 · Make repeated settlement uploads converge on one batch
- BILL-104 · Match settlement lines without combining currencies
- BILL-105 · Carry partial refunds across settlement days
- BILL-106 · Record discrepancy decisions without editing source entries
- BILL-107 · Freeze a close report against a reproducible cutoff
Acceptance criteria
- Stream a stable report revision in bounded pages without omissions or duplicate rows.
- Neutralize spreadsheet formula prefixes in text cells.
- Abort export promptly on client disconnect and preserve authorization on resume.
Implementation constraints
- Use a repeatable 250,000-row synthetic benchmark and report peak memory rather than assuming scalability.
Verification to include
- Compare streamed row identities with the frozen report count.
- Export malicious-looking references and cancel halfway through; check escaping and cleanup.
Deliverables
- Bounded CSV export and benchmark report
Rollout and recovery
Offer the streamed export alongside the old limit; rollback the route while retaining report revisions.
Value of the work
For the engineer: Practice monetary invariants, concurrent writes, reconciliation, and operational recovery across one service boundary.
For the team: Review how an engineer makes discrepancies explainable and recoverable before a financial workflow is trusted.
Evidence boundaries
Outcome Evidence: Tests, patches, and runbooks are requested deliverables. They become Outcome Evidence only through a qualified Mission and immutable Evidence IDs.
Ownership Evidence: Independent adaptation must be observed under a declared verification policy and cite immutable Evidence IDs. Completing a planning ticket establishes no Ownership Evidence.