Fix: Preserve Row-Level Validation When Batch Amounts Are Malformed

[jahrulezfrancis]

Problem

A single malformed amount in an uploaded batch crashes summary generation
and wipes out the row-level validation results that had already been
computed — leaving the user with a generic error instead of the specific
row that needs fixing.

Severity: Medium
Location: lib/stellar/summary.ts:7-20, contexts/BatchFlowContext.tsx:296-321,327-340

Description

getBatchSummary calls totalAmount.plus(instruction.amount) using
big.js before calling validatePaymentInstruction on that same
instruction. An amount like "not-a-number" throws immediately inside
big.js, before validation gets a chance to flag it as an ordinary invalid
row. In handleFileSelect
(contexts/BatchFlowContext.tsx:372-389), setValidationResult(parsed) is
called first with correct row-level data, but the subsequent
getBatchSummary throw is caught by the surrounding try/catch, which then
calls setValidationResult(null) — discarding the already-correct
validation data — and shows a generic "Failed to parse payment file" toast.
handleManualContinue (contexts/BatchFlowContext.tsx:392-406) calls
getBatchSummary with no surrounding try/catch at all, so the same input
would throw uncaught on that path.

Steps to Reproduce

1. Upload an otherwise valid CSV with one row containing amount=not-a-number.
2. parsePaymentFile correctly returns row-level validation info,
   including the specific bad row.
3. getBatchSummary throws before that validation info is surfaced.
4. The UI clears the validation result and shows only a generic parse
   error — the actionable per-row error is lost.

Expected Behavior

A malformed amount should behave as an ordinary invalid row; valid rows and
the summary for them should remain visible and usable for review/correction.

Suggested Fix Approach

Validate each instruction before performing arithmetic on it, and sum only
already-validated amounts — or wrap the per-row arithmetic in its own
try/catch that preserves the parser's validation result instead of
discarding it.

Acceptance Criteria

• A malformed amount in one row no longer clears validation results for
  the rest of the batch
• The specific invalid row and its reason are still shown to the user
• handleManualContinue no longer throws uncaught on a malformed manual
  entry
• Test covers both file-upload and manual-entry paths with a malformed
  amount

---

[ShantelPeters]

Hi, I’d like to work on this issue.

I have experience working with TypeScript applications and debugging validation and data processing flows. From the issue description, I understand that malformed amounts currently throw an exception during getBatchSummary because big.js attempts to process the value before row-level validation can report it properly. This causes the existing validation result to be discarded and, in some cases, results in an uncaught exception.

My approach would be to preserve the row-level validation output, prevent malformed amount values from interrupting the validation pipeline, and ensure both upload paths produce consistent behavior without overwriting valid validation results. I’ll also add or update tests to cover this regression and verify that invalid rows are reported correctly instead of causing generic parsing failures.

I’d be happy to work on this issue and provide a clean, well-tested solution.

[JoyLight00]

I'll take #702.

Fix: Preserve row-level validation when batch amounts are malformed:

Validate before arithmetic in getBatchSummary

Handle malformed amounts without clearing existing validation results

Fix handleManualContinue to not throw uncaught

Tests for file + manual paths

ETA: 2 hours. Assign me.

[grantfox-oss]

🦊 GrantFox — @JoyLight00 has been assigned to this issue as part of the Official Campaign | FWC26 campaign!

Next steps:

1. Open a Pull Request referencing this issue (e.g., Closes #702)
2. Your PR will be reviewed by the Batch-Pay maintainers

Good luck! Track your progress on GrantFox.