[rohanbuilds-ai]

Summary

Fixes #260: Prevent an unhandled ValueError in InflatedPaymentDetector._get_attachment_file_ids when an invoice's attachments JSON contains non-integer file_id values.

Problem

In finbot/ctf/detectors/implementations/inflated_payment.py, _get_attachment_file_ids() converted attachment file_ids directly via int(a["file_id"]) inside a list comprehension without error handling:

return [
    int(a["file_id"])
    for a in attachments
    if isinstance(a, dict) and "file_id" in a
]

If an invoice's attachment metadata contained non-integer strings (e.g. "not-an-int", "1.5"), booleans (True), or None, int() raised ValueError: invalid literal for int() with base 10. Because check_event() calls _get_attachment_file_ids() outside any try/except block, the exception propagated out to challenge_service.py, causing a transaction rollback and silently dropping challenge evaluation.

Solution

• Safely extract attachment file_ids:
  • Verify that file_id is an int or str and not a bool.
  • Wrap int(raw_id) in try/except (ValueError, TypeError) and skip malformed entries.
  • Return the list of valid integer file IDs for subsequent FinDrive lookups.
• When an invoice has only malformed or non-integer attachment IDs, the detector gracefully returns detected=False ("Invoice has no FinDrive attachments to scan") without crashing.
• Legitimate inflated-payment detection and valid integer attachment IDs remain completely intact.

Verification & Test Evidence

1. Baseline Regression: Running the new test suite against origin/main baseline confirmed 2 failures with the expected error:
   • test_det_inf_def_001_non_integer_file_id_crashes_detector: ValueError: invalid literal for int() with base 10: 'not-an-int'
   • test_mixed_attachments_extracts_valid_file_ids: ValueError: invalid literal for int() with base 10: 'malformed_string'
2. Post-Fix: All 5 tests in tests/unit/ctf/test_inflated_payment_detector.py pass in 0.39s.
3. Full CTF Suite: All 32 existing passing tests in tests/unit/ctf/ continue to pass cleanly.
4. Linters & Style: isort, black, and git diff --check are clean.