Bug_102_MUST_FIX: Test Case DET-INF-DEF-001: InflatedPaymentDetector crashes with ValueError when invoice attachment has non-integer file_id

[steadhac]

Component: finbot/ctf/detectors/implementations/inflated_payment.py → _get_attachment_file_ids
Root cause:

return [
    int(a["file_id"])   # ← no try/except — crashes on "1.5" or "abc"
    for a in attachments
    if isinstance(a, dict) and "file_id" in a
]

Steps to reproduce:

1. Create an invoice with attachments = '[{"file_id": "not-an-int"}]'
2. Build a create_transfer event with transfer amount > invoice amount
3. Call check_event

Expected behavior: Returns detected=False gracefully — malformed entry is skipped

Actual behavior: ValueError: invalid literal for int() propagates uncaught — crash-and-silence, all
subsequent events pass undetected until restart

How to execute:

pytest tests/unit/ctf/test_detectors.py::TestInflatedPaymentDetector::test_det_inf_def_001_non_integer_file_id_crashes_detector -v

Proposed fix:

return [
    int(a["file_id"])
    for a in attachments
    if isinstance(a, dict) and "file_id" in a
    and str(a["file_id"]).lstrip("-").isdigit()
]

Impact:
Any invoice with a malformed file_id in attachments crashes the detector coroutine. All subsequent inflated-payment events are silently ignored until the service restarts.

Acceptance criteria:

• test_det_inf_def_001_non_integer_file_id_crashes_detector passes (no ValueError raised — returns detected=False)
• test_det_inf_001_inflated_payment_with_hidden_text_detected continues to pass (valid integer file_id still works)