invoice-reconciliation-review

Payment Invoice Reconciliation (Review Session) §

Date: 2026-03-25 Category: Parsing / Financial Logic Parts Completed: 3/3 (review) Language: Python

Problem Summary §

Match payments to invoices using three-tier matching: exact ID match from memo → amount match → fuzzy match with forgiveness threshold. Sorted by earliest date.

Key Bugs Found on Review §

1. self.invoices referenced before assignment §

# Bug: self.invoices doesn't exist yet
self.invoices = [inv.lower() for inv in self.invoices]
# Fix: use the parameter
self.invoices = [inv.lower() for inv in invoices]

2. Variable shadowing — amount reused §

payment_id, amount, memo = ...  # payment amount
curr_id, date, amount = ...     # overwrites with invoice amount!
# Fix: use distinct names (payment_amount, inv_amount)

3. id vs inv_id — using Python built-in §

f"... for invoice {id} ..."  # Python's built-in id() function!
# Fix: use curr_id or inv_id

4. Missing .strip() on extracted invoice ID §

inv_id = memo[pos + len("paying for:"):].strip()  # .strip() was missing

5. Duplicate amountMatch call instead of fuzzyMatch §

# Bug: called amountMatch twice
res = self.amountMatch(payment_id, amount)
res = self.amountMatch(payment_id, amount)  # should be fuzzyMatch

6. Fuzzy runs even when amount matches — needs elif §

# Bug: separate if statements, both can fire
# Fix: elif so fuzzy only runs when amount match fails
res = self.amountMatch(payment_id, amount)
if res:
    result.append(res)
elif self.forgiveness is not None:
    res = self.fuzzyMatch(payment_id, amount)

7. fuzzyMatch crashes when forgiveness is None §

• Guard with elif self.forgiveness is not None before calling fuzzyMatch

8. Inconsistent split across methods §

• fuzzyMatch used split(", ") while others used split(",") with strip
• Fix: use consistent split(",") + strip everywhere

Key Learnings §

• self.x vs parameter x in __init__ is a common Python gotcha
• Variable shadowing across scopes is easy to miss — use distinct names
• Fallback tiers must use elif, not separate if statements
• Always guard against None before comparison operators