You are helping me build the following AI agent workflow.

## Goal
Credit Card Payment Reminder & Tracking: Fetches credit card statements from eight Taiwanese banks, logs due dates and amounts in Google Sheets.

## Specification
- What it does: Never miss a payment date as you automatically receive credit card statements from eight Taiwanese banks into your Google Sheets. The system extracts due dates and amounts for each bill, then adds calendar reminders so you can track everything in one place without manual entry. You can also update the status of any payment directly through the provided webhook to keep your records current.
- Trigger: Triggered by an event (Event · on new email)
- Autonomy: Fully hands-off
- Expected setup effort: about an afternoon
- Tools/services involved:
  - Gmail: Retrieve credit card statement emails
  - LLM: Extract payment details from text or PDFs
  - Google Sheets: Store extracted payment data
  - Google Calendar: Create and update payment reminders

## Known pitfalls, handle each one explicitly in your implementation
1. Bank email formats change frequently so you must implement fallback regex patterns if the LLM extraction fails on new layouts.
2. Timezone mismatches can cause late payments so always normalize extracted dates to UTC before creating calendar events.
3. PDF attachments often require separate processing steps so ensure your pipeline handles binary file decoding before sending text to the LLM.

## Reference implementation
https://n8n.io/workflows/2867 (workflow template)
Fetch and inspect this before building. If it matches my stack, adapt it;
if not, rebuild the pattern with my tools.

## Process requirements
1. Before building: ask me which of the listed tools I actually use and
   what my platform is (n8n / Make / code / other). Do not assume.
2. Adapt the pattern to my answers; do not force the reference stack.
3. Address every pitfall above; tell me how you handled each.
4. Provide a test plan I can run before letting this touch real data.
5. Ask before any step that sends messages, modifies data, or spends money.

Source: https://usecasesforagents.com/use-case/credit-card-payment-reminder-tracking/ via usecasesforagents.com