You are helping me build the following AI agent workflow.

## Goal
Sales Proposals And Payments: When a Calendly call is booked, the agent generates an AI proposal deck, creates a Stripe payment link.

## Specification
- What it does: Get a tailored sales proposal in Google Slides and a secure Stripe payment link automatically generated as soon as you book a call via Calendly. You can then instantly send your client both the customized deck and checkout details through a personalized follow-up email without any manual work.
- Trigger: Triggered by an event (Event · on new Calendly booking)
- Autonomy: Fully hands-off
- Expected setup effort: under an hour
- Tools/services involved:
  - Calendly: Trigger source for booked calls
  - Google Sheets: Lightweight CRM lookup
  - OpenAI: Generate proposal content and JSON
  - Google Slides: Create visual proposal deck
  - Stripe: Generate payment links

## Known pitfalls, handle each one explicitly in your implementation
1. OpenAI token limits may truncate long proposals so you should set a maximum word count or chunk the generation process.
2. Google Slides API requires precise slide ID mapping so verify your template structure before automating the content insertion.
3. Stripe webhooks can fail silently if the client's email is invalid so add validation logic before creating the payment link.

## Reference implementation
https://n8n.io/workflows/12530 (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/automated-sales-proposals-and-payments/ via usecasesforagents.com