You are helping me build the following AI agent workflow.

## Goal
Notion Contact Management API: Manages contacts in a Notion database by email, blocking duplicates on creation and returning structured JSON for frontend apps.

## Specification
- What it does: You can manage your Notion contacts by email with a backend API that automatically blocks duplicates on creation. This workflow updates existing details or fetches specific information instantly, returning structured JSON ready for your frontend apps.
- Trigger: Triggered by an event (Event · on webhook POST request)
- Autonomy: Fully hands-off
- Expected setup effort: about an afternoon
- Tools/services involved:
  - n8n: Workflow orchestration and API handling
  - Notion: Contact database storage and retrieval

## Known pitfalls, handle each one explicitly in your implementation
1. Email properties in Notion are often stored as text rather than email types so ensure your filter logic matches the exact string format used during creation.

## Reference implementation
https://n8n.io/workflows/14304 (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/notion-contact-management-api/ via usecasesforagents.com