You are helping me build the following AI agent workflow.

## Goal
Multi-City Weather Forecast Emailer: Submit up to three cities and receive a color-coded 5-day weather briefing with safety warnings via email.

## Specification
- What it does: Submit up to three cities to instantly receive a color-coded five-day weather briefing with safety warnings delivered directly to your email. You get professionally formatted daily summaries that highlight critical conditions so you can plan ahead without checking multiple sources.
- Trigger: Run manually (Manual · on form submission)
- Autonomy: Fully hands-off
- Expected setup effort: about an afternoon
- Tools/services involved:
  - OpenWeatherMap: fetching weather data
  - Gmail: sending formatted emails
  - OpenAI: generating HTML email content

## Known pitfalls, handle each one explicitly in your implementation
1. OpenWeatherMap free tier limits requests per minute so you must add a small delay between API calls to avoid 429 errors.
2. HTML injection risks exist if city names contain special characters so sanitize all input strings before embedding them in the email body.
3. API responses may lack data for obscure locations so implement a fallback message that gracefully handles missing forecast information.

## Reference implementation
https://n8n.io/workflows/9909 (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/multi-city-weather-forecast-emailer/ via usecasesforagents.com