Diagrams / Architecture

AWS architecture poster

Which services exist, and how does a request move through them?

Transfer fraud decision

When to use it

Use an AWS architecture poster when you need to show which services handle a request, the account or zone boundaries, and the numbered path through them.

What it makes clear

Official AWS service icons make the components identifiable.
Account and zone frames show the boundaries of the system.
Numbered arrows and a matching step list explain the order of the request.

When another type fits

For calls and responses over time, use a sequence diagram. For a technology-neutral system decomposition, use the C4 container diagram. For a comparison of alternatives, use a comparison table.

Start with the actual example

The request and source document use the selected language.

prompt.mdmarkdown

# Prompt

```text
Read site-pranchas/exemplos-i18n/en/aws-architecture/antifraud-decision.md and create an AWS architecture poster
for real-time transfer fraud prevention, with numbered steps and badges.
Save it in site-pranchas/exemplos-i18n/en/aws-architecture/output/, with the source in output/_src/.
No client in the header; version V1 and the default footer. Language: en.
```

Accompanying data file: `antifraud-decision.md`.

antifraud-decision.mdmarkdown

# Decision: real-time fraud prevention for transfers

Status: approved · 2026-10

## Context

Every transfer initiated in the app goes through a risk decision before leaving the account. The current rule runs in batches every 15 minutes and only catches fraud after the money has left. The decision must happen within the transfer request, with a 300 ms budget at p99.

Measured volume: 1.8 million transfers per day, peaking at 120 per second at lunchtime.

## Decision

1. The app calls `POST /transferencias` on **API Gateway**, with the session token.
2. API Gateway invokes the **Decision Lambda** synchronously.
3. The Lambda reads account and recipient features from **DynamoDB features** (average amount over the last 30 days, number of new recipients in 24 hours, age of the destination key).
4. The Lambda calls the **SageMaker endpoint** with the feature vector and receives a score from 0 to 1.
5. Depending on the score band, the Lambda returns `approve`, `review` or `block` to the app and publishes the `decision recorded v1` event to **Kinesis Data Streams**, using the account ID as the partition key.
6. The **Features Lambda** consumes the stream and recalculates account aggregates.
7. Updated aggregates return to DynamoDB features and apply to the next transfer.
8. The **Alert Lambda** consumes the same stream and filters `review` and `block` decisions.
9. The Alert Lambda publishes to the **SNS** topic for review cases.
10. The **fraud analyst** receives the case through the topic subscription and decides in the internal console.

## Score bands

| Band | Decision | Effect |
|---|---|---|
| below 0.40 | approve | transfer proceeds |
| 0.40 to 0.85 | review | transfer held until the analyst decides, with a 30-minute deadline |
| above 0.85 | block | transfer declined and customer notified |

## Rejected alternatives

- Batch rule in Aurora: does not decide before the money leaves.
- Calling the model directly from API Gateway: no place to read features and apply the score band.

## Out of scope

Training and publishing a new model version belong to the ML pipeline, documented separately.

What the gate checks

Geometry checks help catch drawing defects. Review the meaning of the diagram yourself.

Arrow ends touch a box or frame border, within a 6 px tolerance.
Arrows do not cross unrelated boxes or share a collinear segment.
Badges 1..N match the step list, and each badge sits on its arrow.
Measured labels, icons, badges and chips do not overlap; arrows do not pass over text.
Edge labels stay within 30 px of an arrow; arrowheads do not end inside a box.
Nothing crosses the page width or the capture height.
Colors and fonts use the selected theme tokens; the source includes its style marker.

A rejected case

BADGE-SOLTO: a step badge sits away from its arrow. Move its center onto the arrow line, then run the gate again.

Measured compatibility

Results for this type, read from docs/models/runs.json.

Measured compatibility by diagram type and model
Diagram type	Template gate2026-11-07	Claude CodeSonnet 4.5	Claude CodeOpus 5.5	Claude CodeSonnet 5.5	Claude CodeHaiku 5.5	Codex CLI	Kiro CLISonnet 4.5
AWS architecture poster	Passed	Gate only1	Passed2	Passed3	Defectno side margin2	Not measured4	Not measured5