Systems Decomposition

Before implementing, let's properly decompose this feature:

Context

• What are we building? Describe the feature.

• Who triggers it? User action, system event, scheduled?

• What should happen? The happy path outcome.

Data Flow Mapping

Map the complete flow:

[Trigger] → [Input] → [Validation] → [Business Logic] → [Side Effects] → [Output]

For each step:

• What data comes in?

• What transformation happens?

• What data goes out?

• What can go wrong?

Interface Contracts

Define explicit interfaces:

Input Schema

• What fields are required?

• What are the types and constraints?

• Validation rules?

Output Schema

• Success response format?

• Error response format?

• All possible error types?

Error Enumeration

List ALL possible errors:

• Validation errors

• Not found errors

• Authorization errors

• External service errors

• System errors

Boundaries

Clarify ownership:

• What does this component OWN?

• What does it NOT own?

• What are the integration points?

Dependencies

For each external dependency:

• What is it?

• Sync or async?

• What if it fails?

• How do we recover?

This decomposition will guide implementation.