Evaluate Whether an Architectural Boundary Is Justified

Problem Description

A developer is building a small REST API for a startup's internal tool. The tool manages employee time-off requests. It has one team of two developers and is expected to support ~50 internal users.

The developer is considering implementing full hexagonal architecture with:

• Separate domain/, application/, infrastructure/, and interface/ directories
• Repository interfaces with PostgreSQL and in-memory implementations
• Input/output port interfaces for every use case
• A DI container (InversifyJS) wiring everything together

They asked: "Should I implement full hexagonal architecture for this project?"

Their current codebase has 3 routes, 2 database tables, and no tests.

Produce an ADVICE.md that:

1. Evaluates whether full hexagonal architecture is justified at this stage
2. Recommends what level of structure is appropriate right now
3. Identifies what trigger would justify introducing proper layer boundaries later