modular-monolith-correct-for-small-team-single-tenant-internal
For single-tenant internal platforms with 3 or fewer engineers and under 1000 users, a modular monolith (3 deployable processes: api, worker, web; 1 codebase) is the correct topology — microservices are premature optimization at this scale. Module boundaries are enforced via Python packages with service interfaces; service extraction is deferred to year 2 only when load profiles diverge. This is the R-Same v1 topology and should be referenced when justifying architecture to stakeholders.