Work.

I take the same problem twice. First, what shape does the platform need to ship the next eighteen months. Second, what shape does it need to ship the eighteen months after that.

Modular monolith, microservices, hybrid. I pick the smallest shape that gets you both, and I document the seams that let the next engineer move it.

The vertical slice template. The override system that lets a tenant ship a behavioral variant without forking the base code. The workflow engine for long-running operations like payment and activation. The Roslyn analyzers that block the conventions from drifting at compile time.

The patterns are how the team ships features without rewriting the platform every quarter.

Database-per-tenant, shared-schema multi-tenant, or shared-database multi-schema. Each one comes with different operational costs. I have shipped all three in production and can tell you what each one costs at fifty tenants, two hundred, a thousand.

The onboarding flow matters more than the choice. Adding a new tenant should kick off a saga, not a runbook.

Terraform for the infra. Azure DevOps or GitHub Actions for the pipelines. Azure Container Apps or AKS for runtime.

The boring infra is the boring infra. The work is in the patterns the team uses to ship features through it without breaking the build.