Repository Standard

Executive Summary

Repository Standard defines module-owned persistence rules for the Spring Boot Modulith. PostgreSQL is the primary operational database, and repositories are private to the module that owns the data.

Repository Rules

Rule	Requirement
Module private	Repositories are not injected into other modules.
Source fact ownership	Repositories persist only source facts owned by the module.
Tenant filtering	Repositories enforce tenant and organization context for customer data.
No cross-module joins for ownership	Cross-module reads require APIs, events, projections, or approved query contracts.
Migrations follow ownership	Schema changes are owned by the owning module.
Audit support	Material data changes must produce audit evidence where required.

Persistence Boundary

flowchart LR
    Module[Owning Module]
    Repository[Private Repository]
    PostgreSQL[(PostgreSQL Owned Records)]
    Other[Other Module]
    Event[Event or API Contract]

    Module --> Repository
    Repository --> PostgreSQL
    Module --> Event
    Event --> Other

Forbidden Patterns

• One module writing another module's table.
• One module querying another module's repository.
• Shared generic repositories for business data.
• Treating Analytics, search, or AI memory as operational source facts.