Dependency rules

Allowed directions

app → modules, presentation, integrations (thin), routes, providers
modules → _core, platform/db, integrations/auth (as needed)
presentation → utils, integrations/i18n (nav), not Drizzle
integrations → platform/env, vendor SDKs
platform → env schemas, DB drivers

Hard no

• Domain/use-case files importing React client components
• UI importing Drizzle tables directly for business rules
• Redefining admin / customer role strings outside auth.access.ts
• Scattering path literals — use ROUTES

Practical test

If a change requires editing five unrelated folders for one concept, the ownership boundary is wrong — colocate under the owning module or route _lib.