Row-Level Multitenancy in Rails: Building a Bulletproof Tenant Isolation Layer from Scratch

If you've reached for acts_as_tenant or apartment without really understanding what's happening underneath, this tutorial is the correction. We're building a row-level multitenant system from first principles — the kind you can actually reason about when something goes wrong at 2am. By the end, you'll have: Middleware that resolves the current tenant from a subdomain or JWT claim A Current -based tenant context that threads safely through the request lifecycle An ApplicationRecord mixin that enf