basecamp/rails-to-rust/rails-inventory

Rails Migration Inventory

Read the app before designing its replacement. Run bin/rails-to-rust inspect reference and inspect the resulting source inventory, then read routes, database config, initializers, models/concerns, filters, helpers, background jobs, plugins and deployment scripts. The static inventory only supplies locations and counts; derive actual behavior from the running reference.

Record the compatibility boundary

Preserve the existing database(s), text encodings, persisted class/enum values, timestamp precision, external keys, cookies, authentication flows, routes, API formats, assets and configuration unless the user has deliberately chosen a change. Distinguish retirement from unfinished implementation. Record chosen differences and rollback consequences explicitly.

Determine the actual Ruby/Rails versions from locked runtime evidence. List loaded gems and private forks, not just Gemfile declarations. Inventory framework-generated endpoints, external systems, scheduled jobs, mail ingress/egress, search, realtime, storage and deployment roles. A private gem source or unsupported runtime is a setup task, not permission to invent behavior.

Select the UI bar: equivalent behavior, normalized DOM, byte-exact responses, or pixel parity on a named browser/viewport/theme/language matrix. Choose pixel parity or interaction parity with the user; neither is a universal requirement.

Deliver a usable plan

Group domain areas around complete operations and transaction ownership. Keep shared contracts (sessions, params, routes, escaping, time) ahead of dependent controllers. Map every route and state to its owner, including mobile/API/admin/error/unauthorized states. A route table alone does not cover empty/populated, role, browser or mutation states.

Add uncertain assumptions and their probes to the plan. Create isolated fixture/service setup and define how each layer will be tested. Carry state in the contract ledger and record any missing evidence. Use architecture.md when selecting crate and service boundaries; it explains which decisions transfer between the two example ports.