Architecture decision records

Every non-obvious choice in the template has a record: the context, the decision, the consequences, and - for patterns we left out - the condition under which you should add them.

#	Decision	One line
001	Feature-first layout, rings inside	Delete a feature = delete a folder; rings still enforced
002	No DI library	FastAPI Depends + explicit overrides in bootstrap
003	No mediator, no CQRS bus	Use cases are classes you call; read models when queries hurt
004	Transaction per request, no Unit of Work	Session opened/committed by the HTTP layer
005	Domain events dispatched in-process	Outbox + broker only when a handler can't be awaited
006	FastAPI, SQLAlchemy 2 async, Alembic, uv, Ruff, mypy	Mainstream, typed, replaceable at the edges
007	Shape in Pydantic, rules in the domain	The domain must hold on every entry path
008	Separate row model + explicit mapping	Frozen dataclass domain, table free to evolve
009	Authentication is an adapter, authorization a rule	API key → Actor; use cases decide, domain records organizer_id
010	Optimistic concurrency on aggregates	version checked on save; stale write → ConflictError → 409, on both adapters

Format: Michael Nygard's ADR. Add a new one with the next number when you change a decision in your fork; keep the old one and mark it superseded.