Database Transaction for Business Logic Entry Points

Goal

Every business-logic entry point that interacts with a database must wrap its entire flow in a single database transaction, when the underlying persistence technology supports transactions.

Use the project's existing library, framework, or ORM to open and manage the transaction. Do not introduce a custom transaction mechanism when the project stack already provides one.

The transaction must encompass the full entry-point flow: business constraints, business rules, business operations, and persistence. The entire flow succeeds or fails atomically.

If the persistence technology does not support transactions (e.g., some NoSQL databases, object stores, or file-based storage), this skill does not apply.

Exception: read-only query handlers may read over the connection pool

A business-logic entry point that performs no writes and only needs the least-blocking isolation level — a read-only query handler under Command-Query Separation — MAY skip the interactive transaction entirely and read over the connection pool instead of wrapping its flow in one.

The rationale: