choplin/my-agent-skills/app-reference-backend

Backend Apps

Choose the implementation language

• Recommend Rust for a new backend when no stronger ecosystem constraint favors

another language. Apply lang-reference-rust after selecting Rust.

• Treat Rust as a recommendation, not a requirement. Choose another language

when required SDKs or frameworks, an existing runtime and shared codebase, deployment-platform support, operational tooling, or team capability gives it a concrete advantage. State that advantage.

• Do not add another backend language solely for local convenience or a small

reduction in implementation effort.

Choose deployment boundaries

• Start with one deployable backend and organize it as a modular monolith.
• Split out a service only when it needs an independent deployment, scaling or

failure boundary, security boundary, or clearly owned data lifecycle.

• Do not create a service merely because a domain concept or module is distinct.

State why an in-process boundary is insufficient before adding a network boundary.

Test database behavior

• Test SQL, migrations, and transaction behavior against the supported database

engine rather than replacing database semantics with mocks.