backend-systems-guidancelisted

# Backend Systems Guidance This is a composable overlay, not a standalone workflow. Use alongside the repo's implementation skill when the change touches backend code. Choose activity independently from backend depth. A review request is read-only unless the user also asks for remediation; use the architecture and reliability rules as inspection criteria and report findings instead of changing code. This is the canonical backend overlay in this repo. It extends the thin baseline `backend-guidance` overlay with stronger guidance for non-trivial service boundaries, repositories, reliability, and trust boundaries. Prefer it over `backend-guidance` when the task includes new endpoints or consumers, multi-layer refactors, repository or transaction work, auth or trust-boundary logic, or backend review that needs explicit testing and reliability checks. Use the bundled references only when needed: - [references/trigger-evals.md](references/trigger-evals.md) for lightweight prompt checks when revising the trigger or scope ## When to use - the repo has server-side networked code such as HTTP handlers, gRPC methods, webhooks, queue consumers, or message producers - the task adds or reshapes routes, controllers, services, repositories, middleware, or request-processing boundaries - the task changes auth, authorization, validation, idempotency, retries, external requests, caching, or observability - the task needs backend review beyond basic handler thinness, especially f