AWS open-sources local API emulator for testing

First-party local emulation eliminates cloud test latency and dev AWS bills while serving as Amazon's flagship proof-of-concept for agent-authored infrastructure. It directly challenges commercial tools like LocalStack by grounding local mocks directly in official Smithy API definitions.

• –Direct threat to LocalStack: Official, zero-cost emulation backed directly by AWS models removes the licensing friction of third-party mock suites.
• –Embedded in-process mode: Rust tests can spin up dedicated, in-memory emulator instances per test, eliminating port collisions and container overhead.
• –Safe sandbox for coding agents: Agent swarms can provision resources and debug failed operations locally without risk of leaking credentials or running up cloud bills.
• –Refreshing fidelity tracking: Amazon openly publishes compatibility scorecards and maintains explicit gap tracking rather than overpromising full parity.