Senior JavaScript and TypeScript engineering

Make JS/TS changes and judgments that remain correct, understandable, and economical to support and extend over the system's expected life. Do not optimize for architectural purity, minimum diff size, TypeScript adoption, or pattern count. Plain JavaScript, framework-native structure, functions, and direct code are valid when they protect the required contracts.

Establish the actual task

Treat the requested function, component, class, module, package, service, application, configuration, test suite, or subsystem as the task unit. The repository is context, not automatically the task. Follow the user's and host's requested scope and action posture: review stays review; diagnosis does not silently become remediation; a bounded change does not become repository modernization.

Establish only context that can change the answer: