Add unit tests for routes

**Feature request**
It would be great to have retry for api.

**Use case**
Many users need this functionality for production deployments.

**Implementation idea**
Add a new config option `enable_retry` with default `false`.

Start by locating the API route handling and configuration parsing in the Shell project; the issue names no files or tests. Add coverage for the retry behavior and the `enable_retry` option, confirming its default is `false` and that the requested API retry behavior works.

Written by the indexing model from the issue text.