pinin4fjords

Spin up a shinyngs Shiny app on test data to demo or verify a code change. Use whenever asked to run the app, demo this change, show me the UI, spin up a test app, click through a module, or verify something in the browser for this repo — including comparing before/after, old vs new, or two branches side by side, which this also handles by running both versions simultaneously on separate ports. Covers building a throwaway R env with all deps, installing local changes on top, getting test data (zhangneurons or synthetic), launching a full app vs a single module, and the pitfalls that waste time (stale ports, Docker memory limits, wrapped validate() errors).