Hi! Here's what I was able to put together in ~90 minutes. It's functionally complete, but a bit messy. I've left FIXME: comments on things I would update. I've also kept a work log here with my thoughts over time as I set about the project, as well as a time breakdown for transparency.
I use PNPM. If you don't have that, you might need it to have a smooth experience. It might also just work with NPM out of the box.
npm i -g pnpm
Install dependencies
pnpm i
Create a .env file
cp .env.example .env
Migrate the database
pnpm prisma migrate dev
Seed the database
pnpm prisma db seed
Start the app
pnpm dev
The app will be running on http://localhost:3000.
It only does the main requirements, plus basic validation on the uploaded data. Click [Upload CSV] to open the upload dialog, select a file to preview it, and click [Upload] to send it to the server. The server should process a valid file and automatically reload the main table, because Remix just does that. I put in some rudimentary toast notifications for basic feedback.
Since the provided "town hall" CSV includes format errors on email addresses (😉) I made a copy where those errors were fixed to test successful upload. Try either one.
Deduplication is done entirely at the database level. Anything else wouldn't be resilient to multi-process/multi-node scenarios (without... a lot of extra work), but hey, that's what database constraints are for!
Given time constraints I did very simple, sync CSV parsing server-side. In a real app I would use streams or (since Remix seems to prefer) async iterators. The library I pulled in doesn't seem to work off-the-shelf with iterators, it's something where I would look into shimming or research some other options if I had more time.
Also, for whatever reason, Remix' starter kit with Tailwind has hydration errors related to the Tailwind style injection. That surprised me. I haven't attempted to fix it, but would definitely track that down in a production app before shipping.