I work in a large monorepo that has very many files that are processed by Webpack. One of our main patterns is that we use fully-qualified filenames for every module name and import. For example, if I have a file with path "/path/to/module/MyCoolModule.js", the import would simply look like import MyCoolModule from 'MyCoolModule' without needing any explicit path to the module. This is enabled by recursively scanning the project's directories for all relevant .js files/folders at Webpack init and then passing in the scanned files into resolve.modules and resolve.alias.

We like this pattern, and it works well for general usage when webpack is run in watch mode; however, it breaks down when new folders and files are added to the project while Webpack is already running. Because the files and folders are only scanned at Webpack init, Webpack is unable to resolve imports for new files/folders added since it started, so compilation will fail. This requires us to restart Webpack, which takes 1-2 minutes on our project. Across many engineers when switching between git branches or updating changes from master, this can add up to a significant slowdown in raw time and in breaking flow.

I'd like to write a plugin that will dynamically update the resolve.modules and resolve.alias such that we do not have to restart Webpack when new folders and files are added to the project. However, I am at a loss for how to do this. It seems like I have three main questions:

1. What hook(s) can I tap into to be notified when Webpack detects new files or folders?
2. Where would I put this plugin to access the above hooks? Would it exist in the top-level plugins config? resolve.plugins? etc.. As I'm understanding it, where the plugin is placed/configured will affect what hooks are available to it
3. How would I make Webpack aware of these dynamic updates? I am guessing there's a reference to the resolve obj somewhere that holds resolve.modules and resolve.aliases that Webpack actively references, but I'm not sure where that would live or where to access it (this could be completely wrong too)

(note: we are technically using Webpack 4, but answers for Webpack 5 are welcomed because I know we're behind there, and I'd guess a Webpack 5 solution would still point me in the right direction)

Thanks!