NPM Workspace dependency resolution differing in production builds

[someguynamedmatt]

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I think this is an npm workspace question, but for full context this is within an Nx monorepo:

I have a few apps which use varying dependency versions (I know, I know...not ideal, we're working on it). When running appA locally everything "just works". When it gets built for production, it crashes due to an older version of a dependency being used (and, thus, the code being incorrect).

The "older version" of the dep is found in the root node_modules, and the "newer" (correct) version is found in appA's node_modules. Why is the root-level dependency being used in prod builds, but the app-level dependency being used locally?

This application is being built with craco. Using node@18, npm@9.6.7, nx@16.9

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[someguynamedmatt]

Thanks for the most thorough response I've received thus far.

One follow-up question, though: Why is the root-level used in prod, but not locally? What are the mechanisms behind that (oooh, bonus point: Where is this documented?)

[someguynamedmatt]

Thanks so much for those responses!