It would be a great help to have a Harper corpus tool for Harper devs to help research new linting rules

This is even more important than it already was due to the rise of AI-generated rules, which are still terrible at including real-world examples rather than contrived examples made on assumptions that are too short-sighted to avoid false positives.

(Humans also do this, but humans that become Harper contributors can learn how to overcome this. So far AIs can't.)

An ideal tool would use existing corpora and XML/database dumps, feeds, and APIs of coding and tech-related sites.

I believe Stack Overflow still publishes database dumps, or at least that older ones are still available.
Neither Slashdot nor Hacker News publish dumps but that do seem to have real-time feeds. For GitHub we might be able to leverage their search API.

Such a tool would probably not belong in the Harper repo, but as one or more separate projects. But ideally may be installed on a server that authorized Harper devs/contributors would be able to access for reasons of storage space, API limits, etc.

No repository files, tests, or entry points are identified; start by scoping the proposed separate project and reviewing the available Stack Overflow dumps, Slashdot and Hacker News feeds, and GitHub search API. Done means an authorized Harper contributor can use a maintained corpus tool containing relevant real-world coding and technology examples.

Written by the indexing model from the issue text.