This repository is a customized fork of https://github.com/bluesky-social/feed-generator
The FirehoseSubscription.ts is a class that collects selected messages in the database. It also removes them from the feed if they are removed upstream.
The isPolitical function defined in src/bridging/index.ts decides if content should be saved to database.
You can find the algorithm generating the feed in src/algos/bridging-feed.ts. It simply fetches all known records from database sorted by indexing time, there's no sophisticated logic involved.