[matthewberry]

Removes get_connection() from app/db/database.py. Nothing calls it: all DB access goes through the pool via Database/get_db.

How I checked that nothing calls it:

git grep -n "get_connection\b" <ref> -- . ':!app/db/database.py'   # origin/main + all 18 remote branches: no hits
grep -rn "get_connection\b" --include='*.py' --include='*.ipynb' .  # untracked local files: definition only

Verified: pytest (2 passed) and ruff check app/db/database.py pass.