projects_parity built both its invoices and its bill through one closure that
passed party_id, and spec_projects looped over (invoice, bill) with one
spelling; with the aliases gone each names customer or vendor as its tool
takes it.
Co-Authored-By: Claude Fable 5.1 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01HS8WZziDnyxunC23MUxrLp