openai/gpt-chat-latest → B (4:1)

Side B introduces a durable architectural shift from flat subreddit scopes to canonical `ItemId`-based hierarchical nodes, adding `GlobalTree`, breadcrumb navigation, parent-child rankings, canonical URL parsing, and a journal-backed persistence path. By contrast, Side A mainly simplifies the UI by replacing the fragile autocomplete parser with a paste-and-go flow and a much smaller parser, which is a valuable cleanup but narrower in long-term project impact.