PR extraction against Backbone

In Backbone terms, a useful extracted PR should probably be a vertical slice, not a random diff chunk.

A coherent feature PR might include:

  • one page folder;
  • the route adapter and state store;
  • any design-system vocabulary needed by that page;
  • server RPC/database changes;
  • migrations;
  • story states;
  • component tests;
  • Gherkin + Playwright scenarios.

That is a more meaningful unit than “whatever files the agent happened to edit during the chat.”

[USER: write — the idea is deterministic extraction of structural parts from PR messages. Not LLM-based parsing of the whole thing, but targeted extraction of specific structural elements. What are those parts? What format do PR messages follow? What makes non-deterministic extraction a problem?]