How to Extract the “Why” from a PR into a CHANGELOG with Jev

Frontend engineer @nyaomaru is developing an AI-assisted tool, changelog-bot, designed to automatically extract the rationale behind code changes from pull requests. The project aims to solve the difficulty of identifying the "why" behind a commit, moving away from AI-generated summaries toward a selection-based approach. By using Jev, the bot evaluates candidate snippets from PR descriptions based on their explicit reasoning and relevance to the specific change. The developer emphasizes a "deterministic-first" pipeline where AI enriches rather than replaces human-written documentation. By keeping the original PR text as the source of truth and utilizing a benchmark corpus of 50 cases for validation, the project ensures that changelogs remain accurate and reliable. The goal is to maintain a clear boundary where deterministic code manages the structure, while AI provides optional, validated enrichment, ensuring that if no reliable reason is found, none is invented.