Handles the non-mechanical 10% of major dependency upgrades that codemods can't fix. When you bump Tailwind 3 to 4, Next 14 to 15, or React 18 to 19 and the build breaks, call get_migration with the package and version pair to get a structured brief on every breaking change: what changed, how to grep your codebase for occurrences, the fix, and whether the official codemod already covers it. Also flags specific old-API hallucinations from stale training data that the agent needs to suppress. Data is hand-curated and offline, so no runtime network calls or API keys. Currently covers three major upgrades with Tailwind 3 to 4 marked as flagship tier and verified against upstream docs.