Prompt Drift Kills: How to Make Prompts Stable

A small prompt edit or model change can break output structure, increase hallucinations, or blow up token budgets, and teams often notice only after users complain. This talk at Conf42 Prompt Engineering 2026 presents prompt contracts, a way to turn prompts into enforceable specifications using structured outputs, explicit invariants, and automated tests.

It includes a demo of how a contract handles a tone edit, a tool boundary, and a change in meaning, and how the test fixtures fit into CI and the release process.