A costly experiment gone wrong: two teams read the same event and report opposite outcomes. In this 15‑minute panel Gustavo (instrumentation & measurement) and Michelle (brand & UX) turn that composite mishap into a compact, actionable playbook. We define a one‑page event contract: naming rules, a one‑line JSON schema, versioning, and a short owner sign‑off. Gustavo walks tag‑manager‑friendly patterns, a lightweight lint snippet, and a dashboard parity test case for safe cutovers. Michelle provides a three‑question UX sign‑off, a one‑page exec summary to win stakeholders, and copy guardrails to avoid brand fractures. The episode ends with a 72‑hour pilot plan and an explicit CTA: grab the one‑page contract template, tag‑manager snippet, and migration checklist in the show notes. Three listen‑ready takeaways for social: ship three contracts this week; run a dual‑write parity check; measure success by lower event variance and faster time‑to‑insight.