Google Permanently Removes the Legacy Gemini Interactions API Schema on June 8 — Breaking Change for Agent Builders

Google AI for Developers·low signal

As of June 8, 2026, Google's Gemini API permanently removed the legacy v1beta Interactions API schema. The new shape replaces the flat 'outputs' array with a structured 'steps' timeline of each interaction turn and consolidates output controls into a polymorphic 'response_format' (dropping response_mime_type), with the redesign explicitly enabling future mid-flight steering and asynchronous tool calls. Developers who hadn't opted into the Api-Revision: 2026-05-20 header now face hard breakage — a real, dated migration deadline for anyone building agents on the Gemini API.