[breaking] Google schedules the Gemini 2.5 GA family shutdown for October 16, 2026

The Gemini deprecations schedule lists the stable gemini-2.5-pro, gemini-2.5-flash, and gemini-2.5-flash-lite (all GA since mid-2025) for earliest shutdown October 16, 2026. Replacements per the table: gemini-3.1-pro-preview, gemini-3.5-flash, and gemini-3.1-flash-lite respectively. The changelog carries no dated announcement; announced_at reflects the capture date. Effective: 2026-10-16. Affected: google/gemini-2.5-pro, google/gemini-2.5-flash, google/gemini-2.5-flash-lite. Severity: breaking. Verification: verified.