Google Antigravity’s October 5 cutoff turns an agent upgrade into an API migration
Google’s older managed agent shuts down on October 5, and its replacement changes the tool contract for integrations that inspect more than final text.
The cutoff is live
Google is shutting down antigravity-preview-05-2026 on October 5 and directing users to antigravity-preview-09-2026. Simple remote-sandbox workflows that consume only final output may need little more than a new agent identifier.
Where integrations break
For local tool execution and function_call processing, the contract changes: new file tools, PascalCase parameters and line-range edits replace parts of the old interface. A stale parser can therefore miss an action even while the agent completes it successfully.
What we would do
Virtual Arc would isolate the new version behind an adapter, replay real production cases and test auditing, permissions, budgets and failure handling. We would not approve the migration merely because the final text still looks correct.
Google’s October 5 shutdown of antigravity-preview-05-2026 is a useful warning against treating managed-agent versions like invisible model refreshes. Virtual Arc would treat the harness as an external execution system with a versioned API contract. Teams that read only final text from Google’s remote sandbox may get away with changing one agent ID, but teams that execute tools locally, inspect function_call events, enforce permissions or record audit trails must adapt to new file tools, PascalCase parameters and line-range edits. We would place 09-2026 behind our own compatibility adapter, replay representative production traces and block traffic migration until contract tests verify every tool call, access boundary and output path. Longer term, we would remove Google-specific event shapes from business logic. If a harness update can silently disable auditing or approval while the agent still completes its task, that integration is not production-ready yet.