Gemini API's new schema is now the default — legacy responses get cut off June 8
TL;DR
Google flipped the default response format for the Gemini Interactions API on May 26 to a new steps-based schema, with the legacy schema set for permanent removal on June 8. Older SDKs and direct REST integrations will break unless they upgrade or pin the temporary opt-out header before the sunset.
May 26, 2026
Default flip — new steps-based schema is now the standard response format for the Gemini Interactions API
June 8, 2026
Sunset — legacy schema permanently removed; Python 1.x.x and JavaScript 1.x.x SDKs stop working on Interactions API
2.0.0+
Python and JavaScript SDK versions required for automatic compatibility with the new schema
Api-Revision
REST header — set to "2026-05-07" to temporarily opt out before June 8, or "2026-05-20" to opt in to the new schema during the transition
Google's Gemini Interactions API hit the default-flip milestone on May 26, 2026. The new response schema is now the default for every request — the legacy schema you may have built against still works, but only if your code explicitly opts out, and only until June 8, 2026, when Google removes the legacy schema permanently. After that, older Python and JavaScript SDKs stop functioning against the Interactions API and the opt-out header is ignored.
What changed in the API shape. The redesigned schema replaces the legacy outputs array with a new steps array that gives a structured timeline of each interaction turn. Each step has a type field — model_output, function_call, thought, google_search_call, and others — letting clients reason about the model's intermediate work, not just its final answer. A new polymorphic response_format field consolidates all output-format controls and removes response_mime_type. Google says the redesign is to support future capabilities like mid-flight steering and asynchronous tool calls — features the old shape could not cleanly express.
The three dates that matter. According to Google's official migration guide (last updated May 19), the timeline is:
- May 7, 2026 — opt-in phase. New Python (2.0.0+) and JavaScript (2.0.0+) SDKs become available; REST users can add the header `Api-Revision: 2026-05-20` to adopt the new schema voluntarily. - May 26, 2026 — default flip. The new schema is now standard. REST users can temporarily revert with `Api-Revision: 2026-05-07` for a few more weeks if they cannot upgrade immediately. - June 8, 2026 — sunset. The legacy schema is permanently removed. Older SDK versions (Python 1.x.x, JavaScript 1.x.x) cease functioning for Interactions API calls. The Api-Revision header is disregarded.
Who is affected. Three categories. Anyone calling the Gemini Interactions API directly via REST, anyone running Python or JavaScript SDKs at version 1.x, and anyone whose integration framework — LangChain, LlamaIndex, n8n, Zapier custom code, internal wrappers — pins to the older Gemini SDK. If your code reads from `response.outputs` or sets `response_mime_type`, you have work to do before June 8. If your code uses one of the recent Google AI SDKs (Python 2.0.0+, JavaScript 2.0.0+), the SDK handles the opt-in automatically and you mostly need to update how you read responses.
What is not changing. Model capabilities, pricing, rate limits, authentication, and the Gemini API surface beyond Interactions are unchanged by this migration. Other Gemini API endpoints — embeddings, fine-tuning, file APIs — are not affected. The deprecation is specifically scoped to the Interactions API response shape.
Why this matters for AI tool users and developers. Most builders who plug Gemini into a product have an Interactions integration somewhere — a chatbot, a research agent, a content-generation pipeline. The new schema is more expressive and will be the only option after June 8. If you maintain the integration directly, you have about ten days from the publish date of this article to test the new schema, update your response-parsing code, and verify nothing downstream relies on the legacy shape. If you depend on a third-party tool that wraps Gemini, check that tool's changelog — your job is to confirm they have shipped a compatible release before June 8.
Practical checklist before June 8. Check your installed SDK version. Run a representative integration test against the new schema, either by upgrading the SDK or by adding `Api-Revision: 2026-05-20` to a REST request. Audit downstream consumers — anything that reads `outputs` needs to read `steps` instead. If you use response_mime_type, replace it with the new response_format. For tooling built on third-party wrappers, confirm the wrapper has shipped a 2026-05-20-compatible release.
Where to read the official guide. Google has published a dedicated breaking-changes migration guide on Google AI for Developers covering both schema changes and SDK upgrade paths. The Gemini API changelog also lists the API revision dates. See our Gemini review for the current capability baseline of the underlying model, our Claude vs Gemini comparison for the head-to-head, and our best AI coding tools roundup for how Gemini-integrated coding tools handle their own SDK upgrades.
Why It Matters
Most builders who plug Gemini into a product have an Interactions integration somewhere — and after June 8 the legacy shape is gone. The redesign itself is sensible: a steps array that captures intermediate model work supports features the old shape could not. The practical issue is timing. Anyone with a direct REST integration, an older SDK pin, or a third-party wrapper that has not yet shipped a compatible release has roughly ten days from publish to verify their integration survives the sunset. The good news is the migration is mechanical, not conceptual — but mechanical migrations still break production when they are not done in time.
Who's Affected
- — Developers calling the Gemini Interactions API directly via REST. If your code reads from response.outputs or sets response_mime_type, you have a migration to do. The Api-Revision: 2026-05-20 header lets you test against the new schema today; switching to it now buys you certainty before the June 8 sunset.
- — Anyone running Python 1.x.x or JavaScript 1.x.x Gemini SDKs. The SDKs do not automatically pull new API versions — you need to upgrade to 2.0.0 or later. Test the upgrade in a staging environment, particularly the response-reading code, before pushing to production.
- — Builders using third-party wrappers around Gemini. LangChain, LlamaIndex, internal abstractions, custom Zapier or n8n code paths — any layer that wraps the SDK can pin to an older Gemini library. Check the wrapper's changelog or release notes; the wrapper maintainer needs to have shipped a compatible version before June 8.
- — Teams running Gemini-backed chatbots, agents, or content pipelines in production. Treat June 8 as a hard deadline. Run your end-to-end integration test against the new schema this week — do not leave it until June 7.
What To Do Now
- 1. Upgrade the SDK before changing your application code. Bump Python or JavaScript to 2.0.0+ and let the SDK handle the schema opt-in automatically. Then update only the response-parsing code that reads outputs/response_mime_type. Doing it in that order isolates each change.
- 2. Test the new schema against a representative request before the default flip affects your traffic. If you have not yet validated your code against the steps array, add the Api-Revision: 2026-05-20 header to a test request today and run your full pipeline against it. The post-sunset surprises are the ones that matter — find them now.
- 3. Audit anything downstream that reads the response shape. Logging, analytics, prompt-replay tools, and human review systems often parse the response independently. Each of these is a separate migration. Inventory them before June 8.
- 4. If you use a wrapper, do not assume it is ready. Check the wrapper's release notes for explicit Gemini 2026-05-20 support before June 8. If support is not yet shipped and the wrapper is critical, consider opening an issue with the maintainer — the timeline is tight.
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