In short: Google released Antigravity Agent 09-2026 on September 17, 2026 under the identifier antigravity-preview-09-2026. It replaces and deprecates antigravity-preview-05-2026, which is scheduled to shut down on October 5, 2026. For integrations that use environment: "remote" and only consume output_text or model_output steps, the official guidance is to change the agent identifier. Applications that run tools locally or inspect function_call steps need to adapt to the new built-in tool schema. Google documented the changes in the Gemini API release notes, while the deadline is listed on the official deprecations page.
What changes from Antigravity 05-2026 to 09-2026
The main compatibility break is in the tool layer. Several function names changed, parameters now use PascalCase instead of snake_case, and file editing moves away from full-file rewrites toward line-range replacements.
| Capability | 05-2026 | 09-2026 | Migration impact |
|---|---|---|---|
| Agent identifier | antigravity-preview-05-2026 | antigravity-preview-09-2026 | All projects need to point to the new version before the old one shuts down. |
| File creation | write_file(path, content) | write_to_file(TargetFile, CodeContent, Overwrite, Description) | Update the tool name, argument names, and any validator that depends on the old payload. |
| File editing | write_file(path, content), full rewrite | replace_file_content(TargetFile, StartLine, EndLine, TargetContent, ReplacementContent) | The local executor must accept line-range edits and the new fields. |
| File reading | read_file(path, offset, limit), using byte offsets | view_file(AbsolutePath, StartLine, EndLine, ContentOffset) | Parsers and mocks need to follow the new name and argument set. |
| Directory listing | list_files(path) | list_dir(DirectoryPath) | Calls and rules based on the old name need review. |
| File and code search | No dedicated tool, agents used shell commands | find_by_name(SearchDirectory, Pattern, MaxDepth) and grep_search(SearchPath, Query, IsRegex) | Two dedicated built-in tools can now appear in function_call steps. |
| Shell execution | code_execution(command, timeout_seconds) | No documented change | No signature migration is documented for this tool. |
| Web search | google_search(queries) | No documented change | No signature migration is documented for this tool. |
Who can migrate by changing only the agent identifier
The simplest case is an application that lets Antigravity operate inside Google's remote sandbox and only reads the final result. The release note is explicit: if the request uses environment: "remote" and the application only consumes output_text or model_output steps, changing the agent string to antigravity-preview-09-2026 is enough. In that flow, the application does not implement filesystem tools locally or interpret their arguments.
Even so, a smoke test before rollout is useful. It should verify authentication, interaction creation, final status, output reading, and any custom timeout, streaming, or persistence logic around the API.
Who needs code changes beyond the agent string
The migration requires more work when an integration uses local_environment or directly inspects function_call steps. In those cases, the software will see different names and arguments for the built-in tools. This is especially relevant for local adapters, tool routers, argument validators, audit filters, and tests whose fixtures encode the 05-2026 schema.
- Parameters: the documentation says the modified tools move from snake_case to PascalCase.
- Tool names: write_file, read_file, and list_files no longer represent the same operations in the old form.
- Filesystem search: find_by_name and grep_search are part of the documented 09-2026 tool set.
- function_call parsing: dispatch logic based on the function name or argument-key validation must accept the new schema.
What changes specifically for file edits
The most important change for integrations with local tools is replace_file_content. In the 05-2026 preview, the same write_file(path, content) tool could be used to rewrite a full file. In 09-2026, an edit is described with TargetFile, StartLine, EndLine, TargetContent, and ReplacementContent.
In practice, a local executor should no longer assume that every edit arrives as the complete contents of a file. It needs to be ready to apply a replacement inside a line-bounded region and validate the target content before writing the replacement. New-file creation now uses write_to_file, with dedicated fields for the destination, content, overwrite behavior, and description.
File reading also changes its reference model. read_file, which documented a byte offset and limit, is replaced by view_file, which uses an absolute path, start and end lines, and a content offset. If your integration calculates offsets, reconstructs excerpts, or maintains snapshots for tests, this deserves dedicated validation.
Migration checklist before October 5
- Find old-version references: search for antigravity-preview-05-2026 in code, environment variables, configuration files, and tests.
- Switch to antigravity-preview-09-2026: make the change first in a test environment or a controlled slice of traffic.
- Classify your flow: confirm whether you only use environment: "remote" and final output, or whether you run tools locally and inspect function_call.
- Update tool dispatch: implement the new names and PascalCase keys for file creation, editing, reading, listing, and search.
- Review file editing: test line-range replacements, including cases where the target content does not match expectations.
- Update mocks, validation, and observability: logs, metrics, allowlists, and tests that depend on old tool names may need changes.
- Run regression tests: validate tasks that create, edit, read, and search files, plus workflows using code_execution and google_search.
- Finish rollout before the deadline: Google lists October 5, 2026 as the shutdown date for antigravity-preview-05-2026.
What does not change and what the deadline actually means
In the release notes, code_execution(command, timeout_seconds) and google_search(queries) are listed as unchanged. The October 5 deadline applies specifically to the antigravity-preview-05-2026 preview, not to the Gemini API as a whole. The deprecations page lists antigravity-preview-09-2026 as the recommended replacement and, as of September 18, 2026, does not announce a shutdown date for the new version.
Google also continues to label Antigravity as a Public Preview feature. The current Antigravity Agent guide describes it as a general-purpose managed agent available through the Interactions API and Google AI Studio, with code execution, file management, and web access inside a sandbox. Because it is still in preview, features and schemas can change, so avoiding unnecessary hard dependencies on internal step formats can reduce future migration work.
Official sources to track the migration
- Gemini API release notes, including the Antigravity 09-2026 change table.
- Gemini API deprecations, with the 05-2026 shutdown date and recommended replacement.
- Antigravity Agent guide, with current API examples and preview limitations.
