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HomeDocsClaude Code CLI 16 Oct 2026
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Agent SDK reference - Python changedagent-sdk/python

Nearest release: v2.1.302, published 2 hours before upstream edited the page. Shown because the two are within 24 hours of each other. Nothing here says the release caused the edit.

Upstream edited this page at 16 Oct 2026 19:45 UTC, give or take a minute or two: the time comes from Anthropic’s own sitemap rather than from a commit. This site recorded the change at 16 Oct 2026 20:07 UTC.

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35593559<Note>
35603560 The sandbox depends on platform support and, on Linux, tools like `bubblewrap` and `socat`. By default, when `enabled` is `True` but the sandbox can't start, commands run unsandboxed with a warning on stderr. This default differs from the TypeScript SDK, where `failIfUnavailable` defaults to `true`.
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3562 Set `"failIfUnavailable": True` in your sandbox settings to stop instead. The key isn't declared on `SandboxSettings` yet, but the SDK forwards it to Claude Code, which honors it. `query()` then reports a `ResultMessage` with `subtype="error_during_execution"` and the reason in `errors`. Because this is a single-shot `query()` call, the SDK raises after yielding that error result, so wrap the loop in a try block to continue past it. See [Handle the result](/docs/en/agent-sdk/agent-loop#handle-the-result) for the error contract.
3562 Set `"failIfUnavailable": True` in your sandbox settings to stop instead. The SDK forwards `failIfUnavailable` to Claude Code along with the declared `SandboxSettings` fields. `query()` then reports a `ResultMessage` with `subtype="error_during_execution"` and the reason in `errors`. Because this is a single-shot `query()` call, the SDK raises after yielding that error result, so wrap the loop in a try block to continue past it. See [Handle the result](/docs/en/agent-sdk/agent-loop#handle-the-result) for the error contract.
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3565To keep sandboxed commands from writing to a file, list its absolute path under [`denyWrite`](/docs/en/settings-reference#sandbox-filesystem-denywrite) in your sandbox settings, such as `"filesystem": {"denyWrite": ["/home/user/project/.env"]}`. The SDK forwards `filesystem` to Claude Code along with the declared `SandboxSettings` fields. Once the sandbox starts, it blocks writes to each listed path. If you list `.env` or `./.env`, sandboxed commands can write to the `.env` file in the session's working directory.
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35653567#### Example usage
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