Claude Platform release notes — June 18, 2026
- The Python, TypeScript, Go, Java, Ruby, PHP, and C# SDKs now include support for
code_execution_20260120, the code execution tool version that adds REPL state persistence and is the minimum version for programmatic tool calling. To adopt it, set the tool'stypetocode_execution_20260120; no beta header is required. It's available on Claude Fable 5, Claude Mythos 5, Claude Opus 4.5 and newer, and Claude Sonnet 4.5 and newer; see the model compatibility table.