# Current limits and diagnosis [Back to Python](https://rustic-game-engine.pages.dev/markdown/scripting/python.md). The embedded Play viewport forwards held WASD, arrows, and Shift. Other keys, press/release events, named actions, and separate runtime-window input are not wired in this build. Collision callbacks remain unavailable. API 1.1 provides cross-language `Events` for every supported script type; see [Shared gameplay actions](https://rustic-game-engine.pages.dev/markdown/guides/gameplay-actions.md). Each instance runs in its own process with a safe environment allowlist and a temporary working directory. Sources and responses are limited to 1 MiB; callbacks have three seconds to finish. An exception, invalid engine value, process exit, timeout, or rejected call disables the behavior. Failed build/reload validation keeps the last good instance running. - **Toolchain unavailable:** check PATH in the editor's environment, then restart it. - **Nothing moves:** check attachment, owner transform, Play focus, and held KeyW. - **Property rejected:** declare it in the editor and preserve its type. - **Wrong parent:** pass the ID returned by Find, not the path string. - **SDK missing when running manually:** run the behavior through Rustic Play. - **Callback failed:** read the Rustic Console/build diagnostic. Use `rustic.log` for gameplay logs; external stdout belongs to the engine's private transport. - **Old script has a request loop:** replace it with the [complete behavior callback setup](https://rustic-game-engine.pages.dev/markdown/scripting/python/complete-behavior.md). If the old starter defines its own SDK classes, remove those definitions and keep your gameplay logic in the callbacks. Rustic now supplies the SDK.