OpenHands canvas UI compatibility module

tools/canvas_ui_tool.py from OpenHands/OpenHands at tag v1.18.0 (commit 9120ff6cbbe23640f0e475661e5a9c9729cdbf1f). The OpenHands Agent Canvas launchers import it into the agent server through --import-modules canvas_ui_tool.

It is required because the automation preset builds its agent with a finish_tool_response_schema, which registers the SDK’s builtin FinishTool only inside the preset’s own process while advertising it to the agent server as openhands.sdk.tool.builtins.finish. That SDK module does not self-register, so every automation-dispatched remote conversation fails to resolve FinishTool unless the compatibility module registers it in the agent server process first.

The module also keeps persisted pre-client_tools conversations resolvable. It is vendored rather than copied so the upstream revision, license, and provenance stay with the third-party tree.

Upstream license: MIT, see LICENSE.