Create and fix Unity 2D physics

Do not weigh 3D physics options. If evidence shows the user means 3D, say so and stop.

Important

• Use the unity cli (unity command --format json) and the unity-cli and unity-pipeline skills for each step.
• Before making changes, establish a baseline of the current behavior so you can tell whether a later result is actually caused by your change.
• Create a restore point you can roll back to if your changes fail.
• Do only what's asked. Don't change unrelated assets or files.
• Avoid long explanations.
• Verify runtime behaviour with temporary Debug.Log lines, then remove them, because the user didn't ask for logging and leftover lines clutter their script and console. Don't build settle-detection or permanent logging they didn't ask for. See Final step.
• Never reflect over types to discover an API — fetch the member page instead. The system probe is the one exception.

Passing C# to script eval

script eval compiles a statement block, not a file, so write the code without using directives and with fully qualified types. return what you want to read; it arrives at data.result.result. If the code doesn't compile, look up the error here: