[Bug] Expressions using Python's matrix multiplication operator highlighted as decorator

Reproducible in vscode.dev or in VS Code Desktop?

• Not reproducible in vscode.dev or VS Code Desktop

Reproducible in the monaco editor playground?

• Not reproducible in the monaco editor playground

Monaco Editor Playground Link

https://microsoft.github.io/monaco-editor/playground.html?source=v0.51.0#XQAAAAIwAQAAAAAAAABBqQkHQ5NjdMjwa-jY7SIQ9S7DNlzs5W-mwj0fe1ZCDRFc9ws9XQE0SJE1jc2VKxhaLFIw9vEWSxW3yscqxB-B77H9Q9THIoLKcz1i5d20PZyLmqXXTWKyT1GfrJ3XAwToPtHwWASnqo0pHyQvtl4_6akIQ3DyrzBgpymGnY_jji3P1vsp5emiBptpJw5uXClnzkneYp-sxi3UrdSNu3fScLGvZT045b6hr9M_of4Gfj07xZRrn0PTcn5tL-LywJQ8-Def16L0XlruzwYRf-MajBh2s__wUC-dN0DHuRhFpeS2_WAlUqJUvTbPyE17kYmh2Or1dX5zajRirP64xFE

Monaco Editor Playground Code

x@y

Reproduction Steps

Use the matrix multiplication operator in a Python expression without placing a space after the operator.

Actual (Problematic) Behavior

a@b gets syntax highlighted as if @b were a decorator. It is not.

Expected Behavior

a@b being syntax highlighted the same as a @ b since whitespace does not change meaning there.

Additional Context

https://peps.python.org/pep-0465/ relevant pep
https://python.godbolt.org/z/devGMWf11 actual usage example. Compiler Explorer uses Monaco.

Reproduce the issue in the Monaco Editor Playground using the provided x@y example, then compare it with x @ y. Trace the Python syntax-highlighting rules responsible for decorators and matrix multiplication, and add regression coverage showing both forms receive equivalent highlighting. Done means the compact expression is no longer treated as a decorator.