Grey cell sum of two digits, need tester

[Thorsby]

EDIT: THIS PUZZLE IS BROKEN

I am looking for a tester for a sudoku puzzle. 4 star difficulty?

Rules: Normal sudoku rules apply.

A digit in a grey cell is part of a string of 3 digits in a straight line, going either horizontally or vertically. (Not diagonally.) The digit in the grey cell is always at the start or end of the string, never in the middle. The digit in the grey cell is the sum of the other two digits in the string.

All possible grey cells are given.

Example:


The puzzle:

Solve in penpa.