Logic Masters Deutschland e.V.

Set for Scojo's Setting Saturdays. The prompt was Mad Fold-In. You can find more Mad Fold-In puzzles here:
https://logic-masters.de/Raetselportal/Suche/erweitert.php?skname=x&sktext=x&suchtext=Fold-in

• Standard sudoku rules apply. The digits 1 through 9 appear in every row, column, and box.
• Mad Fold-In. If the cells between the dashed columns are removed, all clues fold into valid clues in the resulting 4x9 grid.
• Each question mark represents some number, to be determined by the solver. The value of a question mark doesn't change when folding.
• Cage Sums. Digits in a cage add to the total in the top left corner of the cage. Digits cannot repeat in cages.
• Diagonal Sums. An arrow clue outside the grid gives the sum of the digits along the indicated diagonal. Digits may repeat if allowed by other rules.
• X-Sums. An X-sum clue outside the grid gives the sum of the first X numbers placed in the corresponding row or column, where X is digit in the cell next to the X-sum clue.

Play in SudokuPad

Thank you to Cirne for testsolving, feedback on puzzle visuals, helping me come up with the title, and CSS.