Logic Masters Deutschland e.V.

Previous Dutch Flat Mate Puzzles
This has been a weekly series since '18 Oct 23'. Here is a spreadsheet link for all the previous puzzles in the series, which also has a few teasers for upcoming constraints/guest setters in the series (subject to change).
This alternative link offers a limited LMD search for Dutch Flat Mates.

Special Thanks
Summit Lines were created by vythic who has made multiple puzzles using this constraint.

To play the puzzle, please click the image:

Initial Setter Difficulty: 2-2.5 / 5

Normal Sudoku rules apply
Place the digits 1-9 so that they do not repeat in any row, column, or 3x3 box.

Dutch Flats
Every 5 in the grid must have a '1' directly above it or a '9' directly below it. It may have both, but it doesn't need both.

Summit Lines
Digits along a line must always be strictly ascending or descending, with ascension/descension only reversing once a 1 or 9 is placed on the line.

Hint to start

All looped segments of Summit Lines must have at least one of each of 1 and 9, or the ascension/descension flow would be broken in one direction - this impacts on Flat Mates. You cannot immediately place 5 in C2, but you can at least ensure he isn't homeless.