(This post is part of the Genuinely Approachable Sudoku (GAS) series.)
The outside clues in this Sudoku variation will have you considering some pretty constrained sums to get to the solution.

PDF

or solve online (using SudokuPad)

Theme: Squashed Sums

Author/Opus: This is the 153rd puzzle from Clover, part of the Genuinely Approachable Sudoku (GAS) team.

Rules: Standard Sudoku rules (insert a number from 1 to 9 into each cell so that no number repeats in any row, column, or bold region). Clues on the outside of the grid indicate the sum of the largest and the smallest numbers of the first three cells seen in that direction. (For instance, the R3 outside clue (6) indicates that the sum of the largest number and smallest number out of the rightmost three numbers in that row is 6.)

GAS Time Standards (highlight to view): Two party hats (🎩🥳): 7:30; One party hat (🥳): 14:00. All other solvers earn a 🦕: squeezed Stygimoloch.

Thomas Hits the GAS (highlight to view): 2:00, with SudokuPad replay file shared as a download for now (requires loading via settings menu with improvements expected before people should use this regularly).

Solution: PDF; solving video with explanation to be added later from GAS team.

Note: Follow this link for other less common variations of Sudoku.

Note 2: Comments on the blog are great! For a more interactive discussion, please also consider using our Daily GAS discussion post on the GMPuzzles Discord. Not a member of the Discord? Click this link for basic access.