This puzzle was created as a birthday gift for my wonderful tester, polar.

Crypto Lying Japanese Cavescraper Ring

Rules:

Place some numbers from 1 to 9 in the unshaded area of the grid such that all numbers in the unshaded area are orthogonally connected, and all orthogonally connected groups of empty cells touch either the inner or outer boundary of the ring. A number must not repeat in any row or column of the unshaded area.

Clues outside the grid indicate the sums of connected groups of numbers in the respective row or column. For each row or column, one of the two provided sets of clues is wholly meaningless and can be ignored. The other provides the complete set of clues for the row or column, but if more than one number is listed, the sums given must not be in order of appearance.

The numbers from 1 to 6 must be placed once each in every row and column of the inner shaded area. Treat each number N as a building of height N. A number placed in the unshaded area that lies adjacent to the shaded area indicates the number of buildings seen in the shaded area from that direction, where taller buildings hide shorter buildings.

The letters from DEAR POLAR, ENJOY replace numbers from 0 to 9, and no two letters may replace the same number. A question mark can be any number from 0 to 9, and for all clues, none may have a leading zero. For the sake of correctness, a single question mark is correct as long as it refers to a single digit total, and a double question mark is correct as long as it refers to a double digit total