This is a Killer-X.
Prelims
a) R2C78 = {49/58/67}, no 1,2,3
b) R7C34 = {29/38/47/56}, no 1
c) 19(3) cage at R4C1 = {289/379/469/478/568}, no 1
d) 10(3) cage at R5C5 = {127/136/145/235}, no 8,9
e) 30(4) cage at R8C3 = {6789}
f) 14(4) cage at R9C6 = {1238/1247/1256/1346/2345}, no 9
1a. 45 rule on N12 1 innie R3C6 = 2
1b. 45 rule on N3 2 innies R3C78 = 13 = {49/58/67}, no 1,3
1c. 45 rule on N3 2 remaining outies R45C7 = 10 = {19/37/46}, no 5,8
2. 45 rule on N47 5 outies R56789C4 = 33 = {36789/45789}, no 1,2, 7,8,9 locked for C4
2a. R4C4 = 2 (hidden single in C4), placed for D\
2b. 45 rule on N5 3 innie R56C4 + R6C6 = 22 = {589/679}, 9 locked for N5
2c. 10(3) cage at R5C5 = {136/145}, no 7, 1 locked for N5
2d. Killer pair 5,6 in R56C4 + R6C6 and 10(3) cage
2e. R4C4 = 2 -> R4C56 = 11 = {38/47}
2f. R56789C4 = {36789/45789} -> R7C4 = {34}, R7C3 = {78}
2g. 2 in C5 only in R789C5, locked for 32(6) cage at R7C5
3a. 45 rule on N1 1 outie R3C4 = 1 innie R1C3 + 3 -> R1C3 = {123}, R3C4 = {456}
3b. 45 rule on C1234 1 outie R1C5 = 1 remaining innie R2C4 + 6 -> R1C5 = {79}, R2C4 = {13}
3c. 1 in C4 only in R12C4, locked for N2
3d. Min R1C35 = 8 -> max R1C4 = 5
3e. 45 rule on N2 3 innies R1C45 + R3C4 = 16 = {169/457} (cannot be {349} which clashes with R7C4, cannot be {367} = [37]6 because 13(3) cage at R1C3 cannot be [337]), no 3
4. 45 rule on N457 4(1+3) innies R6C6 + R789C3 = 30
4a. Max R789C3 = 24 -> min R6C6 = 6
4b. Min R6C6 = 6 -> max R6C7 + R7C6 = 9, no 9 in R6C7 + R7C6
5. 45 rule on R6789 3 innies R6C345 = 11 = {128/137/146} (cannot be {236} = [263] which clashes with 10(3) cage = {136}, cannot be {245} = [254] which clashes with 10(3) cage = {145}), no 5,9, 1 locked for R6
5a. R6C4 = {678} -> no 6,7,8 in R6C35
5b. R56C4 + R6C6 (step 2b) = {589/679}
5c. 8 of {589} must be in R6C4 -> no 8 in R5C4 + R6C6
6. R56C4 + R6C6 (step 2b) = {589/679}
6a. R56C4 + R6C6 = {589} must be [589] when 15(3) cage at R6C6 = [924/951]
6b. 45 rule on N1236 3 innies R6C789 = 17 = {278/359/368/458/467} (cannot be {269} which clashes with R56C4 + R6C6)
6c. R6C789 = {278/359/368/458} (cannot be {467} because R56C4 + R6C6 = {589} + 15(3) cage = [924/951] doesn’t include 4,6,7 in R6C7 and {467} clashes with R56C4 + R6C6 = {679})
6d. R56C4 + R6C6 = {679} (cannot be {589} = [589] which clashes with R6C789), 6,7 locked for N5
6e. R4C56 (step 2e) = {38}, locked for R4, 3 locked for N5
6f. R5689C4 = {6789} -> R7C4 = 3 (step 2), R7C3 = 8, placed for D/, R4C6 = 3, placed for D/, R4C5 = 8, R2C4 = 1
6g. R13C4 = {45} (hidden pair in C4), locked for N2, R1C45 + R3C4 = 16 (step 3e) -> R1C5 = 7, R1C34 = 6 = [15/24]
6h. Naked pair {45} in R13C4, CPE no 4,5 in R1C1
6i. 8 in C4 only in R89C4, locked for N8
6j. R6C345 (step 5) = {137/146}, no 2
6k. R6C789 = {278/359/458} (cannot be {368} which clashes with R6C345), no 6
6l. Combined cages R6C345 + R6C789 = {137}{458}/{146}{278}/{146}{359}, 4 locked for R6
Clean-ups: no 5 in R2C7, no 5 in R3C8 (step 1b), no 7 in R5C7 (step 1c)
7a. 36(6) cage at R1C1 = {156789/246789/345789}, 7,8,9 locked for N1
7b. 12(3) cage at R1C2 = {156/246/345}
8. 31(6) cage at R4C2 = {135679/234679}, 3 locked for C3 and N4
8a. 3 in R6 only in combined cages R6C345 + R6C789 (step 6l) = {137}{458}/{146}{359}, no 2
8b. R6C789 = {359/458}, 5 locked for R6 and N6
8c. 2 in R6 only in R6C12, locked for R6 -> 31(6) cage = {135679}, no 4, 5 locked for N4
8d. 2,4 in C3 only in R123C3, locked for N1
8e. 12(3) cage at R1C2 (step 7b) = {156/345} (cannot be {246} because 2,4 only in R2C3), no 2
8f. R1C3 = 2 (hidden single in N1) -> R1C4 = 4 (cage sum), R3C4 = 5
8g. R3C78 (step 1b) = {49/67}, no 8
8h. R45C7 (step 1c) = {19}/[73] (cannot be {46} which clashes with R3C78), no 4,6
8i. 25(5) cage at R3C6 = 2{49}[73]/2{67}{49}, CPE no 7,9 in R12C7, clean-up: no 4,6 in R2C8
8j. R2C9 = 2 (hidden single in N3)
8k. R5C8 = 2 (hidden single in N6)
8l. R9C7 = 2 (hidden single in N9)
8m. R8C2 = 2 (hidden single on D/) -> R67C2 = 10 = [64/91]
8n. R6C1 = 2 (hidden single in C1)
8o. Naked triple {679} in R6C246, locked for R6
8p. R6C789 = {458}, 4 locked for R6, 4,8 locked for N6 -> R6C35 = [31], R6C4 = 7 (step 6j), placed for D/
8q. Naked pair {45} in R5C56, locked for R5
8r. R4C1 = 4 (hidden single in N4) -> R5C12 = {78} (hidden pair in N4), 7 locked for R5
8s. 30(4) cage at R8C2 = {6789}, 7 locked for C3 and N7
8t. Min R6C67 = 10 -> max R7C6 = 5
8u. 7 in R7 only in R7C789, locked for N9
8v. R2C1 = 7 (hidden single in R2) -> R5C12 = [87]
8w. R3C2 = 8 (hidden single in N1)
8x. R7C7 = 7 (hidden single on D\), R45C7 (step 8h) = {19}, locked for C7 and N6, 9 locked for 25(5) cage at R3C6) -> R3C78 (step 8g) = [67], 6 placed for D/, R4C8 = 6, R5C9 = 3
8y. R7C5 = 2 (hidden single in N8)
8z. Naked triple {689} in R126C6, 6,9 locked for C6
9a. R5C5 = 4 (hidden single on D/), placed for D\ -> R5C6 = 5
9b. 5 in C5 only in R89C5, locked for 32(6) cage at R7C5
9c. Naked triple {159} on D/, CPE no 1 in R1C1 + R9C9
9d. Naked pair {14} in R7C26, locked for R7
9e. 14(4) cage at R9C6 = {1238/2345} (cannot be {1247} because R9C9 only contains 5,6,8, cannot be {1256} which clashes with R7C78), no 6,7
9f. 14(4) cage at R9C6 = {1238/2345} -> R9C8 = 3
9g. R8C6 = 7 (hidden single in N8) -> R9C3 = 7 (hidden single in N7)
9h. 32(6) cage contains 2,5,7 = {125789/245678}, 8 locked for R8 and N9
9i. R9C9 = 5, placed for D\, R9C78 = [23] -> R9C6 = 4 (cage sum), R7C6 = 1, R7C2 = 4 -> R6C2 = 6 (cage sum), R6C6 = 9, placed for D\, R6C7 = 5 (cage sum), R7C89 = [96]
9j. Naked pair {19} in R9C12, locked for N7, 9 locked for R9
9k. R2C8 = 5 -> R2C7 = 8, R1C8 = 1, R1C9 = 9, placed for D/
and the rest is naked singles, without using the diagonals.