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Prelims

a) R12C7 = {29/38/47/56}, no 1
b) R4C45 = {18/28/36/45}, no 9
c) R5C34 = {14/23}
d) R89C9 = {59/68}
e) 21(3) cage at R2C1 = {489/579/678}, no 1,2,3
f) 19(3) cage at R4C8 = {289/379/469/478/568}, no 1
g) 20(3) cage at R5C5 = {389/479/569/578}, no 1,2
h) 9(3) cage at R7C1 = {126/135/234}, no 7,8,9
i) 23(3) cage at R8C3 is a must repeat cage = {599/788/779}, no 1,2,3,4,6
j) 12(4) cage at R8C8 = {1236/1245}, no 7,8,9
k) 38(8) cage at R2C8 = {12345689}, no 7

1a. 45 rule on N9 1 outie R6C7 = 3, clean-up: no 8 in R12C7
1b. 3 in N9 only in 12(4) cage at R8C8 = {1236}, 1,2,6 locked for N9, clean-up: no 8 in R89C9
1c. Naked pair {59} in R89C9, locked for C9 and N9
1d. Naked triple {478} in R789C7, locked for C7
1e. 45 rule on N6 2 remaining innies R45C7 = 11 = {29/56}, no 1
1f. R3C7 = 1 (hidden single in C7)
1g. 45 rule on C789 2 outies R45C6 = 11 = {29/38/56}, no 4
1h. 38(8) cage at R2C8 = {12345689}, 4 locked for N3
1i. 1 in N6 only in 12(3) cage at R5C9 = {129/147/156}, no 8
1j. 45 rule on N7 3 innies R789C3 = 21 = {579/678} (cannot be {489} because must repeat 23(3) cage cannot contain both of 8,9), 7 locked for C3 and N7
1k. 45 rule on N7 1 outie R8C4 = 1 innie R7C3 + 2, no 8,9 in R7C3, no 5 in R8C4
1l. 45 rule on N12 two outies R4C13 = 12 = {57}/[84/93], no 1,2,6, no 5 in R4C1, no 9 in R4C3
1m. 45 rule on N2 two outies R34C3 = 9 = [45/54/63], clean-up: no 4 in R4C1
1n. 45 rule on N124 two outies R56C4 = 5 = {14}/[32], clean-up: no 3 in R5C3
1o. Whatever is in R5C3 must be in R6C4 and in N6 in R4C789, no 1 in R4C789 -> no 1 in R5C3, no 1 in R6C4, clean-up: no 4 in R5C4
1p. 1 in N5 only in R4C45 = {18} or in R56C4 = [14] -> no 4 in R4C45 (locking-out cages), clean-up: no 5 in R4C45
1q. 45 rule on R12345 2 innies R5C59 = 10 = [37]/{46}/[82/91], no 5,7 in R5C5
1r. Naked quad {2569} in R1245C7, CPE no 2,5,6,9 in R2C8 + R3C78
1s. Naked triple {348} in R2C8 + R3C78, 3,8 locked for N3 and 38(7) cage
1t. 18(3) cage at R1C8 = {279/567} -> R1C8 = {59}, R12C9 = {27/67}, 7 locked for C9, clean-up: no 3 in R5C5

2a. 12(3) cage at R5C9 (step 1i) = {129/147/156} -> R6C8 = {579}, R56C9 = {12/14/16}, 1 locked for C9
2b. 20(3) cage at R5C5 = {479/578} (cannot be {569} which clashes with R45C6), no 6, 7 locked for N5, clean-up: no 2 in R4C45, no 4 in R5C9 (step 1q)
2c. 12(3) cage = {129/156} (cannot be {147} = [174] which clashes with 20(3) cage = 9{47} using R5C59 = 10, step 1q), no 4,7
2d. 19(3) cage at R4C8 = {478} (hidden triple in N6)
2e. R789C8 = {126} (hidden triple in C8), 2,6 locked for N9 -> R7C9 = 3
2f. R4C13 (step 1l) = [75/93] (cannot be [84] which clashes with R4C9), no 4,8, clean-up: no 5 in R3C3 (step 1m)
[Now the key step which cracks the puzzle]
2g. Combined cage R4C13 + R4C45 = [75]{18}/[93]/{18] (cannot be [75]{36} which clashes with {56} in either R45C6 or R45C7 (steps 1e and 1g), which are both part of 38(7) cage at R2C8) -> R4C45 = {18}, locked for R4 and N5 -> R4C89 = [74], R3C9 = 8, R5C8 = 8, R4C13 = [93], R3C3 = 6 (step 1m), R5C4 = 3 -> R5C3 = 2, R6C4 = 2 (step 1n), R4C7 = 2 (hidden single in R4) -> R5C7 = 9 (step 1e), R5C5 = 4 -> R5C9 = 6, R6C89 = [51], R1C8 = 9, R45C6 = [65], R4C2 = 5, naked pair {17} in R5C12, 7 locked for N4, clean-up: no 8 in R8C4 (step 1k)
2h. R789C3 (step 1j) = {579}, 5,9 locked for C3 and N7
2i. 9(3) cage at R7C1 = {126/234}, 2 locked for C1 and N7
2j. 8 in N7 only in 15(3) cage at R7C2, locked for C2
2k. 15(3) cage = {168/348}
2l. Killer pair 4,6 in R6C2 and 15(3) cage, locked for C1
2m. 1 in C3 only in R12C3, locked for N1
2n. R4C1 = 9 -> R23C1 = 12 = {57} (cannot be [84] which clashes with R23C3, ALS block), locked for N1, 7 locked for C1 -> R5C12 = [17], clean-up: no 6 in 9(3) cage at R7C1
2o. Naked triple {234} in 9(3) cage, 3,4 locked for C1 and N7
2p. R1C1 = 8 -> R1C23 = 6 = [24], R12C9 = [72], R2C3 = 1
2q. 15(3) cage at R1C4 = {159} (only remaining combination) -> R1C4 = 1, R23C4 = {59}, locked for C4 and N2 -> R4C45 = [81], R8C4 = 7 -> R7C3 = 5 (step 1k, or 7 must repeat in 23(3) cage), R89C3 = [97]
2r. R1C6 = 3 -> R23C6 = 12 = [84], 15(3) cage at R1C5 = [672]
2s. Naked triple {129} in R789C6, 9 locked for N8
2t. 12(3) cage at R8C5 = {345} (only remaining combination) -> R9C4 = 4

and the rest is naked singles.

1j, would become R789C3 = {579/678} for the repeating cage and {489/678} for a standard {689} cage with R7C3 = {47}
in which case after step 1o
R34C3 = [45/54/63] (cannot be [27] which clashes with R5C3 = {24} and R7C3 = {47}, ALS block, or is eliminated by R789C3 = {579/678}, 7 locked for C3 for the repeating cage combinations)
That all becomes unnecessary, of course, because the key step 2g would eliminate R4C13 = [57] in addition to eliminating [75]