Prelims
a) R1C23 = {29/38/47/56}, no 1
b) R12C9 = {29/38/47/56}, no 1
c) 8(2) cage at R4C9 = {17/26/35}, no 4,8,9
d) R56C1 = {18/27/36/45}, no 9
e) R56C9 = {16/25/34}, no 7,8,9
f) R7C89 = {14/23}
g) R89C3 = {59/68}
h) 19(3) cage at R3C3 = {289/379/469/478/568}, no 1
i) 9(3) cage at R4C4 = {126/135/234}, no 7,8,9
j) 19(3) cage at R6C7 = {289/379/469/478/568}, no 1
k) 21(3) cage at R7C1 = {489/579/678}, no 1,2,3
l) 7(3) cage at R8C2 = {124}
1a. 45 rule on N5 1 outie R6C3 = 1, clean-up: no 8 in R56C1, no 6 in R5C9
1b. R6C3 = 1 -> R5C4 + R6C45 = 22 = {589/679}, 9 locked for N5
1c. R7C3 = 3 (hidden single in N7) -> R78C4 = 14 = {59/68}, clean-up: no 8 in R1C2, no 2 in R7C89
1d. 45 rule on N9 1 innie R7C7 = 6 -> R6C78 = 13 = {49/58}, clean-up: no 8 in R8C4
1e. Naked pair {14} in R7C89, locked for R7 and N9
1f. Naked triple {124} in 7(3) cage at R8C2, 4 locked for N7
1g. 2 in R7 only in R7C56, locked for N8
1h. 17(3) cage at R4C7 = {179/269/278/368/467} (cannot be {359/458} which clash with R6C78), no 5
1i. Hidden killer pair 8,9 in 17(3) cage and R6C78 for N6, R6C78 contains one of 8,9 -> 17(3) cage must contain one of 8,9 = {179/269/278/368}, no 4
1j. 6 of {368} must be in R4C8 -> no 3 in R4C8
2a. 12(3) cage at R7C5 contains 2 = {129/237} (cannot be {246} because 4,6 only in R8C6) -> R7C56 = {27/29}, R8C6 = {13}
2b. 21(3) cage at R7C1 = {579}/{78}6
2c. R78C4 = {59}/[86], R7C56 = {27/29} -> combined cage R78C4 + R7C56 = [86]{27}/[86]{29} (cannot be {59}{27} which clashes with 21(3) cage) -> R78C4 = [86]
2d. R9C3 = 6 (hidden single in N7) -> R8C3 = 8, clean-up: no 3,5 in R1C2
2e. 5 in R7 only in R7C12, locked for N7
2f. 18(3) cage at R8C9 = {279/378}, no 5, 7 locked for N9
2g. 16(3) cage at R8C7 = {259/358}
2h. 8 of {358} must be in R9C7 -> no 3 in R9C7
2i. R5C4 + R6C45 (step 1b) = {589/679} -> R6C5 = {68}, R56C4 = {59/79}, 9 locked for C4
3a. 45 rule on C89 3 innies R468C8 = 22 = {589} (cannot be {679} because 6,7 only in R4C8), locked for C8, 8 locked for N6, clean-up: no 3 in R4C9, no 5 in R6C8 (step 1c)
3b. Naked pair {89} in R46C8, 9 locked for C8 and N6 -> R8C6 = 5
3c. 17(3) cage at R4C7 (step 1i) = {179/278}, no 3, 7 locked for C7 and N6, clean-up: no 1 in 8(2) cage at R4C9
3d. R56C9 = [16]/{34} (cannot be {25} which clashes with 8(2) cage at R4C9), no 2,5
3e. Killer pair 1,4 in R56C9 and R7C9, locked for C9, clean-up: no 7 in R12C9
3f. 45 rule on N3 3 innies R123C7 = 15 = {159/249/348} (cannot be {258} which clashes with R12C9)
4a. 4 in N6 only in R56C9 and R6C7
4b. R56C9 = [16]/{34}, R6C78 = [49/58] -> combined cage R56C9 + R6C78 = [16][49]/{34}[58]
4c. Killer pair 6,8 in R6C5 and R6C89, locked for R6, clean-up: no 3 in R5C1
5a. 45 rule on N1 3 outies R4C123 = 19 = {379/469/478/568} (cannot be {289} which clashes with R4C8), no 2
5b. Killer pair 8,9 in R4C123 and R4C8, locked for R4
5c. 19(3) cage at R3C3 = 19 = {379/469/478} (cannot be {289} = [289] which clashes with R4C8, cannot be {568} because 6,8) only in R4C2), no 2,5
5d. 3,6,8 only in R4C2 -> R4C2 = {368}
5e. 45 rule on N1 1 innie R3C3 = 1 outie R4C1, R3C3 = {479} -> R4C1 = {479}
5f. R4C123 = {379/469/478}
5g. 8 in N4 only in R45C2, locked for C2
5h. 16(3) cage at R5C2 = {259/358} (cannot be {349/367/457} which clash with R4C123, cannot be {268} because 6,8 only in R5C2), no 4,6,7, 5 locked for N4, clean-up: no 4 in R56C1
5i. 8 of {358} must be in R5C2 -> no 3 in R5C2
5j. 4 in N4 only in R4C13, locked for R4 -> R4C123 = {469/478}, no 3
5k. 19(3) cage at R3C3 = {469/478}, 4 locked for C3, clean-up: no 7 in R1C2
5l. 3 in N4 only in R6C12, locked for R6, clean-up: no 4 in R5C9
5m. 4 in N6 only in R6C79, locked for R6
6a. 9(3) cage at R4C4 = {126/135/234}
6b. R6C6 = {25} -> no 2,5 in R4C4 + R5C5
6c. 2 in C4 only in R123C4, locked for N2
6d. Consider placement for 8 in N5
R5C6 = 8 => R4C56 = 6 = {15}, locked for N4 => R6C6 = 2
or R6C5 = 8 => R6C8 = 9, R56C4 = [95], R6C6 = 2
-> R6C6 = 2, clean-up: no 7 in R5C1
[Alternatively, to reduce the rating of my walkthrough, this can be written as
8 in N5 only in R5C6 + R6C5, combined cage 14(3) at R4C5 + R56C4 + R6C5 = {15}8{79}6/{167/347}{59}8, 5 locked for N5 -> R6C6 = 2]
6e. 9(3) cage = {126/234}
6f. 4,6 only in R5C5 -> R5C5 = {46}
6g. R7C5 = 2 (hidden single in R7) -> R78C6 = [73/91]
6h. 45 rule on N2 3 innies R123C6 = 17 = {368/458/467} (cannot be {179} which clashed with R7C6, cannot be {359} which clashes with R78C6), no 1,9
6i. 45 rule on N2 1 outie R3C7 = 1 innie R1C6 + 1 -> R1C6 = {3478}, R3C7 = {4589}
6j. 9 in N2 only in R123C5, locked for C5
6k. 14(3) cage at R4C5 = {158/167/347} (cannot be {356} which clashes with R5C4 + R6C45)
6l. 4,8 of {158/347} must be in R5C6 -> no 3,5 in R5C6
6m. R4C56 of {167} must be {16/17} (cannot be {67} which clashes with R4C123) -> no 1 in R5C6
6n. 1 in N5 only in R4C456, locked for R4
6o. 2 in R4 only in R4C79, locked for N6, clean-up: no 6 in R4C9
7a. R4C78 + R5C7 = [287] (cannot be [791] which clashes with R4C123), R4C2 = 6, R4C9 = 5 -> R5C8 = 3, R6C78 = [49], R56C9 = [16], R7C89 = [14], clean-up: no 5 in R1C3, no 3 in R1C6 (step 6i)
7b. R5C1 = 2 -> R6C1 = 7, R78C1 = [59], R7C2 = 7, R8C7 = 3 -> R9C7 = 8 (cage sum), R78C6 = [91], R4C1 = 4, R4C3 = 9, R3C3 = 4 (cage sum), R5C23 = [85], R6C2 = 3, R5C4 = 9, R6C45 = [58], R9C1 = 1
7c. Naked pair {24} in R89C2, 2 locked for C2, R1C2 = 9 -> R1C3 = 2, R2C3 = 7, clean-up: no 7 in R1C6 (step 6i), no 2,9 in R2C9
7d. R4C1 = 4 -> R3C12 = 9 = [81], R2C2 = 5
7e. R9C9 = 9 (hidden single in N9)
7f. R123C6 (step 6h) = {368/458} (cannot be {467} which clashes with R5C6), no 7
7g. 18(3) cage at R2C6 = {369/459} (cannot be {468} because 4,8 only in R2C6) -> R3C7 = 9, R12C7 = [51], R1C6 = 8 (cage sum), R12C9 = [38], R12C1 = [63]
7h. R2C5 = 9 (hidden single in N2) -> R1C45 = 5 = {14}, 4 locked for R1 and N2
7i. R2C6 = 6 -> R3C6 = 3 (cage sum)
7j. R45C6 = [74] -> R4C5 = 3 (cage sum)
and the rest is naked singles.