Thanks Afmob for your detail corrections.
Prelims
a) R1C12 = {59/68}
b) R1C45 = {19/28/37/46}, no 5
c) R1C67 = {29/38/47/56}, no 1
d) R2C23 = {29/38/47/56}, no 1
e) R5C45 = {39/48/57}, no 1,2,6
f) R78C2 = {49/58/67}, no 1,2,3
g) 24(3) cage at R6C7 = {789}
h) 11(3) cage at R8C8 = {128/137/146/236/245}, no 9
i) 22(3) cage at R9C5 = {589/679}
j) 18(5) cage at R3C5 = {12348/12357/12456}, no 9
k) 18(5) cage at R6C3 = {12348/12357/12456}, no 9
l) 18(5) cage at R8C3 = {12348/12357/12456}, no 9
m) 42(3) cage at R1C3 = {12456789}, no 3
1. 22(3) cage at R9C5 = {589/679}, 9 locked for R9
1a. 36(7) cage at R8C4 must contain 9 -> caged X-Wing for 9 in 36(7) cage and 22(3) cage, no other 9 in N89
1b. Naked pair {78} in R7C67, locked for R7 and 24(3) cage at R6C7 -> R6C7 = 9, clean-up: no 2 in R1C6, no 5,6 in R8C2
1c. R7C8 = 9 (hidden single in N9), clean-up: no 4 in R8C2
1d. 9 in R8 only in R8C12, CPE no 9 in R5C2
2. 42(3) cage at R1C3 = {12456789}, CPE no 9 in R2C123, clean-up: no 2 in R2C23
3. R1C67 = {38/47}/[92] (cannot be {56} which clashes with R1C12), no 5,6 in R1C67
3a. R2C23 = {38/47} (cannot be {56} which clashes with R1C12), no 5,6 in R2C23
4. 45 rule on R1 3 innies R1C389 = 10 = {127/136/145/235}, no 8,9
4a. 3 of {136} must be in R1C9 -> no 6 in R1C9
4b. 9 in C9 only in 24(4) cage at R1C9 in R23C9
4c. Caged X-Wing for 9 in 42(8) cage at R1C3 and 24(4) cage for R23, no other 9 in R23
5. 45 rule on N89 3(2+1) innies R7C59 + R8C4 = 6
5a. Min R7C59 = 3 -> max R8C4 = 3
5b. Min R7C5 + R8C4 = 3 -> max R7C9 = 3
5c. Min R7C9 + R8C4 = 2 -> max R7C5 = 4
5d. R7C59 + R8C4 must contain 1, CPE no 1 in R7C4
6. Hidden killer triple 7,8,9 in R8C1, R8C2 and 18(5) cage at R8C3 for N7, R8C2 = {789}, 18(5) cage cannot contain more than one of 7,8 -> R8C1 = {789}, 18(5) cage = {12348/12357}, no 6
6a. R78C2 = {49/67} (cannot be [58] which clashes with 18(5) cage), no 5 in R7C2, no 8 in R8C2
6b. Killer pair 4,7 in R78C2 and 18(5) cage, locked for N7
6c. 6 in N7 only in R7C123, locked for R7
7. 45 rule on N6 2 remaining innies R45C7 = 1 outie R7C9 + 2
7a. Max R7C9 = 3 -> max R45C7 = 5, no 5,6,7,8 in R45C7
8. 45 rule on N5 2 innies R6C45 = 1 outie R3C4 + 7, IOU no 7 in R6C5
9. 45 rule on N5 4(3+1 for step 9a, 2+1+1 for step 9b) outies R3C4 + R67C3 + R7C5 = 11
9a. Min R67C3 + R7C5 = 6 -> max R3C4 = 5
9b. Min R3C4 + R7C35 = 4 -> max R6C3 = 7
10. 45 rule on R89 2 innies R8C12 = 1 remaining outie R7C4 + 12
10a. 9 in R8 only in R8C12 = [89/97] = 16,17 -> R7C4 = {45}
10b. R7C24 + R8C12 = [4589/6497], 4 locked for R7
10c. 4 in N8 only in R79C4 + R8C56, locked for 36(7) cage at R7C4, no 4 in R8C7 + R9C8
10d. 4 in N9 only in 11(3) cage at R8C8 = {146/245}, no 3,7,8
[Only just spotted …]
11. 45 rule on R12 3 outies R3C389 = 1 innie R2C1 + 22
11a. Max R3C389 = 24 -> max R2C1 = 2
11b. R2C1 = {12} -> R3C389 = 23,24 = {689/789}, 8 locked for R3
11c. 18(5) cage at R3C5 = {12357/12456}, 5 locked for R3
11d. Killer pair 6,7 in R3C389 and 18(5) cage, locked for R3
11e. Killer quad 1,2,3,4 in R23C1, R2C23 and R3C2, locked for N1
12. R1C389 (step 4) = {127/136/145/235}
12a. R1C3 = {567} -> no 5,6,7 in R1C89
13. 42(8) cage at R1C3 = {12456789}, CPE no 1,2,4 in R2C89
13a. 6 of 42(8) cage must be in R13C3 + R2C4567 (R13C3 + R2C4567 cannot contain both of 7,8 with would clash with R2C23), no 6 in R3C8
14. 45 rule on C89 3 remaining innies R139C8 = 12
14a. Min R3C8 = 7 -> max R19C8 = 5, no 5,6,7,8 in R9C8
14b. 7,8 in N9 only in R789C7, locked for C7, clean-up: no 3,4 in R1C6
15. 24(4) cage at R1C9 contains 9 = {1689/2589/2679/3489/3579/4569}
15a. Hidden killer pair 5,6 in R89C7 and 11(3) cage for N9, 11(3) cage contains one of 5,6 -> R89C7 must contain one of 5,6
15b. Hidden killer pair 5,6 in R23C7 and R89C7 for C7, R89C7 contains one of 5,6 -> R23C7 must contain one of 5,6
15c. Hidden killer pair 5,6 in R23C7 and 24(4) cage for N3, R23C7 contains one of 5,6 -> 24(4) cage must contain one of 5,6 = {1689/2589/2679/3579} (cannot be {3489} which doesn’t contain 5 or 6, cannot be {4569} which contains both of 5,6), no 4
15d. R1C9 = {123} -> no 3 in R2C89
[Cracked. The rest is fairly straightforward.]
16. 3 in R2 only in R2C23 = {38}, locked for R2 and N1, clean-up: no 6 in R1C12
16a. Naked pair {59} in R1C12, locked for R1 and N1, clean-up: no 1 in R1C45, no 2 in R1C7
16b. Naked pair {67} in R13C3, locked for C3 and 42(8) cage at R1C3, no 6,7 in R2C4567 + R3C8 -> R3C8 = 8
16c. R3C8 = 8 -> R19C8 = [13] (step 14)
16d. Naked pair {78} in R17C6, locked for C6
16e. R2C1 = 1 (hidden single in R2)
16f. R3C9 = 9 (hidden single in R3)
16g. Naked pair {24} in R3C12, locked for R3
16h. 9 in C3 only in R45C3, locked for N4
17. 16(4) cage at R2C1 contains 1 = {1258/1267/1348/1357/1456} (cannot be {1357} because R3C1 only contains one of 2,4)
17a. R3C1 = {24} -> no 2,4 in R45C1
18. R1C389 (step 4) = {127/136}
18a. R1C45 = {28/46} (cannot be {37} which clashes with R1C389), no 3,7 in R1C45
18b. 3 in R1 only in R1C79, locked for N3
19. Naked triple {567} in R2C89 + R3C7, locked for N3
19a. 4 in N3 only in R12C7, locked for C7
19b. 18(5) cage at R3C5 (step 11c) = {12357} (only remaining combination) -> R3C5 = 7, R13C3 = [76], R1C6 = 8 -> R1C7 = 3, R1C9 = 2, R23C7 = [45], R3C6 = 3 -> R3C4 = 1, clean-up: no 5 in R5C4
20. Naked pair {12} in R45C7, locked for C7 and N6, R7C9 = 1
20a. Naked triple {678} in R789C7, locked for N9
20b. Naked pair {45} in R89C9, locked for C9 and N9 -> R8C8 = 2, R8C4 = 3, R7C5 = 2, clean-up: no 9 in R5C5
21. 14(3) cage at R4C8 = {347/356}, no 8
21a. 4,5 only in R4C8 -> R4C8 = {45}
21b. R6C9 = 8 (hidden single in N6)
22. R6C45 = R3C4 + 7 (step 8)
22a. R3C4 = 1 -> R6C45 = 8 = [71] (cannot be [53] which clashes with R7C2), clean-up: no 5 in R5C5
22b. R6C45 + R7C5 = [712] = 10 -> R67C3 = 8 = {35}, locked for C3 -> R2C23 = [38]
23. 12(3) cage at R4C6 = {246} (only remaining combination), locked for C6 and N5, clean-up: no 8 in R5C45
23a. R5C45 = [93]
23b. Naked pair {58} in R4C45, locked for R4 -> R4C8 = 4, R4C9 = 3 (hidden single in N6), R5C9 = 7 (cage sum)
24. R4C3 = 9 (hidden single in C3) -> R34C2 = 5 = [41], R4C67 = [62], R234C1 = [127] = 10 -> R5C1 = 6 (cage sum)
24a. R5C2 = 8 (hidden single in R5)
and the rest is naked singles.