If I want to design a standard cell that can be integrated "seemlessly" with the

sky130_fd_sc_hd__

cells using magic, is there a guide for that ? Anything special to pay attention to ? Things like should I use the

scnfet

scpfet

instead of the normal ones ?

Set the cell boundary with

property FIXED_BBOX llx lly urx ury

Ack, yeah, I knew about that one. Might also want

MASKHINTS_...

for various implant layers to make sure the border overlap properly too.

Apart from the documentation that seems to be written by teams of interchangeable Software Suits, for whom Public Relations is way more important than reality, because in software, reality is a Social Construct, are there useful files for hardware engineers who don't want to guess the information from standard cell examples, and where would I find the authoritative documentation, not the clones with subtle inconsistencies?

The FIXED_BBOX and the maskhints are the main thing. You can try the (still considered experimental)

gds maskhints true

option to attempt to automatically construct the difference between the original GDS and what magic would generate as a set of mask hints. Not tested nearly enough.