March 20th, the spring equinox
Sudo, the trickster god of hackers appears to Lu and give her a strange snippet of code, presented as a puzzle. Lu isn't a hacker and doesn't have any friends who code.
She doesn't know what to do with it, and ignores it.
March 24th
[Ollie Says Hello] occurs, and Lu realizes that Tavi codes, and might know what to do with the weird puzzle she was given.
Tavi recognizes the description and realizes that Lu has no idea about this kind of internet lore, and is like "holy shit the goddess sudo is real and has appeared to this blessed normie."
Over the next few weeks…
Tavi is excited about it and reaches out to her online community to see if anyone else got their hands on something similar. No one had, but Gershom (who is online friends with Tavi—and Tavi knows he likes to code puzzles) is interested and takes a look.
(parallel to this, Lu and Ollie are becoming acquainted in Ollie Goes to the Park)
(also parallel to this, The Barista and The City and becoming friends)
The code is weird, it references old obsolete shit but also really new shit, appears to be written in a mix of languages and is full of seeming-redundancies. Its surprisingly short but also full of holes. Tavi and Gershom go in on it together, Gershom is level about it but Tavi gets kind of obsessed. Tavi knows about Gershom's store, and when they gets close Tavi freaks out and go to find him in person.