@Barkeep49 this example is wonderful and precisely the kind of story/experience we hoped this question would inspire! Thank you for putting thought to this question and for sharing such a specific and vivid example.
"This article passes the GA criteria. Congratulations, and good work! It's clear you've put a lot of work into it – you should be proud of what you've created. Kevin (aka L235 · t · c) 21:22, 6 September 2018 (UTC)"
...it must've felt great to receive User:L235's message after your, Innisfree987's and others' work in the week's after your 25 August 2018 rewrite.
In an effort to understand this in a bit more detail, I had a few questions for you...
1. "...the edit summaries built our collaboration." Can you say more to this? What do you mean your edit summaries "built" your collaboration?
Reading these edit summaries, it seems to me, like y'all are narrating/describing your work...it's not immediately clear to me whether you're working in tandem/coordinating your efforts.
2. Do you remember what led you to writing on Innisfree987's talk page and what you hoped would come of that interaction?
It looks like you'd contributed to The Hate U Give article a couple of times before writing so I'm just wondering what might've prompted you to venture to their talk page.
3. Have you noticed this pattern elsewhere? This "pattern" being, you or someone else showing an interest in contributing to a page you've done a good amount of work on and their interest inspiring you to reengage with it?
I ask the above noticing in the month preceding your 25 August 2018 edit, Innisfree987 had made 2 edits and in the month following, they made 18 edits...how cool.
4. More broadly, how did you feel after this collaboration? Did it help you see/think about Wikipedia in a new or slightly different way?
I appreciate by 25 August 2018, you would've been editing for ~13 years, but I'm still curious if this collaboration "unlocked" anything for you.