Back in December 2024, I was around a month into working on Metro (at the time still called Lattice) and realized it crossed the threshold from "is this anything" to "oh shit this has wheels". I'd been talking informally with a few folks in the community at the time, but it was ready for a proper design review to get more feedback.
So, like anyone, I spent the holidays writing a 30-something page design doc. Shared it early January with a group of around 10 people, and more or less finished it up by end of January. Most of this doc is what eventually made it on to the Metro doc site.
After a few requests and clearing with all the original commenters, I'm happy to share the original design doc for anyone that's interested, including discussions. This was great and the open source community at its best.
The published google doc is below (which doesn't allow including read-only comments unfortunately).
For a version with comments, I've published an exported html dump to the metro doc site here: https://zacsweers.github.io/metro/0.8.0-SNAPSHOT/designdoc.html. Comments are annotated footnotes.
After the next release, that link will have a more permanent home here: https://zacsweers.github.io/metro/latest/designdoc.html