Comment by burnt-resistor

A workflow that works well is one that takes the better ideas from Meta's "hg"+"arcanist"+edenfs+"phabricator" diff and land strategy. Git, by itself, is too low-level for shared, mostly single-source-of-truth yet distributed dev.

Make test cases all green locally before pushing, but not in a way that interferes with pushing code and they shouldn't be tied to a particular (D)VCS. Allow uploading all of the separate proposed PRs you want in a proposed "for review" state. After a PR is signed-off and sent for merging, it goes into a linearizing single source of truth backed by an automated testing/smoke testing process before they land "auto-fast-forwarded" in a mostly uncontrolled manner that doesn't allow editing the history directly. Standardization and simplicity are good, and so is requiring peer review of code before it's accepted for existing, production, big systems.

Disallow editing trunk/main/master and whenever there's merge conflict between PRs, manual rebasing of one or the other is required. Not a huge deal.

Also, have structured OWNERS files that include people and/or distribution list(s) of people who own/support stuff. Furthermore, have a USERS file that keeps lists of people who would be affected by restarting/interrupting/changing a particular codebase/service for notification purposes too. In general, monorepo and allowing submitting code for any area by anyone are roughly good approaches.