[nonameiguess]

ADRs are the only way I've ever seen it done well for a sufficiently large enough project, let alone something like an entire product line or suite of many projects. Sometimes those span multiple organizations. Think of the Internet and the IETF RFCs. Yes, they don't give a complete picture. Implementations may not match the specification. I don't really agree they require maintenance. It's just you have to write up a new one any time you change a decision and give a reason why. Yes, it takes a lot of organizational discipline to do that. You probably can't be in panic mode and it won't work for a startup that needs to ship in five weeks or they can't make payroll. But there isn't really a substitute for discipline.

As maligned as it can be, the single best organization I've ever been a part of for code archaeology, on a huge multi-decade project that spanned many different companies and agencies of the government, simply made diligent use of the full Atlassian suite. Bitbucket, Jira, Confluence, Fish Eye, and Crucible all had the integrations turned on. Commits and PRs had a Jira ticket number in them. Follow that link to the original story, epic, whatever the hell it was, and that had further links to ADRs with peer review comments. I don't know that I ever really had to ask a question. Just find a line of interest and follow a bunch of links and you've got years of history on exactly what a whole bunch of different people (not just the one who committed code) were thinking and why they made the decisions they made.

I've always thought about the tradeoffs involved. They were waterfall. They didn't deliver fast. Their major customers were constantly trying to replace them with cheaper, more agile alternatives. But competitors could never match the strict non-functional requirements for security, reliability, and performance, and non-tolerence of regressions, so it never happened and they've had a several decades monopoly in what they do because of it.