Check out Inventiv. https://inventiv.io We used it a couple years ago and really liked it—super responsive team and flexible tool. Source: over 2 years ago

You already mentioned documentation. Good! Document everything. Why you chose X method over Y, or this framework over that. This helps later with onboarding and when people want to come up with suggestions, because they can see you already did explore this option earlier on so why bring it up again? Doucmentation really requires a culture of openness and transparency. Some people do not like to work this way,... Source: about 1 year ago

You could always upload/embed the pdf as part of a "post" and then use the comments section of the post to discuss. The P2 theme might also be an option as its discussion functionality is better than just straight up blog comments: https://wordpress.com/p2/. Source: over 1 year ago

- Most deep discussions happen on blog posts including project status. We use (and built) https://wordpress.com/p2/. We don’t use email. - Source: Hacker News / about 2 years ago

Yes it does! https://wordpress.com/p2/. - Source: Hacker News / about 2 years ago

Actually, Automattic, the distributed company behind WordPress uses blogs for this. Each team has their own 'blog' and you can link them, comment, etc. Then there are company wide blogs with different topics, watercooler blogs, etc. Really useful to refer to revisit past decisions and as a company wide knowledgebase. They even created a product out of it: https://wordpress.com/p2/ Disclaimer: I work there, but on... - Source: Hacker News / about 2 years ago