Agency owners: how do you handle client approvals without endless email threads?

I've seen client sign-offs get lost in long email chains, where nobody is sure which version was approved or what the last round of feedback was. What helped me most was keeping one place per project where the deliverable, the comments and the final approval all live together. I'm curious how others do it. What tools or process do you use for sign-offs, and how do you stop feedback from dragging on for weeks?