Reapply the full remaining diff from #7014 on current main, retaining the shared-compute UX, smoke coverage, and mesh agent E2E updates. Mic Neale's foundation from #6189 is already present in main.
Co-authored-by: Michael Neale <michael.neale@gmail.com>
Signed-off-by: Alessandro Joabar <sandro@squareup.com>
