A request body still arriving at SIGTERM held the drain to its deadline — resolved

A design note from the engineering record, moved out of ROADMAP.md on 2026-09-03 and kept as written. The roadmap itself now holds only the project's state; the reasoning lives here.

The drain loop read nothing new, so a half-received upload was neither completed nor closed until the 5 s budget expired: the client was reset and the process exited at 5.09 s. Found by the soak driver's uploads population on color-separation, reproduced bare by scripts/drain_upload_probe.py, fixed by running ordinary loop passes during the drain (see "The drain does not read a request body in flight" above). Gated by D9, every PR, in both execution shapes.