Round four, both findings confirmed against the code.
A cycle is the one wrong graph that passes a per-link check: every type
matches, every id exists, every required input is filled. build() returned it
as queueable, and ComfyUI caught it at execution instead -- a run accepted and
then killed from inside the executor, with the reason in a place the app has no
reason to be reading. Walked with an explicit stack: slots come from a request,
so a long chain must produce a refusal, not a RecursionError.
The window clamp measured size against the viewport and position against the
viewport minus a grabbable strip. Those are two budgets that do not add up, so
a 900px window remembered at x=1000 opened at x=720 of an 800px screen with its
close button and grip past the right edge -- while every "a strip is reachable"
assertion still passed. Dragging keeps the loose rule, because putting a window
half off the screen on purpose is ordinary; opening, restoring and a shrinking
viewport are not placements anybody made, so the window is placed whole when it
fits.