Comment only; no behaviour change. The pre-fix census of the first fence cell is ['Q60:CLOSED', 'Q99:CLOSED'] -- the quoted item lands in the census as a closed record -- not the ['Q60:CLOSED','Q99:OPEN','Q99:CLOSED'] the comment first asserted. Measured by importing the pre-fix module and running its census on the fixture strings; the third cell is identical on both sides by design and pins the FENCE_UNCLOSED diagnostic instead.