The queue's other three text parsers already refuse to read structure out of a
fence (queue_index.py:207/:266, checkin_check.py:251, citation_resolve_check.py
after efe7ec6). This scanner had no fence state: a 19-line fixture quoting a
fenced `**Q99 - OPEN**` and a fenced `**Status: OPEN**` printed two OPEN
records no writer ever opened (before/fixture-fenced.txt).
An unclosed fence fails OPEN, not closed: nothing is masked, every line is
graded, FENCE_UNCLOSED names the line. Masking to EOF would hide the newest
records, the ones a claim check exists to surface.
Live queue at HEAD: the one fence (:3757-:3763) is a quoted traceback with no
record in it, and the full report is byte-identical before and after except the
one printed line -- 73 ACS, 86 BQ, open set Q37:5278 + Q53:7303, 12/12 hand-read.