Answers the backlog's open "first step: diff the two readers across the disc and
count disagreements", statically over every IDXD object.
Of 7750 objects and 738922 named fields whose true value is numeric, legacy
get_f32 is correct 39.42%, returns None (harmless) 43.04%, and returns a WRONG
NUMBER 17.54% (129612 fields).
The wrongness has an exact predicate: single-record objects 0 of 29822 wrong
(0.00%); multi-record objects 129612 of 709100 (18.28%). The mechanism is in
get_raw itself -- it flattens the pool to a token list, finds the FIRST occurrence
of the key, and returns the preceding token, with no notion of records. So every
record after the first inherits record 0's value: Weight truth=1.0 legacy=0.3,
Points truth=10000 legacy=4000.
Practical rule recorded: a get_f32 number from a single-record object is safe; from
a multi-record object only the first record is.
Withdrawn in the same document: my first sweep compared against "the string before
THIS field's own key" and reported 65.90% -- that is not what get_raw does, so the
figure is not the legacy reader's error rate.
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