The grounding guard tokenized with .lower().split() and split sentences on bare
.!?, so faithful claims were wrongly marked ungrounded: 'volume,' != 'volume',
and a decimal like 'V = 1.5' split into a 1-word fragment '5' that fell below
the 5-content-word floor.
- _content_words now strips edge sentence-punctuation (.,;:!?"') from tokens
while preserving math delimiters ()=+; claim and chunk are normalised
identically so matching stays consistent.
- _SENTENCE_SPLIT_RE splits on .!? only when followed by whitespace/end, so
decimals no longer create spurious sentence boundaries.
Regression test: a 5-word claim with a trailing comma now grounds.
Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>
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