Sixty of the failures in the 2026-08-05 temperature sweep were one error,
`phraser: model output starts as JSON but does not parse`, all of them in the
reply family and two of them in all twelve runs. The write-up read that as
truncation. It is not: no run hit the token cap.
The string rule in both grammars was `[^"\\]`, which admits a literal
newline. A model that wants two lines writes one, the generation satisfies the
grammar, and json.Unmarshal then rejects it with "invalid character '\n' in
string literal". The object starts with "{", so it came back as errBrokenJSON
and the reply was an empty string. The router's rule also admitted `"\\" .`,
so \q satisfied it and failed to parse the same way.
Both string rules are now llama.cpp's own json.gbnf class: the control range is
out and the escape alternatives are exact. Verified against the resident model
on 8899 — llama-server accepts both grammars and both still emit what they did.
escapeRawControls is the second line, for NoGrammar and for a remote server that
ignores a grammar: a reply whose only fault is a raw newline is readable, so it
is read rather than dropped.
claude
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