The existing strict gemma4 tool parser is still the primary path, but if
this fails, we try to repair by fixing some of the most commonly seen
mistakes these models seem to make in practice.
We repair by building up a set of candidates, and use the first candidate
that parses.
Repairs cover:
- missing Gemma string delimiters
- single-quoted string values, including a dangling Gemma delimiter
- raw terminal string values (if the corresponding tool schema indicates
it should be a string) - missing object close only after a concrete repair
Add regression coverage for malformed tool calls from issue #15315 and
focused unit tests for the individual repair helpers and candidate
pipeline.
