qwen3:14b (and deepseek-r1, other reasoning models) wrap their output
in <think>…</think> chains-of-thought before emitting real output.
With format=json the constrained sampler terminated immediately at
`{}` because the thinking block wasn't valid JSON; without format the
model thinks normally and appends the actual JSON at the end.
OllamaClient now omits the format flag and extracts the outermost
balanced `{…}` block from the response (brace depth counter, string-
literal aware). Works for reasoning models, ```json``` code-fenced
outputs, and plain JSON alike.
Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>
