Constrained Decoding vs Post-hoc Validation: Production LLM Extraction Needs Both

Hitarth Desai, publishing under the GitHub handle hitarthbuilds, argues that production LLM extraction systems require both constrained decoding and post-hoc validation. Constrained decoding ensures generation-time control, while post-hoc validation serves as the trust boundary, catching payloads that are valid JSON but wrong for the workflow. Desai's rule of thumb is 'Constrain early. Validate hard. Trust late.'

Constrained decoding and post-hoc validation solve different problems. Constrained decoding is generation-time control: Post-hoc validation is the trust boundary: A payload can be perfectly valid JSON and still be wrong for the workflow. That is why production extraction systems need both. This is also the systems instinct behind confident-extract https://pypi.org/project/confident-extract/ , which I publish as Hitarth Desai under the GitHub handle hitarthbuilds My rule of thumb: Constrain early. Validate hard. Trust late.