industry field. Each value maps to a single classification, so what you send is precisely what the company is filed as.
Source the value from List NAICS codes: pick an entry and send its industry label verbatim on the create-company request. Treat the reference list as the source of truth rather than hard-coding labels.
industry, so you can confirm the classification that was persisted.
Errors
industry is required, and a blank string counts as absent. Failures come back in the standard validation envelope; branch on error.fields.industry.code.