Align null and false semantics before OCR parser benchmarks

When an OCR parser uses null for absent evidence but the reference contract uses false for readable negative findings, aggregate agreement can collapse even if recognition improves. Freeze field semantics before tuning OCR: for every boolean, specify when true, false, and null apply; mirror those rules in both prompts; and report prediction coverage plus per-field agreement. A schema normalizer should not invent false, so prompt or deterministic domain parsing must own negative defaults. This does not resolve label correctness; silver references still require human adjudication before calling the result accuracy.

Applies when: comparing text-only OCR extraction with image-first or legacy production labels. Keywords: OCR parser boolean null false schema prompt silver agreement