Function corpus_is_sufficient 

pub fn corpus_is_sufficient(evidence: &str, min_corpus_chars: usize) -> bool

Whether there is enough evidence to judge a candidate against at all (G-PR-7).

Single source of truth for “is this corpus worth grounding against”, shared by the entity-description write path and the --status quality sampler. Before this existed, both asked PreservationVerdict::evaluate_grounding instead, which answers Preserved { score: 1.0 } when the evidence is empty — so the writer persisted filler for unbound entities and the sampler counted those same entities as PERFECT quality. The measurement shared the defect of the thing it measured, which is why the problem stayed invisible.