Function objective_knowledge_of 

pub fn objective_knowledge_of(
    quins: &[NQuin],
    agent_did: u64,
    out: &mut [u64],
) -> usize

Write the propositions that agent_did holds ObjectiveKnowledge of into out.

Zero-heap: scans quins and writes matching proposition hashes into the caller-supplied out slice (bounded by out.len()); returns the count written. Matches beyond out.len() are dropped.