Constant MEAN_VEC_PIN_THRESHOLD 

pub const MEAN_VEC_PIN_THRESHOLD: u64 = 256;

EU-5a2 — number of documents required before the workspace’s _fathomdb_embedder_profiles.mean_vec is pinned for the default profile. Per dev/design/embedder.md §0.3 (compute-once-on-first- ingest lifecycle). Public-visible so the EU-5a2 machinery test can assert the value.