Function check_read_js_safe 

pub fn check_read_js_safe(
    rows: &[Vec<OwnedValue>],
    guarded: bool,
) -> Result<(), SessionError>

The strict-i64 guard for the LEGACY bare-cell read wire (design 226 §8): an unguarded session’s reply goes through session_read_json, whose bare cells ride owned_to_json — an Int outside ±(2^53−1) would flatten to a rounded f64. The contract is a typed error, never a rounded number, so the read fails like any other statement error (the tagged /v1/sql wire carries such cells exactly; guarded sessions therefore skip this). Mirrors the napi/wasm mandatory strict_i64 walk — the daemon HTTP JSON wire is a JS boundary too.