Function build_lazyframe 

pub fn build_lazyframe(
    parts: &[ResolvedPartition],
    columns: Option<&[&str]>,
) -> Result<LazyFrame, TesseraError>

Build a (possibly concatenated) LazyFrame over the resolved partitions.

For multi-partition reads, a coin and month column identifying the source partition are appended so rows stay attributable after concatenation.

Errors

Returns TesseraError::Network when a Parquet path fails to register.