Function estimated_compression_workspace_bytes 

pub fn estimated_compression_workspace_bytes(level: CompressionLevel) -> usize

Estimated steady-state heap footprint of a one-shot compression context at level (window history + match-finder tables + block staging), in bytes. Computed from the same per-level tuning table the encoder resolves at frame start, so the estimate tracks the real allocations; it is an upper-bound style budget figure, not an exact accounting.