Per terminal basin of DrainageAnalysis (reused, untouched): the spill cell/height on the
render flow surface (boundary minimum of FullFilled, cross-checked bit-for-bit against
BitDecrement(min inside)), lake-identity on classify (in-basin non-ocean classify water
>= ISLA_LAKE_MIN_PX, 20000), and the downstream edge (the reference's FullFilled descent
started at the spill, cross-checked against Plan.Dir). Seabed pits — terminal basins entirely
under the classify sea — tagged and excluded from statistics. Per-lake ownership table.
BasinGraphTool: chain → analysis → layer → CSVs → plate, height digests asserted around it.
DrainageRenderer: five primitives private→internal. No height mutated, no water filled.
Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01EppUMXNhSeuA5Mu51UnTyP
