PERF.10 Memory ceilings: 850 MB for an 8 MB DWG, 1.5 GB for a 47 MB IFC in Node; 867 to 932 MB heap peaks in the browser — a budget per format, measured in the suite

Measured 2026-11-08: Node RSS after read + write of Plans.dwg (8.2 MB) 854 MB; after open + geometry + save of IFC Schependomlaan (47 MB) 1.47 GB, the 22.5 MB showcase 1.18 GB; browser JS heap peaks: ModelCraft glTF 932 MB (10.7 MB file), BimCraft IFC 867 MB (22.5 MB), CadCraft DWG 250 MB (8.2 MB). A tab on a phone or an iPad is killed around 1 to 1.5 GB (Studio for iPad is milestone 09), and a 100 MB IFC would pass that today.

Plan: tools/perf/io-bench.mjs and open-file.mjs record bytes per source MB per format at every release (PERF.6); targets: cc-dwg under 30x, cc-ifc under 20x (strings and the STEP line index kept once, not per entity), browser peak under 3x after PERF.7 to PERF.9; the apps say so before opening a file that will not fit (navigator.deviceMemory + the file's size), instead of a dead tab. Wave 3 (scale-1000x.md, apps-3d.md): cc-dwg 35 bytes of heap per file byte (76 MB → 2.6 GB), cc-ifc about 1 GB per 100 MB in the browser, ModelCraft about 2 KB per face, DXF 38 bytes per file byte, LandXML 14 times the file; point clouds 3.8 GB for 100 M points with the in-memory store. These are the per-format budget numbers.