Mirrors hmwebviewer's rust/dwg-wasm change into the sample: the wasm
artifact plus the parser wrapper, which now goes through parse_dwg_json
and JSON.parse instead of the JsValue-returning parse_dwg.
Building the whole result as a serde_json::Value tree pushed the live
wasm heap near 2.9GB for a 19MB drawing, and the allocator's cost grows
with that heap, so parsing went quadratic — 354s, with the tab frozen
throughout. Streaming one entity at a time keeps it linear: 2.5s.
The same build also fixes three bugs that drew stray 4km grey shapes
where two CF-PATT SOLID hatches should be. Max hatch span 4655 -> 110.
Adds two docs recording both investigations, in the format of the
existing ones: measurements, the hypotheses that were ruled out, the
fixes, regression checks, and the MPL-2.0 position (acadrust is
unmodified, so no new source-disclosure obligation arises).
Co-Authored-By: Claude Opus 5 (1M context) <noreply@anthropic.com>
