Two terminals with equal configs share one TextureAtlas (CharAtlasCache).
When the atlas merges pages it raises a consume-once clear-model flag
(TextureAtlas.beginFrame); only the first terminal to render consumes it and
rebuilds its vertex model. Every other terminal keeps stale texture-page
indexes/coords and draws wrong glyphs on its next partial render even though
its buffer is intact.
The test churns terminal A to force merges, then gives terminal B a tiny
partial update: B's untouched header row garbles (signature diff ~130/255 vs
tolerance 14) while B's buffer still reads HEADER_REF. A DOM-renderer control
runs the same workload without GPU acceleration and passes: the corruption is
exclusive to the WebGL path.
RED on current code by design; the fix lands separately.
Anthony Kim
3113eaefaa