The streaming markdown renderer (StreamingMarkdown) was rewritten to chunk large outputs into frozen segments rather than keeping everything in a single growing string. Open code fences are tracked across chunks so streaming inside a code block is handled correctly. This improves rendering performance and token-cache efficiency for very long streamed responses.
Evidence
Chunked streaming renderer (search for "openFence" and "gapAfterChunks" in the renderer)
Strings lifted out of the shipped bundle, so the claim above can be checked against them.