Shiki's Oniguruma engine, a 600 KB wasm, is no longer built. Shiki's full bundle names it for its shorthand highlighter, which the app never uses, since @streamdown/code highlights with Shiki's JavaScript engine, so the wasm was built and precompressed on every build but never loaded. vite.config.ts aliases shiki/wasm to a stand-in, parts/no-wasm.ts, that fails to load with a message saying why, so anything that did reach for the engine would say so rather than highlight nothing. Code built through the alias still highlights in Chrome. The web UI spec says so beside the rehype-raw stand-in.