- busyReason had no reader: the chat engine sets isBusy through the store's
generic set, like every other flag.
- The isSameDocument comment says the two "same document" rules disagree
in both directions, so neither is a subset of the other.
- The import boundary test bundles minified with one pako (the MCP core
resolves its own copy) and caps the canvas core at 160 KB (134 KB now).
The boundary test scans the canvas modules' imports and bundles the canvas components with esbuild; both fail on anything from components/chat, the tool handlers, next/navigation, next/font, next/script, next/headers or a server-only module. The card test renders VersionCard and VersionStrip on a fake VersionsSource.