AssistantProvider was imported statically by the root layout, so
assistant-ui, the Lexical composer, the Markdown renderer and Mermaid were
downloaded and evaluated on every page. The existing getAvailability gate
only skipped rendering, and the disabled branch still imported the board
widget, which pulls the whole conversation surface. An instance with the
assistant switched off paid the full cost, and so did the login page.
Measured on two production builds, /auth/login went from 42 chunks /
3.81MB including an 820KB assistant-ui chunk to 36 chunks / 2.40MB with
none, and the board page from 55 / 5.35MB to 56 / 4.56MB with none.
Adds getFeatureFlagsAsync as one source of truth for instance-level
feature switches, exposed both to the root layout and through a small
GET /api/features endpoint. Resolving the flag on the server is what makes
this work: next/dynamic never references the heavy chunk when the feature
is off, while enabled instances still server-render it, so there is no
loading flash and no remount.
Thomas Camlong
a4e1c3c60e