Two things went wrong when the window was small and the AI chat docked:
1. Libraries / Output painted over the board selector. The editor zone
has min-width: max-content, but its child .editor-toolbar-wrapper is
an inline-size query container, and size containment makes it
contribute zero intrinsic width — so the floor resolved to nothing,
flexbox squeezed the zone under its buttons and the bar never got to
wrap. Containment is now off for the in-bar mount (the wrapper keeps
it for its standalone mobile mount); the two label collapses that
depended on it are re-keyed to the unified-toolbar container at the
same thresholds the canvas controls use (1010 / 905px), so the row
degrades in step and, when it truly cannot fit, wraps instead.
2. The explorer / Code / Both / Circuit segmented toggle now hides once
the shared bar is under 760px (its inline display moved to CSS so a
container query can do that). Every switch it had is a checkmarked
row in the View menu: File Explorer, and Code / Both / Circuit as a
radio group under a View mode label. explorerOpen moves from
EditorPage state into useEditorStore so the menu can read it.
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