[css-contain] contain:layout incorrectly claims "nothing outside can affect its internal layout"

[cbiesinger]

https://www.w3.org/TR/css-contain-1/#valdef-contain-layout

layout
This value turns on layout containment for the element. This ensures that the containing element is totally
opaque for layout purposes; nothing outside can affect its internal layout, and vice versa.

However, I can't find anything in the description of contain: layout that disallows sizing to the available space (<div style="width: auto">) or fit-content sizing. So the inline-size of the containing element, in the common case, depends on the size of its parent.

[tabatkins]

Right, the size of the element itself is not the element's "internal layout".

Normal sizing negotiation isn't meant to be covered by that wording; it's about outside things directly influencing inside things (and vice versa).