Whitespace and Break Kinds

Pretext does not treat all separators the same. Segment kind matters because it changes where lines may break and what text remains visible at line edges.

White space modes

Mode	Behavior
`WhiteSpaceMode.Normal`	Ordinary spaces, tabs, line breaks, and form feeds collapse like normal web-style wrapping. Leading and trailing collapsible whitespace is removed.
`WhiteSpaceMode.PreWrap`	Ordinary spaces are preserved, hard breaks stay explicit, tabs stay explicit, and whitespace-only lines remain visible.

Segment break kinds

Kind	Meaning	Visible at line end?	Break behavior
`Text`	Normal text run	Yes	May wrap internally when the run is breakable
`Space`	Ordinary collapsible space	No	Break opportunity after the space
`PreservedSpace`	Preserved space in `PreWrap`	Yes	Break opportunity after the space
`Tab`	Explicit tab in `PreWrap`	Yes	Break opportunity after the tab
`Glue`	Non-breaking separator such as NBSP or word joiner	Yes	Prevents a break between surrounding content
`ZeroWidthBreak`	Explicit soft break opportunity	No	Break opportunity without visible width
`SoftHyphen`	Discretionary hyphen point	Only when used	Adds the discretionary hyphen when a break is taken there
`HardBreak`	Forced line boundary	No	Ends the current line immediately

Important behaviors

Ordinary whitespace collapses in WhiteSpaceMode.Normal
Spaces and tabs are preserved in WhiteSpaceMode.PreWrap
Hard breaks remain explicit line boundaries in PreWrap
Non-breaking spaces stay glued to surrounding content
Zero-width spaces create explicit break opportunities
Soft hyphens can introduce a discretionary hyphen when a break is taken

Hanging whitespace

In PreWrap, trailing spaces and tabs remain part of the visible line content. That is why the test suite checks:

hanging spaces at line end
trailing spaces before a hard break
tabs aligned to tab stops
consecutive tabs producing distinct tab advances
whitespace-only lines between hard breaks

Why this matters

These rules make the engine useful for UI that needs more than simple TextBlock wrapping. The tests cover preserved spaces, tabs, empty lines, trailing spaces before hard breaks, and discretionary hyphen insertion.

Supported special cases

The current parity tests cover:

non-breaking spaces and narrow no-break spaces
word joiners
zero-width spaces
discretionary soft hyphens
opening and closing quote attachment
URL-like runs and punctuation chains
Arabic, Devanagari, Myanmar, CJK, Hangul, and astral CJK punctuation behavior

Those cases are the practical behavior contract for the current implementation.