Remarks
Wrappable when any child is — mirrors Apply's first-wrapping-child delegation.
Highest child priority (including negative — a composite of auto-detection rules must not be promoted to explicit-markup priority 0), so longest-match ordering tries the composite as early as its strongest child. Without it the default 0 lets a shorter standalone marker (a * rule) preempt a composite that wraps a longer one (**), splitting the longer marker into the shorter.
public static T FindLeaf(ParseRule root)The syntax-family lookup mirroring CompositeModifier.FindLeaf: returns root itself, or the first composite child (depth-first), of type T; null when none. Syntax-specific consumers address the family through here so composites are never invisible.
public override string Apply(ReadOnlySpan<char> content, string parameter)Delegates to the first child with a wrapping form, so a composite that merges differently-typed rules (a tag with a marker) stays inline-applicable in the first listed child's syntax.
public override int TryMatch(ReadOnlySpan<char> text, int index, PooledList<ParsedRange> results)public override void Finalize(ReadOnlySpan<char> text, PooledList<ParsedRange> results)public override void PostParse(ReadOnlySpan<char> cleanText, PooledList<ParsedRange> results)