K3-21 D, red. The NISO-STS reader clips `depth` to 6 once and writes that
one value into BOTH the ATX heading, where markdown has six levels, and the
`OutlineMark` the declared route builds its plan from, where nothing clips.
On one standard 9 of 2 761 titled sections sit at depth 7; the plan read them
at 6, and `--shell-parent` gave its two depth-7 shells the ancestor one level
too high.
`sts-deep.xml` (invented setting) reproduces it: the two depth-7 shells point
at the depth-5 section on e717b1c's code and must point at the depth-6 one.
Held: the mark carries depth 7; the heading stays `######` and the extracted
headings do not move one character; the shells point at their depth-6
ancestor.
2 of 3 red on 5970369; the green one is the text guard.
Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>
