---
title: 'Debugging and visual annotation'
part: 'Part III — The Language'
partNumber: 3
order: 9
subtitle: 'print, assert, chalk, the scrubber, debug helpers, and warning taxonomy'
---

_Content coming soon._ The preview-only `chalk` command replaces the old `mark`-centred plan.
The chapter will cover labelled points and paths, `std.debugx` overlays, assertions, warnings,
the scrubber, and stitch/coverage diagnostics without altering exported machine events.

<Run>{`// Chalk is visible in the preview but never sewn or exported
let side = 20
print 'Drawing a square'
print side
let guide = trace [ repeat 4 [ fd side rt 90 ] ]
chalk guide 'planned boundary' 'line'
sewpath(guide)`}</Run>

<Checkpoint chapterId="ch-21">Chapter content coming soon.</Checkpoint>