The bar for shipping PureXML in an IDE: correctness total and characterized,
false positives at zero, not "passes the suite." Four stoppers (reject no valid
input; accept no faulty input; characterize correctness via differential + fuzz,
no silent under-rejection debt; interactive safety: bounded resources, located
recoverable errors) plus a per-iteration checklist and definition of done.
Wired into the per-iteration protocol (schema-validity-burndown.md) and the
session Read First list (CLAUDE.md) so it is read every iteration.