# A write over a damaged `.marks.json` wiped the booth

_2026-09-21 · booth_

**A write over a damaged `.marks.json` was wiping every mark in
the booth.** Shipped in `v0.2.0`, found by the panel (Kimi, converged with
Hulda), fixed in `v0.2.1`. `marks_for` is deliberately lenient — unparseable
reads as `[]` so a review page still loads — and the write path inherited that
leniency through the same reader, so one flag click appended to an empty list and
atomically replaced the file. The fix is an **asymmetry**, which is the reusable
part: reads stay lenient, writes go strict (`MarksCorrupt`), damaged bytes stay
on disk, routes answer 409 not 500. A page that renders without an annotation is
recoverable; a file that overwrote the operator's judgment is not. Kimi also
named the class correctly — "an author steeped in the design conversation would
likely read past" it — and that was accurate.