_emit_scalar quotes a frontmatter scalar with json.dumps when it holds
punctuation that would change how the line reads back. _parse_scalar undid that
with a bare raw[1:-1]: it stripped the quotes but never decoded the escapes. So
a description containing ü was written as the escape sequence \u00fc, read
back with that escape still sitting literally in the value, and re-escaped on
the next save. The backslash run doubles every save, so a non-English skill
description degrades into backslash noise after a few edits, and the escapes are
shown verbatim in the skills list and the /skills catalog.
This is not limited to non-ASCII. Any description containing a quote takes the
same path, since the quote is itself what forces the quoted form.
Make the two halves symmetric: emit with ensure_ascii=False, since SKILL.md is
UTF-8 at both ends (skills.py reads it, atomic_write_text writes it) and the
ASCII-escaped form bought nothing; and parse double-quoted scalars with
json.loads, falling back to the previous literal reading when the value is not
valid JSON. Files already corrupted heal one level per load.
ensure_ascii=False on its own would open a smaller hole. json.dumps escapes
every C0 control character but passes NEL, LINE SEPARATOR and PARAGRAPH
SEPARATOR through literally, and parse_frontmatter reads one scalar per line via
str.splitlines(), which breaks on all three. Re-escape those three, and add them
plus the remaining splitlines characters to the set that forces a quoted scalar,
so none of them can reach the file bare.
Co-authored-by: Alexandre Teixeira <111787685+alteixeira20@users.noreply.github.com>
