improvise-dy3j (P1). CategoryKind::Label had no spelling in `.improv` at
all: format_md wrote every category as a bare `## Category: Name` and
build_category read every section back through add_category. The kind was
dropped on the way out AND on the way in, so a round-trip equality test
could not see it.
A label is outside MAX_CATEGORIES = 12 by design and the import wizard
scores it as zero, so twelve categories plus a label is legally
constructible. On load every label came back Regular, the thirteenth was
refused, and parse_md failed: any such document was permanently
unloadable. Below the limit the loss was quieter — a label silently
became a pivot category.
Grammar first. The ticket proposed `## Category: Note [label]`, and
improvise-pczv forbids it: a section header takes its name as the WHOLE
line, so the suffix is indistinguishable from a category named
`Note [label]`. The kind is therefore an entry inside the section,
`kind: label`, spelled with a real token rather than a lookahead — the
grammar-walking generator skips predicates. Absence means `regular`, so
every existing file parses unchanged and a pivot category's section is
byte-identical to before.
Tests assert the parsed Category::kind, never the emitted line. Both
rival faults were injected against the fixed tree and both fail two
tests: a writer that omits the line, and a reader that discards the kind
it parsed (whose file text is correct, so any text-comparing test passes
it). Reasoning in context/code/formula-and-io.md; evidence in
context/test-evidence/formula-and-io.md.
Co-Authored-By: Claude Opus 5 (1M context) <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01FC2jVn8Au7E9JPkw6bwXXH
Edward Langley
d9f732c529