round-trip/ — <name>.json + <name>.md: the markdown adfToMarkdown must emit for that document, byte for byte, and that markdownToAdf must read back to it (AGENTS.md §2). Grouped by what the fixture exercises.
normalization/ — <name>.md + <name>.json: markdown input, and the document markdownToAdf must build from it, which must in turn emit and read back to itself. The markdown is not canonical.
errors/ — <name>.md: markdown input that must not convert. A <name>.error beside it pins which error.
real-payloads/ — <name>.json: sanitized live ADF, round-tripped ADF→markdown→ADF. No expected markdown.
commonmark-spec/ — spec.json (the pinned CommonMark suite, read as corpus data per AGENTS.md §1) and exceptions.json (examples a documented divergence exempts, keyed by check and example with a reason). Three checks an example must pass: the §2 canonical fixpoint — a named error, or markdown that parses and emits back to itself; the reference HTML's text, tags stripped and entities decoded, against the parsed document's concatenated text; and a count of the CommonMark subset's elements against the nodes and marks they map to.

JSON is editor-normal (AGENTS.md §2), two-space indent, keys sorted. spec.json is the vendored, upstream machine-readable suite (CommonMark 0.31.2, CC-BY-SA-4.0, © John MacFarlane) and is not re-serialized by the corpus gate.