The files codegraph writes that are not the interchange model. Each is a derived model: a second model built from the first, self-describing, deterministic, and never mistakable for a model.jsonl — the kind field says what it is.

Artifact	Written by	kind / artifact	Shape
city.json	city, replay, history --city	codegraph.city/1	one JSON document
navigator.json	navigator	codegraph.navigator/1	one JSON document
history.jsonl	scm	"artifact": "history"	JSONL, section-ordered
domain-facts.json	domain-facts	codegraph.domainFacts/1	one JSON document
<model>.insights.jsonl	explain	codegraph.insights/1	JSONL, header/records/trailer

Two more files are not artifacts in this sense: model.jsonl is the interchange contract, and model.db is a derived, disposable cache.

What every artifact carries

• Its own kind. A consumer can refuse a file that is not what it expected.
• Its view. A city, a navigator model or a set of dossiers computed under --internal-only or --declared-only states that view in the artifact, because a coupling number without its view is not a fact. The ViewDescriptor is {name, filters}.
• Its corpus. A display name and the model roots the artifact was built from, verbatim.
• Its diagnostics. Whatever the transform dropped, could not place, or could not measure — counted, and named where naming is affordable.

Determinism

Two runs over one unchanged model produce byte-identical artifacts. Arrays are sorted (never Sets, which do not survive JSON.stringify), dimensions are rounded to a fixed number of decimals, and no artifact body carries a timestamp. The one exception is stated where it applies: the insights.jsonl trailer carries generatedAt, and nothing else in that file does.