Formats

Every artifact is JSON validated by a pydantic model with extra="forbid"; the normative description of each format is the docstring of the module that owns it, rendered in the API reference. These pages are the guided tour.

Page	Covers
Layouts, naming and pins	classic and collection trees, mamut-collection.json, file names, sha256-pinned sidecar references
Static instances	CVRP and VRPTW .vrp.json, embedded versus slim (collection) instances, arc-cost sources, metadata
Time-dependent instances	the td block and its three travel models, ATF sidecars, IGP profiles, road graphs and traffic overlays, the piecewise-linear primitive
Distances and geo sidecars	the distance matrix and the map-drawing sidecar
Solutions, BKS and optimality	solution files, BKS files, the checker statuses, optimality metadata
CVRPLIB .vrp export	the classic-format export contract shared by the CLI, the workbench and the website
Release archives	per-family zip archives and snapshot-manifest.json

Common rules, everywhere:

• Canonical JSON. Sorted keys, deterministic serialization; gzip sidecars are written with mtime=0.
• Sha256 pins hash the uncompressed canonical bytes, so .json and .json.gz forms of a sidecar share one pin.
• The checker's cost is the stored cost. Solutions carry cost: null or the checker's value; nothing else.
• Formats are tagged and versioned (format, format_version) so readers can refuse what they do not know.