cadmpeg-ir

The provenance-rich intermediate representation (IR) and codec contract at the heart of the cadmpeg CAD transcoder.

What the IR is

A decoded CAD document is a [CadIr]: units, tolerances, and an exact B-rep stored as flat, id-referenced arenas following the ACIS/ASM topology hierarchy body → region → shell → face → loop → coedge → edge → vertex, with geometry attached by reference (surfaces, curves, pcurves, points). In v1, entity provenance and exactness are stored in the sparse document-wide [Annotations] tables, keyed by globally unique entity id. Records the decoder recognized but could not interpret are preserved as [UnknownRecord]s rather than dropped.

What is deliberately reserved

Feature history is represented as ordered, source-provenanced operations. Assembly structure remains reserved. See docs/cad-ir.md.

The codec contract

Format plugins implement [Codec]: [Codec::detect], [Codec::inspect] (container enumeration), and [Codec::decode] (into a [DecodeResult] with an honest [DecodeReport]). [validate] checks a document with in-IR arithmetic only.