Workspace

fang init creates a workspace beside your sources; fang build fills it.

.copperhead/
  manifest.json       what produced this state
  design.jsonl        the design, as a canonical record stream
  plan.json           the tool plan
  mapping.json        the CAD mapping table, after an import
  import-report.json  what an import could not represent
  sources/            declared, hashed inputs
  evidence/           external results, before they are ingested
  simulations/        decks and raw backend output
  views/              rendered views
  cache/              reconstructible; safe to delete

Only cache/ may be deleted. Everything else is either canonical state or the record of where canonical state came from. Deleting the cache loses no engineering fact; deleting anything else does.

The manifest

{
  "schema_version": "1.1",
  "revision_id": "...",
  "compiler_version": "0.1.0",
  "snapshot": "...",
  "project_id": "PRJ-LOCAL",
  "lock_id": "unlocked",
  "entity_count": 42
}

The manifest exists so a snapshot’s producer is reconstructible. snapshot is the content hash; schema_version is the serialized-EIR version, which moves independently of the compiler version.

An artifact declaring an unimplemented major schema version is ELAB-0009. It is refused, not read on a guess.

The design stream

design.jsonl is the canonical record stream: one record per line, written in canonical form. Two properties follow from that and are what the format is for:

• Byte-identical for identical inputs, across processes with differing hash seeds. A diff between two builds shows engineering change and nothing else.
• Diffable by ordinary tools, because it is line-oriented text whose line order is deterministic.

Magnitudes are decimal strings, never binary floats. Keys sort by Unicode code point, except for the collections whose order is semantic.

Options

Every command that reads a program takes:

Option	Does
-C, --directory	The project directory. Defaults to .
--project	The project identifier. Defaults to PRJ-LOCAL
--system	Which system to build, when a file defines several

The project identifier is the namespace identifiers are derived in, so changing it changes every identifier in the design. It is not a label.

Importing CAD

An import writes two files beside the design:

• mapping.json, the mapping table, saying which kernel entity each CAD construct became
• import-report.json, the loss report

A construct the adapter cannot represent is named in the report as IMPORT-0001 rather than dropped. The import is lossy in the open, which is what makes one safe round trip possible. What survived is stated, and so is what did not.