# Domains — two sides of one relation

A **domain** is an ontoref extension (ADR-012). Every domain has two sides, and
they live in different places:

| Side | Where | Owns |
|---|---|---|
| **Authority** | `code/domains/<id>/` (here) | the contract: `domain.ncl`, `commands.nu`, `repo_kinds.txt`, and either a co-located `ontology/` (e.g. `framework/`) or a `schema_cmd` that resolves schemas from an external project (e.g. `rustelo/`) |
| **Consumer** | `.domains-ontoref/<id>/` in the consuming project | the project's **bond** to the domain, plus its optional implementation spine |

The authority declares what the domain *is*; the consumer declares *this project's
relation to it*. A bond resolves against the authority (its definitions, states,
capabilities), never on the consumer edge (`glossary::bond`).

## Consumer side — `.domains-ontoref/<domain>/`

One container directory, one subfolder per bonded domain. Multi-domain membership
is just multiple subfolders — it is **not** derived from the manifest's scalar
`repo_kind` (carrier-only, decided 2026-07-17; `formalization-vs-adoption`:
cardinality is uncapped and orthogonal to whether ontoref manages the project).

```
<project>/
  .domains-ontoref/
    rustelo/
      bonds.ncl             # REQUIRED — : BondSet   (schema: code/ontology/schemas/bond.ncl)
      ontology/schemas/*.ncl   # OPTIONAL — implementation spine (federated domain schemas)
      reflection/modes/*.ncl   # OPTIONAL — runnable modes for this implementation
    web/
      bonds.ncl             # a second, dependency-axis bond (a plane)
```

### What every bonded project carries

- `bonds.ncl` — a `BondSet` (`{ domain, bonds }`), importing the `bond.ncl` schema (the carrier
  is named `bondS.ncl` precisely so `import "bond.ncl"` resolves the schema and does not
  self-recurse). Each `Bond` names an `axis`
  (`Governance` → the project is an ontoref-node in the domain's DAG /
  `Dependency` → it inhabits an ontoref-plane), a `state`
  (`None|Linked|Node|Managed`), and — by axis — a `resolution`
  (`Delegate|Override|Compose`) or a DDD `dep_kind` (+ `mutual`, `plane`).
  This is the ONLY required file: a project may bond **without** being managed by
  ontoref (no `.ontoref/` spine needed).

### What a *managed / implementing* project additionally carries

The optional implementation spine — relocated here from the deprecated flat
`.{domain}.ontoref/` marker. Its shape is domain-specific (inventoried 2026-07-17):

- an app/impl declaration (`app.ncl`) validated against the domain's `schema_cmd`
  schema (e.g. `website-htmx-rustelo`);
- federated `ontology/schemas/*.ncl` when the domain authors its schema in the
  consumer (e.g. `DD7pasos/.librosys.ontoref/ontology/schemas/`);
- `reflection/modes/*.ncl` discovered by the mode runner (e.g. `jpl/rustelo-website`).

## Detection

`domain.nu :: project-domains` recognizes membership four ways:

| kind | signal |
|---|---|
| `config_flag` | `domain_<id> = true` in `.ontoref/config.ncl` |
| `domain_origin` | `domain_origin` record in `manifest.ncl` |
| `impl_dir` | **deprecated** flat marker `.{domain}.ontoref/` |
| `bonded_dir` | `.domains-ontoref/<id>/` subfolder (the current layout) |

`impl_dir` and `bonded_dir` are detected **simultaneously** during the migration
window (0047); a project carrying both forms for the same id is de-duplicated
(the flat form wins until removed). New projects use `.domains-ontoref/<id>/` only.

## Migration

The three precedent projects still on the flat form live in **independent external
repos** and are relocated by their maintainers, not by an in-place edit from this
constellation (migration 0047 documents the consumer-run step):

- `DD7pasos/.librosys.ontoref/` → `.domains-ontoref/librosys/`
- `website-htmx-rustelo/.rustelo.ontoref/` → `.domains-ontoref/rustelo/`
- `jpl/rustelo-website/.rustelo.ontoref/` → `.domains-ontoref/rustelo/`

## References

- `code/ontology/schemas/bond.ncl` — the `Bond` / `BondSet` contract
- `.ontoref/ontology/glossary.ncl` — `bond`, `ontoref-node`, `ontoref-plane`
- `.ontoref/reflection/modules/domain.nu` — `project-domains` detection
- ADR-012 (domain extension), ADR-018/045 (level hierarchy, co-tenancy)