The custom kind

Sometimes a real system contains a box the catalogue does not name. An importer meets it, or you are drawing something the vocabulary has not caught up with yet. Refusing to record it would make the design a lie by omission, so Zeema ships an escape hatch.

What it is

The custom kind is the only member of the custom category, and it defines no properties at all.

1schemaVersion: "1"
2type: "kind"
3id: "custom"
4category: "custom"
5properties: {}

A custom node is still a node. It has an id, it takes edges, it sits in a group, it is drawn, and it appears in the diff. What it does not have is anything a rule can read.

1nodes:
2  - id: "quota-broker"
3    component: "custom"
4    label: "Quota broker"
5    group: "core"

The label is the whole point. It is the real name from the real system, kept verbatim, and it is what turns a hole in the model into evidence.

Why it warns

Two rules fire on custom nodes, and neither of them is a style opinion.

custom-node is written as prop: "anyProperty", exists: false. Since the kind defines no properties, nothing ever resolves on one of these nodes, so that predicate is how the fixed predicate vocabulary spells "always". The message says what is actually wrong:

Node 'quota-broker' is custom: no rule can judge it. Replace it with a catalogue component or contribute one.

A custom node is meant to be temporary. Warning on every one of them is what makes staying temporary the path of least resistance.

The labels are the intake queue

This is the part that makes the escape hatch a feature rather than a leak.

Every custom node carries a real label from a real design. A word that keeps appearing in custom nodes across published designs is a kind or a component asking to exist, and the designs that used it are exactly the evidence a governance pull request has to cite.

So the flow is:

1. An import meets a box with no component. It becomes a custom node with the source label.
2. The rules warn, and keep warning, so it stays visible.
3. When the same label has appeared enough times, someone proposes the kind or the component, citing those designs.
4. The designs are updated to use it, and the warnings go away on their own.

Nothing in that loop requires a registry, a plugin mechanism or a private extension. The stated path for a missing component is a pull request, and the custom kind is what keeps the design honest in the meantime.