# D&D Spell-Catalog Overlays

This document defines the optional JSON overlay consumed by the D&D spell
extractor. An overlay contributes campaign spell names and aliases for
recognition. It does not define spell rules, effects, levels, classes, or
transcript evidence. Bind the optional `spell_catalog` reference as described
in [Configuration](../config.md#references-and-ordered-handoffs).

## Contract Identity

| Property | Value |
| --- | --- |
| Consumer | D&D spell extraction and normalization |
| Reference slot | `spell_catalog` |
| Media type | `application/json` |
| Required schema version | `notarius.dnd.spell-catalog-overlay.v1` |
| Base catalog | Embedded D&D 5e 2014 SRD catalog |

At most one overlay document may be bound. The maintained example is
[dnd-spell-catalog.json](../../examples/dnd-spell-catalog.json).

## Wire Shape

This is a minimal valid overlay:

```json
{
  "schema_version": "notarius.dnd.spell-catalog-overlay.v1",
  "catalogs": [
    {
      "id": "campaign.example",
      "ruleset": "dnd-5e-2014",
      "source": {"title": "Example campaign spells"},
      "spells": [{"name": "Aegis of Emberfall"}]
    }
  ]
}
```

| Field | Required | Meaning and constraints |
| --- | --- | --- |
| `schema_version` | Yes | Exactly `notarius.dnd.spell-catalog-overlay.v1`. |
| `catalogs` | Yes | Non-empty array of catalog objects with unique IDs. |
| `catalogs[].id` | Yes | Non-empty trimmed string. |
| `catalogs[].ruleset` | Yes | Exactly `dnd-5e-2014`. |
| `catalogs[].source.title` | Yes | Non-empty trimmed string. |
| `catalogs[].source.version` | No | String when present. |
| `catalogs[].source.url` | No | String when present. |
| `catalogs[].source.license` | No | String when present. |
| `catalogs[].spells` | Yes | Non-empty array of spell objects. |
| `catalogs[].spells[].name` | Yes | Non-empty trimmed string. |
| `catalogs[].spells[].aliases` | No | Array of non-empty trimmed strings when present. |

Unknown fields are rejected at every object level. The document must contain
one JSON value; `null` is not accepted for optional strings or aliases.

## Composition And Compatibility

Notarius starts with the embedded base catalog, then applies overlay catalogs
in ascending catalog-ID order. A new canonical spell name adds a recognition
entry. If an overlay names an existing canonical spell, it augments that spell
with aliases while retaining the established display spelling.

Repeated aliases for the same spell are accepted. A canonical-name, canonical-
to-alias, or alias-to-alias collision between different spells is rejected,
including a collision with the embedded catalog. Matching uses the catalog’s
case, whitespace, and apostrophe normalization, so authors should avoid names
or aliases that normalize to another spell.

The overlay is a recognition aid only. The durable spell-artifact schema and
source-evidence rules are defined by the
[D&D spell artifact contract](dnd-spell-artifacts.md).