--- title: "Create a relation" method: POST path: "/api/v2/relation" tags: ["Relation"] --- # Create a relation `POST /api/v2/relation` ## Request - Base URL: `https://www.onlyworlds.com` - URL: `https://www.onlyworlds.com/api/v2/relation` - Auth: API key in header `API-Key` and API key in header `API-Pin` ## Headers - `Idempotency-Key` string - `X-OW-Agent` string ## Request body - RelationWrite: A full relation write (POST creates; PUT creates or fully replaces, resetting omitted fields to empty). Any key that is neither a field below nor an extension field (atlas_*, shadow_*, x_*) is a 422, including the server-managed type, created_at, updated_at and change_seq. - `id` string, uuid: POST: optional client-minted id (any RFC 4122 UUID; the server mints a UUIDv7 otherwise). PUT/PATCH: ignored, the path id wins. - `name` string, nullable, required: Name of the element. null stores ''. - `description` string, nullable: Any kind of details about the element. null stores ''. - `supertype` string, nullable: The top level category to which the element belongs. null stores ''. - `subtype` string, nullable: The sub level category through which the element is further classified. null stores ''. - `image_url` string, nullable: URL to an image representing the element. null stores ''. - `background` string, nullable: History and origin of the relation. null stores ''. - `start_date` integer, nullable: Date when the relation began, defined in world TIME units. - `end_date` integer, nullable: Date when the relation ended if any, defined in world TIME units. - `intensity` integer, nullable: Significance of the relation, on a relative scale of 0 to 100. - `actor` string, uuid, nullable: Primary character defining the relation. Links a Character: an existing one in this world. - `events` string[], nullable: Events where the relation is involved or relevant. Links Event elements; replaces the whole list (null is the same as []). Every id must name an existing one in this world. - `characters` string[], nullable: Characters relevant to the relation. Links Character elements; replaces the whole list (null is the same as []). Every id must name an existing one in this world. - `objects` string[], nullable: Objects relevant to the relation. Links Object elements; replaces the whole list (null is the same as []). Every id must name an existing one in this world. - `locations` string[], nullable: Locations relevant to the relation. Links Location elements; replaces the whole list (null is the same as []). Every id must name an existing one in this world. - `species` string[], nullable: Species relevant to the relation. Links Species elements; replaces the whole list (null is the same as []). Every id must name an existing one in this world. - `creatures` string[], nullable: Creatures relevant to the relation. Links Creature elements; replaces the whole list (null is the same as []). Every id must name an existing one in this world. - `institutions` string[], nullable: Institutions relevant to the relation. Links Institution elements; replaces the whole list (null is the same as []). Every id must name an existing one in this world. - `traits` string[], nullable: Traits relevant to the relation. Links Trait elements; replaces the whole list (null is the same as []). Every id must name an existing one in this world. - `collectives` string[], nullable: Collectives relevant to the relation. Links Collective elements; replaces the whole list (null is the same as []). Every id must name an existing one in this world. - `zones` string[], nullable: Zones relevant to the relation. Links Zone elements; replaces the whole list (null is the same as []). Every id must name an existing one in this world. - `abilities` string[], nullable: Abilities relevant to the relation. Links Ability elements; replaces the whole list (null is the same as []). Every id must name an existing one in this world. - `phenomena` string[], nullable: Phenomena relevant to the relation. Links Phenomenon elements; replaces the whole list (null is the same as []). Every id must name an existing one in this world. - `languages` string[], nullable: Languages relevant to the relation. Links Language elements; replaces the whole list (null is the same as []). Every id must name an existing one in this world. - `families` string[], nullable: Families relevant to the relation. Links Family elements; replaces the whole list (null is the same as []). Every id must name an existing one in this world. - `titles` string[], nullable: Titles relevant to the relation. Links Title elements; replaces the whole list (null is the same as []). Every id must name an existing one in this world. - `constructs` string[], nullable: Concepts, contracts, or principles relevant to the relation. Links Construct elements; replaces the whole list (null is the same as []). Every id must name an existing one in this world. - `narratives` string[], nullable: Narratives relevant to the relation. Links Narrative elements; replaces the whole list (null is the same as []). Every id must name an existing one in this world. - `world` unknown - `created_by` unknown - `changed_by` unknown - `changed_via` unknown ## Response `201` Created: the full element. - Relation: A relation as the API returns it. Single links are an id or null, multi links an array of ids; extension fields appear inline. `?fields=` returns only the named keys, and `?expand=` replaces the named links' ids with ElementStub objects. - `type` 'relation', required - `id` string, uuid, required - `name` string, required: Name of the element. - `description` string, required: Any kind of details about the element. - `supertype` string, required: The top level category to which the element belongs. - `subtype` string, required: The sub level category through which the element is further classified. - `image_url` string, required: URL to an image representing the element. - `background` string, required: History and origin of the relation. - `start_date` integer, nullable, required: Date when the relation began, defined in world TIME units. - `end_date` integer, nullable, required: Date when the relation ended if any, defined in world TIME units. - `intensity` integer, nullable, required: Significance of the relation, on a relative scale of 0 to 100. - `actor` string, uuid, nullable, required: Primary character defining the relation. A Character's id. - `events` string[], required: Events where the relation is involved or relevant. Event ids. - `characters` string[], required: Characters relevant to the relation. Character ids. - `objects` string[], required: Objects relevant to the relation. Object ids. - `locations` string[], required: Locations relevant to the relation. Location ids. - `species` string[], required: Species relevant to the relation. Species ids. - `creatures` string[], required: Creatures relevant to the relation. Creature ids. - `institutions` string[], required: Institutions relevant to the relation. Institution ids. - `traits` string[], required: Traits relevant to the relation. Trait ids. - `collectives` string[], required: Collectives relevant to the relation. Collective ids. - `zones` string[], required: Zones relevant to the relation. Zone ids. - `abilities` string[], required: Abilities relevant to the relation. Ability ids. - `phenomena` string[], required: Phenomena relevant to the relation. Phenomenon ids. - `languages` string[], required: Languages relevant to the relation. Language ids. - `families` string[], required: Families relevant to the relation. Family ids. - `titles` string[], required: Titles relevant to the relation. Title ids. - `constructs` string[], required: Concepts, contracts, or principles relevant to the relation. Construct ids. - `narratives` string[], required: Narratives relevant to the relation. Narrative ids. - `created_at` string, date-time, required - `updated_at` string, date-time, required - `change_seq` integer, required: The world change sequence at this element's last write. - `created_by` string, uuid, nullable, required: The world membership that created this element, or null when the world's owner did. - `changed_by` string, uuid, nullable, required: The world membership that last changed this element, or null when the world's owner (or the server) did, or no write has touched it since doors were recorded. - `changed_via` 'seat' | 'mcp' | 'declared' | 'api' | 'v1' | 'sync' | 'server' | 'null', nullable, required: The door of the last change: `seat` (an agent seat), `mcp` (the MCP server), `declared` (the request sent an X-OW-Agent header), `api`, `v1`, `sync` (the mobile app's sync) or `server` (the server, on its own behalf). The first three mean an agent made it. Null: no write since doors were recorded. - `known_of` true: Present, and true, only on an element this reader knows of but does not see whole: a guest or player reaches it only because its own Character's sheet links to it (one step out). Such a row keeps `id`, `type`, `name`, `description`, `supertype`, `subtype`, `image_url`, `created_at`, `updated_at` and `change_seq`; every other field reads as unset (text "", numbers and single links null, multi links [], `created_by`, `changed_by` and `changed_via` null, no extension fields), its files are 404, and search matches only its name and description. Absent: the element is whole. Any other grant (it names the reader's Character, the reader knows it, it is on the roster, the reader made it) makes it whole; a hidden element is never even a stub. ## Other responses - `400`: A link names an element that does not exist in this world (code invalid_link). - `401`: Missing, invalid or revoked credential, or a wrong PIN (authentication_error; code key_revoked for a revoked key, invalid_credentials otherwise). - `403`: The credential is valid but lacks the scope: a read key on a write route (permission_error). - `409`: Conflict: an element with this id already exists (id_conflict), or an Idempotency-Key was reused with a different body (idempotency_error), or a request with this Idempotency-Key is still in flight (idempotency_in_flight; retry after the Retry-After header's seconds). - `422`: Invalid request: unknown or read-only field, bad value, unknown query parameter, over-long text, extensions over the size cap (invalid_request); `param` names the culprit. - `429`: Too many failed PIN attempts; see the Retry-After header (rate_limited). Or too many requests: over the request budget (code too_many_requests, type rate_limited): 300 requests a minute per key or account token, 60 a minute per address for a request with neither. Retry after the Retry-After header's seconds. - `503`: The server is busy: every request slot stayed full for 10 s (code server_busy, type api_error). Retry after the Retry-After header's seconds. ## Changes - **2026-10-20** `4dd5b1cd0687`: 14 warning, 1 info - added the new `character_taken` enum value to the `error/code` response property for the response status `400` - added the new `character_taken` enum value to the `error/code` response property for the response status `401` - added the new `character_taken` enum value to the `error/code` response property for the response status `403` - added the new `character_taken` enum value to the `error/code` response property for the response status `409` - …11 more [Operation history](https://skmtc.dev/onlyworlds/apis/onlyworlds-api/changes/api/v2/relation/post.md) --- [API](https://skmtc.dev/onlyworlds/apis/onlyworlds-api.md) · [All operations](https://skmtc.dev/onlyworlds/apis/onlyworlds-api/llms.txt) · [OpenAPI document](https://skmtc.dev/onlyworlds/apis/onlyworlds-api/revisions/4dd5b1cd0687?raw)