Start a document builder session for a contract template version. The endpoint mints a short-lived session token your dashboard uses to launch the embedded document builder, where you configure field placements and signer roles on the template before publishing. It returns the template identifiers, the session token, and the browser host to load the builder against.

Authentication & access

• Requires a client API token: Authorization: Bearer <token>.
• The caller must hold the contracts.templates.write permission and have one of the OWNER, OPERATIONS, or DEVELOPER roles.
• The client must have contract signing enabled. If the feature is disabled the request returns 403.

Path parameters

• template_version_id (string, required) — the contract template version to open a builder session for. It must belong to your client.

Template preconditions

The template version must already be provisioned with the signing provider, and it must not be archived:

• A template that has not yet been provisioned for signing is rejected with 400.
• An ARCHIVED template is rejected with 400. Restore it to draft first if you need to edit it.

Response

Returns 200 with a ContractTemplateBuilderSessionResponse:

• template_id — the local template version ID.
• signing_template_id — the template ID in the signing provider.
• external_id — the external identifier for the template.
• token — a short-lived session token for the document builder UI.
• base_url — the browser host the embedded builder must be loaded against. Use this value as the builder host rather than the API origin.

Error responses

Standard 401 (authentication), 403 (insufficient permission or role), and 429 (rate limit) responses apply to every endpoint and are documented in the Error reference.