> ## Documentation Index > Fetch the complete documentation index at: https://docs.lerian.studio/llms.txt > Use this file to discover all available pages before exploring further. # Activate a rail for the caller's tenant > Until a rail is active for a tenant the Courier carries none of its inbound traffic: the Pix ingress resolves no tenant and the SPB drain reads nothing from the vendor. Engine sends, queries and mailbox reads pass regardless; to stop an engine's sends, disable the engine, which also stops its deliveries. Activating spb starts the drain of the vendor queue, whose read is destructive: from then on the Courier, not the engines, consumes it. The tenant is the caller's, the validated identity's in multi-tenant and local in single-tenant, and is returned as tenantId — the identifier an engine's credential path names. The first activation records the operator as registeredBy; every activation that changes the state, first or resume, records it as activatedBy and in the rail's history. Activating a suspended rail resumes it; an active one is returned unchanged and records nothing. A single-tenant Courier carries one tenant per rail: activating a rail another tenant holds active is refused 409 JDC-0117. Needs the admin grant (channels activation:write); channels write is not enough. ## OpenAPI ````yaml /pt/openapi/v3-current/jd-courier.yaml put /v1/channels/{channelId}/activation openapi: 3.1.0 info: contact: email: support@lerian.studio name: Lerian Studio Support description: >- JD Courier lets several core engines share one JD channel and one ISPB on the SPB and Pix rails. Operators use this API to register the engines, keep the ownership map that decides which engine each message belongs to, activate the rails, re-run the routing of retained messages and reconcile what the channel carried. Engines use it to resolve and claim ownership and to relay a same-bank payment to the core that owns the payee account; their SPB sends and reads go through the Courier's mirror of the vendor's SOAP surface, and their Pix calls through its JDPI transit, not through this API. license: name: Lerian Studio General License title: JD Courier API version: v1.0.0 servers: [] security: - BearerAuth: [] tags: - description: >- The engine registry: the cores that consume the JD channel through the Courier, each with its participant set name: Engines - description: 'The ownership map: which engine owns each key. Every change is audited.' name: ownership - description: >- The rails: what each declares about itself, its activation and state per tenant, and its delivery modes name: channels - description: >- The engines' side of the ownership map: resolution for the on-us gate, authoritative and never advisory, the claim of the accounts, charger documents and Pix Automático recurrences the engine holds, and the declaration of a payment leg it holds. name: ownership-query - description: >- A same-bank Pix or TED between two cores: the Courier asks the map who owns the payee account, forwards the body byte for byte to that engine's address for the rail, and relays its answer. It stores, retries and posts nothing; bodies are not modelled. name: cross-core - description: >- The durable message store: redelivery on demand, without asking the vendor again name: ledger - description: >- Count reconciliation per rail: E(m) = C(m) + T(m) + R(m), the sequence gaps it saw, and the sends whose return leg never arrived name: assurance - description: >- The SPB send journal: every send, written before it leaves, and the sends whose outcome is unknown. A by-hand close records an operator's finding and never resends. name: send-journal - description: >- Per-(tenant, channel) state an operator acts on: lifting a durable channel halt name: channel-leases - description: >- Messages the Courier holds because no engine could receive them. A routing or delivery retention leaves by itself once its cause lifts, or when an operator asks for its routing decision to be run again. name: retained paths: /v1/channels/{channelId}/activation: put: tags: - channels summary: Activate a rail for the caller's tenant description: >- Until a rail is active for a tenant the Courier carries none of its inbound traffic: the Pix ingress resolves no tenant and the SPB drain reads nothing from the vendor. Engine sends, queries and mailbox reads pass regardless; to stop an engine's sends, disable the engine, which also stops its deliveries. Activating spb starts the drain of the vendor queue, whose read is destructive: from then on the Courier, not the engines, consumes it. The tenant is the caller's, the validated identity's in multi-tenant and local in single-tenant, and is returned as tenantId — the identifier an engine's credential path names. The first activation records the operator as registeredBy; every activation that changes the state, first or resume, records it as activatedBy and in the rail's history. Activating a suspended rail resumes it; an active one is returned unchanged and records nothing. A single-tenant Courier carries one tenant per rail: activating a rail another tenant holds active is refused 409 JDC-0117. Needs the admin grant (channels activation:write); channels write is not enough. operationId: activateChannel parameters: - description: >- The rail. Closed vocabulary — a value outside it is a 404, never a new rail. in: path name: channelId required: true schema: description: >- The rail. Closed vocabulary — a value outside it is a 404, never a new rail. enum: - spb - pix type: string - description: Idempotency key; a retry with the same key replays the first answer. in: header name: X-Idempotency required: true schema: description: >- Idempotency key; a retry with the same key replays the first answer. type: string responses: '200': content: application/json: schema: $ref: '#/components/schemas/ChannelActivation' description: OK '400': content: application/problem+json: schema: $ref: '#/components/schemas/Detail' description: Bad Request '401': content: application/problem+json: schema: $ref: '#/components/schemas/Detail' description: Unauthorized '403': content: application/problem+json: schema: $ref: '#/components/schemas/Detail' description: Forbidden '404': content: application/problem+json: schema: $ref: '#/components/schemas/Detail' description: Not Found '409': content: application/problem+json: schema: $ref: '#/components/schemas/Detail' description: Conflict '422': content: application/problem+json: schema: $ref: '#/components/schemas/Detail' description: Unprocessable Entity '500': content: application/problem+json: schema: $ref: '#/components/schemas/Detail' description: Internal Server Error '503': content: application/problem+json: schema: $ref: '#/components/schemas/Detail' description: Service Unavailable components: schemas: ChannelActivation: additionalProperties: false properties: activatedAt: description: When the rail last began carrying inbound traffic. format: date-time type: string activatedBy: description: >- The operator who last activated or resumed the rail. Absent on an activation that predates the rail audit. maxLength: 128 type: string channelId: enum: - spb - pix type: string registeredAt: format: date-time type: string registeredBy: description: The operator who first activated the rail for the tenant. maxLength: 128 type: string state: description: Only an ACTIVE rail carries the tenant's inbound traffic. enum: - REGISTERED - ACTIVE - SUSPENDED type: string suspendReason: maxLength: 512 type: string suspendedAt: format: date-time type: string suspendedBy: description: >- The operator who suspended the rail. Absent when not suspended, or suspended before the rail audit. maxLength: 128 type: string tenantId: description: >- The caller's tenant: the validated identity's in multi-tenant, local in single-tenant. The identifier an engine's credential path names. maxLength: 255 type: string required: - tenantId - channelId - state - registeredAt - registeredBy type: object Detail: additionalProperties: true properties: code: description: >- Stable, machine-readable domain error code scoped to the emitting service (format: -NNNN). type: string detail: description: >- A human-readable explanation specific to this occurrence of the problem. examples: - Property foo is required but is missing. type: string errors: description: Optional list of individual error details items: $ref: '#/components/schemas/ErrorDetail' type: - array - 'null' instance: description: >- A URI reference that identifies the specific occurrence of the problem. examples: - https://example.com/error-log/abc123 format: uri type: string status: description: HTTP status code examples: - 400 format: int64 type: integer title: description: >- A short, human-readable summary of the problem type. This value should not change between occurrences of the error. examples: - Bad Request type: string type: default: about:blank description: A URI reference to human-readable documentation for the error. examples: - https://example.com/errors/example format: uri type: string upstream: $ref: '#/components/schemas/Upstream' description: >- RFC 9457 extension member: the error a proxied third-party provider reported. Absent unless the emitting service explicitly surfaced one. type: object ErrorDetail: additionalProperties: false properties: location: description: >- Where the error occurred, e.g. 'body.items[3].tags' or 'path.thing-id' type: string message: description: Error message text type: string value: description: The value at the given location type: object Upstream: additionalProperties: false properties: code: description: The upstream provider's own error code, verbatim. examples: - E4001 type: string message: description: >- The upstream provider's own error message, verbatim (bounded, never its raw response body). examples: - account not found at provider type: string type: object securitySchemes: BearerAuth: bearerFormat: JWT description: JWT bearer token issued by the identity provider. scheme: bearer type: http ```` This documentation is built and hosted on [Mintlify](https://mintlify.com), a developer documentation platform.