> ## Documentation Index
> Fetch the complete documentation index at: https://docs.trylath.com/llms.txt
> Use this file to discover all available pages before exploring further.

> ## Agent Instructions
> Every Lath operation is POST https://platform.trylath.com/<operation name with dots replaced by slashes>, with a JSON body and `Authorization: Bearer <key>`. `email.send` is POST /email/send.
> Branch on `error.code`, never on `error.message`. Every refusal also carries `error.fix`, which names the next step.
> Send an `Idempotency-Key` header on any operation that is not retry-safe, so a retry cannot run it twice.
> A `lath_test_` key emails only the account's own members and sends no SMS; a `lath_live_` key reaches real recipients and is billed.
> The OpenAPI document, generated from the same registry as the routes, is at https://platform.trylath.com/openapi.json.

# billing.passthrough.record

> Records a fee the carrier charged, to be passed through at cost on this environment's bill for the period. Used for carrier registration fees, which have no unit price — the amount is what was actually charged. Recording the same providerRef twice is refused rather than billed twice. This does not move money: it adds a line to the month, which is collected when the period closes.



## OpenAPI

````yaml /api-reference/openapi.json post /billing/passthrough/record
openapi: 3.1.0
info:
  title: Lath API
  version: 0.1.0
  description: >-
    Every operation is one POST. The same set is reachable over MCP, the SDK and
    the CLI; nothing is dashboard-only.
servers:
  - url: https://platform.trylath.com
    description: This deployment
security: []
paths:
  /billing/passthrough/record:
    post:
      tags:
        - billing
      summary: billing.passthrough.record
      description: >-
        Records a fee the carrier charged, to be passed through at cost on this
        environment's bill for the period. Used for carrier registration fees,
        which have no unit price — the amount is what was actually charged.
        Recording the same providerRef twice is refused rather than billed
        twice. This does not move money: it adds a line to the month, which is
        collected when the period closes.
      operationId: billing.passthrough.record
      parameters:
        - name: Idempotency-Key
          in: header
          required: false
          schema:
            type: string
          description: >-
            Replays the stored response for the same key and input; refuses
            different input.
      requestBody:
        required: true
        content:
          application/json:
            schema:
              $schema: https://json-schema.org/draft/2020-12/schema
              type: object
              properties:
                metric:
                  type: string
                  enum:
                    - sms.registration
                  description: Which pass-through line this belongs to
                description:
                  type: string
                  minLength: 1
                  maxLength: 200
                  description: What the fee was for, as it should read on the bill
                amountCents:
                  type: integer
                  minimum: 0
                  maximum: 1000000
                  description: >-
                    The amount actually charged, in cents. Zero is allowed: a
                    waived fee is still worth showing.
                providerRef:
                  description: >-
                    The carrier's own reference. Recording the same one twice is
                    refused, which is what makes a retry safe.
                  type: string
                  minLength: 1
                  maxLength: 200
                period:
                  description: >-
                    Calendar month, UTC, as YYYY-MM. Defaults to the current
                    month.
                  type: string
                  pattern: ^\d{4}-(0[1-9]|1[0-2])$
              required:
                - metric
                - description
                - amountCents
              additionalProperties: false
      responses:
        '200':
          description: '{ activityId, result }. activityId is empty for reads.'
          content:
            application/json:
              schema:
                type: object
                properties:
                  activityId:
                    type: string
                    description: The activity this call created, or empty for a read.
                  result:
                    $schema: https://json-schema.org/draft/2020-12/schema
                    type: object
                    properties:
                      recorded:
                        type: boolean
                      reason:
                        type: string
                        const: already_recorded
                      id:
                        type: string
                        format: uuid
                        pattern: >-
                          ^([0-9a-fA-F]{8}-[0-9a-fA-F]{4}-[1-8][0-9a-fA-F]{3}-[89abAB][0-9a-fA-F]{3}-[0-9a-fA-F]{12}|00000000-0000-0000-0000-000000000000|ffffffff-ffff-ffff-ffff-ffffffffffff)$
                      amountCents:
                        type: integer
                        minimum: -9007199254740991
                        maximum: 9007199254740991
                      period:
                        type: string
                    required:
                      - recorded
                      - id
                      - amountCents
                      - period
                    additionalProperties: {}
                required:
                  - activityId
                  - result
        '400':
          description: invalid_input or invalid_json
        '401':
          description: unauthenticated
        '403':
          description: forbidden
        '404':
          description: not_found
        '409':
          description: 'conflict: idempotency_mismatch, email_taken, last_key'
        '413':
          description: body_too_large
        '429':
          description: rate_limited
      security:
        - bearer: []
components:
  securitySchemes:
    bearer:
      type: http
      scheme: bearer
      description: >-
        A Lath API key: lath_live_sk… or lath_test_sk… on a server,
        lath_live_pk… or lath_test_pk… in a browser.

````