> ## 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/, with a JSON body and `Authorization: Bearer `. `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. # audience.preferences.set > Public, for the hosted preferences page and one-click unsubscribe: given the token from a message's link, subscribes or unsubscribes the contact per topic on either channel, or unsubscribes from all marketing on one. Every change is an appended consent record naming the preference page as its source. Subscribing here is the only thing that lifts a bounce or complaint suppression, because the token proves the person holds the address. ## OpenAPI ````yaml /api-reference/openapi.json post /audience/preferences/set 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: /audience/preferences/set: post: tags: - audience summary: audience.preferences.set description: >- Public, for the hosted preferences page and one-click unsubscribe: given the token from a message's link, subscribes or unsubscribes the contact per topic on either channel, or unsubscribes from all marketing on one. Every change is an appended consent record naming the preference page as its source. Subscribing here is the only thing that lifts a bounce or complaint suppression, because the token proves the person holds the address. operationId: audience.preferences.set 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: $schema: https://json-schema.org/draft/2020-12/schema type: object properties: token: type: string pattern: ^lath_pt_[0-9A-Za-z]{43}$ description: The token from an unsubscribe or preferences link email: type: object properties: topics: description: topic key → subscribed type: object propertyNames: type: string minLength: 1 maxLength: 64 additionalProperties: type: boolean unsubscribeAll: description: >- true: revoke every topic on this channel and suppress the address for marketing; a later explicit subscribe lifts it type: boolean additionalProperties: false sms: type: object properties: topics: description: topic key → subscribed type: object propertyNames: type: string minLength: 1 maxLength: 64 additionalProperties: type: boolean unsubscribeAll: description: >- true: revoke every topic on this channel and suppress the address for marketing; a later explicit subscribe lifts it type: boolean additionalProperties: false required: - token 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: $schema: https://json-schema.org/draft/2020-12/schema type: object properties: activityId: type: string format: uuid pattern: >- ^([0-9a-fA-F]{8}-[0-9a-fA-F]{4}-[1-8][0-9a-fA-F]{3}-[89abAB][0-9a-fA-F]{3}-[0-9a-fA-F]{12}|00000000-0000-0000-0000-000000000000|ffffffff-ffff-ffff-ffff-ffffffffffff)$ environmentId: 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)$ projectName: type: string email: type: - string - 'null' phone: type: - string - 'null' channels: type: object properties: email: type: object properties: topics: type: array items: type: object properties: key: type: string name: type: string description: type: - string - 'null' subscribed: type: boolean required: - key - name - description - subscribed additionalProperties: {} unsubscribedAll: type: boolean suppressionReason: type: - string - 'null' required: - topics - unsubscribedAll - suppressionReason additionalProperties: {} sms: type: object properties: topics: type: array items: type: object properties: key: type: string name: type: string description: type: - string - 'null' subscribed: type: boolean required: - key - name - description - subscribed additionalProperties: {} unsubscribedAll: type: boolean suppressionReason: type: - string - 'null' required: - topics - unsubscribedAll - suppressionReason additionalProperties: {} required: - email - sms additionalProperties: {} required: - activityId - environmentId - projectName - email - phone - channels 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: [] ````