> ## Documentation Index > Fetch the complete documentation index at: https://docs.superx.so/llms.txt > Use this file to discover all available pages before exploring further. # Generate an AI cover image > Generates a 2.5:1 cover image from the article's TITLE (a title is required) and, by default, attaches it as the article's cover. `attach: false` generates without touching the current cover; attach later via PATCH `cover_url`. `style_text` (max 8000 chars) steers the artwork. Slow (60-100 seconds) and paid: spends AI credits against daily and monthly caps, all enforced server-side. 429 responses carry `remaining_day` / `remaining_month` / `limit_day` / `limit_month` counters. Supports `Idempotency-Key`, recommended. Main account only in v1. ## OpenAPI ````yaml /api-reference/openapi.yaml post /v1/articles/{id}/cover openapi: 3.1.0 info: title: SuperX API version: 1.0.0 description: > The SuperX public API: your Twitter/X content, analytics, audience and scheduling data over REST. All endpoints require an API key (`Authorization: Bearer sxk_...`) except `GET /v1/docs`. Keys are created in the SuperX app under Account > API / MCP / CLI and are server-side secrets. Timestamps are UTC ISO-8601 in both directions; inputs must carry an explicit `Z` or numeric offset. Every authenticated response carries `X-RateLimit-Limit`, `X-RateLimit-Remaining` and `X-RateLimit-Reset` headers. contact: name: SuperX url: https://superx.so servers: - url: https://api.superx.so security: - apiKey: [] tags: - name: Identity - name: Content - name: Analytics - name: Inspiration - name: Audience - name: Contact Lists - name: Signals - name: Media - name: Scheduling - name: Tags - name: Context - name: Queue - name: Articles - name: Meta paths: /v1/articles/{id}/cover: post: tags: - Articles summary: Generate an AI cover image description: > Generates a 2.5:1 cover image from the article's TITLE (a title is required) and, by default, attaches it as the article's cover. `attach: false` generates without touching the current cover; attach later via PATCH `cover_url`. `style_text` (max 8000 chars) steers the artwork. Slow (60-100 seconds) and paid: spends AI credits against daily and monthly caps, all enforced server-side. 429 responses carry `remaining_day` / `remaining_month` / `limit_day` / `limit_month` counters. Supports `Idempotency-Key`, recommended. Main account only in v1. operationId: generateArticleCover parameters: - name: id in: path required: true schema: type: string - $ref: '#/components/parameters/IdempotencyKey' requestBody: required: false content: application/json: schema: type: object properties: style_text: type: string maxLength: 8000 description: Optional style description steering the artwork. attach: type: boolean default: true account_id: type: string example: style_text: dark, minimal, geometric responses: '200': description: The generated cover. headers: X-RateLimit-Limit: $ref: '#/components/headers/X-RateLimit-Limit' X-RateLimit-Remaining: $ref: '#/components/headers/X-RateLimit-Remaining' X-RateLimit-Reset: $ref: '#/components/headers/X-RateLimit-Reset' content: application/json: schema: type: object properties: data: type: object properties: cover: type: object properties: url: type: string attached: type: boolean description: Whether the cover was attached to the article. remaining_day: type: integer nullable: true remaining_month: type: integer nullable: true example: data: cover: url: https://media.superx.so/covers/example.jpg attached: true remaining_day: 3 remaining_month: 11 '400': $ref: '#/components/responses/InvalidParameter' '401': $ref: '#/components/responses/Unauthorized' '403': description: >- Read-only key (`insufficient_scope`), linked account (`writes_main_account_only`), cover generation disabled (`feature_disabled`), or a lapsed subscription. content: application/json: schema: oneOf: - $ref: '#/components/schemas/ErrorEnvelope' - $ref: '#/components/schemas/LegacyErrorEnvelope' example: error: code: insufficient_scope message: >- This API key is read-only. Create a key with the write scope to use this endpoint. '404': $ref: '#/components/responses/ArticleNotFound' '409': description: >- A cover is already being generated for this article (`cover_gen_in_progress`), or the Idempotency-Key was reused with a different body. content: application/json: schema: $ref: '#/components/schemas/ErrorEnvelope' example: error: code: cover_gen_in_progress message: >- A cover is already being generated for this article. Try again once it finishes. '429': description: >- Rate limited, generation caps reached (`cover_gen_cap_daily` / `cover_gen_cap_monthly` with counters), or AI credits exhausted (`ai_credits_exhausted`). content: application/json: schema: $ref: '#/components/schemas/ErrorEnvelope' example: error: code: cover_gen_cap_daily message: The daily cover generation cap has been reached. remaining_day: 0 remaining_month: 7 limit_day: 6 limit_month: 13 '502': $ref: '#/components/responses/UpstreamError' '504': description: >- AMBIGUOUS timeout. The render may still have completed. GET the article to check its cover before retrying. content: application/json: schema: $ref: '#/components/schemas/ErrorEnvelope' example: error: code: upstream_timeout message: >- Cover generation did not respond in time and may still have completed. GET the article to check its cover before retrying. components: parameters: IdempotencyKey: name: Idempotency-Key in: header required: false description: >- Unique key (max 64 characters) for safe retries. Replays carry the "Idempotency-Replayed" response header set to "true". Keys are retained for 24 hours. schema: type: string maxLength: 64 headers: X-RateLimit-Limit: description: The limit of the rate window closest to exhaustion. schema: type: integer X-RateLimit-Remaining: description: Requests remaining in that window. schema: type: integer X-RateLimit-Reset: description: Unix timestamp (seconds) when that window resets. schema: type: integer responses: InvalidParameter: description: A parameter is missing, malformed, or out of range. content: application/json: schema: $ref: '#/components/schemas/ErrorEnvelope' example: error: code: invalid_parameter message: since must be a UTC ISO-8601 timestamp Unauthorized: description: >- Missing/malformed Authorization header (`unauthorized`) or an unknown/revoked key (`invalid_api_key`). content: application/json: schema: $ref: '#/components/schemas/ErrorEnvelope' example: error: code: invalid_api_key message: Unknown or revoked API key ArticleNotFound: description: No article with that id belongs to this account. content: application/json: schema: $ref: '#/components/schemas/ErrorEnvelope' example: error: code: not_found message: No article with that id belongs to this account. UpstreamError: description: A dependent SuperX service returned an unexpected response. content: application/json: schema: $ref: '#/components/schemas/ErrorEnvelope' example: error: code: upstream_error message: Failed to fetch scheduled posts. Try again shortly. schemas: ErrorEnvelope: type: object required: - error properties: error: type: object required: - code - message properties: code: type: string description: Stable machine-readable error code. message: type: string retry_after: type: integer description: Seconds to wait before retrying (rate-limit errors only). LegacyErrorEnvelope: type: object required: - error description: | Legacy shape used ONLY by the shared subscription middleware: a plain string `error` field. Seen on `403` when the subscription has lapsed (string starts with "subscription_required:") and on `500` when subscription verification fails (string starts with "internal_error:"). properties: error: type: string example: >- subscription_required: The SuperX API requires an active subscription securitySchemes: apiKey: type: http scheme: bearer description: >- A SuperX API key ("sxk_..."), created in the SuperX app under Account > API / MCP / CLI. Keys are server-side secrets. ````