> ## Documentation Index > Fetch the complete documentation index at: https://docs.semicola.com/llms.txt > Use this file to discover all available pages before exploring further. # Start a creative session (saves the brief and generates drafts with your key) ## OpenAPI ````yaml /openapi/buyer.yaml post /api/v2/buyer/campaigns/{id}/creative-sessions openapi: 3.1.0 info: title: Semicola Exchange buyer API version: 2.0.0 description: >- Buyer endpoints: advertisers, storefronts and connections, product discovery, campaigns, proposals, media buys, creatives and reporting. Every write accepts an Idempotency-Key header. servers: - url: https://api.semicola.com security: - bearerAuth: [] - sessionCookie: [] tags: - name: Advertisers - name: Storefronts - name: Product Discovery - name: Campaigns - name: Media Buys - name: Update Proposals - name: Optimization Suggestions - name: Creatives - name: Catalogs - name: Property Lists - name: Audiences - name: Syndication - name: Reporting - name: Event Sources - name: Webhooks - name: Tasks - name: Audit Logs - name: Activity paths: /api/v2/buyer/campaigns/{id}/creative-sessions: post: tags: - Creatives summary: >- Start a creative session (saves the brief and generates drafts with your key) operationId: postBuyerCampaignsByIdCreativeSessions parameters: - name: id in: path required: true schema: type: string minLength: 1 requestBody: required: true content: application/json: schema: type: object properties: prompt: type: string minLength: 1 maxLength: 5000 title: type: string maxLength: 200 objective: type: string maxLength: 500 persona: type: string maxLength: 500 engine: type: object properties: engineId: type: string pattern: ^[1-9]\d{0,18}$ connectionId: type: string minLength: 1 required: - engineId - connectionId additionalProperties: false provider_type: type: string enum: - openai - gemini - fal format_kind: type: string enum: - image - audio_hosted - video_hosted params: default: {} type: object properties: width: type: integer exclusiveMinimum: 0 maximum: 4096 height: type: integer exclusiveMinimum: 0 maximum: 4096 duration_ms_exact: type: integer exclusiveMinimum: 0 maximum: 600000 additionalProperties: false reference_asset_ids: maxItems: 10 type: array items: type: string minLength: 1 variant_count: type: integer minimum: 1 maximum: 4 action_key: type: string minLength: 8 maxLength: 128 required: - prompt - format_kind responses: '200': description: OK content: application/json: schema: type: object properties: data: anyOf: - type: object properties: session: type: object properties: creative_session_id: type: string campaign_id: type: string engine: type: object properties: engineId: type: string connectionId: type: string required: - engineId - connectionId additionalProperties: false title: type: string persona: type: string objective: type: string prompt: type: string accumulated_feedback: type: array items: type: string status: type: string enum: - drafting - refining - evaluating - finalized revision: type: integer minimum: -9007199254740991 maximum: 9007199254740991 session_generation: type: integer minimum: -9007199254740991 maximum: 9007199254740991 creative_plan: type: object properties: provider_type: type: string modality: type: string enum: - image - video - audio format_kind: type: string enum: - image - audio_hosted - video_hosted params: type: object propertyNames: type: string additionalProperties: type: number required: - modality - format_kind - params additionalProperties: false flow: type: array items: type: object properties: label: type: string state: type: string enum: - done - current - pending summary: type: string required: - label - state - summary additionalProperties: false variants: type: array items: type: object properties: build_variant_id: type: string parent_build_variant_id: type: string name: type: string direction: type: string rationale: type: string quality: type: string enum: - draft - production status: type: string enum: - draft - selected - refined - finalized recommended: type: boolean preview: type: object properties: type: type: string enum: - image - video - audio url: type: string required: - type - url additionalProperties: false score: type: number evaluation: type: array items: type: object properties: evaluator_id: type: string evaluator_version: type: string category: type: string enum: - readiness - asset - brand_brief - format_seller - policy_safety - performance code: type: string label: type: string stage: type: string enum: - draft - final status: type: string enum: - pass - warn - fail detail: type: string severity: type: string enum: - hard - soft blocking: type: boolean required: - evaluator_id - evaluator_version - category - code - label - stage - status - detail - severity - blocking additionalProperties: false required: - build_variant_id - name - direction - rationale - quality - status - preview additionalProperties: false selected_variant_id: type: string refined_variant_id: type: string approval: type: object properties: variant_id: type: string session_revision: type: integer minimum: -9007199254740991 maximum: 9007199254740991 output_hash: type: string required: - variant_id - session_revision - output_hash additionalProperties: false format_renders: type: array items: type: object properties: format_id: type: string required: - format_id additionalProperties: false notices: type: array items: type: object properties: code: type: string const: variant_count_mismatch severity: type: string enum: - info - warn message: type: string required: - code - severity - message additionalProperties: false finalization: type: object properties: creative_id: type: string manifest_id: type: string sync_status: type: string summary: type: string required: - creative_id - manifest_id - sync_status - summary additionalProperties: false truncated: type: boolean omitted: type: array items: type: string required: - creative_session_id - campaign_id - title - persona - objective - prompt - accumulated_feedback - status - revision - session_generation - creative_plan - flow - variants - format_renders - notices additionalProperties: false revision: type: integer minimum: -9007199254740991 maximum: 9007199254740991 sessionGeneration: type: integer minimum: -9007199254740991 maximum: 9007199254740991 actionId: type: string status: type: string enum: - submitted - completed - partial - failed - uncertain leaves: type: array items: type: object properties: leafId: type: string status: type: string enum: - submitted - completed - failed - uncertain taskId: type: - string - 'null' variantIds: type: array items: type: string error: type: string required: - leafId - status - taskId - variantIds additionalProperties: false funding: type: object properties: fundedBy: type: string const: buyer provider: type: string keySource: type: string enum: - engine_connection - model_credential connectionId: type: - string - 'null' credentialId: type: - string - 'null' required: - fundedBy - provider - keySource - connectionId - credentialId additionalProperties: false sessionTruncated: type: boolean sessionOmitted: type: array items: type: string required: - session - revision - sessionGeneration - actionId - status - leaves - funding additionalProperties: false - type: 'null' error: anyOf: - type: object properties: code: type: string message: type: string field: type: string details: {} required: - code - message additionalProperties: false - type: 'null' required: - data - error additionalProperties: false default: description: >- Error envelope `{data: null, error: {code, message, field?, details?}}`. components: securitySchemes: bearerAuth: type: http scheme: bearer description: API key or OAuth access token. sessionCookie: type: apiKey in: cookie name: sc_session ````