> ## Documentation Index > Fetch the complete documentation index at: https://docs.ankra.ai/llms.txt > Use this file to discover all available pages before exploring further. # Check Demo Build > Preflight a branch demo: resolve the branch's head SHA and probe the container registry for a matching image tag. GitHub or registry problems are reported inside the 200 payload's error and guidance fields, not as HTTP errors. A browser session twin is mounted at the same path without the /api/v1 prefix (cookie authentication). ## OpenAPI ````yaml https://platform.ankra.app/openapi.json get /api/v1/org/applications/{application_id}/demos/build openapi: 3.1.0 info: title: FastAPI version: 0.1.0 servers: - url: https://platform.ankra.app security: [] paths: /api/v1/org/applications/{application_id}/demos/build: get: tags: - Applications API summary: Check Demo Build description: >- Preflight a branch demo: resolve the branch's head SHA and probe the container registry for a matching image tag. GitHub or registry problems are reported inside the 200 payload's error and guidance fields, not as HTTP errors. A browser session twin is mounted at the same path without the /api/v1 prefix (cookie authentication). operationId: >- check_demo_build_api_v1_org_applications__application_id__demos_build_get parameters: - in: path name: application_id required: true schema: title: Application Id type: string - in: query name: branch required: true schema: title: Branch type: string - in: header name: authorization required: false schema: anyOf: - type: string - type: 'null' title: Authorization - in: header name: x-ankra-organisation-id required: false schema: anyOf: - type: string - type: 'null' title: X-Ankra-Organisation-Id responses: '200': content: application/json: schema: $ref: '#/components/schemas/DemoBuildCheckResponse' description: Successful Response '400': content: application/json: schema: $ref: '#/components/schemas/DemoDetailError' description: '"A ''branch'' query parameter is required."' '401': description: Unauthorized '404': content: application/json: schema: $ref: '#/components/schemas/DemoDetailError' description: Not found ("Application not found") '422': content: application/json: schema: $ref: '#/components/schemas/HTTPValidationError' description: Validation Error components: schemas: DemoBuildCheckResponse: description: >- Whether the branch has a built image and which tag a deploy would run. GitHub or registry problems ride in error and guidance rather than failing the request. properties: available_images: description: >- The available_tags entries in the same order, each with the push time that ranks it. items: $ref: '#/components/schemas/RegistryImageTag' type: array available_tags: items: type: string type: array branch: type: string candidate_tags: items: type: string type: array component: type: string components: items: $ref: '#/components/schemas/DemoComponentBuild' type: array error: anyOf: - type: string - type: 'null' guidance: anyOf: - type: string - type: 'null' head_sha: anyOf: - type: string - type: 'null' image_exists: type: boolean image_tag: anyOf: - type: string - type: 'null' image_kind: type: string description: >- Classifies what code the matched tag's image was built from: branch_head (immutable sha tag of this branch's head), merge_result (a pull_request build of the branch's open PR - the image is the branch merged into its base, not the branch head), or branch (the mutable branch tag a push build refreshes). Absent when no image matched. Mirrors the selected component's classification. image_note: type: string description: >- Human-readable caveat for a merge_result image; absent for every other kind. required: - branch - head_sha - component - image_exists - image_tag - candidate_tags - available_tags - available_images - guidance - components - error type: object DemoDetailError: description: >- The FastAPI-style detail envelope the demo routes use for 400/403/404/409/502 responses. properties: detail: type: string required: - detail type: object HTTPValidationError: properties: detail: items: $ref: '#/components/schemas/ValidationError' title: Detail type: array title: HTTPValidationError type: object RegistryImageTag: description: >- One pushed image tag with the moment its artifact landed in the registry, so a picker can rank builds that tag names alone cannot. properties: pushed_at: description: >- The artifact's registry push time (RFC 3339), or empty when the registry reported none. type: string tag: type: string required: - tag - pushed_at type: object DemoComponentBuild: description: >- One component's build verdict inside a build check. container_port is the resolved demo port (never the raw component record) and container_port_source names where it came from: component, dockerfile, manifest, analysis, or default. properties: app_subdir: type: string available_images: description: >- The available_tags entries in the same order, each with the push time that ranks it. items: $ref: '#/components/schemas/RegistryImageTag' type: array available_tags: items: type: string type: array container_port: type: integer container_port_source: type: string guidance: anyOf: - type: string - type: 'null' image_exists: type: boolean image_repository: type: string image_tag: anyOf: - type: string - type: 'null' image_kind: type: string description: >- Classifies what code the matched tag's image was built from: branch_head (immutable sha tag of this branch's head), merge_result (a pull_request build of the branch's open PR - the image is the branch merged into its base, not the branch head), or branch (the mutable branch tag a push build refreshes). Absent when no image matched. image_note: type: string description: >- Human-readable caveat for a merge_result image; absent for every other kind. name: type: string entry_default: type: boolean description: >- Whether the entry heuristic would hand this component the demo host's root path. ingress_path_default: type: string description: >- Path prefix a default launch would give this component on the demo host. required: - name - app_subdir - image_repository - container_port - container_port_source - image_exists - image_tag - available_tags - available_images - guidance type: object ValidationError: properties: loc: items: anyOf: - type: string - type: integer title: Location type: array msg: title: Message type: string type: title: Error Type type: string required: - loc - msg - type title: ValidationError type: object ````