> ## Documentation Index > Fetch the complete documentation index at: https://docs.gable.ai/llms.txt > Use this file to discover all available pages before exploring further. # Compose a field's cross-service chain over strand edges. > EXPERIMENTAL. Walk connected strand edges from one (component, payload, field) start state — upstream toward the fields the start field comes from (the default), or downstream toward the fields it flows to — and return every traversal branch: CONNECTED chains with their terminal group, UNMAPPED_HOP branches where a translated path nothing on the landing side exposes ends the walk visibly, and CYCLE branches where a traversal state repeats on its own path. Every involved component is evaluated at its latest scan; a traversal that would cross a composition contract limit fails as a typed error rather than returning a partial graph. ## OpenAPI ````yaml /api-reference/bundled.yaml get /v0/experimental/component/{id}/discriminator_composition openapi: 3.1.0 info: title: Gable API description: > API to interact with the Gable platform ## Authorization All API requests require an API key to be passed in the `X-API-KEY` header. For instructions on finding your API key and api endpoint check out the [API Key documentation](../docs/api-keys.md). Example: `curl -H "X-API-KEY: " https://api-{organization}.gable.ai/v0/ping` contact: name: Gable Engineering url: https://gable.ai email: engineers@gable.ai version: 1.54.0 servers: - url: https://{hostname}.gable.ai description: Gable API variables: hostname: default: demo-api description: Customer environment assigned by Gable security: - ApiKeyAuth: [] tags: - name: action - name: api-keys - name: auth - name: changelog - name: config - name: debug - name: settings - name: slack - name: sso - name: webhook - name: notifications - name: telemetry - name: component - name: components - name: sca - name: cross-service-components - name: lineage - name: events - name: measurements - name: defect-report - name: data-tagging description: Tag vocabulary management and field level tagging of lineage boundaries. paths: /v0/experimental/component/{id}/discriminator_composition: get: tags: - lineage summary: Compose a field's cross-service chain over strand edges. description: >- EXPERIMENTAL. Walk connected strand edges from one (component, payload, field) start state — upstream toward the fields the start field comes from (the default), or downstream toward the fields it flows to — and return every traversal branch: CONNECTED chains with their terminal group, UNMAPPED_HOP branches where a translated path nothing on the landing side exposes ends the walk visibly, and CYCLE branches where a traversal state repeats on its own path. Every involved component is evaluated at its latest scan; a traversal that would cross a composition contract limit fails as a typed error rather than returning a partial graph. operationId: getExperimentalComponentDiscriminatorComposition parameters: - in: path name: id required: true schema: type: string format: uuid description: UUID of the component the walk starts on. - in: query name: payloadName required: true schema: type: string description: >- The payload_name coordinate of the start payload group on the component. - in: query name: fieldPath required: true schema: type: string description: The field to trace, as a dot-separated path. - in: query name: direction required: false schema: type: string enum: - upstream - downstream default: upstream description: >- Traversal direction. Upstream walks toward the fields the start field comes from; downstream walks toward the fields it flows to. responses: '200': description: Every traversal branch from the start state. content: application/json: schema: $ref: '#/components/schemas/DiscriminatorCompositionResponse' '400': description: Bad Request (e.g. unparseable start field path) content: application/json: schema: $ref: '#/components/schemas/ErrorResponse' '404': description: Component not found content: application/json: schema: $ref: '#/components/schemas/ErrorResponse' '500': description: >- Internal Server Error (includes typed stamp-integrity, committed field-path, and composition-limit errors) content: application/json: schema: $ref: '#/components/schemas/ErrorResponse' components: schemas: DiscriminatorCompositionResponse: type: object description: >- Every branch of walking connected strand edges upstream from one (component, payload, field) start state. Branches are complete — a traversal that would cross a contract limit fails as a typed error rather than returning a partial graph. properties: branches: type: array items: $ref: '#/components/schemas/DiscriminatorCompositionBranch' required: - branches additionalProperties: false ErrorResponse: type: object required: - message properties: id: type: number title: type: string message: type: string DiscriminatorCompositionBranch: type: object description: >- One traversal branch of an upstream composition walk. `kind` selects which fields beyond `hops` are present — CONNECTED carries `terminal`, UNMAPPED_HOP carries `edgeId`/`mapping`/`translatedPath`/`inputPath`, and CYCLE carries `repeatedState`. properties: kind: type: string enum: - CONNECTED - UNMAPPED_HOP - CYCLE hops: type: array items: $ref: '#/components/schemas/DiscriminatorCompositionHop' terminal: type: object description: Where a CONNECTED branch ends. properties: componentId: type: string format: uuid payload: $ref: '#/components/schemas/DiscriminatorGroupAddress' group: anyOf: - $ref: '#/components/schemas/DiscriminatorGroupAddress' - type: 'null' description: Null when the start state itself had no upstream edges. groupId: anyOf: - type: string - type: 'null' fieldPath: type: string required: - componentId - payload - group - groupId - fieldPath additionalProperties: false edgeId: type: string format: uuid description: The edge an UNMAPPED_HOP branch failed to cross. mapping: anyOf: - $ref: '#/components/schemas/DiscriminatorEdgeFieldMapping' - type: 'null' description: >- The winning mapping whose translated path nothing upstream exposed; null when no stored mapping applied to the input path at all. translatedPath: anyOf: - type: string - type: 'null' description: Null when there was no applicable mapping to translate through. inputPath: type: string description: The field entering the unmapped hop. repeatedState: type: object description: The traversal state a CYCLE branch revisited on its own path. properties: componentId: type: string format: uuid payload: $ref: '#/components/schemas/DiscriminatorGroupAddress' fieldPath: type: string required: - componentId - payload - fieldPath additionalProperties: false required: - kind - hops additionalProperties: false DiscriminatorCompositionHop: type: object description: >- One traversed hop in an upstream composition walk: the winning stored edge mapping that translated the downstream field, and the upstream field-mapping group the translated path landed on. properties: edgeId: type: string format: uuid mapping: $ref: '#/components/schemas/DiscriminatorEdgeFieldMapping' matchKind: type: string enum: - exact - prefix inputPath: type: string description: The downstream field entering the hop, canonical form. translatedPath: type: string description: The upstream field after translation, canonical form. sourceComponentId: type: string format: uuid sourcePayload: $ref: '#/components/schemas/DiscriminatorGroupAddress' destinationComponentId: type: string format: uuid destinationPayload: $ref: '#/components/schemas/DiscriminatorGroupAddress' landedGroup: $ref: '#/components/schemas/DiscriminatorGroupAddress' landedGroupId: type: string suppressed: type: boolean description: The landed group or its payload is suppressed — context, not hiding. competingMappings: type: array description: >- Sorted competing equal-length mapping winners when translation fanned out; absent when the winner was unique. items: $ref: '#/components/schemas/DiscriminatorEdgeFieldMapping' competingGroups: type: array description: >- Sorted competing group addresses when the join fanned out; absent when exactly one group exposed the translated path. items: $ref: '#/components/schemas/DiscriminatorGroupAddress' required: - edgeId - mapping - matchKind - inputPath - translatedPath - sourceComponentId - sourcePayload - destinationComponentId - destinationPayload - landedGroup - landedGroupId - suppressed additionalProperties: false DiscriminatorGroupAddress: type: object description: The metadata coordinates for a discriminator group properties: componentId: type: string format: uuid description: The component this group lives on. Must equal the route component. level: $ref: '#/components/schemas/DiscriminatorLevel' ancestors: type: array description: >- Root-to-immediate-parent ancestor chain. Empty for a `payload`; exactly one `payload` entry for a `field_mapping`. Every ancestor carries the same component and config identity as this wrapper. items: $ref: '#/components/schemas/DiscriminatorGroupAncestor' coordinates: $ref: '#/components/schemas/DiscriminatorGroupCoordinates' required: - componentId - level - ancestors - coordinates additionalProperties: false DiscriminatorEdgeFieldMapping: type: object description: >- One cross-service field mapping carried by an edge. Paths are dot-separated field paths (e.g. `order.customer.id`); a literal dot in a field name is not supported and is rejected as FIELD_PATH_UNSUPPORTED. properties: sourceFieldPath: type: string description: Field path on the edge's source payload. destinationFieldPath: type: string description: Field path on the edge's destination payload. notes: type: string description: Optional free-text note for this mapping. dataStoreEvidence: type: array description: >- Scanner-derived evidence describing which part of a whole application value the mapped data-store field contributes to. These entries enrich this field mapping; they do not declare additional discriminator fields or nested field mappings. items: type: object additionalProperties: false properties: derivation: type: string enum: - direct - computed - aggregate - unknown projectionLabel: type: string description: SQL projection or mapper label proven for this contribution. applicationFieldPath: type: string description: >- Unambiguous path within the whole application value, when the scanner can prove one. required: - derivation required: - sourceFieldPath - destinationFieldPath additionalProperties: false DiscriminatorLevel: type: string description: >- A level in the product_canonical group hierarchy. `payload` is the root level; `field_mapping` is its child. The group_by dimensions for each level are defined by the config, not enumerated by this API (see DiscriminatorGroupCoordinates). enum: - payload - field_mapping DiscriminatorGroupAncestor: type: object description: >- One ancestor group in a canonical address chain. Ancestors are ordered root-to-immediate-parent: a `field_mapping` carries its `payload`, and a `payload` carries none. The chain's depth and each level's coordinate dimensions are the discriminator config's, not this API's — copy an ancestor's coordinates verbatim rather than rebuilding them. The service derives the parent chain from these coordinates; clients never supply an authoritative parent group ID. properties: level: $ref: '#/components/schemas/DiscriminatorLevel' coordinates: $ref: '#/components/schemas/DiscriminatorGroupCoordinates' required: - level - coordinates additionalProperties: false DiscriminatorGroupCoordinates: type: object description: >- Discriminator-group coordinates — the durable address of a group, as key-value pairs of the facts the group is grouped by. Keys are the discriminator config's group_by dimensions for the group's level, verbatim; the dimension vocabulary is defined by the config, not by this API. Values are the exact grouping facts; null is the engine's null coordinate (fact unknown). Edges and BYO metadata attach to lineage by these coordinates, never by group ID (group IDs are derived from coordinates by the discriminator engine and are only stable within one discriminator config). additionalProperties: description: >- A grouping fact. The engine's coordinate value algebra: null, boolean, integer, string, or array of strings. anyOf: - type: 'null' - type: boolean - type: integer - type: string - type: array items: type: string securitySchemes: ApiKeyAuth: type: apiKey in: header name: X-API-KEY ```` This documentation is built and hosted on [Mintlify](https://mintlify.com), a developer documentation platform.