> ## Documentation Index > Fetch the complete documentation index at: https://docs.niadra.com/llms.txt > Use this file to discover all available pages before exploring further. # Who saw a fact > Every delivery in which a fact appeared, with the source and the time. ## OpenAPI ````yaml openapi/en/cell.json GET /v1/lineage/fact/{fact_id} openapi: 3.1.0 info: title: Niadra data API version: '1' description: >- Writing, context, history, objects, identity, privacy and governance of one space. Every space has a stable address, with the space and the region in its name. servers: - url: https://{space}.{region}.api.niadra.com variables: space: default: acme-prod description: The space, which comes in the source key. region: default: us-east-1 description: The region of the space, which also comes in the key. security: [] paths: /v1/lineage/fact/{fact_id}: get: tags: - governance summary: Who saw a fact description: >- Answers "who saw this fact?": every receipt in which the fact was delivered, with the source, the audience and the time of each read. **Authentication.** Console person token with the `security` role (or admin), or a source key with the `admin` scope. operationId: fact_viewers_v1_lineage_fact__fact_id__get parameters: - in: path name: fact_id required: true schema: format: uuid title: Fact Id type: string example: 0192f7a2-5d10-7a8e-b1c4-3f6e8d9a0b12 - description: Origin handle id. in: query name: handle required: false schema: anyOf: - format: uuid type: string - type: 'null' description: Origin handle id. title: Handle responses: '200': content: application/json: schema: $ref: '#/components/schemas/FactViewers' example: fact_id: 0192f7a2-5d10-7a8e-b1c4-3f6e8d9a0b12 receipts: - receipt_id: 0192f7a4-0e21-7f9b-a2d5-4a7f9e0b1c23 kind: history surface: search audience: customer_agent day: '2026-09-22' read_at: '2026-09-22T17:07:09Z' source_id: 0192f79e-11aa-7b20-9f3e-6c1d2e4f5a60 profile_id: 0192f7a0-3b2e-7d41-8c5a-2e9f4b7a1c03 conversation_id: call-4471 purpose: customer_service verification: V1 policy_version: pol-14 item_ids: - 0192f7a3-7c32-7b0c-9e16-5b8a0f1c2d34 - 0192f7a2-5d10-7a8e-b1c4-3f6e8d9a0b12 withheld: 1 slice: 3 seq: 88214 prev_hash: sha256:0d9f3a61c2 hash: sha256:7e21c8a4b9 description: The receipts that delivered the fact. '422': content: application/problem+json: schema: $ref: '#/components/schemas/Problem' description: The request does not match the contract. security: - sourceKey: [] - personToken: [] components: schemas: FactViewers: additionalProperties: false description: 'Answers "who saw fact F?": every receipt that delivered it.' properties: fact_id: title: Fact Id type: string receipts: items: $ref: '#/components/schemas/ReceiptOut' title: Receipts type: array required: - fact_id - receipts title: FactViewers type: object Problem: additionalProperties: false description: RFC 9457 problem details; `code` comes from the versioned error catalog. properties: code: title: Code type: string detail: anyOf: - type: string - type: 'null' default: null title: Detail request_id: anyOf: - type: string - type: 'null' default: null title: Request Id status: title: Status type: integer title: title: Title type: string type: default: about:blank title: Type type: string required: - title - status - code title: Problem type: object ReceiptOut: additionalProperties: false properties: about_handle_id: anyOf: - type: string - type: 'null' title: About Handle Id audience: $ref: '#/components/schemas/Audience' conversation_id: anyOf: - type: string - type: 'null' title: Conversation Id day: format: date title: Day type: string experiment_group: anyOf: - type: string - type: 'null' title: Experiment Group hash: description: >- Hex SHA-256 over the previous hash and this receipt's canonical encoding. title: Hash type: string item_ids: items: type: string title: Item Ids type: array kind: $ref: '#/components/schemas/ReceiptKind' manifest_hash: anyOf: - type: string - type: 'null' title: Manifest Hash object_id: anyOf: - type: string - type: 'null' title: Object Id pack_hash: anyOf: - type: string - type: 'null' title: Pack Hash person_id: anyOf: - type: string - type: 'null' title: Person Id policy_version: anyOf: - type: string - type: 'null' title: Policy Version prev_hash: description: Hex SHA-256 of the previous link of this chain. title: Prev Hash type: string profile_id: anyOf: - type: string - type: 'null' title: Profile Id purpose: anyOf: - type: string - type: 'null' title: Purpose read_at: format: date-time title: Read At type: string receipt_id: title: Receipt Id type: string seq: title: Seq type: integer slice: title: Slice type: integer source_id: anyOf: - type: string - type: 'null' title: Source Id surface: $ref: '#/components/schemas/ReceiptSurface' task_id: anyOf: - type: string - type: 'null' title: Task Id verification: anyOf: - type: string - type: 'null' title: Verification withheld: default: 0 title: Withheld type: integer required: - receipt_id - kind - surface - audience - read_at - slice - day - seq - prev_hash - hash title: ReceiptOut type: object Audience: enum: - customer_agent - internal_agent - human - reviewer - analyst - trigger_target - export title: Audience type: string ReceiptKind: enum: - read - history - analytics - admin - holdout title: ReceiptKind type: string ReceiptSurface: enum: - pack - live - delta - search - timeline - open - object - console title: ReceiptSurface type: string securitySchemes: sourceKey: type: http scheme: bearer description: nia_sk_... personToken: type: http scheme: bearer bearerFormat: JWT ````