> ## Documentation Index > Fetch the complete documentation index at: https://docs.beliefsystems.xyz/llms.txt > Use this file to discover all available pages before exploring further. # List reconstitutions > Completed composition changes for an index, newest first: when each one took effect and how many markets it added. Reconstitution is how a perpetual index keeps measuring its stated theme as underlying markets resolve and new ones list. Levels are chain-linked across the change, so the series stays continuous. Which markets entered or left is composition detail, published in the free snapshot bundles rather than here. ## OpenAPI ````yaml /api-reference/openapi.json get /v1/indices/{ticker}/reconstitutions openapi: 3.1.0 info: contact: name: Belief Systems url: https://beliefsystems.xyz/data description: >- Rules-based benchmark data for prediction markets: Belief index levels and Belief Volatility series, read over HTTPS with an API key. The API is read-only. Every endpoint is a `GET`, every successful response is `{ data, meta }`, and every failure is a single `error` object with a stable `code`. Keys are free and take about a minute to mint at https://beliefsystems.xyz/data. Attribution is required on anything you publish from this data: "Source: Belief Systems (beliefsystems.xyz)". Production, redistribution, and commercial use require a license (https://beliefsystems.xyz/license). license: name: Belief Systems Data License url: https://beliefsystems.xyz/license termsOfService: https://beliefsystems.xyz/terms title: Belief Systems Data API version: '1.0' servers: - description: Production. There is no separate test host; the API is read-only. url: https://api.beliefsystems.xyz security: - bearerAuth: [] - apiKeyAuth: [] tags: - description: >- Belief indices are rules-based benchmarks of how prediction markets price a defined set of events. Levels are exact decimal strings based at 100 on the index's inception date. name: Indices - description: >- Belief Volatility measures how much prediction-market probabilities are expected to move over a stated horizon, in probability points. Always name the tenor when quoting a value. name: Belief Volatility - description: >- The service index, which reports your key's live quota, and pointers to the free point-in-time snapshot bundles. name: Service paths: /v1/indices/{ticker}/reconstitutions: get: tags: - Indices summary: List reconstitutions description: >- Completed composition changes for an index, newest first: when each one took effect and how many markets it added. Reconstitution is how a perpetual index keeps measuring its stated theme as underlying markets resolve and new ones list. Levels are chain-linked across the change, so the series stays continuous. Which markets entered or left is composition detail, published in the free snapshot bundles rather than here. operationId: listIndexReconstitutions parameters: - description: >- Ticker, case-insensitive. `GET /v1/indices` and `GET /v1/volatility` are the catalogs. example: CONFLICT in: path name: ticker required: true schema: type: string - description: Maximum events to return, newest first. 1 to 50. example: 10 in: query name: limit required: false schema: default: 10 maximum: 50 minimum: 1 type: integer responses: '200': content: application/json: example: data: count: 2 events: - addedMarketCount: 6 completedAt: '2026-07-01T13:20:56.453458Z' eventId: 396ea69c-e747-478c-a1e9-117efce624d4 - addedMarketCount: 2 completedAt: '2026-05-23T17:04:28.471161Z' eventId: 1152fa89-3ca8-4509-a7e6-038ecaf60f21 ticker: CONFLICT meta: attribution: 'Source: Belief Systems (beliefsystems.xyz)' generatedAt: '2026-08-31T14:01:22.277647Z' license: https://beliefsystems.xyz/license termsUrl: https://beliefsystems.xyz/terms schema: $ref: '#/components/schemas/ReconstitutionListResponse' description: Success. '401': content: application/json: example: error: code: invalid_api_key docsUrl: >- https://docs.beliefsystems.xyz/api-reference/limits#invalid-api-key message: >- This endpoint requires a Data API key. Create one free at https://beliefsystems.xyz/data ; programmatic or commercial licensing is at https://beliefsystems.xyz/license. requestId: 9f2c1ad4e6b74c0f8a3d5e1b7c904a26 schema: $ref: '#/components/schemas/Error' description: Missing or unresolvable API key. '404': content: application/json: example: error: code: not_found docsUrl: >- https://docs.beliefsystems.xyz/api-reference/limits#not-found message: >- No Belief index 'NOPE'. GET /v1/indices lists the published catalog. requestId: 9f2c1ad4e6b74c0f8a3d5e1b7c904a26 schema: $ref: '#/components/schemas/Error' description: No index or volatility series matches that ticker on this surface. '422': content: application/json: example: error: code: invalid_interval docsUrl: >- https://docs.beliefsystems.xyz/api-reference/limits#invalid-interval message: >- interval must be '1h' or '1d'. Full granularity is part of the licensed feed. requestId: 9f2c1ad4e6b74c0f8a3d5e1b7c904a26 schema: $ref: '#/components/schemas/Error' description: A parameter failed validation. '429': content: application/json: example: error: code: rate_limited docsUrl: >- https://docs.beliefsystems.xyz/api-reference/limits#rate-limited message: 'Rate limit exceeded: 60 requests per minute per key.' requestId: 9f2c1ad4e6b74c0f8a3d5e1b7c904a26 schema: $ref: '#/components/schemas/Error' description: >- Rate limited. Sleep for `Retry-After` seconds, which is exact on both windows. default: content: application/json: schema: $ref: '#/components/schemas/Error' description: Error. Every /v1 failure uses this shape. x-codeSamples: - label: curl lang: curl source: >- curl -s "https://api.beliefsystems.xyz/v1/indices/CONFLICT/reconstitutions?limit=10" \ -H "Authorization: Bearer $BELIEF_API_KEY" - label: Python lang: python source: |- import os import requests resp = requests.get( "https://api.beliefsystems.xyz/v1/indices/CONFLICT/reconstitutions?limit=10", headers={"Authorization": f"Bearer {os.environ['BELIEF_API_KEY']}"}, timeout=10, ) resp.raise_for_status() payload = resp.json() print(payload["data"]) - label: JavaScript lang: javascript source: >- const res = await fetch("https://api.beliefsystems.xyz/v1/indices/CONFLICT/reconstitutions?limit=10", { headers: { Authorization: `Bearer ${process.env.BELIEF_API_KEY}` }, }); if (!res.ok) throw new Error(`Belief Systems API ${res.status}`); const { data, meta } = await res.json(); console.log(data); components: schemas: ReconstitutionListResponse: properties: data: properties: count: type: integer events: description: Newest first. items: properties: addedMarketCount: description: >- How many markets this reconstitution added. Which markets entered or left is published in the free snapshot bundles. type: integer completedAt: description: When the composition change took effect. format: date-time type: string eventId: description: Stable identifier for this reconstitution. type: string type: object type: array ticker: example: CONFLICT type: string type: object meta: properties: attribution: description: >- The attribution line required on anything you publish from this data. Reproduce it verbatim. example: 'Source: Belief Systems (beliefsystems.xyz)' type: string generatedAt: description: >- When this response was generated. UTC timestamp with microsecond precision, `Z`-suffixed. format: date-time type: string license: description: Terms covering production, redistribution, and commercial use. format: uri type: string termsUrl: description: Terms of Service. format: uri type: string required: - attribution - license - termsUrl - generatedAt type: object required: - data - meta type: object Error: description: >- Every failure replaces `data` and `meta` with a single `error` object. Match on `code`, which is a stable contract. `message` is written for a person and may be reworded. properties: error: properties: code: description: Stable machine-readable error code. enum: - invalid_api_key - ip_rate_limited - rate_limited - daily_limit_reached - not_found - invalid_parameter - invalid_interval - invalid_window - method_not_allowed - internal_error - unavailable - error type: string docsUrl: description: Deep link to this code on the limits and errors page. format: uri type: string message: description: Human-readable explanation. Not a stable contract. type: string requestId: description: >- Correlation id, also returned as the X-Request-Id header. Quote it in support requests. type: string required: - code - message - docsUrl - requestId type: object required: - error title: Error type: object securitySchemes: bearerAuth: description: >- Your Data API key as a Bearer token: `Authorization: Bearer belief_live_...`. This is the canonical form. Keys belong on a server, never in a browser. scheme: bearer type: http apiKeyAuth: description: >- The same key sent as `X-API-Key` instead. Accepted everywhere the Bearer header is. Send one or the other, not both. in: header name: X-API-Key type: apiKey ````