> ## Documentation Index
> Fetch the complete documentation index at: https://docs.beliefstate.ai/llms.txt
> Use this file to discover all available pages before exploring further.

# Historical queries

> Use as_of to read data available at a historical cutoff.

## Use as\_of

Set BELIEFSTATE\_TICKER to the requested symbol and BELIEFSTATE\_AS\_OF to the RFC 3339 cutoff for your question. Set BELIEFSTATE\_REQUEST\_ID to a new UUID; reuse it only when retrying this exact query.

```bash theme={null}
curl --fail-with-body \
  --header "Authorization: Bearer $BELIEFSTATE_API_KEY" \
  --header "X-Request-ID: ${BELIEFSTATE_REQUEST_ID:?Set a new UUID for this request; keep it for retries}" \
  "https://beliefstate.ai/v1/beliefs?ticker=${BELIEFSTATE_TICKER:?Set the requested ticker from current coverage}&as_of=${BELIEFSTATE_AS_OF:?Set the requested RFC3339 cutoff}"
```

Future values are clamped.

## Find changed beliefs

`GET /v1/beliefs` accepts `changed_since` as an exclusive lower bound for changes and `as_of` as an inclusive observation cutoff. Use both with a ticker when you need changes within a historical window.

Reuse the same values on retries. Changing either timestamp creates a different logical request.

## Store the cutoff

Persist the request cutoff with every research artifact and paginated response.

> Do not substitute the time your client downloaded a response for the observation-time fields inside the response.

## Agent feedback

Report unclear, stale, or incorrect documentation through [BeliefState support](https://beliefstate.ai/contact). Include this page URL and the smallest reproducible detail.

*Last updated: 2026-09-26 · API version: v1 (Latest) · OpenAPI publication: 2026-09-13.*


This documentation is built and hosted on [Mintlify](https://mintlify.com), a developer documentation platform.