updates.yaml

get:
  operationId: getLightClientUpdatesByRange
  summary: Get `LightClientUpdate` instances in a requested sync committee period range
  description: |
    Requests the [`LightClientUpdate`](https://github.com/ethereum/consensus-specs/blob/v1.3.0/specs/altair/light-client/sync-protocol.md#lightclientupdate) instances in the sync committee period range `[start_period, start_period + count)`, leading up to the current head sync committee period as selected by fork choice.
    Depending on the `Accept` header they can be returned either as JSON or SSZ-serialized bytes.

    Servers SHOULD provide results as defined in [`create_light_client_update`](https://github.com/ethereum/consensus-specs/blob/v1.3.0/specs/altair/light-client/full-node.md#create_light_client_update). They MUST respond with at least the earliest known result within the requested range, and MUST send results in consecutive order (by period). The response MUST NOT contain more than [`min(MAX_REQUEST_LIGHT_CLIENT_UPDATES, count)`](https://github.com/ethereum/consensus-specs/blob/v1.3.0/specs/altair/light-client/p2p-interface.md#configuration) results.
  tags:
    - Beacon
  parameters:
    - name: start_period
      in: query
      required: true
      schema:
        $ref: '../../../beacon-node-oapi.yaml#/components/schemas/Uint64'
    - name: count
      in: query
      required: true
      schema:
        $ref: '../../../beacon-node-oapi.yaml#/components/schemas/Uint64'
  responses:
    "200":
      description: Success
      content:
        application/json:
          schema:
            title: GetLightClientUpdatesByRangeResponse
            type: array
            items:
              type: object
              required: [version, data]
              properties:
                version:
                  $ref: '../../../beacon-node-oapi.yaml#/components/schemas/ConsensusVersion'
                data:
                  anyOf:
                    - $ref: '../../../beacon-node-oapi.yaml#/components/schemas/Altair.LightClientUpdate'
                    - $ref: '../../../beacon-node-oapi.yaml#/components/schemas/Capella.LightClientUpdate'
        application/octet-stream:
          schema:
            description: |
              Sequence of zero or more `response_chunk`. Each _successful_ `response_chunk` MUST contain a single `LightClientUpdate` payload:
              ```
              (
                response_chunk_len: Little-endian Uint64 byte length of `response_chunk`
                response_chunk: (
                  context: 4 byte `ForkDigest`
                  payload: SSZ serialized payload bytes
                )
              )
              ```
              Use Accept header to choose this response type

              For each `response_chunk`, a `ForkDigest`-context based on `compute_fork_version(compute_epoch_at_slot(update.attested_header.beacon.slot))` is used to select the fork namespace of the Response type. Note that this `fork_version` may be different from the one used to verify the `update.sync_aggregate`, which is based on `update.signature_slot`.

              Per `context = compute_fork_digest(fork_version, genesis_validators_root)`:

              | `fork_version`                                                      | Response chunk SSZ type               |
              | ------------------------------------------------------------------- | ------------------------------------- |
              | `GENESIS_FORK_VERSION`                                              | n/a                                   |
              | <nobr>`ALTAIR_FORK_VERSION` through `BELLATRIX_FORK_VERSION`</nobr> | `altair.LightClientUpdate`            |
              | <nobr>`CAPELLA_FORK_VERSION` and later</nobr>                       | `capella.LightClientUpdate`           |
    "400":
      description: Malformed or missing request parameter
      content:
        application/json:
          schema:
            $ref: "../../../beacon-node-oapi.yaml#/components/schemas/ErrorMessage"
          examples:
            InvalidSyncPeriod:
              value:
                code: 400
                message: "Invalid sync committee period requested"
            InvalidCount:
              value:
                code: 400
                message: "Invalid count requested"
            MissingStartPeriodValue:
              value:
                code: 400
                message: "Missing `start_period` value"
            MissingCountValue:
              value:
                code: 400
                message: "Missing `count` value"
    "406":
      description: Unacceptable media type
      content:
        application/json:
          schema:
            $ref: "../../../beacon-node-oapi.yaml#/components/schemas/ErrorMessage"
          example:
            code: 406
            message: "Accepted media type not supported"
    "500":
      $ref: "../../../beacon-node-oapi.yaml#/components/responses/InternalError"