Solana Resolve the Current Epoch's Leader Schedule

arazzo: 1.0.1
info:
  title: Solana Resolve the Current Epoch's Leader Schedule
  summary: Read epoch position and schedule, fetch the leader schedule, and identify the current and upcoming leaders.
  description: >-
    The routing path a latency-sensitive client uses to send a transaction
    straight to the validator that is about to produce blocks. The workflow
    reads where the cluster sits inside the current epoch, reads the epoch
    schedule that governs how slots map onto epochs, fetches the leader schedule
    for the current epoch, identifies the validator leading right now, and lists
    the leaders for the slots immediately ahead. Every step spells out its
    JSON-RPC request inline so the flow can be read and executed without opening
    the underlying OpenAPI description.
  version: 1.0.0
sourceDescriptions:
- name: clusterApi
  url: ../openapi/solana-cluster-api-openapi.yml
  type: openapi
workflows:
- workflowId: leader-schedule
  summary: Resolve who leads now and who leads next in the current epoch.
  description: >-
    Walks from epoch position to the concrete validators producing the current
    and upcoming slots.
  inputs:
    type: object
    properties:
      upcomingLeaderCount:
        type: integer
        description: How many upcoming slot leaders to list, starting at the current slot.
        default: 10
  steps:
  - stepId: epochInfo
    description: >-
      Read the current epoch, the absolute slot, and the position inside the
      epoch, which anchors every schedule lookup that follows.
    operationId: getEpochInfo
    requestBody:
      contentType: application/json
      payload:
        jsonrpc: "2.0"
        id: 1
        method: getEpochInfo
        params: []
    successCriteria:
    - condition: $statusCode == 200
    - context: $response.body
      condition: $.result
      type: jsonpath
    outputs:
      epoch: $response.body#/result/epoch
      absoluteSlot: $response.body#/result/absoluteSlot
      slotIndex: $response.body#/result/slotIndex
      slotsInEpoch: $response.body#/result/slotsInEpoch
  - stepId: epochSchedule
    description: >-
      Read the schedule that maps slots onto epochs, including the warmup period
      and the offset at which a leader schedule is published ahead of its epoch.
    operationId: getEpochSchedule
    requestBody:
      contentType: application/json
      payload:
        jsonrpc: "2.0"
        id: 1
        method: getEpochSchedule
        params: []
    successCriteria:
    - condition: $statusCode == 200
    - context: $response.body
      condition: $.result
      type: jsonpath
    outputs:
      slotsPerEpoch: $response.body#/result/slotsPerEpoch
      leaderScheduleSlotOffset: $response.body#/result/leaderScheduleSlotOffset
      warmup: $response.body#/result/warmup
      firstNormalEpoch: $response.body#/result/firstNormalEpoch
      firstNormalSlot: $response.body#/result/firstNormalSlot
  - stepId: leaderSchedule
    description: >-
      Fetch the leader schedule for the current epoch, keyed by validator
      identity with the slot indices each one is assigned.
    operationId: getLeaderSchedule
    requestBody:
      contentType: application/json
      payload:
        jsonrpc: "2.0"
        id: 1
        method: getLeaderSchedule
        params: []
    successCriteria:
    - condition: $statusCode == 200
    - context: $response.body
      condition: $.result
      type: jsonpath
    outputs:
      schedule: $response.body#/result
  - stepId: currentLeader
    description: >-
      Identify the validator leading the current slot, the node a client would
      forward a transaction to right now.
    operationId: getSlotLeader
    requestBody:
      contentType: application/json
      payload:
        jsonrpc: "2.0"
        id: 1
        method: getSlotLeader
        params: []
    successCriteria:
    - condition: $statusCode == 200
    - context: $response.body
      condition: $.result
      type: jsonpath
    outputs:
      leader: $response.body#/result
  - stepId: upcomingLeaders
    description: >-
      List the leaders for the slots immediately ahead of the current one, which
      is what lets a client pre-connect to the next producer instead of the
      current one.
    operationId: getSlotLeaders
    requestBody:
      contentType: application/json
      payload:
        jsonrpc: "2.0"
        id: 1
        method: getSlotLeaders
        params:
        - $steps.epochInfo.outputs.absoluteSlot
        - $inputs.upcomingLeaderCount
    successCriteria:
    - condition: $statusCode == 200
    - context: $response.body
      condition: $.result
      type: jsonpath
    outputs:
      leaders: $response.body#/result
      nextLeader: $response.body#/result/0
  outputs:
    epoch: $steps.epochInfo.outputs.epoch
    slotsPerEpoch: $steps.epochSchedule.outputs.slotsPerEpoch
    leaderSchedule: $steps.leaderSchedule.outputs.schedule
    currentLeader: $steps.currentLeader.outputs.leader
    upcomingLeaders: $steps.upcomingLeaders.outputs.leaders