Solana Estimate Transaction Fees and Priority Fees

arazzo: 1.0.1
info:
  title: Solana Estimate Transaction Fees and Priority Fees
  summary: Fetch a blockhash, price a message, sample recent priority fees, and re-check blockhash validity.
  description: >-
    The pre-flight budgeting path a wallet or bot runs before submitting. The
    workflow fetches a recent blockhash, prices the caller's encoded message
    with getFeeForMessage, samples the prioritization fees recently paid for the
    accounts the transaction will lock so a compute-unit price can be chosen,
    and then re-checks that the blockhash is still valid before the transaction
    is signed and sent. The final validity check matters because blockhashes
    expire after roughly 150 slots, and a fee quote against an expired blockhash
    returns null. 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: transactionsApi
  url: ../openapi/solana-transactions-api-openapi.yml
  type: openapi
workflows:
- workflowId: fee-estimation
  summary: Price a transaction message and sample the priority fee market.
  description: >-
    Produces a base fee quote, a recent prioritization-fee sample, and a
    freshness check on the blockhash the quote was made against.
  inputs:
    type: object
    required:
    - encodedMessage
    properties:
      encodedMessage:
        type: string
        description: >-
          The base64-encoded transaction message (not a full signed
          transaction) to be priced.
      writableAccounts:
        type: array
        description: >-
          Base58-encoded account addresses the transaction will write-lock, used
          to sample the relevant priority fee market.
        items:
          type: string
  steps:
  - stepId: fetchBlockhash
    description: >-
      Fetch a recent blockhash and the last block height at which it remains
      valid. The fee quote is only meaningful while this blockhash lives.
    operationId: getLatestBlockhash
    requestBody:
      contentType: application/json
      payload:
        jsonrpc: "2.0"
        id: 1
        method: getLatestBlockhash
        params:
        - commitment: confirmed
    successCriteria:
    - condition: $statusCode == 200
    - context: $response.body
      condition: $.result.value.blockhash
      type: jsonpath
    outputs:
      blockhash: $response.body#/result/value/blockhash
      lastValidBlockHeight: $response.body#/result/value/lastValidBlockHeight
  - stepId: priceMessage
    description: >-
      Ask the cluster what base fee it would charge for the supplied message.
      A null value means the blockhash inside the message has already expired.
    operationId: getFeeForMessage
    requestBody:
      contentType: application/json
      payload:
        jsonrpc: "2.0"
        id: 1
        method: getFeeForMessage
        params:
        - $inputs.encodedMessage
        - commitment: confirmed
    successCriteria:
    - condition: $statusCode == 200
    outputs:
      baseFeeLamports: $response.body#/result/value
      pricedAtSlot: $response.body#/result/context/slot
  - stepId: samplePriorityFees
    description: >-
      Sample the prioritization fees recently paid by transactions touching the
      same write-locked accounts, so a competitive compute-unit price can be
      set rather than guessed.
    operationId: getRecentPrioritizationFees
    requestBody:
      contentType: application/json
      payload:
        jsonrpc: "2.0"
        id: 1
        method: getRecentPrioritizationFees
        params:
        - $inputs.writableAccounts
    successCriteria:
    - condition: $statusCode == 200
    - context: $response.body
      condition: $.result
      type: jsonpath
    outputs:
      fees: $response.body#/result
      mostRecentFee: $response.body#/result/0/prioritizationFee
      mostRecentSlot: $response.body#/result/0/slot
  - stepId: verifyBlockhashStillValid
    description: >-
      Confirm the blockhash fetched at the start has not expired while the fees
      were being sampled. If it has, the caller must restart with a fresh
      blockhash before signing.
    operationId: isBlockhashValid
    requestBody:
      contentType: application/json
      payload:
        jsonrpc: "2.0"
        id: 1
        method: isBlockhashValid
        params:
        - $steps.fetchBlockhash.outputs.blockhash
        - commitment: processed
    successCriteria:
    - condition: $statusCode == 200
    - context: $response.body
      condition: $.result.value == true
      type: jsonpath
    outputs:
      stillValid: $response.body#/result/value
  outputs:
    blockhash: $steps.fetchBlockhash.outputs.blockhash
    lastValidBlockHeight: $steps.fetchBlockhash.outputs.lastValidBlockHeight
    baseFeeLamports: $steps.priceMessage.outputs.baseFeeLamports
    recentPriorityFee: $steps.samplePriorityFees.outputs.mostRecentFee
    blockhashStillValid: $steps.verifyBlockhashStillValid.outputs.stillValid