OPDATA-4861: Add buffer-layout endpoint to solana-functions

[dskloetc]

OPDATA-4861

Description

The solana-functions EA already supported reading account data with a buffer layout, but so far it was only used in the sanctum-infinity endpoint.
This PR makes the functionality available directly in a buffer-layout endpoint.

NOTE: I copied the sanctum-infinite endpoint, transport and tests in a separate commit, to make it easier to ignore boilerplate while reviewing.

Changes

1. Add buffer-layout endpoint which uses the shared buffer-layout reading support to read fields from programs with a supported buffer layout.
2. Added the result of

ACCOUNT="EPjFWdd5AufqSSqeM2qN1xzybapC8G4wEGGkZwyTDt1v"

curl -X POST https://rpcs.cldev.sh/solana/mainnet -H 'Content-Type: application/json' -d '{
  "jsonrpc": "2.0",
  "id": 1,
  "method": "getAccountInfo",
  "params": [
    "'$ACCOUNT'",
    {
      "encoding": "base64"
    }
  ]
}' | jq

as packages/sources/solana-functions/test/fixtures/usdc-minter-account-data-2025-10-27.json to be used as test fixture.

Steps to Test

1. Unit and integration tests added.
2. Tested manually to read the supply of USDC:

curl --silent -S -X POST http://localhost:8080 -H 'Content-Type: application/json' -d '{
    "data": {
  "endpoint": "buffer-layout",
  "stateAccountAddress": "EPjFWdd5AufqSSqeM2qN1xzybapC8G4wEGGkZwyTDt1v",
  "field": "supply"
}
  }'
{
  "data": {
    "result": "10123912051543186"
  },
  "statusCode": 200,
  "result": "10123912051543186",
  "timestamps": {
    "providerDataRequestedUnixMs": 1761563502565,
    "providerDataReceivedUnixMs": 1761563502979
  },
  "meta": {
    "adapterName": "SOLANA_FUNCTIONS",
    "metrics": {
      "feedId": "{\"stateAccountAddress\":\"epjfwdd5aufqssqem2qn1xzybapc8g4weggkzwytdt1v\",\"field\":\"supply\"}"
    }
  }
}

Quality Assurance

• If a new adapter was made, or an existing one was modified so that its environment variables have changed, update the relevant infra-k8s configuration file.
• If a new adapter was made, or an existing one was modified so that its environment variables have changed, update the relevant adapter-secrets configuration file or update the soak testing blacklist.
• If a new adapter was made, or a new endpoint was added, update the test-payload.json file with relevant requests.
• The branch naming follows git flow (feature/x, chore/x, release/x, hotfix/x, fix/x) or is created from Jira.
• This is related to a maximum of one Jira story or GitHub issue.
• Types are safe (avoid TypeScript/TSLint features like any and disable, instead use more specific types).
• All code changes have 100% unit and integration test coverage. If testing is not applicable or too difficult to justify doing, the reasoning should be documented explicitly in the PR.

[changeset-bot]

🦋 Changeset detected

Latest commit: f8245de

The changes in this PR will be included in the next version bump.

This PR includes changesets to release 1 package

Name	Type
@chainlink/solana-functions-adapter	Minor

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