Item 'rs_...' of type 'reasoning' was provided without its required following item.

[mihbor]

Getting the following error:

ERROR a.k.a.core.agent.entity.AIAgentNode - Error executing node (name: nodeSendToolResult): Error from client: OpenAILLMClient
Status code: 400
Error body:
{
  "error": {
    "message": "Item 'rs_0533a28c592458cc006963ba85a2a48196b82273cf39f40c92' of type 'reasoning' was provided without its required following item.",
    "type": "invalid_request_error",
    "param": "input",
    "code": null
  }
}

when running OpenAI gpt-5.1-codex-mini model with singleRunStrategy(runMode=SEQUENTIAL) (the default) after the first tool call during "nodeSendToolResult".

Simply switching runMode to SINGLE_RUN_SEQUENTIAL solves the problem, which makes me think the issue is probably in koog rather than on OpenAI side or in my code.

koog version 0.6.0

[jay-anbaric]

For me we got this working with sending store: false. This is actually an OpenAI requirement.
When operating statelessly (managing conversation history ourselves), we need:

• store=false: tells OpenAI we're not using server-side state
• include REASONING_ENCRYPTED_CONTENT: provides encrypted reasoning that can be replayed

Without both, multi-turn tool conversations fail with: "Item 'rs_...' of type 'reasoning' was provided without its required following item."

Someone else posted on openai's community with the exact same issue too: https://community.openai.com/t/one-potential-cause-of-item-rs-xx-of-type-reasoning-was-provided-without-its-required-following-item-error-stateless-using-agents-sdk/1370540

[aozherelyeva]

Hi @mihbor, thank you for bringing this up! And @jay-anbaric, thank you for the detailed explanation.
@mihbor, please let me know if the solution above works for you.

[mihbor]

Hi @aozherelyeva, I don't know how to apply the suggested workaround.

I figured out how to pass store=false (although I couldn't find in the documentation how to pass provider-specific configuration to the agent). But I don't know what to do to "include REASONING_ENCRYPTED_CONTENT"

Here's what I tried adding to the AIAgent arguments, which didn't work:

      agentConfig = AIAgentConfig(
        prompt = prompt(
          id = "chat",
          params = OpenAIResponsesParams(store = false)
        ) {
...

Instead of the exception above, I got a different one:

    "message": "Item with id 'rs_0472df8e78c822b001697926d2fbc08190af952ca8bd37e7ae' not found. Items are not persisted when `store` is set to false. Try again with `store` set to true, or remove this item from your input.",

The workaround that works is to use SINGLE_RUN_SEQUENTIAL as the runMode.

I think the proper fix would need to be addressed inside koog's implementation to include that REASONING_ENCRYPTED_CONTENT.