[BUG] Chat request fails with unknown reasoning.isValid after creating a new agent version

[EkaLinMan]

Describe the bug
After updating the instructions of a prompt agent that has a reasoning configuration and creating a new version, subsequent chat requests fail with:

400: Unknown parameter: 'reasoning.isValid'

During debugging, an isValid property was found in the agent’s reasoning configuration. This property does not appear to be supported by the service API and may be related to the serialization of Reasoning.isValid().

Exception or Stack Trace

com.openai.errors.BadRequestException: 400: Unknown parameter: 'reasoning.isValid'
    at com.openai.errors.BadRequestException$Builder.build(BadRequestException.kt:88)
    at com.openai.core.handlers.ErrorHandler$errorHandler$1.handle(ErrorHandler.kt:48)
    at com.openai.core.handlers.ErrorHandler$errorHandler$1.handle(ErrorHandler.kt:40)
    at com.openai.services.blocking.ResponseServiceImpl$WithRawResponseImpl.create(ResponseServiceImpl.kt:143)
    at com.openai.services.blocking.ResponseServiceImpl.create(ResponseServiceImpl.kt:62)
    at com.openai.services.blocking.ResponseService.create(ResponseService.kt:64)
    at com.azure.ai.agents.ResponsesClient.createAzureResponse(ResponsesClient.java:66)

To Reproduce

• Retrieve the latest agent version using AgentsClient.
• Obtain its PromptAgentDefinition.
• Change only instructions.
• Create a new agent version using the typed createAgentVersion method.
• Send a response request using the newly created/latest agent version.

Code Snippet

final AgentVersionDetails latestVersion = agentsClient
    .getAgent(agentName)
    .getVersions()
    .getLatest();

final PromptAgentDefinition definition =
    (PromptAgentDefinition) latestVersion.getDefinition();

definition.setInstructions("Updated system prompt");

agentsClient.createAgentVersion(
    agentName,
    definition,
    null,
    latestVersion.getMetadata(),
    latestVersion.getDescription()
);

// A subsequent response request using the latest agent version fails with:
// 400: Unknown parameter: 'reasoning.isValid'

Expected behavior
Creating a new version after updating instructions should preserve the existing agent definition, and the resulting version should remain usable for response requests.

Setup (please complete the following information):

• OS: Ubuntu 25.04, Linux kernel 6.14.0-37-generic, x86-64

• IDE: IntelliJ IDEA 2025.3

• Libraries:

  • com.azure:azure-ai-agents:2.0.0
  • com.openai:openai-java:4.19.0
  • com.openai:openai-java-core:4.19.0
  • com.azure:azure-core:1.57.1
  • com.azure:azure-core-http-netty:1.16.3

• Java version: Amazon Corretto 25.0.2

• App Server/Environment: Spring Boot application using embedded Tomcat, run from IntelliJ IDEA

• Frameworks: Spring Boot 4.1.0

Information Checklist

• Bug Description Added
• Repro Steps Added
• Setup information Added

[github-actions]

🎯 Agentic Issue Triage — Needs Manual Review

🏷️ Label Decision

• Candidate labels considered: Client + AI Agents — the issue explicitly references com.azure:azure-ai-agents:2.0.0, AgentsClient, PromptAgentDefinition, createAgentVersion, and a stack trace through com.azure.ai.agents.ResponsesClient, all pointing unambiguously to the azure-ai-agents client library and an SDK-side serialization defect (the reasoning.isValid field being emitted where the service does not expect it). No other service or category was plausible.
• Confidence blockers: None for the label pair itself — category (Client) and service (AI Agents) are both clearly implied by the referenced package and API surface, and neither is the excluded Service/Central-EngSys label.
• Outcome: Requested Client + AI Agents (plus customer-reported and question since the reporter is an external, non-org-member contributor with read-only repo access) — prediction was confident.

👥 Owner Routing

• CODEOWNERS scan: Scanned .github/CODEOWNERS bottom-to-top for a # ServiceLabel: entry matching AI Agents and/or Client. The file only contains # PRLabel: %AI Agents entries (lines 94–96, mapping /sdk/ai/azure-ai-agents/ and /sdk/ai/azure-ai-agents-persistent/ to @dargilco Gerardo Lecaros (@glecaros) Jose Alvarez (@jpalvarezl) Kaylie (@kaylieee) Travis Wilson (@trrwilson) @Azure/azure-java-sdk``); there is no corresponding # ServiceLabel: %AI Agents block with `AzureSdkOwners`/`ServiceOwners`, and there is no `%Client` catch-all entry.
• Matched entry: No match found — no # ServiceLabel: entry exists for AI Agents or Client.
• Owners found: None listed under a ServiceLabel entry (PR-only routing owners exist but are not usable for issue ServiceLabel-based routing per the defined flow).
• Outcome: Requested needs-team-triage — no ServiceLabel entry matched the predicted labels, so automated owner assignment/mention could not be completed. A network restriction in this environment also prevented fetching the Azure SDK release-metadata CSV to run the deprecated-package check for com.azure:azure-ai-agents; a human reviewer should confirm package lifecycle status if relevant.

Generated by Agentic Triage for #50399 · auto · 115 AIC · ⌖ 3.44 AIC · ⊞ 15.9K · ◷

[vcolin7]

Hi EkaLinMan, thanks for reporting this issue, I'll route it to the team for review.

Darren Cohen (@dargilco), Gerardo Lecaros (@glecaros), Glenn Harper (@glharper), Jose Alvarez (@jpalvarezl), Kaylie (@kaylieee), Ryan Hurey (@rhurey) mind taking a look when you get a moment? Thanks! :)