Agentforce Live Preview fails with 422 Unprocessable Entity on Session Init for Committed Versions with Apex Actions

Hi everyone,

I'm encountering an issue where an Employee Service Agent fails during session initialization in Live Preview, but only after committing a version that includes an Apex Invocable Action.

Here is the exact setup and breakdown of the behavior:

Context & Setup

• Agent Type: AgentforceEmployeeAgent (running under System Admin context).
• Action: @InvocableMethod Apex Class (also tested with a minimal dummy Apex Class).

Steps to Reproduce

1. Create agent backbone with 0 actions. Commit version and test in Live Preview -> Works fine (200 OK).
2. Add an Invocable Apex Action to a Subagent. Test in Draft Live Preview -> Works fine.
3. Commit the version (Popup confirms successful commit).
4. Refresh/re-open Live Preview on the Committed Version -> Session fails to initialize with a generic UI error "Something went wrong".

Error Log (Network Tab): The request to https://api.salesforce.com/einstein/ai-agent/v1/agents/{AgentId}/sessions returns a 500 Internal Server Error, containing the root exception:

{    "status": 500,    "path": "v6.0.0/agents/{AgentId}/sessions",    "mode": "preview",    "requestId": "7c375608-b352-48d1-8895-dd65dbcb1874",    "error": "AgentApiException",    "message": "Internal Server Error: org.springframework.web.reactive.function.client.WebClientResponseException$UnprocessableEntity: 422 Unprocessable Entity from POST https://api.salesforce.com:9443/einstein/copilot/v1/planner/{PlannerId}/sessions",    "timestamp": 1785923824404,    "expected": false,    "details": null}

Key Isolation Observations

• Scratch Org Test: Deployed the same Apex class and Agent metadata to a Scratch Org -> It works 100% fine on Committed versions.
• Org-Specific Issue: On the affected Org, creating a brand new dummy Apex Action and a brand new Agent still reproduces the 422 error as soon as any action is attached to a committed version.
• Permissions: Running as System Admin with API Enabled and Agentforce User permissions.

Has anyone encountered this issue where the GenAiPlanner fails to resolve action schemas specifically on Committed versions for a particular Org? Is there a way to flush/force-sync the Einstein Planner Engine cache?

Thanks for any insights!