[Bug] `azure.ai.agent` host does not persist `agent.yaml` environment_variables into the deployed agent version

[qiaozha]

Summary

With the azure.ai.agent host (azure.ai.agents beta.5), the "Registering agent environment variables" step is effectively a no-op: the environment_variables declared in agent.yaml are not embedded into the deployed agent version's definition.

What happens

Our hosted Foundry agent crashes on boot:

AZURE_APPCONFIG_ENDPOINT env var is required
-> 424 session_not_ready
-> /agent/chat returns 500

even though AZURE_APPCONFIG_ENDPOINT is declared in agent.yaml. The deployed version simply doesn't carry the env.

Related: azure.yaml ${VAR} interpolation for image: is resolved at project-load (before predeploy), so we also can't point image: at the freshly-built immutable tag. (Filed separately.)

Current workaround

agent-postdeploy.ts -> ensureAgentAppConfigEnv() uses the Foundry data-plane API:

1. GET .../agents/<name>/versions/@latest
2. if image != AGENT_DEPLOYED_IMAGE or environment_variables.AZURE_APPCONFIG_ENDPOINT is missing -> POST a new version cloning the definition, pinning the image, embedding env
3. idempotent — no-op when already correct

Ask

The azure.ai.agent host should actually persist agent.yaml environment_variables (and the pinned image) into the deployed version's definition. That would let us delete ensureAgentAppConfigEnv.

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Context: encountered while deploying a multi-component AI/chat service (App Service + Function App + Logic App + Foundry hosted agent) end-to-end with azd provision/deploy in Azure/azure-sdk-tools tools/sdk-ai-bots/deployment. We currently work around this with a TypeScript hook.