Summary

Every agent created by the build-agent skill has an empty harness and model config in the Agenta Playground, making it immediately broken. The skill's own success message is false.

Tested against: Agenta host https://bighetzner.agenta.dev, workspace mahmoud/Default.

Repro

1. Run the build-agent skill with any prompt (tested with multiple prompts across Claude Code and Codex).
2. Skill transcript claims agent was "created and registered" and may even claim it "updated the agent config to use the OpenAI-backed provider."
3. Open the Agenta Playground for the created agent.
4. Observe: Harness = unselected, Model = "Select a provider" — config is empty.
5. Try to invoke the agent — fails with pi_core: model authentication failed, which is misleading because the real cause is no model being configured at all.
6. Manually select Harness = Pi + any model in the UI → agent immediately works.

Confirmed agents:

• support-ticket-summarizer (app 019f33ef-0520-7a11-8011-c032968ff71b)
• complaint-reply-agent (app 019f3466-c979-7002-a34c-0cc00cdaaef2)
• A third agent (same pattern)

Reproduced: 3/3 times, across different prompts and different coding agents (Claude Code, Codex).

Required fix

The skill must explicitly set harness + model at creation time via the API, and must verify the resulting config is non-empty before declaring the agent "created successfully." As-is, the skill's own success message is false.

Environment