Github Copilot Desktop App chat model overrides Squad defaultModel for spawned agents #2258

Summary

When I start the Squad agent from Copilot Desktop with GPT 6.1 Sol selected in chat, a Squad-spawned sub-agent runs with that same chat-selected model instead of the model configured by Squad. In the workspace I checked, .squad/config.json sets defaultModel to gpt-6-luna.

Copilot Desktop appears to run the CLI in the background, but the spawned agent does not appear to honor Squad's configured model. I cannot tell whether the Desktop integration ignores the requested model or does not support passing it through.

Reproduction

1. Set .squad/config.json defaultModel to a model different from the one selected in Copilot Desktop chat (for example, gpt-6-luna).
2. Select GPT 6.1 Sol in Copilot Desktop chat and start the Squad agent.
3. Have Squad spawn a sub-agent and inspect the model it uses.

Expected behavior

When the runtime supports per-agent model selection, Squad-spawned agents use the model selected through Squad's configured model-resolution rules, rather than silently inheriting the Desktop chat model. If the Desktop/CLI integration cannot honor the configured model, Squad should clearly disclose that limitation.

Actual behavior

The spawned sub-agent uses the model selected in Copilot Desktop chat (GPT 6.1 Sol), rather than the configured defaultModel (gpt-6-luna).

Environment

• GitHub Copilot Desktop
• Squad agent started from a Desktop chat using GPT 6.1 Sol
• Workspace .squad/config.json has defaultModel: gpt-6-luna

Related issues

These related issues are closed, but cover different cases:

• Squad forgets which model I want agents to use #284: persistent model preference across sessions
• explicit model picker - aligned to sesson model #618: model picker aligned to the session model
• Coordinator bypasses documented per-agent model selection #1720: coordinator bypassing documented per-agent model selection
• Spawn cast members as sub-sessions in Copilot App #1377: spawning cast members as Copilot App sub-sessions