Copilot CLI bug: ACP mode hides Fusion model and tier config from third-party clients
simonsteiner · ghdev · 2026-11-05
A new issue (#5354) in github/copilot-cli (v1.0.105) reports that Copilot Fusion, available in the interactive CLI's model picker, is advertised only as the routing model Auto when the CLI runs as an ACP server (copilot --acp), with no Fusion/Auto-tier configuration exposed — preventing ACP clients like T3 Code from showing Fusion or its tier selector.
The author provides full JSON-RPC reproduction steps (initialize → session/new → inspect model options → setconfigoption), observing duplicate auto options and config IDs limited to mode, model, reasoningeffort, agent, and allowall. Setting COPILOTCLIENABLEDFEATUREFLAGS=DYNAMICAUTOTIERS had no effect. The report concerns model discovery/configuration parity, not proof that auto cannot route to Fusion internally.
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