"Failed to get download URL for dependencies" on Unity 6000.2.14f1

[JT5D]

Environment

• Unity 6000.2.14f1 (Unity 6)
• CoPlay v8.15.1 (beta branch)
• macOS
• uv installed and in PATH

Issue

Opening CoPlay AI Window (Cmd+G) and clicking "Download Dependencies" shows:

Error: failed to get download url for dependencies

Investigation

• The 2022.3 DLL loads on Unity 6000.2 (6000.3 DLL is gated by UNITY_6000_3_OR_NEWER)
• CoplayApiClient.DownloadDependencyAsync is the failing method
• MCP connection works fine — check_compile_errors, execute_script, create_game_object all work
• uv is installed (uv 0.9.26) and accessible
• Cleared ~/.local/share/Coplay, Temp/Coplay, and package cache — same error
• No relevant errors in ~/Library/Logs/Unity/Editor.log

Possible Cause

The 2022.3 DLL may be calling an outdated API endpoint or missing auth context that the 6000.3 DLL handles. Unity 6000.2 falls into a gap between the two DLLs.

Expected

Download dependencies should succeed on Unity 6000.2.x, which is current stable Unity 6.