When triggering an MCP Prompt with /prompt, only the final user message returned by the MCP server is actually appended to the conversation, breaking multi-message prompts. This appears to only occur in the Goose CLI, and works correctly in the Goose UI.

To Reproduce
Steps to reproduce the behavior:

1. Configure this trivial MCP server as an extension in Goose.
2. Run /prompt test_mcp_prompt.
3. Only the final user message ("Huh??") is interpreted by the model.

Expected behavior
All three prompt messages are appended to the conversation.

Screenshots
N/A

Please provide the following information

• OS & Arch: MacOS 26.2 (aarch64)
• Interface: CLI
• Version: 1.19.1
• Extensions enabled: GitHub,MCP Documentation,Prompts MCP Test,chatrecall,computercontroller,developer,memory,skills,todo
• Provider & Model: Bedrock - global.anthropic.claude-opus-4-5-20251101-v1:0

Additional context
Add any other context about the problem here.