Bug: Invalid prompt at compaction

[jerome-benoit]

Description

At compaction with latest git on a regular basis:

AI_InvalidPromptError: Invalid prompt: The messages must be a ModelMessage[]. If you have passed a UIMessage[], you can use convertToModelMessages to convert them.

Plugins

No response

OpenCode version

git

Steps to reproduce

1. Use GitHub Copilot provider (Claude Opus 4.5, but does not matter)
2. Prompt until compaction is triggered
3. Repeat until the error occurs

Screenshot and/or share link

No response

Operating System

GNU/Linux

Terminal

tmux