stuck in busy forever after toolcall

Description

After several successful tool calls suddenly one toolcall ends and opencode TUI remains stuck in busy (ping pong animation ongoing). Double ESC to interrupt does nothing.
The last log message is either "level=INFO run=XXXX message=loop session.id=ses_XXXX step=N" or something like "level=INFO run=XXXX message=evaluated permission=bash pattern="...." action.permission=* action.action=allow action.pattern=*"
No permission dialog is shown and the operation wouldn't have required one, so I guess this is not a hidden dialog issue, even though the log seems to imply this.
The only way to recover from this is CTRL+C, restart opencode with the same session and issue a prompt to continue.
It is possible that it occurs more frequently with bash commands that take a few seconds to complete or are piped through head or something like that, but it can also be coincidence.

Additional information:
Agent is running a local instance of qwen-3.6 27b served via vllm (openai compatible backend).
Right now got an update to 1.18.13 and it still happens. Oldest known release with this issue: 1.18.11.

Plugins

none

OpenCode version

1.18.12

Steps to reproduce

1. In an opencode session issue prompts that would result in tool-calls like bash shell commands.
2. Wait until one of the tool calls gets perpetually stuck in busy mode.

Screenshot and/or share link

No response

Operating System

Debian trixie (Linux 6.12.63+deb13-amd64)

Terminal

Konsole 25.04.2 (KDE plasma) running bash