I wanted to see multi-agent costs at a glance, so I wrote a 150-line plugin

OpenCode shows total tokens per session. That's fine with one agent. With six - planner, backend-dev, frontend-dev, reviewer, QA, scriber - you have to open each sub-agent's history to figure out where the money went.

opencode-costs puts a per-agent cost breakdown in the sidebar. Install from the plugin manager, done.

It's my first npm package.

link