opencode-session-cost

Do you know how much you're really spending on a session? Subagent costs hide from you by default in OpenCode. This plugin adds a sidebar block showing your true total — session + every subagent it spawned — and lets you expand it to see the cost of each one.

Installation

This is a TUI-only plugin. It has no server-side hook and must be added to tui.json, not opencode.json.

Quick install (recommended)

Run this from a terminal — it installs the package and adds it to your global tui.json automatically:

opencode plugin opencode-session-cost --global

Restart the OpenCode TUI afterwards for the sidebar block to appear.

Manual install

Add this to tui.json yourself instead:

{
"plugin": [["opencode-session-cost", { "enabled": true }]]
}

Using a local checkout instead of the npm package? Point at the directory:

{
"plugin": [
["/absolute/path/to/opencode-session-cost", { "enabled": true }]
]
}

Restart the OpenCode TUI after editing tui.json.

Options

Option	Type	Default	Description
enabled	boolean	true	When false, the plugin's tui() returns immediately and registers nothing.

There is no provider allow-list and no other configuration — this works for every session regardless of model or provider.

Development

bun install
bun run typecheck # tsc --noEmit
bun test# bun:test, pure logic in src/cost.test.ts
bun run build # Bun.build (JSX) + tsc --emitDeclarationOnly (types)

Contributing

Contributions are welcome. See CONTRIBUTING.md for development setup, coding standards, and the pull request process.

License

MIT — see LICENSE.