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.