opencode-c3-plugin

An opencode plugin that automatically generates a stable, opaque metadata.user_id for every Anthropic API call made through opencode.

opencode does not set a user identifier by default. This plugin adds one — derived deterministically from the current project and session, so it stays consistent without exposing any personally identifiable information.

Install

Add the plugin to your opencode config (opencode.json or ~/.config/opencode/opencode.json):

{
  "plugins": ["opencode-c3-plugin"]
}

Or point at a local checkout:

{
  "plugins": ["./path/to/opencode-c3-plugin/dist/index.js"]
}

Then restart opencode.

What it does

On each chat turn that uses the @ai-sdk/anthropic provider, the plugin sets metadata.userId to a JSON value with three opaque fields:

{
  "device_id": "<64-char hex>",
  "account_uuid": "<uuid>",
  "session_id": "<uuid>"
}

• device_id and account_uuid are derived from the opencode project id (stable per project).
• session_id is derived from the opencode session id (stable within a session).

All three are SHA-256 derivations — opaque, with no embedded PII. Non-Anthropic providers are left untouched, and an existing metadata.userId is never overwritten.

Configuration

To pin a fixed identifier instead of the derived one, set:

export OPENCODE_ANTHROPIC_USER_ID="your-opaque-id-here"

The value must be opaque and contain no PII (UUIDs, prefixed tokens like user_abc123, or hex strings). An invalid value throws; an empty value is treated as unset.

Development

npm install
npm run typecheck && npm run test
npm run build

License

MIT — see LICENSE.