@braintrust/trace-opencode

Trace OpenCode sessions in Braintrust. The plugin sends events to the local bt daemon, which builds and uploads traces. OpenCode keeps running if tracing fails.

• Session spans: Root span for each OpenCode session with metadata (workspace, hostname, etc.)
• Turn spans: Captures each user-assistant interaction
• LLM spans: Records completed model messages with available inputs, outputs, and usage
• Tool spans: Records individual tool executions with inputs and outputs

Quickstart

Install OpenCode and the Braintrust CLI, then run:

bt login
bt trace enable opencode --project my-coding-agent
opencode

This registers the npm plugin and saves its configuration. Use --profile or --org to choose a profile or organization. Restart OpenCode if it is already open.

For one invocation without changing global tracing configuration:

bt trace run --project my-coding-agent opencode -- run "summarize this repository"

Historical import and live attach are not supported for OpenCode.

Compatibility

The package declares @opencode-ai/plugin and @opencode-ai/sdk peers at >=1.2.25. CI checks package installation at that minimum and at latest, and runs real-agent integration tests with the latest OpenCode CLI.

Configuration

Settings load from these files, with project settings overriding global settings:

• Global: $XDG_CONFIG_HOME/opencode/braintrust.json, or ~/.config/opencode/braintrust.json if XDG_CONFIG_HOME is unset
• Project: .opencode/braintrust.json

bt trace run overrides tracing settings for one invocation. Files are merged at the top level: a project route replaces the global route.

{
  "trace_to_braintrust": true,
  "enable_tools": true,
  "route": {
    "auth": { "profile": "work", "org_name": "acme" },
    "destination": { "type": "project_logs", "project_name": "my-project" }
  },
  "debug": true
}

Settings

Older files can still use top-level profile, org_name, project, and additional_metadata. For new files, use bt trace enable or the nested route format above. Include a destination when supplying a route.

Only enable_tools and debug read environment variables directly. Tracing settings come from these files or bt trace run.

Disable Braintrust tools

Set enable_tools to false to trace OpenCode sessions without registering Braintrust-branded tools (braintrust_query_logs, braintrust_list_projects, braintrust_log_data, braintrust_get_experiments):

{
  "trace_to_braintrust": true,
  "enable_tools": false,
  "route": {
    "destination": { "type": "project_logs", "project_name": "my-project" }
  }
}

Or use the environment variable:

BRAINTRUST_OPENCODE_ENABLE_TOOLS=false opencode

Add root metadata

Set route.additional_metadata to add fields to the root span:

For one invocation without changing the persistent configuration, use bt trace run --additional-metadata '{"ci": true, "run_id": "abc-123"}' opencode -- run "do the thing", or set BRAINTRUST_ADDITIONAL_METADATA before that command (bt trace run still accepts it; a plain opencode session's plugin does not).

You can also set it via the config file:

{
  "route": {
    "destination": { "type": "project_logs", "project_name": "my-project" },
    "additional_metadata": { "team": "platform" }
  }
}

The value must be a JSON object. Built-in session metadata wins if keys conflict.

Trace structure

The daemon reconstructs sessions, turns, model messages, and tool executions:

Session (task)
├── Turn 1 (task)
│   ├── Model response (llm)
│   ├── Tool execution (tool)
│   └── Model response (llm)
└── Turn 2 (task)

Model usage and metadata are included when OpenCode provides them. Child sessions are attached to their parent's active turn when that relationship is available to the translator.

Manage tracing

bt trace doctor opencode
bt trace status
bt trace update opencode
bt trace disable opencode

Runtime architecture

Tracing sends events to the local daemon over JSON-RPC. The four optional Braintrust tools call bt commands. Both use bt for credentials and API access.

Development

From the monorepo root, run make validate-opencode to build, check, and test the package. See the contribution guide for development instructions. The npm package contains compiled entrypoints; source changes belong in the monorepo.