Enabling the tracing workflow

• Codex tracing is not a single-switch operation; it requires installing the tracing plugin via the Codex CLI's marketplace functionality, then activating it by setting plugin_hooks = true within the project's config file.0:28
• Beyond plugin activation, you must enable the relay to LangSmith by exporting the environment variable TRACE_TO_LANGSMITH=true and providing a valid LangSmith API key.1:15
• The system defaults to routing all traces to a project named Codex, unless you override this behavior by setting the LANGSMITH_CODEX_PROJECT environment variable.

Trace visibility and hierarchy

• Once configured, the LangSmith trace captures a hierarchical view of the agent's work, including raw conversation logs, individual tool calls, and model metadata like token usage and stop reasons.2:51
• The system preserves complex execution flows, such as when a primary agent spawns nested sub-agents, which appear in the trace as distinct parent-child relationships rather than a flattened list.
• Even if a user cancels an active Codex run, the system is designed to upload the session data to LangSmith once completion routines conclude.

Troubleshooting

• If you encounter an empty trace dashboard, follow a specific diagnostic order: verify that plugin_hooks and the tracing plugin are active, then confirm TRACE_TO_LANGSMITH is true, your API key is valid, and the target project name is correct.3:37