Under the hood
Workflow run IDs now use a dedicated ID format with their own telemetry hashing path
What
Workflow run IDs now follow a specific recognizable shape (a wf_ prefix followed by hex characters). Internally, IDs matching this shape are now hashed and redacted differently from other custom identifiers before being included in telemetry data.
Why
This is an internal bookkeeping change affecting how workflow run identifiers are anonymized before being sent in telemetry; it doesn't change what you see or do when using workflows.
Names in the bundlewf_
Documented inclaude-code/monitoring-usage
The entry above is what we published on the day. These lines were added later, as Anthropic's own pages caught up, and they sit beside the original rather than replacing it.
Confirmed since
Anthropic's documentation has since written up wf_, on Monitoring.
| `workflow.run_id` | Run identifier of the [Workflow](/docs/en/workflows) tool run that spawned this agent, prefixed `wf_`. Absent for agents not spawned by a workflow | |monitoring-usage see the edit
One source agreesOne thing we can check says the same as this entry.
Anthropic's documentation agrees
Anthropic's documentation has since written up wf_, on Monitoring.