Missing API endpoint that accesses model.Workflow referenced by workflow_id from /api/workflows/{workflow id}/invocations

workflow_id returned by `GET /api/workflows/{workflow id}/invocations` is not the same as {workflow id}, what does it refer to?

Start by tracing GET /api/workflows/{workflow id}/invocations and the workflow_id field in its response. Inspect the API route and the model.Workflow references to determine what the returned identifier represents and whether an endpoint is missing. Done means the relationship is documented or exposed through the requested API behavior, with tests covering the response.

Written by the indexing model from the issue text.