@step on a harness method records a plain-English line for every call, in
order, as repeated JUnit step properties. Labels are templates filled from the
call's parameters, like "Generate a virtual key with models: claude-haiku-4-5
and rpm limit: 3", and secret request fields are marked Field(repr=False) so
they never print. ProxyClient and the rate-limit QuotaClient carry steps first;
the other harnesses follow one area at a time. The recorder and JUnit tests run
in the Code Quality workflow's test_e2e_metadata step.
