Review finding on salvaged #28253: the hand-rolled mapping sent
ultra -> medium while xhigh -> high (stronger request, weaker wire
value). Declare NEBIUS_EFFORTS in agent/reasoning_effort.py and use
clamp_effort like the zai/kimi/tokenhub call sites; disable detection
stays ahead of the clamp since clamp_effort('none', ...) returns the
floor, not off. Adds a monotonicity regression test.
Follow-up for salvaged PR #28253: current main's generic profile fetch
passes base_url= to fetch_models and merges curated fallback_models
first (658ac1d86 / #46309), so the mocked-signature and exact-equality
assertions from the PR's era no longer match the contract.
kshitijk4poor