The wire test called drop_thinking_only_and_merge_users directly, so deleting the
drop_nudge_marker kwarg in turn_request_assembly.assemble_api_request left it green.
Replace it with a run_conversation-driven test whose fallback stub flips api_mode to
chat_completions and asserts the captured request carries no nudge fragment, no
codex_reasoning_items and alternating roles (red with the kwarg removed). File is back to
two tests.
f85a7cb684