An unset agent.reasoning_effort already resolves to medium on the Nous Portal,
OpenRouter, AI Gateway and Copilot routes (each profile fills it in
build_api_kwargs_extras). The custom / OpenAI-compatible profile — every
`providers.<name>` block and `--provider custom` — omitted the field instead,
so the endpoint's own default applied; for moonshotai/kimi-k3 that is `max`:
3x the reasoning tokens and ~3x the latency of medium, measured live.
The default is resolved at request time in _reasoning_config_for_wire via
ProviderProfile.default_reasoning_config (the custom profile answers medium),
so it is recorded as what actually went out and the reasoning-rejection
ladder keeps working: a 400 on the field turns the rest of the session back
to "omit". It never touches an explicit effort (low stays low, none stays
none), stays off non chat-completions transports (the Anthropic adapter's
unset = no thinking kwargs stands), off models the catalog or model_overrides
mark supports_reasoning: false, and off local Ollama models pulled without
the thinking capability. Auxiliary calls are untouched: they hand the profile
reasoning_config=None directly, which still omits the field.
Live wire capture (token-injecting proxy, providers.probe -> kimi-k3):
before req_reasoning: {}
after req_reasoning: {'reasoning_effort': 'medium'}
agent.reasoning_effort: low -> {'reasoning_effort': 'low'} (unchanged)