Follow-up to #3851: that PR added `extra_body.thinking={type: disabled}`
for MiMo via OpenRouter, but OR doesn't forward provider-specific
thinking shapes to upstream — it strips unknown extra_body fields and
uses its own unified `reasoning` parameter. So MiMo via OR kept
thinking despite the injection (reproduced by @ClearPlume on #3851
with identical kwargs but provider switched from openrouter → xiaomi_mimo).
For known thinking-capable models (Kimi, MiMo) routed via the
openrouter spec, also inject `extra_body.reasoning = {effort: <effort>}`
in OR's documented enum ("none"|"minimal"|"low"|"medium"|"high"|"xhigh").
OR translates this to the upstream model's native shape.
Existing tests updated to expect both fields on the OR path. The direct
xiaomi_mimo and moonshot paths are unchanged (the new branch is gated
on spec.name == "openrouter"). Flash and non-MiMo models on OR continue
to receive no injection.
The xiaomi_mimo ProviderSpec carries thinking_style="thinking_type", but
gateway providers (OpenRouter etc.) route MiMo under their own spec
which has no thinking_style. As a result, `reasoning_effort="none"` was
silently ignored: `{"thinking": {"type": "disabled"}}` was never
injected and responses still contained reasoning_content.
Mirror the Kimi pattern that already handles the same problem: add an
explicit _MIMO_THINKING_MODELS allowlist (mimo-v2.5-pro, mimo-v2.5,
mimo-v2-pro, mimo-v2-omni — per Xiaomi docs), an _is_mimo_thinking_model
helper that strips publisher prefixes ("xiaomi/mimo-v2.5-pro" matches),
and a sibling branch in _build_kwargs that injects the thinking payload
by model name. mimo-v2-flash is intentionally excluded — it has no
thinking mode.
Also include MiMo in the explicit_thinking predicate so the
reasoning_content backfill (#3554, #3584) covers the gateway path
consistently with the direct path.
Tests cover the gateway disable/enable signals, bare-slug fallback,
flash exclusion, and a non-MiMo sanity check.
The hosted Xiaomi MiMo API accepts {"thinking": {"type": "enabled"|"disabled"}}
to toggle reasoning, which is exactly the shape produced by the existing
thinking_type style. The xiaomi_mimo ProviderSpec just needed to opt in.
Before this fix, setting reasoning_effort="none" had no effect on MiMo
because no thinking_style was configured, so the disable signal never
reached the server. Default-on models (mimo-v2.5-pro and friends) kept
reasoning regardless of user configuration.
Source: https://platform.xiaomimimo.com/docs/en-US/api/chat/openai-api
Co-authored with Claude Opus 4.7. Strategy and review via Claude Desktop,
implementation via Claude Code.
