The implementation currently overrides llmRequest.ReasoningEffort unconditionally. However, the documentation in internal/server/biz/system.go (line 260) states that the suffix should only be applied if the request did not already specify reasoning_effort explicitly. To align with the intended behavior, you should check if ReasoningEffort is empty before assigning the value from the suffix.

if llmRequest.ReasoningEffort == "" {
		llmRequest.ReasoningEffort = reasoningEffort
	}

The inbound field is not used anywhere in the autoReasoningEffortMiddleware struct or its methods. It should be removed to keep the struct clean.

The inbound parameter is unused in the middleware implementation. You should remove it from the function signature and the struct initialization.

func applyAutoReasoningEffort(systemService *biz.SystemService) pipeline.Middleware {
	return &autoReasoningEffortMiddleware{
		systemService: systemService,
	}
}

This check is redundant. The condition lastDash <= 0 at line 69 already ensures that base (which is model[:lastDash]) will not be empty if the function proceeds to this point. If lastDash is 0, the function returns early.

If the inbound parameter is removed from applyAutoReasoningEffort as suggested, the call site here should be updated accordingly.

If the middleware is updated to respect explicit ReasoningEffort values (as suggested in auto_reasoning_effort.go), this test case should be updated to reflect that the explicit value high should be preserved instead of being overridden by xhigh.