fix(openai): recognize MiniMax in thinking disable

Route the MiniMax OpenAI-compatible endpoint (global api.minimax.io and
China api.minimaxi.com hosts, plus the MiniMax-M3/MiniMax-M2.7 model ids)
to the thinking_type disable branch so that disabling thinking writes
thinking:{type:"disabled"} and drops reasoning_effort, matching the
existing MiMo/deepseek/glm behavior.

internal/backend/agent/model/openai.go

@@ -1903,11 +1903,13 @@ func openAIThinkingDisableKind(baseURL string, modelID string, endpoint string)
 		strings.Contains(base, "zhipu") ||
 		strings.Contains(base, "xiaomimimo") ||
 		strings.Contains(base, "mimo") ||
+		strings.Contains(base, "minimax") ||
 		strings.Contains(model, "deepseek") ||
 		strings.Contains(model, "glm") ||
 		strings.Contains(model, "zai") ||
 		strings.Contains(model, "zhipu") ||
-		strings.Contains(model, "mimo"):
+		strings.Contains(model, "mimo") ||
+		strings.Contains(model, "minimax"):
 		return "thinking_type"
 	case openAIModelSupportsReasoningNone(model):
 		return "reasoning_none"

internal/backend/agent/model/openai_thinking_disable_minimax_test.go

@@ -0,0 +1,95 @@
+package modeladapter
+
+import "testing"
+
+// TestOpenAIThinkingDisableKindMiniMax verifies that the MiniMax OpenAI-compatible
+// endpoint is routed to the thinking_type disable branch, so that disabling
+// thinking writes thinking:{type:"disabled"} and drops reasoning_effort. This
+// covers the global endpoint, the China endpoint and a custom proxy that only
+// exposes the MiniMax model id, plus regression cases for the other branches.
+func TestOpenAIThinkingDisableKindMiniMax(t *testing.T) {
+	tests := []struct {
+		name     string
+		baseURL  string
+		modelID  string
+		endpoint string
+		want     string
+	}{
+		// MiniMax global endpoint
+		{name: "minimax global base + M3", baseURL: "https://api.minimax.io/v1", modelID: "MiniMax-M3", endpoint: "/chat/completions", want: "thinking_type"},
+		{name: "minimax global base + M2.7", baseURL: "https://api.minimax.io/v1", modelID: "MiniMax-M2.7", endpoint: "/chat/completions", want: "thinking_type"},
+		// MiniMax China endpoint
+		{name: "minimax cn base + M3", baseURL: "https://api.minimaxi.com/v1", modelID: "MiniMax-M3", endpoint: "/chat/completions", want: "thinking_type"},
+		{name: "minimax cn base + M2.7", baseURL: "https://api.minimaxi.com/v1", modelID: "MiniMax-M2.7", endpoint: "/chat/completions", want: "thinking_type"},
+		// MiniMax model id only (custom base)
+		{name: "minimax model only (custom base)", baseURL: "https://custom.proxy.example.com/v1", modelID: "MiniMax-M3", endpoint: "/chat/completions", want: "thinking_type"},
+		// Regression: enable_thinking branch (qwen) is unaffected
+		{name: "qwen via dashscope", baseURL: "https://dashscope.aliyuncs.com/v1", modelID: "qwen-max", endpoint: "/chat/completions", want: "enable_thinking"},
+		// Regression: reasoning_none branch (gpt-5.1+/gpt-6) is unaffected
+		{name: "gpt-6", baseURL: "https://api.openai.com/v1", modelID: "gpt-6", endpoint: "/chat/completions", want: "reasoning_none"},
+		// Regression: unknown provider does not disable
+		{name: "unknown provider", baseURL: "https://api.unknown-llm.com/v1", modelID: "some-model", endpoint: "/chat/completions", want: ""},
+	}
+	for _, tc := range tests {
+		t.Run(tc.name, func(t *testing.T) {
+			got := openAIThinkingDisableKind(tc.baseURL, tc.modelID, tc.endpoint)
+			if got != tc.want {
+				t.Fatalf("openAIThinkingDisableKind(%q, %q, %q) = %q, want %q", tc.baseURL, tc.modelID, tc.endpoint, got, tc.want)
+			}
+		})
+	}
+}
+
+// TestApplyOpenAIThinkingDisableMiniMax verifies that when ThinkingEffort=disabled
+// and the provider is MiniMax, applyOpenAIThinkingDisable writes
+// thinking:{type:"disabled"} and deletes reasoning_effort on both the global and
+// the China endpoint.
+func TestApplyOpenAIThinkingDisableMiniMax(t *testing.T) {
+	cases := []struct {
+		name    string
+		baseURL string
+		modelID string
+	}{
+		{name: "global endpoint", baseURL: "https://api.minimax.io/v1", modelID: "MiniMax-M3"},
+		{name: "china endpoint", baseURL: "https://api.minimaxi.com/v1", modelID: "MiniMax-M3"},
+	}
+	for _, tc := range cases {
+		t.Run(tc.name, func(t *testing.T) {
+			req := StreamRequest{ThinkingEffort: "disabled", RequestKnobs: map[string]any{}}
+			body := map[string]any{
+				"model":            tc.modelID,
+				"messages":         []map[string]any{{"role": "user", "content": "hi"}},
+				"reasoning_effort": "high",
+			}
+			applyOpenAIThinkingDisable(body, req, tc.baseURL, tc.modelID, "/chat/completions")
+
+			thinking, ok := body["thinking"].(map[string]any)
+			if !ok {
+				t.Fatalf("expected body[thinking] to be map[string]any, got %T (%v)", body["thinking"], body["thinking"])
+			}
+			if thinking["type"] != "disabled" {
+				t.Fatalf("expected thinking.type=disabled, got %v", thinking["type"])
+			}
+			if _, stillPresent := body["reasoning_effort"]; stillPresent {
+				t.Fatalf("reasoning_effort should be deleted when thinking disabled, got %v", body["reasoning_effort"])
+			}
+			if got := req.RequestKnobs["thinking_disabled_provider_param"]; got != "thinking.type" {
+				t.Fatalf("expected request knob thinking_disabled_provider_param=thinking.type, got %v", got)
+			}
+		})
+	}
+}
+
+// TestApplyOpenAIThinkingDisableMiniMaxNotTriggered verifies that a non-disabled
+// thinking effort does not inject the disable field for MiniMax.
+func TestApplyOpenAIThinkingDisableMiniMaxNotTriggered(t *testing.T) {
+	req := StreamRequest{ThinkingEffort: "high", RequestKnobs: map[string]any{}}
+	body := map[string]any{"model": "MiniMax-M3", "reasoning_effort": "high"}
+	applyOpenAIThinkingDisable(body, req, "https://api.minimax.io/v1", "MiniMax-M3", "/chat/completions")
+	if _, present := body["thinking"]; present {
+		t.Fatalf("thinking should not be injected when ThinkingEffort != disabled, got %v", body["thinking"])
+	}
+	if body["reasoning_effort"] != "high" {
+		t.Fatalf("reasoning_effort should be preserved when not disabled, got %v", body["reasoning_effort"])
+	}
+}