diff --git a/internal/smoke/service/smoke_ai_advice_service.go b/internal/smoke/service/smoke_ai_advice_service.go
index a772e76..d37bb27 100644
--- a/internal/smoke/service/smoke_ai_advice_service.go
+++ b/internal/smoke/service/smoke_ai_advice_service.go
@@ -31,8 +31,8 @@ const (
 )
 
 const (
-	SmokeAIAdviceTypeDaily      = "daily_advice"
-	SmokeAIAdviceTypeNextSmoke  = "next_smoke_time"
+	SmokeAIAdviceTypeDaily     = "daily_advice"
+	SmokeAIAdviceTypeNextSmoke = "next_smoke_time"
 )
 
 type SmokeAIAdviceService struct {
@@ -70,16 +70,17 @@ type adviceSnapshot struct {
 }
 
 type adviceUserProfile struct {
-	BaselineCigsPerDay        int      `json:"baseline_cigs_per_day,omitempty"`
-	SmokingYears              float64  `json:"smoking_years,omitempty"`
-	PackPriceCent             int      `json:"pack_price_cent,omitempty"`
-	SmokeMotivations          []string `json:"smoke_motivations,omitempty"`
-	QuitMotivations           []string `json:"quit_motivations,omitempty"`
-	WakeUpTime                string   `json:"wake_up_time,omitempty"`
-	SleepTime                 string   `json:"sleep_time,omitempty"`
-	AwakeMinutes              int      `json:"awake_minutes,omitempty"`
-	BaselineIntervalMinutes   int      `json:"baseline_interval_minutes,omitempty"`
-	OnboardingCompletedAtISO  string   `json:"onboarding_completed_at,omitempty"`
+	BaselineCigsPerDay       int      `json:"baseline_cigs_per_day,omitempty"`
+	SmokingYears             float64  `json:"smoking_years,omitempty"`
+	PackPriceCent            int      `json:"pack_price_cent,omitempty"`
+	SmokeMotivations         []string `json:"smoke_motivations,omitempty"`
+	QuitMotivations          []string `json:"quit_motivations,omitempty"`
+	WakeUpTime               string   `json:"wake_up_time,omitempty"`
+	SleepTime                string   `json:"sleep_time,omitempty"`
+	AwakeMinutes             int      `json:"awake_minutes,omitempty"`
+	BaselineIntervalMinutes  int      `json:"baseline_interval_minutes,omitempty"`
+	UserSegment              string   `json:"user_segment,omitempty"`
+	OnboardingCompletedAtISO string   `json:"onboarding_completed_at,omitempty"`
 }
 
 func (s *SmokeAIAdviceService) GetOrGenerate(ctx context.Context, user *usermodel.User, adviceDate time.Time, promptVersion string) (*smokemodel.SmokeAIAdvice, error) {
@@ -284,9 +285,9 @@ func (s *SmokeAIAdviceService) buildSnapshot(ctx context.Context, uid int, advic
 			timeLabel = t.eventAt.Format("15:04")
 		}
 		nodes = append(nodes, adviceSnapshotNode{
-			Time:  timeLabel,
-			Num:   t.log.Num,
-			Level: t.log.Level,
+			Time:   timeLabel,
+			Num:    t.log.Num,
+			Level:  t.log.Level,
 			Remark: t.log.Remark,
 		})
 	}
@@ -334,6 +335,7 @@ func loadAdviceUserProfile(ctx context.Context, db *gorm.DB, uid int) *adviceUse
 		SleepTime:               sleep,
 		AwakeMinutes:            awake,
 		BaselineIntervalMinutes: baselineIntervalMinutes(awake, profile.BaselineCigsPerDay),
+		UserSegment:             deriveUserSegment(profile.BaselineCigsPerDay, profile.SmokingYears),
 	}
 	if profile.OnboardingCompletedAt != nil {
 		out.OnboardingCompletedAtISO = profile.OnboardingCompletedAt.In(time.Local).Format(time.RFC3339)
@@ -467,3 +469,13 @@ func truncateString(s string, max int) string {
 	}
 	return s[:max]
 }
+
+func deriveUserSegment(baselineCigsPerDay int, smokingYears float64) string {
+	if baselineCigsPerDay >= 20 || smokingYears >= 10 {
+		return "heavy"
+	}
+	if baselineCigsPerDay >= 10 || smokingYears >= 3 {
+		return "moderate"
+	}
+	return "newbie"
+}
diff --git a/internal/smoke/service/smoke_ai_advice_service_test.go b/internal/smoke/service/smoke_ai_advice_service_test.go
new file mode 100644
index 0000000..44432e5
--- /dev/null
+++ b/internal/smoke/service/smoke_ai_advice_service_test.go
@@ -0,0 +1,32 @@
+package service
+
+import "testing"
+
+func TestDeriveUserSegment(t *testing.T) {
+	t.Parallel()
+
+	tests := []struct {
+		name            string
+		baselinePerDay  int
+		smokingYears    float64
+		expectedSegment string
+	}{
+		{name: "新手用户", baselinePerDay: 6, smokingYears: 1.5, expectedSegment: "newbie"},
+		{name: "中度用户_按日均", baselinePerDay: 12, smokingYears: 1, expectedSegment: "moderate"},
+		{name: "中度用户_按烟龄", baselinePerDay: 8, smokingYears: 3.2, expectedSegment: "moderate"},
+		{name: "重度用户_按日均", baselinePerDay: 20, smokingYears: 2, expectedSegment: "heavy"},
+		{name: "重度用户_按烟龄", baselinePerDay: 9, smokingYears: 10, expectedSegment: "heavy"},
+	}
+
+	for _, tc := range tests {
+		tc := tc
+		t.Run(tc.name, func(t *testing.T) {
+			t.Parallel()
+
+			got := deriveUserSegment(tc.baselinePerDay, tc.smokingYears)
+			if got != tc.expectedSegment {
+				t.Fatalf("deriveUserSegment(%d, %.1f)=%s, want=%s", tc.baselinePerDay, tc.smokingYears, got, tc.expectedSegment)
+			}
+		})
+	}
+}