根据提供的code differences信息，由于没有具体的代码变更内容，我将生成一个通用的commit message模板：

```
docs(readme): 更新文档说明

- 添加了项目使用指南
- 完善了API接口说明
- 修正了一些文字错误
```

注：由于未提供具体的代码差异信息，以上为示例格式。请提供具体的代码变更内容以便生成准确的commit message。

康康/Features/Trends/SeriesChartCard.swift

@@ -4,11 +4,23 @@ import Charts
 struct SeriesChartCard: View {
     let bucket: SeriesBucket
 
-    private var allPoints: [(line: SeriesBucket.SeriesLine, point: SeriesBucket.Point)] {
-        bucket.lines.flatMap { line in line.points.map { (line, $0) } }
+    // bucket 不可变,这些派生量在 init 里一次性算好存为 let,避免 body 内被
+    // header / chart / daysSpanLabel 多次访问时反复 flatMap / min / max 重算。
+    private let allPoints: [(line: SeriesBucket.SeriesLine, point: SeriesBucket.Point)]
+    private let dateDomain: ClosedRange<Date>?
+    private let valueDomain: ClosedRange<Double>?
+
+    init(bucket: SeriesBucket) {
+        self.bucket = bucket
+        let pts = bucket.lines.flatMap { line in line.points.map { (line, $0) } }
+        self.allPoints = pts
+        self.dateDomain = Self.makeDateDomain(pts)
+        self.valueDomain = Self.makeValueDomain(pts, lines: bucket.lines)
     }
 
-    private var dateDomain: ClosedRange<Date>? {
+    private static func makeDateDomain(
+        _ allPoints: [(line: SeriesBucket.SeriesLine, point: SeriesBucket.Point)]
+    ) -> ClosedRange<Date>? {
         let dates = allPoints.map(\.point.date)
         guard let lo = dates.min(), let hi = dates.max() else { return nil }
         if lo == hi {
@@ -21,14 +33,17 @@ struct SeriesChartCard: View {
         return lo...hi
     }
 
-    private var valueDomain: ClosedRange<Double>? {
+    private static func makeValueDomain(
+        _ allPoints: [(line: SeriesBucket.SeriesLine, point: SeriesBucket.Point)],
+        lines: [SeriesBucket.SeriesLine]
+    ) -> ClosedRange<Double>? {
         var lo = Double.greatestFiniteMagnitude
         var hi = -Double.greatestFiniteMagnitude
         for (_, p) in allPoints {
             lo = min(lo, p.value)
             hi = max(hi, p.value)
         }
-        for line in bucket.lines {
+        for line in lines {
             if let r = line.referenceRange {
                 lo = min(lo, r.lowerBound)
                 hi = max(hi, r.upperBound)

康康/Features/Trends/TrendDetailView.swift

@@ -506,7 +506,11 @@ private struct TrendInsightCard: View {
         do {
             text = try await TrendInsightService.shared.generate(for: bucket)
         } catch {
-            failedMessage = String(appLoc: "AI 解读暂不可用(模型未就绪或繁忙)")
+            // 区分「模型没下载」与「下载了但这次推理没成功」,前者给下载引导(CLAUDE.md §4)。
+            let downloaded = ModelStore.shared.isComplete(for: .mnnLLM) || ModelStore.shared.isComplete(for: .llm)
+            failedMessage = downloaded
+                ? String(appLoc: "本地推理这次没成功,点右上「解读」重试")
+                : String(appLoc: "AI 解读需先在「我的 · 模型管理」下载模型")
         }
         running = false
     }

康康/Features/Trends/TrendsView.swift

@@ -22,36 +22,32 @@ struct TrendsView: View {
                            customMetrics: customMetrics)
     }
 
-    private var monitorBuckets: [SeriesBucket] {
-        seriesBuckets.filter { $0.kind == .monitor }
-    }
-    private var labBuckets: [SeriesBucket] {
-        seriesBuckets.filter { $0.kind == .lab }
-    }
-
     private func filtered(_ buckets: [SeriesBucket]) -> [SeriesBucket] {
         let q = query.trimmingCharacters(in: .whitespaces)
         guard !q.isEmpty else { return buckets }
         return buckets.filter { $0.title.localizedCaseInsensitiveContains(q) }
     }
-    private var filteredMonitor: [SeriesBucket] { filtered(monitorBuckets) }
-    private var filteredLab: [SeriesBucket] { filtered(labBuckets) }
 
     var body: some View {
-        NavigationStack {
+        // SeriesBucket.build 一次性算,monitor / lab / 过滤全部本地派生 ——
+        // 杜绝一次渲染(及每次搜索按键)对整张指标表重复 build ~7 次。
+        let series = seriesBuckets
+        let monitor = filtered(series.filter { $0.kind == .monitor })
+        let lab = filtered(series.filter { $0.kind == .lab })
+        return NavigationStack {
             ScrollView(showsIndicators: false) {
                 VStack(alignment: .leading, spacing: 18) {
                     header.padding(.top, 4)
-                    if seriesBuckets.isEmpty {
+                    if series.isEmpty {
                         emptyState
-                    } else if filteredMonitor.isEmpty && filteredLab.isEmpty {
+                    } else if monitor.isEmpty && lab.isEmpty {
                         noMatchState
                     } else {
-                        if !filteredMonitor.isEmpty {
-                            section(title: String(appLoc: "长期监测"), buckets: filteredMonitor)
+                        if !monitor.isEmpty {
+                            section(title: String(appLoc: "长期监测"), buckets: monitor)
                         }
-                        if !filteredLab.isEmpty {
-                            section(title: String(appLoc: "化验指标趋势"), buckets: filteredLab)
+                        if !lab.isEmpty {
+                            section(title: String(appLoc: "化验指标趋势"), buckets: lab)
                         }
                     }
                 }