feat(Trends): AI 趋势解读上线 — 数据指纹缓存,秒开不重算

Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>

康康/Services/TrendInsightService.swift

@@ -0,0 +1,94 @@
+import Foundation
+
+/// 趋势 AI 一句话解读:小预算(≤140 token)+ 按数据指纹缓存(UserDefaults)。
+/// 数据没变不重算 —— 进趋势详情页秒开;新增/修改记录改变指纹 → 自动重新生成。
+@MainActor
+final class TrendInsightService {
+    static let shared = TrendInsightService()
+    private init() {}
+
+    struct Cached: Codable, Equatable {
+        var fingerprint: String
+        var text: String
+        var generatedAt: Date
+    }
+
+    nonisolated static let storePrefix = "kk.trendInsight."
+
+    /// 数据指纹:每条线的 key + 点数 + 首末时间 + 末值/极值。体量小,直接当指纹字符串。
+    nonisolated static func fingerprint(for bucket: SeriesBucket) -> String {
+        var parts: [String] = [bucket.id]
+        for line in bucket.lines {
+            let pts = line.points
+            let first = pts.first.map { Int($0.date.timeIntervalSince1970) } ?? 0
+            let last = pts.last.map { Int($0.date.timeIntervalSince1970) } ?? 0
+            let lastV = pts.last?.value ?? 0
+            let minV = pts.map(\.value).min() ?? 0
+            let maxV = pts.map(\.value).max() ?? 0
+            parts.append("\(line.seriesKey)#\(pts.count)#\(first)#\(last)#\(lastV)#\(minV)#\(maxV)")
+        }
+        return parts.joined(separator: "|")
+    }
+
+    /// 命中缓存(指纹一致)返回文本,否则 nil。
+    func cachedText(for bucket: SeriesBucket) -> String? {
+        guard let data = UserDefaults.standard.data(forKey: Self.storePrefix + bucket.id),
+              let c = try? JSONDecoder().decode(Cached.self, from: data),
+              c.fingerprint == Self.fingerprint(for: bucket) else {
+            return nil
+        }
+        return c.text
+    }
+
+    /// 现算一条解读并写缓存。模型未就绪/输出为空时抛错,UI 显示「暂不可用 + 重试」。
+    func generate(for bucket: SeriesBucket) async throws -> String {
+        try await AIRuntime.shared.prepare()
+        let prompt = InsightPrompts.trendInsight(
+            title: bucket.title,
+            unit: bucket.unit,
+            rangeText: Self.rangeText(for: bucket),
+            dataLines: Self.dataLines(for: bucket)
+        )
+        var collected = ""
+        let stream = await AIRuntime.shared.generate(prompt: prompt, maxTokens: 140)
+        for try await chunk in stream { collected += chunk.text }
+        let text = HealthExportService.stripThinkBlocks(collected)
+            .trimmingCharacters(in: .whitespacesAndNewlines)
+        guard !text.isEmpty else { throw AIRuntimeError.inferenceFailed("空输出") }
+        let cached = Cached(fingerprint: Self.fingerprint(for: bucket), text: text, generatedAt: .now)
+        if let data = try? JSONEncoder().encode(cached) {
+            UserDefaults.standard.set(data, forKey: Self.storePrefix + bucket.id)
+        }
+        return text
+    }
+
+    /// 每条线最近 24 个点拼成 "yyyy-MM-dd 值";多线(血压)各占一行带 label 前缀。
+    /// 用 UTC 时区:展示日期仅供模型理解走向,差几小时无影响,但测试与设备时区无关。
+    nonisolated static func dataLines(for bucket: SeriesBucket) -> String {
+        let df = DateFormatter()
+        df.locale = Locale(identifier: "en_US_POSIX")
+        df.timeZone = TimeZone(identifier: "UTC")
+        df.dateFormat = "yyyy-MM-dd"
+        var lines: [String] = []
+        for line in bucket.lines {
+            let pts = line.points.suffix(24)
+            let prefix = bucket.lines.count > 1 ? "\(line.label ?? line.seriesKey):" : ""
+            let series = pts.map { "\(df.string(from: $0.date)) \(fmt($0.value))" }
+                .joined(separator: " / ")
+            lines.append(prefix + series)
+        }
+        return lines.joined(separator: "\n")
+    }
+
+    /// ",参考 lo-hi" 或空串(无参考范围时整段省略)。
+    nonisolated static func rangeText(for bucket: SeriesBucket) -> String {
+        guard let r = bucket.lines.first?.referenceRange else { return "" }
+        return ",参考 \(fmt(r.lowerBound))-\(fmt(r.upperBound))"
+    }
+
+    private nonisolated static func fmt(_ v: Double) -> String {
+        v.truncatingRemainder(dividingBy: 1) == 0
+            ? String(format: "%.0f", v)
+            : String(format: "%.1f", v)
+    }
+}