feat(Me): 性能自检卡 — 后端标识 + prefill/decode 实测 + 引擎对比存档

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

康康/Services/BenchmarkService.swift

@@ -0,0 +1,67 @@
+import Foundation
+
+/// 单次性能自检结果。按后端标签归档,供「MNN·SME2 vs MLX·GPU」对比展示(§12 卖点 2/6)。
+struct BenchmarkResult: Codable, Equatable {
+    var backendLabel: String
+    var promptTokens: Int
+    var genTokens: Int
+    var prefillTokensPerSecond: Double
+    var decodeTokensPerSecond: Double
+    var totalSeconds: Double
+    var date: Date
+}
+
+/// 性能自检服务:跑固定 prompt,取 AIRuntime 的归一统计,按后端标签存 UserDefaults。
+/// UI(ModelSelfTestView)只经本服务调 AIRuntime(§3.1)。
+@MainActor
+struct BenchmarkService {
+    static let shared = BenchmarkService()
+    private init() {}
+
+    nonisolated static let storeKey = "kk.benchmark.results"
+
+    /// 固定测试 prompt:跨设备/引擎可比的前提。
+    static let fixedPrompt = "用中文一句话介绍肝功能里 ALT 这个指标。"
+
+    /// 跑一次自检。onToken 把流式输出交给 UI 展示。
+    func run(onToken: @escaping @MainActor (String, Double) -> Void) async throws -> BenchmarkResult {
+        try await AIRuntime.shared.prepare()
+        let start = Date()
+        let stream = await AIRuntime.shared.generate(prompt: Self.fixedPrompt, maxTokens: 128)
+        for try await chunk in stream {
+            onToken(chunk.text, chunk.decodeRate)
+        }
+        let total = Date().timeIntervalSince(start)
+        let label = await AIRuntime.shared.activeBackendLabel
+        let stats = await AIRuntime.shared.lastGenerateStats
+        let result = BenchmarkResult(
+            backendLabel: label,
+            promptTokens: stats?.promptTokens ?? 0,
+            genTokens: stats?.genTokens ?? 0,
+            prefillTokensPerSecond: stats?.prefillTokensPerSecond ?? 0,
+            decodeTokensPerSecond: stats?.decodeTokensPerSecond ?? 0,
+            totalSeconds: total,
+            date: .now
+        )
+        Self.save(result)
+        return result
+    }
+
+    // MARK: - 存档(静态纯函数,单测覆盖;nonisolated:纯 UserDefaults 操作,无需主线程)
+
+    nonisolated static func save(_ result: BenchmarkResult, defaults: UserDefaults = .standard) {
+        var all = load(defaults: defaults)
+        all[result.backendLabel] = result
+        if let data = try? JSONEncoder().encode(all) {
+            defaults.set(data, forKey: storeKey)
+        }
+    }
+
+    nonisolated static func load(defaults: UserDefaults = .standard) -> [String: BenchmarkResult] {
+        guard let data = defaults.data(forKey: storeKey),
+              let all = try? JSONDecoder().decode([String: BenchmarkResult].self, from: data) else {
+            return [:]
+        }
+        return all
+    }
+}