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+# 播放模式切换功能 — iOS SDK 实施计划
+
+> **For agentic workers:** REQUIRED SUB-SKILL: Use superpowers:subagent-driven-development (recommended) or superpowers:executing-plans to implement this plan task-by-task. Steps use checkbox (`- [ ]`) syntax for tracking.
+
+**Goal:** 把 expo-duooomi-app commit `ac1520f` 的播放模式切换能力同步到 duooomi-ios-sdk —— 在协议字节层完全对齐 Expo 端的同时，提供 Swift 风格 `setPlayMode(_:userId:completion:)` API，并在 demo / README 中体现"必须先 bind 才能切模式"的前置约束。
+
+**Architecture:** 复用 `BIND_DEVICE` (0x0F) 命令字 —— 请求 payload 中携带 `loop` 字段切播放模式（不带则是绑定）。响应仍是 `BindingResponse`。SDK 在 `bind/unbind` 之间新增 `setPlayMode` 公共方法，复用现有 `sendAndWait` 机制；`BindPayload` 自定义 `encode(to:)` 严格省略 `nil`，避免输出 `"loop": null` 干扰固件判定。设备返回的 `DeviceInfo` 增可选 `loop` 字段（旧固件无此字段时为 `nil`）。
+
+**Tech Stack:** Swift 5.0+ / SwiftPM / XCTest / SwiftUI / CoreBluetooth / XcodeGen
+
+**参考 spec：** `docs/superpowers/specs/2026-05-06-play-mode-toggle-design.md`
+
+---
+
+## File Structure
+
+| 文件 | 责任 | 改动类型 |
+|------|------|----------|
+| `Package.swift` | SwiftPM 入口，统一 tools-version 语法 | 修（前置） |
+| `Sources/DuooomiBleSDK/Models/PlayMode.swift` | 播放模式枚举（公开类型） | 新建 |
+| `Sources/DuooomiBleSDK/Models/DeviceInfo.swift` | 设备信息 model 增可选 `loop` | 修 |
+| `Sources/DuooomiBleSDK/Services/DeviceInfoService.swift` | 命令服务：`BindPayload` 增可选 `loop` + 自定义 encode；新增 `setPlayMode` | 修 |
+| `Sources/DuooomiBleSDK/DuooomiBleSDK.swift` | SDK 公开 API：`setPlayMode(_:userId:completion:)`，含 `isActivated` 前置守卫 | 修 |
+| `Tests/DuooomiBleSDKTests/PlayModeTests.swift` | `PlayMode` / `DeviceInfo.loop` / `BindPayload` 编码三组单元测试 | 新建 |
+| `demo/Sources/WrapperTestView.swift` | UI Single/Loop 按钮，`isActivated == false` 时禁用 | 修 |
+| `README.md` | API 章节增 "播放模式" 段落，**显著标注前置条件** | 修 |
+
+`demo/Sources/DemoApp.swift` 已暴露 `@Published deviceInfo`/`isActivated`，无需改动。
+
+---
+
+### Task 0: 修复 SwiftPM tools-version 语法
+
+**背景：** 当前 `Package.swift` 第一行 `// swift-tools-version: 5.0` 在 `:` 后含空格 —— 此语法仅 SwiftPM 5.4+ 支持。本机 Swift 6.3 工具链解析直接失败，`swift test` 无法启动；后续所有 TDD 步骤都依赖此命令。先修。
+
+**Files:**
+- Modify: `Package.swift:1`
+
+- [ ] **Step 1: 编辑文件，去掉冒号后空格**
+
+把第 1 行改成：
+
+```swift
+// swift-tools-version:5.0
+```
+
+- [ ] **Step 2: 验证 SwiftPM 能解析、占位测试能跑通**
+
+Run（在仓库根目录）:
+
+```bash
+swift test 2>&1 | tail -10
+```
+
+Expected: 编译通过，输出包含 `Test Suite 'PlaceholderTests' passed` 或类似 `Executed 1 test, with 0 failures`。
+
+- [ ] **Step 3: 提交**
+
+```bash
+git add Package.swift
+git commit -m "fix: tighten swift-tools-version directive for SwiftPM 5.0 parser"
+```
+
+---
+
+### Task 1: 新增 `PlayMode` 枚举
+
+**Files:**
+- Create: `Sources/DuooomiBleSDK/Models/PlayMode.swift`
+- Create: `Tests/DuooomiBleSDKTests/PlayModeTests.swift`
+
+- [ ] **Step 1: 写失败测试**
+
+新建 `Tests/DuooomiBleSDKTests/PlayModeTests.swift`：
+
+```swift
+import XCTest
+@testable import DuooomiBleSDK
+
+final class PlayModeTests: XCTestCase {
+    func testRawValues() {
+        XCTAssertEqual(PlayMode.single.rawValue, 0)
+        XCTAssertEqual(PlayMode.loop.rawValue, 1)
+    }
+
+    func testInitFromRawValue() {
+        XCTAssertEqual(PlayMode(rawValue: 0), .single)
+        XCTAssertEqual(PlayMode(rawValue: 1), .loop)
+        XCTAssertNil(PlayMode(rawValue: 2))
+    }
+
+    func testCodableRoundTrip() throws {
+        let data = try JSONEncoder().encode(PlayMode.loop)
+        XCTAssertEqual(String(data: data, encoding: .utf8), "1")
+        let decoded = try JSONDecoder().decode(PlayMode.self, from: Data("0".utf8))
+        XCTAssertEqual(decoded, .single)
+    }
+}
+```
+
+- [ ] **Step 2: 运行测试，确认失败**
+
+Run:
+
+```bash
+swift test --filter PlayModeTests 2>&1 | tail -15
+```
+
+Expected: 编译失败 `cannot find 'PlayMode' in scope`。
+
+- [ ] **Step 3: 实现枚举**
+
+新建 `Sources/DuooomiBleSDK/Models/PlayMode.swift`：
+
+```swift
+import Foundation
+
+/// 播放模式（设备端协议字段 `loop`）。
+///
+/// - `single` (0): 单播 —— 设备播完一次后停止
+/// - `loop`   (1): 循环播放 —— 设备循环播放当前内容
+public enum PlayMode: Int, Codable, Equatable {
+    case single = 0
+    case loop = 1
+}
+```
+
+- [ ] **Step 4: 运行测试，确认通过**
+
+Run:
+
+```bash
+swift test --filter PlayModeTests 2>&1 | tail -15
+```
+
+Expected: `Executed 3 tests, with 0 failures`。
+
+- [ ] **Step 5: 提交**
+
+```bash
+git add Sources/DuooomiBleSDK/Models/PlayMode.swift Tests/DuooomiBleSDKTests/PlayModeTests.swift
+git commit -m "feat: add PlayMode enum (single=0, loop=1)"
+```
+
+---
+
+### Task 2: `DeviceInfo` 增可选 `loop` 字段
+
+**Files:**
+- Modify: `Sources/DuooomiBleSDK/Models/DeviceInfo.swift`
+- Modify: `Tests/DuooomiBleSDKTests/PlayModeTests.swift`
+
+- [ ] **Step 1: 写失败测试**
+
+在 `Tests/DuooomiBleSDKTests/PlayModeTests.swift` 文件末尾追加新测试类：
+
+```swift
+final class DeviceInfoLoopTests: XCTestCase {
+    private func decode(_ json: String) throws -> DeviceInfo {
+        try JSONDecoder().decode(DeviceInfo.self, from: Data(json.utf8))
+    }
+
+    func testLoopMissingDecodesToNil() throws {
+        let json = #"{"name":"d1","size":"360","brand":"duomi","powerlevel":80,"allspace":1024,"freespace":512}"#
+        let info = try decode(json)
+        XCTAssertNil(info.loop)
+    }
+
+    func testLoopZeroDecodesToSingle() throws {
+        let json = #"{"name":"d1","size":"360","brand":"duomi","powerlevel":80,"allspace":1024,"freespace":512,"loop":0}"#
+        let info = try decode(json)
+        XCTAssertEqual(info.loop, .single)
+    }
+
+    func testLoopOneDecodesToLoop() throws {
+        let json = #"{"name":"d1","size":"360","brand":"duomi","powerlevel":80,"allspace":1024,"freespace":512,"loop":1}"#
+        let info = try decode(json)
+        XCTAssertEqual(info.loop, .loop)
+    }
+
+    func testLoopInvalidValueDecodesToNil() throws {
+        // 旧/异常固件返回非 0/1 值时不应崩溃，应当作未知 → nil
+        let json = #"{"name":"d1","size":"360","brand":"duomi","powerlevel":80,"allspace":1024,"freespace":512,"loop":7}"#
+        let info = try decode(json)
+        XCTAssertNil(info.loop)
+    }
+}
+```
+
+- [ ] **Step 2: 运行测试，确认失败**
+
+Run:
+
+```bash
+swift test --filter DeviceInfoLoopTests 2>&1 | tail -15
+```
+
+Expected: 4 个测试全部失败 — `value of type 'DeviceInfo' has no member 'loop'`。
+
+- [ ] **Step 3: 修改 model**
+
+替换 `Sources/DuooomiBleSDK/Models/DeviceInfo.swift` 全文为：
+
+```swift
+import Foundation
+
+public struct DeviceInfo: Equatable {
+    public let allspace: UInt64
+    public let freespace: UInt64
+    public let name: String
+    public let size: String
+    public let brand: String
+    public let powerlevel: Int
+    /// 播放模式（旧固件无此字段时为 nil）
+    public let loop: PlayMode?
+}
+
+extension DeviceInfo: Codable {
+    enum CodingKeys: String, CodingKey {
+        case allspace, freespace, name, size, brand, powerlevel, loop
+    }
+
+    public init(from decoder: Decoder) throws {
+        let container = try decoder.container(keyedBy: CodingKeys.self)
+
+        // All string fields: fallback to "" if missing
+        name = (try? container.decode(String.self, forKey: .name)) ?? ""
+        size = (try? container.decode(String.self, forKey: .size)) ?? ""
+        brand = (try? container.decode(String.self, forKey: .brand)) ?? ""
+
+        // powerlevel: Int, may come as Int or String
+        if let num = try? container.decode(Int.self, forKey: .powerlevel) {
+            powerlevel = num
+        } else if let str = try? container.decode(String.self, forKey: .powerlevel),
+                  let num = Int(str) {
+            powerlevel = num
+        } else {
+            powerlevel = 0
+        }
+
+        // allspace/freespace: may come as number, string, or be missing
+        allspace = Self.decodeFlexibleUInt64(container: container, key: .allspace)
+        freespace = Self.decodeFlexibleUInt64(container: container, key: .freespace)
+
+        // loop: optional. Accept Int 0/1; anything else → nil.
+        if let raw = try? container.decode(Int.self, forKey: .loop), let mode = PlayMode(rawValue: raw) {
+            loop = mode
+        } else {
+            loop = nil
+        }
+    }
+
+    private static func decodeFlexibleUInt64(
+        container: KeyedDecodingContainer<CodingKeys>,
+        key: CodingKeys
+    ) -> UInt64 {
+        if let value = try? container.decode(UInt64.self, forKey: key) {
+            return value
+        }
+        if let value = try? container.decode(Int.self, forKey: key) {
+            return UInt64(max(0, value))
+        }
+        if let str = try? container.decode(String.self, forKey: key),
+           let value = UInt64(str) {
+            return value
+        }
+        return 0
+    }
+}
+```
+
+- [ ] **Step 4: 运行测试，确认通过**
+
+Run:
+
+```bash
+swift test --filter DeviceInfoLoopTests 2>&1 | tail -15
+```
+
+Expected: `Executed 4 tests, with 0 failures`。
+
+- [ ] **Step 5: 提交**
+
+```bash
+git add Sources/DuooomiBleSDK/Models/DeviceInfo.swift Tests/DuooomiBleSDKTests/PlayModeTests.swift
+git commit -m "feat: add optional loop field to DeviceInfo"
+```
+
+---
+
+### Task 3: `BindPayload` 支持可选 `loop`（自定义 encode 严格省略 nil）
+
+**背景：** 这是协议字节层最关键的一步。Expo 端用 `zod.optional()` 在 `loop === undefined` 时省略字段。Swift 默认 `JSONEncoder` 对 `Optional<UInt8>` 为 `nil` 时输出 `"loop": null` —— 与 Expo 行为不一致，可能让设备误把"普通绑定"识别为"切模式"。必须自定义 `encode(to:)` 在 `loop == nil` 时不写入 key。
+
+**Files:**
+- Modify: `Sources/DuooomiBleSDK/Services/DeviceInfoService.swift`
+- Modify: `Tests/DuooomiBleSDKTests/PlayModeTests.swift`
+
+- [ ] **Step 1: 把 `BindPayload` 暴露为 internal，写失败测试**
+
+在 `Tests/DuooomiBleSDKTests/PlayModeTests.swift` 文件末尾追加：
+
+```swift
+final class BindPayloadEncodingTests: XCTestCase {
+    private func encode(_ payload: BindPayload) throws -> [String: Any] {
+        let data = try JSONEncoder().encode(payload)
+        return try JSONSerialization.jsonObject(with: data) as? [String: Any] ?? [:]
+    }
+
+    func testBindPayloadWithoutLoopOmitsKey() throws {
+        let payload = BindPayload(type: 0x0F, userId: "u1", loop: nil)
+        let dict = try encode(payload)
+        XCTAssertEqual(dict["type"] as? Int, 0x0F)
+        XCTAssertEqual(dict["userId"] as? String, "u1")
+        XCTAssertNil(dict["loop"], "loop key MUST be omitted when nil (not encoded as null)")
+        XCTAssertEqual(dict.count, 2)
+    }
+
+    func testBindPayloadWithLoopIncludesValue() throws {
+        let payload = BindPayload(type: 0x0F, userId: "u1", loop: 1)
+        let dict = try encode(payload)
+        XCTAssertEqual(dict["type"] as? Int, 0x0F)
+        XCTAssertEqual(dict["userId"] as? String, "u1")
+        XCTAssertEqual(dict["loop"] as? Int, 1)
+        XCTAssertEqual(dict.count, 3)
+    }
+
+    func testBindPayloadWithLoopZeroIncludesValue() throws {
+        let payload = BindPayload(type: 0x0F, userId: "u1", loop: 0)
+        let dict = try encode(payload)
+        XCTAssertEqual(dict["loop"] as? Int, 0)
+    }
+}
+```
+
+- [ ] **Step 2: 运行测试，确认失败**
+
+Run:
+
+```bash
+swift test --filter BindPayloadEncodingTests 2>&1 | tail -15
+```
+
+Expected: 编译失败 `cannot find 'BindPayload' in scope` 或 `'BindPayload' is inaccessible due to 'private' protection level`（因为当前 `BindPayload` 是 `private struct`）。
+
+- [ ] **Step 3: 修改服务层 — 把 `BindPayload` 提升为 internal、增可选 `loop`、自定义 encode、新增 `setPlayMode`**
+
+替换 `Sources/DuooomiBleSDK/Services/DeviceInfoService.swift` 全文为：
+
+```swift
+import Foundation
+
+/// 设备命令服务：发送 JSON 命令（fire-and-forget，响应由协议层回调处理）
+final class DeviceInfoService {
+    private let protocolService: BleProtocolService
+
+    init(protocolService: BleProtocolService) {
+        self.protocolService = protocolService
+    }
+
+    // MARK: - Commands
+
+    func getDeviceInfo() throws {
+        try protocolService.sendJSON(
+            type: .getDeviceInfo,
+            payload: CommandPayload(type: CommandType.getDeviceInfo.rawValue)
+        )
+    }
+
+    func getDeviceVersion() throws {
+        try protocolService.sendJSON(
+            type: .getDeviceVersion,
+            payload: CommandPayload(type: CommandType.getDeviceVersion.rawValue)
+        )
+    }
+
+    func bindDevice(userId: String) throws {
+        try protocolService.sendJSON(
+            type: .bindDevice,
+            payload: BindPayload(type: CommandType.bindDevice.rawValue, userId: userId, loop: nil)
+        )
+    }
+
+    func unbindDevice(userId: String) throws {
+        try protocolService.sendJSON(
+            type: .unbindDevice,
+            payload: BindPayload(type: CommandType.unbindDevice.rawValue, userId: userId, loop: nil)
+        )
+    }
+
+    /// 切换播放模式（复用 BIND_DEVICE 命令字 0x0F，payload 携带 loop 字段）
+    func setPlayMode(userId: String, loop: PlayMode) throws {
+        try protocolService.sendJSON(
+            type: .bindDevice,
+            payload: BindPayload(
+                type: CommandType.bindDevice.rawValue,
+                userId: userId,
+                loop: UInt8(loop.rawValue)
+            )
+        )
+    }
+
+    func deleteFile(key: String) throws {
+        try protocolService.sendJSON(
+            type: .deleteFile,
+            payload: FileKeyPayload(type: CommandType.deleteFile.rawValue, key: key)
+        )
+    }
+
+    func prepareTransfer(key: String, size: Int) throws {
+        try protocolService.sendJSON(
+            type: .prepareTransfer,
+            payload: PrepareTransferPayload(
+                type: CommandType.prepareTransfer.rawValue,
+                key: key,
+                size: size
+            )
+        )
+    }
+}
+
+// MARK: - Command Payloads
+
+private struct CommandPayload: Encodable {
+    let type: UInt8
+}
+
+/// 绑定 / 解绑 / 切模式 共用 payload。
+/// `loop == nil` 时严格省略该字段（不写 null），与 Expo 端 zod.optional 行为对齐。
+struct BindPayload: Encodable {
+    let type: UInt8
+    let userId: String
+    let loop: UInt8?
+
+    enum CodingKeys: String, CodingKey {
+        case type, userId, loop
+    }
+
+    func encode(to encoder: Encoder) throws {
+        var container = encoder.container(keyedBy: CodingKeys.self)
+        try container.encode(type, forKey: .type)
+        try container.encode(userId, forKey: .userId)
+        if let loop = loop {
+            try container.encode(loop, forKey: .loop)
+        }
+    }
+}
+
+private struct FileKeyPayload: Encodable {
+    let type: UInt8
+    let key: String
+}
+
+private struct PrepareTransferPayload: Encodable {
+    let type: UInt8
+    let key: String
+    let size: Int
+}
+```
+
+- [ ] **Step 4: 运行测试，确认通过**
+
+Run:
+
+```bash
+swift test --filter BindPayloadEncodingTests 2>&1 | tail -15
+```
+
+Expected: `Executed 3 tests, with 0 failures`。
+
+再跑全部测试确认未破坏其他用例：
+
+```bash
+swift test 2>&1 | tail -15
+```
+
+Expected: 所有 test class 通过（`PlaceholderTests` + `PlayModeTests` + `DeviceInfoLoopTests` + `BindPayloadEncodingTests`，共 11 个测试）。
+
+- [ ] **Step 5: 提交**
+
+```bash
+git add Sources/DuooomiBleSDK/Services/DeviceInfoService.swift Tests/DuooomiBleSDKTests/PlayModeTests.swift
+git commit -m "feat: extend BindPayload with optional loop field; add setPlayMode service"
+```
+
+---
+
+### Task 4: SDK 公开 `setPlayMode` API（含 `isActivated` 前置守卫）
+
+**背景：** SDK 层方法依赖真实 BLE 通信，无法在 SwiftPM 单测里全程跑通。能单测的部分：**未连接 / 未绑定** 时的前置守卫直接返回错误，不发送任何命令。其余依赖 demo 真机验证。
+
+**Files:**
+- Modify: `Sources/DuooomiBleSDK/DuooomiBleSDK.swift:295-322`（在 `bind` 和 `unbind` 之间插入）
+- Modify: `Tests/DuooomiBleSDKTests/PlayModeTests.swift`
+
+- [ ] **Step 1: 写失败测试 — 仅覆盖前置守卫**
+
+在 `Tests/DuooomiBleSDKTests/PlayModeTests.swift` 文件末尾追加：
+
+```swift
+final class SetPlayModeGuardTests: XCTestCase {
+    private func makeSDK() -> DuooomiBleSDK {
+        DuooomiBleSDK(config: DuooomiBleConfig(apiKey: "test"))
+    }
+
+    func testSetPlayModeFailsWhenNotConnected() {
+        let sdk = makeSDK()
+        let exp = expectation(description: "completion")
+        sdk.setPlayMode(.loop, userId: "u1") { result in
+            switch result {
+            case .success:
+                XCTFail("expected failure when not connected")
+            case .failure(let error):
+                XCTAssertTrue("\(error)".lowercased().contains("connect"),
+                              "expected notConnected-style error, got \(error)")
+            }
+            exp.fulfill()
+        }
+        wait(for: [exp], timeout: 1.0)
+    }
+}
+```
+
+注：未绑定时的守卫测试需要 mock `connectedDevice` —— 当前 SDK 架构难以注入，留给真机验证。本测试只守住"未连接"这一最廉价但最常见的误用路径。
+
+- [ ] **Step 2: 运行测试，确认失败**
+
+Run:
+
+```bash
+swift test --filter SetPlayModeGuardTests 2>&1 | tail -15
+```
+
+Expected: 编译失败 `value of type 'DuooomiBleSDK' has no member 'setPlayMode'`。
+
+- [ ] **Step 3: 在 `DuooomiBleSDK.swift` 中实现公开方法**
+
+在 `Sources/DuooomiBleSDK/DuooomiBleSDK.swift` 找到 `bind(userId:completion:)` 方法的右花括号（第 292 行附近，`unbind(userId:completion:)` 之前），紧接其后插入：
+
+```swift
+    /// 切换播放模式（0=单播 / 1=循环播放）。
+    ///
+    /// 复用 `BIND_DEVICE` (0x0F) 命令通道；响应类型为 `BindingResponse`。
+    /// 成功后自动刷新一次 `deviceInfo`（含最新 `loop` 字段），与 expo 端行为对齐。
+    ///
+    /// - Important: 此方法要求 **设备已和该 `userId` 完成 `bind`**（即 `isActivated == true`）。
+    ///   未绑定状态下设备会返回 `success=0`；SDK 在客户端先做守卫，直接返回失败而不发命令。
+    /// - Note: `bind` / `unbind` / `setPlayMode` 共享 `0x0F` / `0x12` opId 通道，**不能并发**。
+    public func setPlayMode(
+        _ mode: PlayMode,
+        userId: String,
+        completion: @escaping (Result<BindingResponse, Error>) -> Void
+    ) {
+        guard ensureConnected(completion: completion) else { return }
+        guard isActivated else {
+            BleLog.w("setPlayMode called before bind (isActivated=false)", "Command")
+            DispatchQueue.main.async {
+                completion(.failure(DuooomiBleError.bindingFailed("Device not bound; call bind(userId:) first")))
+            }
+            return
+        }
+        BleLog.d("Sending setPlayMode (mode=\(mode), userId=\(userId))", "Command")
+
+        sendAndWait(commandType: .bindDevice, completion: { [weak self] result in
+            guard let self = self else { return }
+            switch result {
+            case .failure(let error):
+                completion(.failure(error))
+            case .success(let data):
+                do {
+                    let resp = try self.decodeResponse(BindingResponse.self, from: data)
+                    if resp.success != 1 {
+                        BleLog.w("setPlayMode failed: device rejected", "Command")
+                        completion(.failure(DuooomiBleError.bindingFailed("Set play mode failed")))
+                        return
+                    }
+                    BleLog.i("setPlayMode success: mode=\(mode)", "Command")
+                    // 自动刷新 deviceInfo（含最新 loop 字段）
+                    self.getDeviceInfo { _ in
+                        completion(.success(resp))
+                    }
+                } catch {
+                    completion(.failure(error))
+                }
+            }
+        }, send: {
+            try self.deviceInfoService.setPlayMode(userId: userId, loop: mode)
+        })
+    }
+
+```
+
+- [ ] **Step 4: 运行测试，确认通过**
+
+Run:
+
+```bash
+swift test --filter SetPlayModeGuardTests 2>&1 | tail -15
+```
+
+Expected: `Executed 1 test, with 0 failures`。
+
+再跑全部测试：
+
+```bash
+swift test 2>&1 | tail -15
+```
+
+Expected: 所有测试通过。
+
+- [ ] **Step 5: 提交**
+
+```bash
+git add Sources/DuooomiBleSDK/DuooomiBleSDK.swift Tests/DuooomiBleSDKTests/PlayModeTests.swift
+git commit -m "feat: add setPlayMode SDK API with isActivated precondition"
+```
+
+---
+
+### Task 5: Demo UI 加 Single/Loop 按钮
+
+**背景：** 单测覆盖完了协议层和守卫；demo 是真机验证入口。按钮需要 `isActivated == true` 才启用，把"必须先绑定"约束在 UI 上体现出来。
+
+**Files:**
+- Modify: `demo/Sources/WrapperTestView.swift:140-155`（Device 区按钮组）
+- Modify: `demo/Sources/WrapperTestView.swift:380-397` 之后（新增 `runSetPlayMode`）
+
+- [ ] **Step 1: 在 Device Section 内 `bind/unbind` 行后追加 PlayMode 行**
+
+打开 `demo/Sources/WrapperTestView.swift`，找到 `private var deviceSection: some View {` 内 `bind`/`unbind` 按钮所在的 `HStack`（约第 146-153 行），把它整体替换为：
+
+```swift
+            HStack {
+                TextField("userId", text: $userId)
+                    .textFieldStyle(.roundedBorder)
+                Button("bind") { runBind() }
+                    .buttonStyle(.bordered)
+                Button("unbind") { runUnbind() }
+                    .buttonStyle(.bordered)
+            }
+
+            HStack {
+                Text("PlayMode")
+                    .font(.caption)
+                Spacer()
+                if let mode = viewModel.deviceInfo?.loop {
+                    Text(mode == .loop ? "循环" : "单播")
+                        .font(.caption)
+                        .foregroundColor(.secondary)
+                }
+                Button("Single") { runSetPlayMode(.single) }
+                    .buttonStyle(.bordered)
+                Button("Loop") { runSetPlayMode(.loop) }
+                    .buttonStyle(.bordered)
+            }
+            .disabled(!viewModel.isActivated || isBusy)
+```
+
+`.disabled(!viewModel.isActivated || isBusy)` 关键：UI 层把"必须先 bind 才能切模式"显式表达出来。
+
+- [ ] **Step 2: 在 `runUnbind` 后新增 `runSetPlayMode` 方法**
+
+找到 `runUnbind` 方法的结束花括号（约 397 行），在其后插入：
+
+```swift
+    private func runSetPlayMode(_ mode: PlayMode) {
+        isBusy = true
+        log("→ setPlayMode(\(mode == .loop ? "loop" : "single"), userId=\(userId))")
+        viewModel.sdk.setPlayMode(mode, userId: userId) { [self] result in
+            DispatchQueue.main.async {
+                self.isBusy = false
+                switch result {
+                case .success(let resp):
+                    self.log("setPlayMode ✓ sn=\(resp.sn)", level: .success)
+                case .failure(let error):
+                    self.log("setPlayMode ✗ \(error.localizedDescription)", level: .error)
+                }
+            }
+        }
+    }
+```
+
+- [ ] **Step 3: 重新生成 Xcode 工程并编译 demo（验证 SwiftUI 引用正确）**
+
+Run:
+
+```bash
+xcodegen generate 2>&1 | tail -5
+xcodebuild -workspace demo.xcworkspace -scheme demo -sdk iphonesimulator -destination 'generic/platform=iOS Simulator' build 2>&1 | tail -10
+```
+
+Expected: 编译成功，最后一行包含 `BUILD SUCCEEDED`。
+
+如未安装 xcodegen：`brew install xcodegen`。
+
+- [ ] **Step 4: 真机/模拟器手测要点（人工验证清单）**
+
+> 这一步不写自动化，但必须人工跑一遍，结果记到 commit message 里。
+
+1. App 起来 → 扫描 → 连接到设备 → "Single" / "Loop" 按钮**应当为禁用态**（因 `isActivated == false`）
+2. 点 "bind"，绑定成功（log 出现 `bind ✓`） → "Single" / "Loop" 按钮变为可点
+3. 点 "Loop" → log 出现 `setPlayMode ✓`，PlayMode 行右侧文字变成 `循环`
+4. 点 "Single" → 同理变为 `单播`
+5. 点 "unbind" → 按钮再次禁用
+6. 不连接情况下点按钮（需注释掉 `.disabled` 临时验证）→ log 出现 `setPlayMode ✗ Not connected`-风格错误
+7. **回归** —— `bind` / `unbind` / `getDeviceInfo` / 文件传输 行为不变
+
+- [ ] **Step 5: 提交**
+
+```bash
+git add demo/Sources/WrapperTestView.swift demo.xcodeproj
+git commit -m "feat(demo): add Single/Loop play-mode buttons gated by isActivated"
+```
+
+---
+
+### Task 6: README 加"播放模式"段落 + 显著前置条件
+
+**Files:**
+- Modify: `README.md:106`（`unbind` 行之后插入）
+- Modify: `README.md:185`（`DeviceInfo` 数据类型块）
+
+- [ ] **Step 1: 在"设备命令"代码块插入 `setPlayMode` 用法**
+
+在 `README.md` 找到这一行：
+
+```
+sdk.unbind(userId: "user-id") { result in /* ... */ }
+sdk.deleteFile(key: "file-key") { result in /* ... */ }
+```
+
+把这两行替换为：
+
+````markdown
+sdk.unbind(userId: "user-id") { result in /* ... */ }
+sdk.deleteFile(key: "file-key") { result in /* ... */ }
+```
+
+#### 播放模式（Play Mode）
+
+> ⚠️ **前置条件 — 必须先绑定。** `setPlayMode` 复用 `BIND_DEVICE` (0x0F) 命令通道，固件设计上要求设备先和该 `userId` 完成 `bind`（即 SDK `isActivated == true`）才能切播放模式。SDK 在客户端做了守卫：未绑定时直接 fail，不会发命令。请在 UI 上禁用切换按钮，直到 `didChangeActivation(true)` 回调到达。
+
+```swift
+// 0 = 单播（播完一次停）/ 1 = 循环播放
+sdk.setPlayMode(.loop, userId: "user-id") { result in
+    switch result {
+    case .success:
+        // 成功后 SDK 自动刷新 deviceInfo，
+        // 通过 didUpdateDeviceInfo 回调拿到最新 info.loop
+        break
+    case .failure(let error):
+        print("setPlayMode failed: \(error)")
+    }
+}
+```
+
+**注意事项：**
+- `bind` / `unbind` / `setPlayMode` 共享 `0x0F` / `0x12` 响应通道，**不要并发调用**
+- 旧固件可能不支持 `loop` 字段 —— 此时 `DeviceInfo.loop` 为 `nil`，调用 `setPlayMode` 设备可能回 `success=0`
+````
+
+- [ ] **Step 2: 在"数据类型"块的 `DeviceInfo` 中加 `loop` 字段、并加 `PlayMode` 类型**
+
+把 `README.md` 中现有的 `DeviceInfo` 块：
+
+```swift
+// DeviceInfo — getDeviceInfo 返回
+public struct DeviceInfo {
+    let name: String         // 设备名
+    let brand: String        // 品牌
+    let size: String         // 屏幕尺寸
+    let powerlevel: Int      // 电量百分比
+    let allspace: UInt64     // 总存储（字节）
+    let freespace: UInt64    // 可用存储（字节）
+}
+```
+
+替换为：
+
+```swift
+// PlayMode — 播放模式
+public enum PlayMode: Int {
+    case single = 0          // 单播
+    case loop = 1            // 循环播放
+}
+
+// DeviceInfo — getDeviceInfo 返回
+public struct DeviceInfo {
+    let name: String         // 设备名
+    let brand: String        // 品牌
+    let size: String         // 屏幕尺寸
+    let powerlevel: Int      // 电量百分比
+    let allspace: UInt64     // 总存储（字节）
+    let freespace: UInt64    // 可用存储（字节）
+    let loop: PlayMode?      // 播放模式（旧固件无此字段时为 nil）
+}
+```
+
+- [ ] **Step 3: 验证 markdown 渲染（无自动化，肉眼快速过一遍）**
+
+Run:
+
+```bash
+grep -n "setPlayMode\|PlayMode\|前置条件" README.md
+```
+
+Expected: 输出至少 5 处匹配，包括 "前置条件 — 必须先绑定" 警示行。
+
+- [ ] **Step 4: 提交**
+
+```bash
+git add README.md
+git commit -m "docs: document setPlayMode API with bind-first precondition"
+```
+
+---
+
+### Task 7: 端到端验收
+
+- [ ] **Step 1: 全量测试**
+
+```bash
+swift test 2>&1 | tail -10
+```
+
+Expected: 总计约 12 个测试全部通过。
+
+- [ ] **Step 2: demo 编译**
+
+```bash
+xcodebuild -workspace demo.xcworkspace -scheme demo -sdk iphonesimulator -destination 'generic/platform=iOS Simulator' build 2>&1 | tail -5
+```
+
+Expected: `BUILD SUCCEEDED`。
+
+- [ ] **Step 3: 协议字节对比（关键回归 — 确认 bind/unbind 字节级未变）**
+
+在 `Tests/DuooomiBleSDKTests/PlayModeTests.swift` 末尾临时加一个对比测试（也可保留作为永久回归）：
+
+```swift
+final class BindPayloadByteRegressionTests: XCTestCase {
+    /// bind 改动前后字节级一致性（loop=nil 时不可输出 "loop":null）
+    func testBindPayloadJSONExactBytes() throws {
+        let payload = BindPayload(type: 0x0F, userId: "abc", loop: nil)
+        let data = try JSONEncoder().encode(payload)
+        let json = String(data: data, encoding: .utf8) ?? ""
+        // 顺序在 Encodable 中由 encode(to:) 决定 → "type" 先于 "userId"
+        XCTAssertEqual(json, #"{"type":15,"userId":"abc"}"#)
+        XCTAssertFalse(json.contains("loop"))
+        XCTAssertFalse(json.contains("null"))
+    }
+
+    func testSetPlayModePayloadJSONExactBytes() throws {
+        let payload = BindPayload(type: 0x0F, userId: "abc", loop: 1)
+        let data = try JSONEncoder().encode(payload)
+        let json = String(data: data, encoding: .utf8) ?? ""
+        XCTAssertEqual(json, #"{"type":15,"userId":"abc","loop":1}"#)
+    }
+}
+```
+
+Run:
+
+```bash
+swift test --filter BindPayloadByteRegressionTests 2>&1 | tail -10
+```
+
+Expected: 2 个测试通过。
+
+- [ ] **Step 4: 提交回归测试**
+
+```bash
+git add Tests/DuooomiBleSDKTests/PlayModeTests.swift
+git commit -m "test: add byte-level regression for bind/setPlayMode JSON encoding"
+```
+
+- [ ] **Step 5: 真机功能验收（人工，按 Task 5 Step 4 清单逐项过）**
+
+完成后：
+
+```bash
+git log --oneline -8
+```
+
+Expected: 看到 7 个新增 commit，按本 plan 顺序排列。
+
+---
+
+## Self-Review
+
+**Spec 覆盖：**
+- §3.1 PlayMode 枚举 → Task 1 ✓
+- §3.1 DeviceInfo.loop → Task 2 ✓
+- §3.2 BindPayload + 自定义 encode + setPlayMode 服务方法 → Task 3 ✓
+- §3.3 SDK 公开 API + isActivated 守卫 → Task 4 ✓
+- §3.4 Demo UI → Task 5 ✓
+- §4 README 文档（含必须先绑定）→ Task 6 ✓
+- §5 验证（编译 + 字节比对 + 真机）→ Task 7 ✓
+
+**类型一致性：**
+- `PlayMode` 在 Models / Service / SDK / DeviceInfo / README 全部一致用同名枚举 ✓
+- `BindPayload(type:userId:loop:)` 三个参数顺序在 service 内部 / 单测 / 回归测一致 ✓
+- `setPlayMode(_:userId:completion:)` 在 SDK 公开 API / demo 调用 / README 示例一致 ✓
+- `DuooomiBleError.bindingFailed("...")` 用现有错误类型，未引入新 case ✓
+
+**Placeholder 扫描：** 全文 grep "TBD/TODO/implement later/类似" → 无遗留。
+
+**前置条件覆盖：**
+- SDK 守卫（Task 4 isActivated 检查）✓
+- UI 守卫（Task 5 `.disabled(!viewModel.isActivated)`）✓
+- README 警示框（Task 6）✓
+- 用户人工验收清单（Task 5 Step 4）✓
diff --git a/docs/superpowers/specs/2026-05-06-play-mode-toggle-design.md b/docs/superpowers/specs/2026-05-06-play-mode-toggle-design.md
new file mode 100644
index 0000000..4bc49c4
--- /dev/null
+++ b/docs/superpowers/specs/2026-05-06-play-mode-toggle-design.md
@@ -0,0 +1,221 @@
+# 播放模式切换功能 — iOS SDK 同步方案
+
+**目标**：把 `expo-duooomi-app`(commit `ac1520f`) 的播放模式切换功能完整同步到 `duooomi-ios-sdk`，保持协议层一致，让 SDK 调用方用 Swift 风格 API 完成"单播 ⇄ 循环播放"切换。
+
+---
+
+## 1. 参考实现（Expo 端）
+
+提交 `ac1520f` 改动 5 个文件，核心机制：
+
+| 层 | 文件 | 改动 |
+|---|---|---|
+| 协议类型 | `ble/protocol/types.ts` | `DeviceInfoZod` 增 `loop: 0\|1\|undefined`；`BindingRequestZod` 增可选 `loop` |
+| 服务层 | `ble/services/DeviceInfoService.ts` | 新增 `setPlayMode(deviceId, userId, loop)` —— 复用 `BIND_DEVICE`(0x0F) 命令字，带上 `loop` 字段 |
+| 管理层 | `ble/managers/bleManager.ts` | 新增 `setPlayMode(loop): Promise<BindingResponse>` —— 复用 `bindDevice` 的 waitable 机制 |
+| UI | `app/device.tsx` | 设备信息卡片中显示当前模式 + 切换按钮 + loading；切换后调 `getDeviceInfo` 刷新 |
+
+**关键协议事实**：
+- 复用 `0x0F`(BIND_DEVICE) 作命令字，请求 payload 中 `loop` 字段为可选
+- 响应仍是 `BindingResponse`（含 `type/sn/success/contents`）
+- 设备返回的 `DeviceInfo` 中新增 `loop`(0=单播 / 1=循环)，旧固件可能没这字段
+- 设备能区分"绑定" vs "切播放模式"是因为 payload 里有无 `loop`，SDK 必须严格按"无 loop 时省略字段（不能传 null）"编码
+- **必须先 `bind` 成功才能 `setPlayMode`**：固件设计上设置播放模式的前置条件是设备已和该 `userId` 完成绑定（`success=1`）。SDK 通过 `isActivated == true` 反映此状态；调用 `setPlayMode` 前必须确保已绑定，否则设备会回 `success=0`
+
+## 2. iOS SDK 当前状态
+
+| Swift 对应位置 |
+|---|
+| `Sources/DuooomiBleSDK/Models/DeviceInfo.swift` |
+| `Sources/DuooomiBleSDK/Services/DeviceInfoService.swift`（私有 `BindPayload`） |
+| `Sources/DuooomiBleSDK/DuooomiBleSDK.swift`（公开 `bind/unbind`） |
+| `demo/Sources/WrapperTestView.swift`（Device Commands 区） |
+
+`DuooomiBleSDK.sendAndWait` 已支持基于 `commandType.rawValue` 的请求-响应配对，新增能力可直接复用。
+
+## 3. 设计
+
+### 3.1 类型与协议
+
+**新增枚举** `Sources/DuooomiBleSDK/Models/PlayMode.swift`：
+
+```swift
+public enum PlayMode: Int, Codable {
+    case single = 0   // 单播
+    case loop = 1     // 循环播放
+}
+```
+
+理由：暴露给业务层的 API 用强类型枚举，比 raw `Int` / `UInt8` 更安全；`rawValue` 直接对接协议层的 0/1 整数。
+
+**修改** `Models/DeviceInfo.swift`：
+
+- 增字段 `public let loop: PlayMode?`（可选，兼容旧固件）
+- `init(from:)` 容错：缺字段或值非 0/1 时返回 `nil`，不抛错
+
+### 3.2 协议层
+
+**修改** `Services/DeviceInfoService.swift`：
+
+将私有 `BindPayload` 替换为可选 `loop` 字段，并自定义 `encode(to:)`：
+
+```swift
+private struct BindPayload: Encodable {
+    let type: UInt8
+    let userId: String
+    let loop: UInt8?  // nil 时编码省略
+
+    enum CodingKeys: String, CodingKey { case type, userId, loop }
+
+    func encode(to encoder: Encoder) throws {
+        var c = encoder.container(keyedBy: CodingKeys.self)
+        try c.encode(type, forKey: .type)
+        try c.encode(userId, forKey: .userId)
+        if let loop = loop { try c.encode(loop, forKey: .loop) }
+    }
+}
+```
+
+**关键约束**：默认 `JSONEncoder` 会把 `nil` 编成 `"loop": null`，与 Expo 端的 `zod.optional()` "省略" 行为不一致 —— 设备固件可能据 key 是否存在区分动作，必须用自定义 encode 严格省略 nil。`bindDevice` / `unbindDevice` 现有调用因 `loop=nil` 走相同路径，报文与改动前完全一致。
+
+新增方法：
+
+```swift
+func setPlayMode(userId: String, loop: PlayMode) throws {
+    try protocolService.sendJSON(
+        type: .bindDevice,
+        payload: BindPayload(
+            type: CommandType.bindDevice.rawValue,
+            userId: userId,
+            loop: UInt8(loop.rawValue)
+        )
+    )
+}
+```
+
+`unbindDevice` 用独立 `UnbindPayload`(已有 `BindPayload` 复用，可保留，或拆出对应 `UnbindPayload` 二选一 —— 当前选择继续复用 `BindPayload(loop:nil)`，最小改动)。
+
+### 3.3 SDK 公开 API
+
+**修改** `DuooomiBleSDK.swift`，在 `bind/unbind` 之间新增：
+
+```swift
+/// 切换播放模式（0=单播 / 1=循环播放）
+/// 复用 BIND_DEVICE 命令通道；响应类型为 BindingResponse。
+/// 成功后自动刷新一次 deviceInfo（与 expo 端行为对齐）。
+public func setPlayMode(
+    _ mode: PlayMode,
+    userId: String,
+    completion: @escaping (Result<BindingResponse, Error>) -> Void
+) {
+    guard ensureConnected(completion: completion) else { return }
+    guard isActivated else {
+        BleLog.w("setPlayMode called before bind", "Command")
+        completion(.failure(DuooomiBleError.bindingFailed("Device not bound; call bind(userId:) first")))
+        return
+    }
+    BleLog.d("Sending setPlayMode (mode=\(mode), userId=\(userId))", "Command")
+
+    sendAndWait(commandType: .bindDevice, completion: { [weak self] result in
+        guard let self = self else { return }
+        switch result {
+        case .failure(let error):
+            completion(.failure(error))
+        case .success(let data):
+            do {
+                let resp = try self.decodeResponse(BindingResponse.self, from: data)
+                if resp.success != 1 {
+                    BleLog.w("setPlayMode failed", "Command")
+                    completion(.failure(DuooomiBleError.bindingFailed("Set play mode failed")))
+                    return
+                }
+                BleLog.i("setPlayMode success: mode=\(mode)", "Command")
+                // 自动刷新 deviceInfo（含最新 loop 字段）
+                self.getDeviceInfo { _ in
+                    completion(.success(resp))
+                }
+            } catch {
+                completion(.failure(error))
+            }
+        }
+    }, send: {
+        try self.deviceInfoService.setPlayMode(userId: userId, loop: mode)
+    })
+}
+```
+
+**重要约束 — 命令字冲突**：`bind` / `unbind` / `setPlayMode` 三者不可并发执行（前两者已有此约束，因都用 `sendAndWait` 的 opId = `"15"` / `"18"`；新方法用 `"15"`，与 `bind` 互斥）。这是与 expo 端一致的协议级限制；后续如需并发，须在协议帧 / opId 维度引入区分维度，超出本次同步范围。在 API 文档注释中明确说明。
+
+### 3.4 Demo 应用
+
+**修改** `demo/Sources/WrapperTestView.swift`，在 `bind / unbind` 按钮行下加一行：
+
+```swift
+HStack {
+    Button("Single (0)") { runSetPlayMode(.single) }
+    Button("Loop (1)")   { runSetPlayMode(.loop) }
+    if let mode = viewModel.deviceInfo?.loop {
+        Text("now: \(mode == .loop ? "循环" : "单播")")
+            .font(.caption)
+            .foregroundColor(.secondary)
+    }
+}
+.buttonStyle(.bordered)
+.disabled(viewModel.connectedDevice == nil || isBusy)
+```
+
+新增方法：
+
+```swift
+private func runSetPlayMode(_ mode: PlayMode) {
+    isBusy = true
+    log("→ setPlayMode(\(mode), userId=\(userId))")
+    viewModel.sdk.setPlayMode(mode, userId: userId) { [self] result in
+        DispatchQueue.main.async {
+            self.isBusy = false
+            switch result {
+            case .success(let resp):
+                self.log("setPlayMode ✓ sn=\(resp.sn)", level: .success)
+            case .failure(let error):
+                self.log("setPlayMode ✗ \(error.localizedDescription)", level: .error)
+            }
+        }
+    }
+}
+```
+
+`viewModel` 需暴露 `deviceInfo`（如未暴露则增 `@Published var deviceInfo: DeviceInfo?`，在 `didUpdateDeviceInfo` 回调里更新 —— 已存在则跳过）。
+
+## 4. 改动文件清单
+
+| # | 文件 | 改动类型 |
+|---|---|---|
+| 1 | `Sources/DuooomiBleSDK/Models/PlayMode.swift` | 新建 |
+| 2 | `Sources/DuooomiBleSDK/Models/DeviceInfo.swift` | 修改：增 `loop: PlayMode?` 字段及解码容错 |
+| 3 | `Sources/DuooomiBleSDK/Services/DeviceInfoService.swift` | 修改：`BindPayload` 增 `loop` + 自定义 encode；新增 `setPlayMode` 方法 |
+| 4 | `Sources/DuooomiBleSDK/DuooomiBleSDK.swift` | 修改：新增公开 `setPlayMode(_:userId:completion:)` |
+| 5 | `demo/Sources/WrapperTestView.swift` | 修改：UI 按钮（仅 `isActivated` 时启用）+ `runSetPlayMode` |
+| 6 | `README.md` | 修改：在 API 章节新增 `setPlayMode` 段落，**显著标注前置条件 — 必须先 `bind` 成功** |
+
+## 5. 验证
+
+1. **编译**：`xcodebuild -workspace demo.xcworkspace -scheme demo -sdk iphonesimulator build`
+2. **协议字节比对**：在真机上抓包/或加日志看发送的 JSON：
+   - `bind(userId)` → `{"type":15,"userId":"..."}`（无 loop 字段）
+   - `setPlayMode(.loop, userId)` → `{"type":15,"userId":"...","loop":1}`
+   - `unbind(userId)` → `{"type":18,"userId":"..."}`（不受影响）
+3. **真机功能**：连接设备 → bind → setPlayMode(.loop) → 设备模式确实切到循环；getDeviceInfo 返回的 `loop` 字段为 `.loop`
+4. **回归**：现有 `bind` / `unbind` 行为不变（payload 不变）
+
+## 6. 不在本次范围
+
+- iOS 端不需要 `userStore` —— Expo 端从全局 store 取 userId，iOS SDK 设计上由调用方（demo/上层 App）传入 `userId`，与 `bind/unbind` 一致
+- 自动重连后的播放模式自动恢复（expo 端也无此能力）
+- 多模式（>2）扩展 —— 当前协议只定义 0/1
+
+---
+
+**来源**：
+- expo-duooomi-app commit `ac1520f`(2026-04-20)
+- duooomi-ios-sdk @ `f42944b`(2026-05-06 当前 HEAD)
+- 对话日期：2026-05-06