diff --git a/AIStudyApp/AIStudyApp/Features/Study/StudyHomeViewModel.swift b/AIStudyApp/AIStudyApp/Features/Study/StudyHomeViewModel.swift
index af61e50..b45acb0 100644
--- a/AIStudyApp/AIStudyApp/Features/Study/StudyHomeViewModel.swift
+++ b/AIStudyApp/AIStudyApp/Features/Study/StudyHomeViewModel.swift
@@ -1,6 +1,41 @@
 import Combine
 import Foundation
 
+// MARK: - Service protocols (for testability)
+
+protocol SessionServicing {
+    func list() async throws -> [LearningSession]
+}
+extension LearningSessionService: SessionServicing {}
+
+protocol ReviewServicing {
+    func dueCards() async throws -> [ReviewCard]
+}
+extension ReviewService: ReviewServicing {}
+
+protocol KBListServicing {
+    func list() async throws -> [KnowledgeBase]
+}
+extension KnowledgeBaseService: KBListServicing {}
+
+protocol QuizListServicing {
+    func listAll() async throws -> [Quiz]
+}
+extension QuizService: QuizListServicing {
+    func listAll() async throws -> [Quiz] { try await list() }
+}
+
+protocol ActivityHomeServicing {
+    func summary() async throws -> ActivitySummary
+    func streak() async throws -> ActivityStreak
+}
+extension ActivityService: ActivityHomeServicing {}
+
+protocol ContinueLearningServicing {
+    func getContinueLearning() async throws -> ContinueLearningResponse
+}
+extension ReadingAPIService: ContinueLearningServicing {}
+
 // MARK: - Action states
 
 enum MainAction: Equatable {
@@ -36,16 +71,39 @@ final class StudyHomeViewModel: ObservableObject {
     private var firstQuizId: String?
     private var firstKbId: String?
 
+    private let sessionService: SessionServicing
+    private let reviewService: ReviewServicing
+    private let quizService: QuizListServicing
+    private let kbService: KBListServicing
+    private let activityService: ActivityHomeServicing
+    private let continueService: ContinueLearningServicing
+
+    init(
+        sessionService: SessionServicing = LearningSessionService.shared,
+        reviewService: ReviewServicing = ReviewService.shared,
+        quizService: QuizListServicing = QuizService.shared,
+        kbService: KBListServicing = KnowledgeBaseService.shared,
+        activityService: ActivityHomeServicing = ActivityService.shared,
+        continueService: ContinueLearningServicing = ReadingAPIService.shared
+    ) {
+        self.sessionService = sessionService
+        self.reviewService = reviewService
+        self.quizService = quizService
+        self.kbService = kbService
+        self.activityService = activityService
+        self.continueService = continueService
+    }
+
     func loadAll() async {
         loadingState = .loading
         banner = nil
 
-        async let sessions = try? LearningSessionService.shared.list()
-        async let dueCards = try? ReviewService.shared.dueCards()
-        async let quizzes = try? QuizService.shared.list()
-        async let knowledgeBases = try? KnowledgeBaseService.shared.list()
-        async let summary = try? ActivityService.shared.summary()
-        async let streak = try? ActivityService.shared.streak()
+        async let sessions = try? sessionService.list()
+        async let dueCards = try? reviewService.dueCards()
+        async let quizzes = try? quizService.listAll()
+        async let knowledgeBases = try? kbService.list()
+        async let summary = try? activityService.summary()
+        async let streak = try? activityService.streak()
 
         let (sRes, dRes, qRes, kRes, sumRes, stRes) = await (sessions, dueCards, quizzes, knowledgeBases, summary, streak)
 
@@ -54,11 +112,9 @@ final class StudyHomeViewModel: ObservableObject {
         let quizzesResult = qRes ?? []
         let kbResult = kRes ?? []
 
-        // Store first IDs for navigation
         firstQuizId = quizzesResult.first?.id
         firstKbId = kbResult.first?.id
 
-        // Evaluate main action
         mainAction = await evaluatePriority(
             sessions: sessionsResult,
             dueCards: dueCardsResult,
@@ -66,7 +122,6 @@ final class StudyHomeViewModel: ObservableObject {
             knowledgeBases: kbResult
         )
 
-        // Stats
         todayReviewCount = dueCardsResult.count
         todayReviewEstimatedMinutes = max(1, dueCardsResult.count)
         availableQuizCount = quizzesResult.count
@@ -75,23 +130,17 @@ final class StudyHomeViewModel: ObservableObject {
         weeklyActiveDays = sumRes?.activeDays ?? 0
         streakDays = stRes?.currentStreak ?? 0
 
-        // Banner
-        banner = computeBanner(
-            sessions: sessionsResult,
-            quizzes: quizzesResult,
-            dueCards: dueCardsResult
-        )
-
+        banner = computeBanner(sessions: sessionsResult, quizzes: quizzesResult, dueCards: dueCardsResult)
         loadingState = .loaded
     }
 
     func refresh() async {
-        async let sessions = try? LearningSessionService.shared.list()
-        async let dueCards = try? ReviewService.shared.dueCards()
-        async let quizzes = try? QuizService.shared.list()
-        async let knowledgeBases = try? KnowledgeBaseService.shared.list()
-        async let summary = try? ActivityService.shared.summary()
-        async let streak = try? ActivityService.shared.streak()
+        async let sessions = try? sessionService.list()
+        async let dueCards = try? reviewService.dueCards()
+        async let quizzes = try? quizService.listAll()
+        async let knowledgeBases = try? kbService.list()
+        async let summary = try? activityService.summary()
+        async let streak = try? activityService.streak()
 
         let (sRes, dRes, qRes, kRes, sumRes, stRes) = await (sessions, dueCards, quizzes, knowledgeBases, summary, streak)
 
@@ -103,12 +152,7 @@ final class StudyHomeViewModel: ObservableObject {
         firstQuizId = quizzesResult.first?.id
         firstKbId = kbResult.first?.id
 
-        mainAction = await evaluatePriority(
-            sessions: sessionsResult,
-            dueCards: dueCardsResult,
-            quizzes: quizzesResult,
-            knowledgeBases: kbResult
-        )
+        mainAction = await evaluatePriority(sessions: sessionsResult, dueCards: dueCardsResult, quizzes: quizzesResult, knowledgeBases: kbResult)
 
         todayReviewCount = dueCardsResult.count
         todayReviewEstimatedMinutes = max(1, dueCardsResult.count)
@@ -127,8 +171,7 @@ final class StudyHomeViewModel: ObservableObject {
         quizzes: [Quiz],
         knowledgeBases: [KnowledgeBase]
     ) async -> MainAction {
-        // Priority 1: API continue-learning (most recent material with progress)
-        if let cl = try? await ReadingAPIService.shared.getContinueLearning(),
+        if let cl = try? await continueService.getContinueLearning(),
            let materialId = cl.materialId, !materialId.isEmpty,
            let resolved = MaterialPathResolver.resolve(materialId: materialId, apiType: cl.type, title: cl.title) {
             let kbTitle = cl.title ?? knowledgeBases.first?.title ?? "学习"
@@ -137,7 +180,6 @@ final class StudyHomeViewModel: ObservableObject {
             return .continueSession(materialId: materialId, filePath: resolved.filePath, materialType: resolved.materialType, kbTitle: kbTitle, elapsed: elapsed, resumePosition: pos)
         }
 
-        // Priority 2: Unfinished session (fallback)
         if let unfinished = sessions
             .filter({ $0.status != nil && $0.status != "completed" })
             .sorted(by: { ($0.startedAt ?? "") > ($1.startedAt ?? "") })
@@ -148,36 +190,25 @@ final class StudyHomeViewModel: ObservableObject {
             return .continueSession(materialId: unfinished.materialId ?? "", filePath: "", materialType: mt, kbTitle: kbTitle, elapsed: elapsed, resumePosition: nil)
         }
 
-        // Priority 2: Today's review
         if !dueCards.isEmpty {
             return .todaysReview(count: dueCards.count, estimatedMinutes: max(1, dueCards.count))
         }
 
-        // Priority 3: Self-test
         if let quizId = firstQuizId, !quizzes.isEmpty {
             return .selfTest(quizId: quizId, count: quizzes.count)
         }
 
-        // Priority 4: Start learning
         if let kbId = firstKbId, !knowledgeBases.isEmpty {
             return .startLearning(knowledgeBaseId: kbId, kbCount: knowledgeBases.count)
         }
 
-        // Priority 5: Empty
         return .empty
     }
 
     // MARK: - Banner
 
-    private func computeBanner(
-        sessions: [LearningSession],
-        quizzes: [Quiz],
-        dueCards: [ReviewCard]
-    ) -> String? {
-        // No banner needed if nothing is happening
-        if dueCards.isEmpty && quizzes.isEmpty && sessions.allSatisfy({ $0.status == "completed" }) {
-            return nil
-        }
+    private func computeBanner(sessions: [LearningSession], quizzes: [Quiz], dueCards: [ReviewCard]) -> String? {
+        if dueCards.isEmpty && quizzes.isEmpty && sessions.allSatisfy({ $0.status == "completed" }) { return nil }
         return nil
     }
 
@@ -188,7 +219,6 @@ final class StudyHomeViewModel: ObservableObject {
         let formatter = ISO8601DateFormatter()
         formatter.formatOptions = [.withInternetDateTime, .withFractionalSeconds]
         guard let date = formatter.date(from: iso) else {
-            // Try without fractional seconds
             formatter.formatOptions = [.withInternetDateTime]
             guard let date2 = formatter.date(from: iso) else { return "最近" }
             return relativeTime(from: date2)
diff --git a/AIStudyApp/AIStudyAppTests/StudyHomeViewModelTests.swift b/AIStudyApp/AIStudyAppTests/StudyHomeViewModelTests.swift
index 3c3dd01..47a9058 100644
--- a/AIStudyApp/AIStudyAppTests/StudyHomeViewModelTests.swift
+++ b/AIStudyApp/AIStudyAppTests/StudyHomeViewModelTests.swift
@@ -1,13 +1,74 @@
 import XCTest
 @testable import AIStudyApp
 
+// MARK: - Mock services
+
+private final class MockSessionService: SessionServicing {
+    var sessions: [LearningSession] = []
+    func list() async throws -> [LearningSession] { sessions }
+}
+
+private final class MockReviewService: ReviewServicing {
+    var cards: [ReviewCard] = []
+    func dueCards() async throws -> [ReviewCard] { cards }
+}
+
+private final class MockQuizListService: QuizListServicing {
+    var quizzes: [Quiz] = []
+    func listAll() async throws -> [Quiz] { quizzes }
+}
+
+private final class MockKBListService: KBListServicing {
+    var kbs: [KnowledgeBase] = []
+    func list() async throws -> [KnowledgeBase] { kbs }
+}
+
+private final class MockActivityHomeService: ActivityHomeServicing {
+    var summary: ActivitySummary?
+    var streak: ActivityStreak?
+    func summary() async throws -> ActivitySummary { try resultOrThrow(summary) }
+    func streak() async throws -> ActivityStreak { try resultOrThrow(streak) }
+}
+
+private final class MockContinueService: ContinueLearningServicing {
+    var response: ContinueLearningResponse?
+    func getContinueLearning() async throws -> ContinueLearningResponse { try resultOrThrow(response) }
+}
+
+private func resultOrThrow<T>(_ value: T?) throws -> T {
+    guard let v = value else { throw NSError(domain: "test", code: -1) }
+    return v
+}
+
+// MARK: - Tests
+
+@MainActor
 final class StudyHomeViewModelTests: XCTestCase {
 
     var vm: StudyHomeViewModel!
+    var mockSession: MockSessionService!
+    var mockReview: MockReviewService!
+    var mockQuiz: MockQuizListService!
+    var mockKB: MockKBListService!
+    var mockActivity: MockActivityHomeService!
+    var mockContinue: MockContinueService!
 
     override func setUp() {
         super.setUp()
-        vm = StudyHomeViewModel()
+        mockSession = MockSessionService()
+        mockReview = MockReviewService()
+        mockQuiz = MockQuizListService()
+        mockKB = MockKBListService()
+        mockActivity = MockActivityHomeService()
+        mockContinue = MockContinueService()
+        vm = StudyHomeViewModel(
+            sessionService: mockSession,
+            reviewService: mockReview,
+            quizService: mockQuiz,
+            kbService: mockKB,
+            activityService: mockActivity,
+            continueService: mockContinue
+        )
     }
 
     override func tearDown() {
@@ -15,46 +76,115 @@ final class StudyHomeViewModelTests: XCTestCase {
         super.tearDown()
     }
 
-    func testInitialState_hasFiveTasks() {
-        XCTAssertEqual(vm.tasks.count, 5)
+    // MARK: - Initial state
+
+    func test_initial_loadingState_is_idle() { XCTAssertEqual(vm.loadingState, .idle) }
+    func test_initial_mainAction_nil() { XCTAssertNil(vm.mainAction) }
+    func test_initial_todayReviewCount_zero() { XCTAssertEqual(vm.todayReviewCount, 0) }
+
+    // MARK: - loadAll() stats
+
+    func test_loadAll_sets_todayReviewCount() async {
+        mockReview.cards = [ReviewCard(id: "r1", front: "Q", back: "A")]
+        await vm.loadAll()
+        XCTAssertEqual(vm.todayReviewCount, 1)
     }
 
-    func testInitialState_twoTasksDone() {
-        XCTAssertEqual(vm.doneCount, 2)
+    func test_loadAll_sets_availableQuizCount() async {
+        mockQuiz.quizzes = [Quiz(id: "q1", knowledgeBaseId: "kb1", title: "Q", questionCount: 3, sourceType: "ai", status: "ready")]
+        await vm.loadAll()
+        XCTAssertEqual(vm.availableQuizCount, 1)
     }
 
-    func testProgress_calculatesCorrectly() {
-        XCTAssertEqual(vm.progress, 0.4, accuracy: 0.01)
+    func test_loadAll_sets_loadingState_loaded() async {
+        await vm.loadAll()
+        XCTAssertEqual(vm.loadingState, .loaded)
     }
 
-    func testToggleTask_changesDoneCount() {
-        let task = vm.tasks.first(where: { !$0.d })!
-        vm.toggleTask(task)
-        XCTAssertEqual(vm.doneCount, 3)
+    // MARK: - evaluatePriority: P1 Continue Session
+
+    func test_priority_continueSession_when_api_returns_progress() async {
+        mockContinue.response = ContinueLearningResponse(
+            type: "knowledge_source", materialId: "mat-001", title: "My Book",
+            lastProgress: 0.5, totalActiveSeconds: 300, lastReadAt: "2026-01-01T00:00:00.000Z", lastPosition: nil
+        )
+        let docs = FileManager.default.urls(for: .documentDirectory, in: .userDomainMask).first!
+        let fileURL = docs.appendingPathComponent("mat-001")
+        FileManager.default.createFile(atPath: fileURL.path, contents: "test".data(using: .utf8))
+        defer { try? FileManager.default.removeItem(at: fileURL) }
+
+        mockKB.kbs = [KnowledgeBase(id: "kb1", title: "My KB", description: nil, knowledgeCount: 5, sourceCount: 1, userId: "u1", createdAt: "2026-01-01")]
+
+        await vm.loadAll()
+
+        guard case .continueSession(let mid, _, _, _, _, _) = vm.mainAction else {
+            return XCTFail("Expected continueSession, got \(String(describing: vm.mainAction))")
+        }
+        XCTAssertEqual(mid, "mat-001")
     }
 
-    func testToggleTask_togglingBackRestoresCount() {
-        let task = vm.tasks.first(where: { $0.d })!
-        vm.toggleTask(task)
-        XCTAssertEqual(vm.doneCount, 1)
+    // MARK: - evaluatePriority: P2 TodaysReview
+
+    func test_priority_todaysReview_when_cards_present() async {
+        mockReview.cards = [ReviewCard(id: "r1", front: "Q", back: "A"), ReviewCard(id: "r2", front: "Q2", back: "A2")]
+        await vm.loadAll()
+
+        guard case .todaysReview(let count, let minutes) = vm.mainAction else {
+            return XCTFail("Expected todaysReview, got \(String(describing: vm.mainAction))")
+        }
+        XCTAssertEqual(count, 2)
+        XCTAssertEqual(minutes, 2)
     }
 
-    func testDoneMinutes_sumsCompletedTasks() {
-        XCTAssertEqual(vm.doneMinutes, 25) // 10 + 15
+    // MARK: - evaluatePriority: P3 SelfTest
+
+    func test_priority_selfTest_when_quizzes_available() async {
+        mockQuiz.quizzes = [Quiz(id: "q1", knowledgeBaseId: "kb1", title: "Q", questionCount: 5, sourceType: "ai", status: "ready")]
+        await vm.loadAll()
+
+        guard case .selfTest(let qid, let count) = vm.mainAction else {
+            return XCTFail("Expected selfTest")
+        }
+        XCTAssertEqual(qid, "q1")
+        XCTAssertEqual(count, 1)
     }
 
-    func testRemainingMinutes_sumsPendingTasks() {
-        XCTAssertEqual(vm.remainingMinutes, 30) // 8 + 12 + 10
+    // MARK: - evaluatePriority: P4 StartLearning
+
+    func test_priority_startLearning_when_kbs_available() async {
+        mockKB.kbs = [KnowledgeBase(id: "kb1", title: "KB", description: nil, knowledgeCount: 5, sourceCount: 1, userId: "u1", createdAt: "2026-01-01")]
+        await vm.loadAll()
+
+        guard case .startLearning(let kbId, let count) = vm.mainAction else {
+            return XCTFail("Expected startLearning")
+        }
+        XCTAssertEqual(kbId, "kb1")
+        XCTAssertEqual(count, 1)
     }
 
-    func testToggleTask_updatesProgress() {
-        let task = vm.tasks.first(where: { !$0.d })!
-        vm.toggleTask(task)
-        XCTAssertEqual(vm.progress, 0.6, accuracy: 0.01)
+    // MARK: - evaluatePriority: P5 Empty
+
+    func test_priority_empty_when_nothing_available() async {
+        await vm.loadAll()
+        XCTAssertEqual(vm.mainAction, .empty)
     }
 
-    func testWeekActivity_hasSevenDays() {
-        XCTAssertEqual(vm.weekActivity.count, 7)
-        XCTAssertEqual(vm.dayLabels.count, 7)
+    // MARK: - Banner
+
+    func test_banner_nil_when_all_empty() async {
+        await vm.loadAll()
+        XCTAssertNil(vm.banner)
+    }
+
+    // MARK: - Weekly stats
+
+    func test_loadAll_sets_weekly_stats_from_summary() async {
+        mockActivity.summary = ActivitySummary(totalMinutes: 120, totalCardsReviewed: 30, activeDays: 5, dailyAverage: 20)
+        mockActivity.streak = ActivityStreak(currentStreak: 3, longestStreak: 7, lastActiveDate: "2026-01-01")
+        await vm.loadAll()
+        XCTAssertEqual(vm.weeklyMinutes, 120)
+        XCTAssertEqual(vm.weeklyCardsReviewed, 30)
+        XCTAssertEqual(vm.weeklyActiveDays, 5)
+        XCTAssertEqual(vm.streakDays, 3)
     }
 }