feat: 实现健康首页（今日大环 + 指标卡片，含 ViewModel 测试）

app/src/main/java/com/placeholder/ringhealth/AppViewModelProvider.kt

@@ -0,0 +1,27 @@
+package com.placeholder.ringhealth
+
+import androidx.lifecycle.ViewModelProvider
+import androidx.lifecycle.viewmodel.CreationExtras
+import androidx.lifecycle.viewmodel.initializer
+import androidx.lifecycle.viewmodel.viewModelFactory
+import com.placeholder.ringhealth.feature.home.HomeViewModel
+
+/**
+ * ViewModel 工厂：把容器中的仓库注入各 ViewModel。
+ * 每个 ViewModel 在这里注册一个 initializer；后续任务按需追加。
+ */
+object AppViewModelProvider {
+
+    val Factory = viewModelFactory {
+        initializer {
+            HomeViewModel(
+                healthDataRepository = ringHealthApplication().container.healthDataRepository,
+                ringDeviceRepository = ringHealthApplication().container.ringDeviceRepository,
+            )
+        }
+    }
+}
+
+/** 从 CreationExtras 中取出 Application 实例。 */
+fun CreationExtras.ringHealthApplication(): RingHealthApplication =
+    this[ViewModelProvider.AndroidViewModelFactory.APPLICATION_KEY] as RingHealthApplication

app/src/main/java/com/placeholder/ringhealth/feature/home/HomeScreen.kt

@@ -1,22 +1,275 @@
 package com.placeholder.ringhealth.feature.home
 
+import androidx.compose.foundation.layout.Arrangement
 import androidx.compose.foundation.layout.Box
+import androidx.compose.foundation.layout.Column
+import androidx.compose.foundation.layout.PaddingValues
+import androidx.compose.foundation.layout.Row
+import androidx.compose.foundation.layout.Spacer
 import androidx.compose.foundation.layout.fillMaxSize
+import androidx.compose.foundation.layout.fillMaxWidth
+import androidx.compose.foundation.layout.height
+import androidx.compose.foundation.layout.padding
+import androidx.compose.foundation.layout.size
+import androidx.compose.foundation.lazy.LazyColumn
+import androidx.compose.foundation.lazy.items
+import androidx.compose.material.icons.Icons
+import androidx.compose.material.icons.filled.Bloodtype
+import androidx.compose.material.icons.filled.Favorite
+import androidx.compose.material.icons.filled.MonitorHeart
+import androidx.compose.material.icons.filled.Spa
+import androidx.compose.material.icons.filled.Thermostat
+import androidx.compose.material.icons.filled.WaterDrop
+import androidx.compose.material.icons.filled.Bedtime
+import androidx.compose.material3.CircularProgressIndicator
+import androidx.compose.material3.Icon
+import androidx.compose.material3.MaterialTheme
 import androidx.compose.material3.Text
 import androidx.compose.runtime.Composable
+import androidx.compose.runtime.getValue
 import androidx.compose.ui.Alignment
 import androidx.compose.ui.Modifier
+import androidx.compose.ui.graphics.Color
+import androidx.compose.ui.graphics.vector.ImageVector
 import androidx.compose.ui.res.stringResource
+import androidx.compose.ui.tooling.preview.Preview
+import androidx.compose.ui.unit.dp
+import androidx.lifecycle.compose.collectAsStateWithLifecycle
+import androidx.lifecycle.viewmodel.compose.viewModel
+import com.placeholder.ringhealth.AppViewModelProvider
 import com.placeholder.ringhealth.R
+import com.placeholder.ringhealth.core.common.formatCalories
+import com.placeholder.ringhealth.core.common.formatDistance
+import com.placeholder.ringhealth.core.common.formatSleepDuration
+import com.placeholder.ringhealth.core.common.formatSteps
+import com.placeholder.ringhealth.core.designsystem.MetricBlue
+import com.placeholder.ringhealth.core.designsystem.MetricCyan
+import com.placeholder.ringhealth.core.designsystem.MetricGreen
+import com.placeholder.ringhealth.core.designsystem.MetricOrange
+import com.placeholder.ringhealth.core.designsystem.MetricPurple
+import com.placeholder.ringhealth.core.designsystem.MetricRed
+import com.placeholder.ringhealth.core.designsystem.MetricYellow
+import com.placeholder.ringhealth.core.designsystem.MetricValueStyle
+import com.placeholder.ringhealth.core.designsystem.RingHealthTheme
+import com.placeholder.ringhealth.core.designsystem.TextSecondary
+import com.placeholder.ringhealth.core.designsystem.component.HealthCard
+import com.placeholder.ringhealth.core.designsystem.component.MetricTile
+import com.placeholder.ringhealth.core.designsystem.component.RingProgress
+import com.placeholder.ringhealth.core.designsystem.component.SectionHeader
+import com.placeholder.ringhealth.domain.model.HealthSummary
 import com.placeholder.ringhealth.domain.model.MetricType
+import com.placeholder.ringhealth.domain.model.RingDeviceState
 
-/** 健康首页（占位，待 Task 8 实现）。 */
+/** 一个指标卡的数据。 */
+private data class MetricCardSpec(
+    val type: MetricType,
+    val icon: ImageVector,
+    val tint: Color,
+    val title: String,
+    val value: String?,
+    val unit: String,
+)
+
+/** 健康首页。 */
 @Composable
 fun HomeScreen(
     onOpenDetail: (MetricType) -> Unit,
     modifier: Modifier = Modifier,
+    viewModel: HomeViewModel = viewModel(factory = AppViewModelProvider.Factory),
 ) {
+    val state by viewModel.uiState.collectAsStateWithLifecycle()
+    HomeContent(state = state, onOpenDetail = onOpenDetail, modifier = modifier)
+}
+
+/** 无状态首页内容，便于 Preview。 */
+@Composable
+private fun HomeContent(
+    state: HomeUiState,
+    onOpenDetail: (MetricType) -> Unit,
+    modifier: Modifier = Modifier,
+) {
+    if (state.loading || state.summary == null) {
         Box(modifier = modifier.fillMaxSize(), contentAlignment = Alignment.Center) {
-        Text(stringResource(R.string.tab_home))
+            CircularProgressIndicator(color = MetricGreen)
+        }
+        return
+    }
+
+    val summary = state.summary
+    // 注意：LazyColumn 的 content lambda 不是 Composable 上下文，
+    // 所有需要 stringResource / Composable 调用的内容都必须在 LazyColumn 之前算好。
+    val cards = buildMetricCards(summary)
+    val notEnabledText = stringResource(R.string.home_not_enabled)
+    LazyColumn(
+        modifier = modifier.fillMaxSize(),
+        contentPadding = PaddingValues(16.dp),
+        verticalArrangement = Arrangement.spacedBy(12.dp),
+    ) {
+        item { DeviceStrip(device = state.device) }
+        item { StepsCard(summary = summary, onClick = { onOpenDetail(MetricType.STEP) }) }
+        item { SectionHeader(title = stringResource(R.string.home_metrics)) }
+        items(cards) { card ->
+            MetricTile(
+                icon = card.icon,
+                iconTint = card.tint,
+                title = card.title,
+                value = card.value ?: notEnabledText,
+                unit = if (card.value == null) "" else card.unit,
+                onClick = { onOpenDetail(card.type) },
+            )
+        }
+    }
+}
+
+/** 顶部设备连接状态条。 */
+@Composable
+private fun DeviceStrip(device: RingDeviceState?, modifier: Modifier = Modifier) {
+    HealthCard(modifier = modifier) {
+        Row(verticalAlignment = Alignment.CenterVertically) {
+            Icon(
+                imageVector = Icons.Filled.MonitorHeart,
+                contentDescription = null,
+                tint = MetricGreen,
+                modifier = Modifier.size(20.dp),
+            )
+            Column(modifier = Modifier.padding(start = 10.dp)) {
+                Text(
+                    text = if (device?.connected == true) {
+                        stringResource(R.string.home_device_connected, device.name)
+                    } else {
+                        stringResource(R.string.home_device_disconnected)
+                    },
+                    style = MaterialTheme.typography.bodyMedium,
+                )
+                if (device != null) {
+                    Text(
+                        text = stringResource(R.string.home_battery, device.batteryPercent),
+                        style = MaterialTheme.typography.bodySmall,
+                        color = TextSecondary,
+                    )
+                }
+            }
+        }
+    }
+}
+
+/** 今日步数大环卡片。 */
+@Composable
+private fun StepsCard(summary: HealthSummary, onClick: () -> Unit, modifier: Modifier = Modifier) {
+    HealthCard(modifier = modifier, onClick = onClick) {
+        Column(
+            modifier = Modifier.fillMaxWidth(),
+            horizontalAlignment = Alignment.CenterHorizontally,
+        ) {
+            Text(text = stringResource(R.string.home_steps_title), style = MaterialTheme.typography.titleMedium)
+            Spacer(modifier = Modifier.height(12.dp))
+            RingProgress(
+                progress = summary.steps.toFloat() / summary.stepGoal.coerceAtLeast(1),
+                color = MetricGreen,
+                trackColor = MetricGreen.copy(alpha = 0.15f),
+            ) {
+                Column(horizontalAlignment = Alignment.CenterHorizontally) {
+                    Text(text = formatSteps(summary.steps), style = MetricValueStyle)
+                    Text(
+                        text = stringResource(R.string.home_steps_goal, formatSteps(summary.stepGoal)),
+                        style = MaterialTheme.typography.bodySmall,
+                        color = TextSecondary,
+                    )
+                }
+            }
+            Spacer(modifier = Modifier.height(12.dp))
+            Row(
+                modifier = Modifier.fillMaxWidth(),
+                horizontalArrangement = Arrangement.SpaceEvenly,
+            ) {
+                SummaryMetric(
+                    value = formatDistance(summary.distanceKm),
+                    label = stringResource(R.string.home_distance_label),
+                    tint = MetricBlue,
+                )
+                SummaryMetric(
+                    value = formatCalories(summary.calories),
+                    label = stringResource(R.string.home_calories_label),
+                    tint = MetricOrange,
+                )
+            }
+        }
+    }
+}
+
+/** 环下方的小结指标。 */
+@Composable
+private fun SummaryMetric(value: String, label: String, tint: Color) {
+    Column(horizontalAlignment = Alignment.CenterHorizontally) {
+        Text(text = value, style = MaterialTheme.typography.titleMedium, color = tint)
+        Text(text = label, style = MaterialTheme.typography.bodySmall, color = TextSecondary)
+    }
+}
+
+/** 组装指标卡列表；value 为 null 表示该指标未开启。 */
+@Composable
+private fun buildMetricCards(summary: HealthSummary): List<MetricCardSpec> = listOf(
+    MetricCardSpec(
+        type = MetricType.HEART_RATE,
+        icon = Icons.Filled.Favorite,
+        tint = MetricRed,
+        title = stringResource(R.string.metric_heart_rate),
+        value = summary.heartRate?.toString(),
+        unit = stringResource(R.string.unit_bpm),
+    ),
+    MetricCardSpec(
+        type = MetricType.SLEEP,
+        icon = Icons.Filled.Bedtime,
+        tint = MetricBlue,
+        title = stringResource(R.string.metric_sleep),
+        value = summary.sleepMinutes?.let { formatSleepDuration(it) },
+        unit = "",
+    ),
+    MetricCardSpec(
+        type = MetricType.BLOOD_OXYGEN,
+        icon = Icons.Filled.Bloodtype,
+        tint = MetricCyan,
+        title = stringResource(R.string.metric_blood_oxygen),
+        value = summary.bloodOxygen?.toString(),
+        unit = stringResource(R.string.unit_percent),
+    ),
+    MetricCardSpec(
+        type = MetricType.STRESS,
+        icon = Icons.Filled.Spa,
+        tint = MetricPurple,
+        title = stringResource(R.string.metric_stress),
+        value = summary.stress?.toString(),
+        unit = "",
+    ),
+    MetricCardSpec(
+        type = MetricType.TEMPERATURE,
+        icon = Icons.Filled.Thermostat,
+        tint = MetricOrange,
+        title = stringResource(R.string.metric_temperature),
+        value = summary.temperature?.toString(),
+        unit = stringResource(R.string.unit_celsius),
+    ),
+    MetricCardSpec(
+        type = MetricType.BLOOD_PRESSURE,
+        icon = Icons.Filled.WaterDrop,
+        tint = MetricYellow,
+        title = stringResource(R.string.metric_blood_pressure),
+        value = summary.bloodPressure,
+        unit = stringResource(R.string.unit_mmhg),
+    ),
+)
+
+@Preview(showBackground = true)
+@Composable
+private fun HomeContentPreview() {
+    RingHealthTheme {
+        HomeContent(
+            state = HomeUiState(
+                loading = false,
+                summary = HealthSummary(8426, 10000, 327, 6.21, 72, 452, 98, 34, 36.5, null),
+                device = RingDeviceState(true, "RingHealth 智能戒指", 78, "1.0.5", false),
+            ),
+            onOpenDetail = {},
+        )
     }
 }

app/src/main/java/com/placeholder/ringhealth/feature/home/HomeViewModel.kt

@@ -0,0 +1,45 @@
+package com.placeholder.ringhealth.feature.home
+
+import androidx.lifecycle.ViewModel
+import androidx.lifecycle.viewModelScope
+import com.placeholder.ringhealth.domain.model.HealthSummary
+import com.placeholder.ringhealth.domain.model.RingDeviceState
+import com.placeholder.ringhealth.domain.repository.HealthDataRepository
+import com.placeholder.ringhealth.domain.repository.RingDeviceRepository
+import kotlinx.coroutines.flow.SharingStarted
+import kotlinx.coroutines.flow.StateFlow
+import kotlinx.coroutines.flow.combine
+import kotlinx.coroutines.flow.stateIn
+
+/**
+ * 首页 UI 状态。summary/device 为 null 表示仍在加载。
+ */
+data class HomeUiState(
+    val loading: Boolean,
+    val summary: HealthSummary?,
+    val device: RingDeviceState?,
+)
+
+/**
+ * 健康首页 ViewModel：合并今日概览与设备状态。
+ */
+class HomeViewModel(
+    healthDataRepository: HealthDataRepository,
+    ringDeviceRepository: RingDeviceRepository,
+) : ViewModel() {
+
+    val uiState: StateFlow<HomeUiState> = combine(
+        healthDataRepository.observeTodaySummary(),
+        ringDeviceRepository.deviceState,
+    ) { summary, device ->
+        HomeUiState(loading = false, summary = summary, device = device)
+    }.stateIn(
+        scope = viewModelScope,
+        started = SharingStarted.WhileSubscribed(STOP_TIMEOUT_MILLIS),
+        initialValue = HomeUiState(loading = true, summary = null, device = null),
+    )
+
+    private companion object {
+        const val STOP_TIMEOUT_MILLIS = 5_000L
+    }
+}

app/src/main/res/values/strings.xml

@@ -14,4 +14,26 @@
     <string name="placeholder_device_settings">设备设置</string>
     <string name="placeholder_workout_history">运动历史</string>
     <string name="placeholder_metric_detail">指标详情</string>
+
+    <string name="home_device_connected">%1$s · 已连接</string>
+    <string name="home_device_disconnected">未连接设备</string>
+    <string name="home_battery">电量 %1$d%%</string>
+    <string name="home_steps_title">今日步数</string>
+    <string name="home_steps_goal">目标 %1$s 步</string>
+    <string name="home_calories_label">千卡</string>
+    <string name="home_distance_label">公里</string>
+    <string name="home_metrics">健康指标</string>
+    <string name="home_not_enabled">未开启</string>
+    <string name="unit_bpm">次/分</string>
+    <string name="unit_percent">%</string>
+    <string name="unit_celsius">°C</string>
+    <string name="unit_mmhg">mmHg</string>
+
+    <string name="metric_heart_rate">心率</string>
+    <string name="metric_sleep">睡眠</string>
+    <string name="metric_blood_oxygen">血氧</string>
+    <string name="metric_stress">压力</string>
+    <string name="metric_temperature">体温</string>
+    <string name="metric_blood_pressure">血压</string>
+    <string name="metric_step">步数</string>
 </resources>

app/src/test/java/com/placeholder/ringhealth/feature/home/HomeViewModelTest.kt

@@ -0,0 +1,52 @@
+package com.placeholder.ringhealth.feature.home
+
+import com.placeholder.ringhealth.data.mock.MockHealthDataRepository
+import com.placeholder.ringhealth.data.mock.MockRingDeviceRepository
+import kotlinx.coroutines.Dispatchers
+import kotlinx.coroutines.ExperimentalCoroutinesApi
+import kotlinx.coroutines.launch
+import kotlinx.coroutines.test.StandardTestDispatcher
+import kotlinx.coroutines.test.advanceUntilIdle
+import kotlinx.coroutines.test.resetMain
+import kotlinx.coroutines.test.runTest
+import kotlinx.coroutines.test.setMain
+import org.junit.After
+import org.junit.Assert.assertEquals
+import org.junit.Assert.assertFalse
+import org.junit.Before
+import org.junit.Test
+
+/**
+ * [HomeViewModel] 的单元测试：验证加载完成后输出的今日概览与设备状态。
+ */
+@OptIn(ExperimentalCoroutinesApi::class)
+class HomeViewModelTest {
+
+    private val dispatcher = StandardTestDispatcher()
+
+    @Before
+    fun setUp() {
+        Dispatchers.setMain(dispatcher)
+    }
+
+    @After
+    fun tearDown() {
+        Dispatchers.resetMain()
+    }
+
+    @Test
+    fun `加载完成后输出今日概览与设备状态`() = runTest(dispatcher) {
+        val viewModel = HomeViewModel(MockHealthDataRepository(), MockRingDeviceRepository())
+
+        // uiState 用 SharingStarted.WhileSubscribed 构建，必须有订阅者才会启动上游数据流；
+        // 否则 .value 永远是初始值（loading = true）。用 backgroundScope 起一个收集者。
+        backgroundScope.launch { viewModel.uiState.collect {} }
+
+        advanceUntilIdle()
+
+        val state = viewModel.uiState.value
+        assertFalse(state.loading)
+        assertEquals(8426, state.summary?.steps)
+        assertEquals(78, state.device?.batteryPercent)
+    }
+}