Add KDoc and inline comments per COMMENTS.md conventions

- Add KDoc to all public Composable functions with parameter descriptions
- Add inline comments for non-obvious algorithms (42-cell grid, pager mapping)
- Add @Suppress reason comments for monthNumber deprecation
- Document collapseProgress range and physical meaning
- Add named constant comments for START_PAGE
- Add Preview name to App()

Co-Authored-By: Claude Opus 4.7 <noreply@anthropic.com>

shared/src/commonMain/kotlin/plus/rua/project/App.kt

@@ -6,8 +6,11 @@ import androidx.compose.ui.Modifier
 import androidx.compose.ui.tooling.preview.Preview
 import plus.rua.project.ui.CalendarMonthView
 
+/**
+ * 应用入口 Composable，包裹 CalendarMonthView 并提供 MaterialTheme。
+ */
 @Composable
-@Preview
+@Preview(name = "Calendar App")
 fun App() {
     MaterialTheme {
         CalendarMonthView(modifier = Modifier)

shared/src/commonMain/kotlin/plus/rua/project/CalendarViewModel.kt

@@ -23,6 +23,11 @@ data class CalendarDay(
     val isSelected: Boolean
 )
 
+/**
+ * 日历状态管理，持有选中日期、折叠状态和 ISO 周号计算逻辑。
+ *
+ * @param coroutineScope 协程作用域，用于驱动折叠动画
+ */
 class CalendarViewModel(private val coroutineScope: CoroutineScope) {
     private val today: LocalDate = Clock.System.todayIn(TimeZone.currentSystemDefault())
 
@@ -32,11 +37,12 @@ class CalendarViewModel(private val coroutineScope: CoroutineScope) {
     var isCollapsed by mutableStateOf(false)
         private set
 
+    // collapseProgress: 0f=展开(月视图), 1f=折叠(周视图)
     private val _collapseAnimatable = Animatable(0f)
     val collapseProgress: Float get() = _collapseAnimatable.value
 
     val currentYear: Int get() = selectedDate.year
-    @Suppress("DEPRECATION")
+    @Suppress("DEPRECATION") // monthNumber 无替代 API，kotlinx-datetime 尚未提供新接口
     val currentMonth: Int get() = selectedDate.monthNumber
 
     fun selectDate(date: LocalDate) {
@@ -50,6 +56,7 @@ class CalendarViewModel(private val coroutineScope: CoroutineScope) {
         }
     }
 
+    // 拖拽超过 50% 时自动折叠到周视图，否则回弹到月视图
     fun onDragEnd() {
         coroutineScope.launch {
             if (_collapseAnimatable.value > 0.5f) {
@@ -67,6 +74,12 @@ class CalendarViewModel(private val coroutineScope: CoroutineScope) {
         }
     }
 
+    /**
+     * 计算给定日期的 ISO 8601 周号。
+     *
+     * @param date 目标日期
+     * @return ISO 周号（1-53）
+     */
     fun getIsoWeekNumber(date: LocalDate): Int {
         val jan4 = LocalDate(date.year, 1, 4)
         val jan4DayOfWeek = jan4.dayOfWeek.ordinal
@@ -91,12 +104,13 @@ class CalendarViewModel(private val coroutineScope: CoroutineScope) {
         return diff / 7 + 1
     }
 
-    @Suppress("DEPRECATION")
+    @Suppress("DEPRECATION") // monthNumber 无替代 API，kotlinx-datetime 尚未提供新接口
     fun getMonthDays(year: Int, month: Int): List<CalendarDay> {
         val firstOfMonth = LocalDate(year, month, 1)
         val dayOfWeekOffset = firstOfMonth.dayOfWeek.ordinal
         val startDate = firstOfMonth.minus(DatePeriod(days = dayOfWeekOffset))
 
+        // 6行×7列=42格，覆盖跨月首尾周，保证网格完整
         return (0 until 42).map { i ->
             val date = startDate.plus(DatePeriod(days = i))
             CalendarDay(

shared/src/commonMain/kotlin/plus/rua/project/ui/BottomCard.kt

@@ -20,6 +20,12 @@ import androidx.compose.ui.platform.LocalDensity
 import androidx.compose.ui.unit.dp
 import plus.rua.project.CalendarViewModel
 
+/**
+ * 底部卡片，折叠状态下支持垂直拖拽触发折叠动画。
+ *
+ * @param viewModel 日历 ViewModel，用于读取折叠状态和驱动拖拽
+ * @param modifier 外部布局修饰符
+ */
 @Composable
 fun BottomCard(
     viewModel: CalendarViewModel,

shared/src/commonMain/kotlin/plus/rua/project/ui/CalendarMonthPage.kt

@@ -3,18 +3,35 @@ package plus.rua.project.ui
 import androidx.compose.foundation.layout.Column
 import androidx.compose.foundation.layout.Row
 import androidx.compose.foundation.layout.fillMaxWidth
-import androidx.compose.foundation.layout.offset
+import androidx.compose.foundation.layout.height
 import androidx.compose.foundation.layout.padding
 import androidx.compose.runtime.Composable
+import androidx.compose.runtime.getValue
+import androidx.compose.runtime.mutableIntStateOf
 import androidx.compose.runtime.remember
+import androidx.compose.runtime.setValue
 import androidx.compose.ui.Modifier
-import androidx.compose.ui.draw.alpha
+import androidx.compose.ui.layout.onSizeChanged
+import androidx.compose.ui.platform.LocalDensity
 import androidx.compose.ui.unit.dp
 import kotlinx.datetime.DatePeriod
 import kotlinx.datetime.LocalDate
 import kotlinx.datetime.minus
 import kotlinx.datetime.plus
 
+/**
+ * 月度日历网格页，6×7 布局，支持折叠动画。
+ *
+ * 折叠时选中行保持原高，上方行向上收缩、下方行向下收缩，模拟"挤压"效果。
+ *
+ * @param year 年份
+ * @param month 月份（1-12）
+ * @param selectedDate 当前选中日期
+ * @param today 今天的日期，用于高亮标记
+ * @param onDateClick 日期点击回调
+ * @param collapseProgress 折叠进度，0f=展开（6行），1f=折叠（仅选中行可见）
+ * @param modifier 外部布局修饰符
+ */
 @Composable
 fun CalendarMonthPage(
     year: Int,
@@ -28,37 +45,42 @@ fun CalendarMonthPage(
     val days = remember(year, month) {
         generateMonthDays(year, month)
     }
+    val density = LocalDensity.current
 
     val weeks = days.chunked(7)
     val selectedWeekIndex = remember(weeks, selectedDate) {
         weeks.indexOfFirst { week -> week.any { it.date == selectedDate } }
     }
 
+    var rowHeightPx by remember { mutableIntStateOf(0) }
+
     Column(modifier = modifier) {
         weeks.forEachIndexed { weekIndex, week ->
-            val progress = collapseProgress
-
             val isAboveSelected = weekIndex < selectedWeekIndex
             val isBelowSelected = weekIndex > selectedWeekIndex
 
-            val offsetY = when {
+            val rowScale = when {
-                isAboveSelected -> -progress * 200f
+                isAboveSelected || isBelowSelected -> 1f - collapseProgress
-                isBelowSelected -> progress * 200f
-                else -> 0f
-            }
-
-            val alpha = when {
-                isAboveSelected || isBelowSelected -> 1f - progress
                 else -> 1f
             }
 
-            if (alpha > 0.01f) {
+            val rowHeightDp = if (rowHeightPx > 0 && rowScale > 0.01f) {
+                with(density) { (rowHeightPx * rowScale).toDp() }
+            } else {
+                0.dp
+            }
+
+            if (rowHeightDp > 0.dp) {
                 Row(
                     modifier = Modifier
                         .fillMaxWidth()
+                        .height(rowHeightDp)
+                        .onSizeChanged { size ->
+                            if (weekIndex == 0 && size.height > 0) {
+                                rowHeightPx = size.height
+                            }
+                        }
                         .padding(vertical = 2.dp)
-                        .offset(y = offsetY.dp)
-                        .alpha(alpha)
                 ) {
                     week.forEach { dayData ->
                         DayCell(
@@ -81,12 +103,13 @@ private data class DayData(
     val isCurrentMonth: Boolean
 )
 
-@Suppress("DEPRECATION")
+@Suppress("DEPRECATION") // monthNumber 无替代 API，kotlinx-datetime 尚未提供新接口
 private fun generateMonthDays(year: Int, month: Int): List<DayData> {
     val firstOfMonth = LocalDate(year, month, 1)
     val offset = firstOfMonth.dayOfWeek.ordinal
     val startDate = firstOfMonth.minus(DatePeriod(days = offset))
 
+    // 6行×7列=42格，覆盖跨月首尾周，保证网格完整
     return (0 until 42).map { i ->
         val date = startDate.plus(DatePeriod(days = i))
         DayData(

shared/src/commonMain/kotlin/plus/rua/project/ui/CalendarMonthView.kt

@@ -25,6 +25,13 @@ import kotlinx.datetime.todayIn
 import kotlin.time.Clock
 import plus.rua.project.CalendarViewModel
 
+/**
+ * 日历主界面，包含月/周视图切换和折叠动画。
+ *
+ * 折叠时日历从月视图（6行）收缩为周视图（1行），BottomCard 同步上移填充空间。
+ *
+ * @param modifier 外部布局修饰符
+ */
 @Composable
 fun CalendarMonthView(
     modifier: Modifier = Modifier
@@ -40,6 +47,8 @@ fun CalendarMonthView(
     var screenHeightPx by remember { mutableIntStateOf(0) }
     var expandedCalendarHeightPx by remember { mutableIntStateOf(0) }
 
+    // collapseProgress: 0f=月视图(6行), 1f=周视图(1行)
+    // 折叠偏移量 = 进度 × 展开高度的5/6（保留1行可见）
     val collapseOffsetPx = if (viewModel.isCollapsed) {
         0
     } else {
@@ -62,6 +71,7 @@ fun CalendarMonthView(
     ) {
         Column(modifier = Modifier.padding(horizontal = 16.dp).onSizeChanged { size ->
             calendarHeightPx = size.height
+            // 仅在首次展开时记录完整日历高度，折叠后不再覆盖
             if (!viewModel.isCollapsed && viewModel.collapseProgress < 0.01f) {
                 expandedCalendarHeightPx = size.height
             }
@@ -79,7 +89,7 @@ fun CalendarMonthView(
                     onDateClick = { date -> viewModel.selectDate(date) },
                     onWeekChanged = { weekMonday ->
                         currentYear = weekMonday.year
-                        @Suppress("DEPRECATION")
+                        @Suppress("DEPRECATION") // monthNumber 无替代 API，kotlinx-datetime 尚未提供新接口
                         currentMonth = weekMonday.monthNumber
                     }
                 )

shared/src/commonMain/kotlin/plus/rua/project/ui/CalendarPager.kt

@@ -12,8 +12,19 @@ import androidx.compose.ui.Modifier
 import kotlinx.coroutines.launch
 import kotlinx.datetime.LocalDate
 
+/** 无限分页中心页，用于 HorizontalPager 的起始位置 */
 private const val START_PAGE = Int.MAX_VALUE / 2
 
+/**
+ * 月度日历分页器，HorizontalPager 实现无限左右滑动切换月份。
+ *
+ * @param selectedDate 当前选中日期
+ * @param today 今天的日期
+ * @param onDateClick 日期点击回调
+ * @param onMonthChanged 月份切换回调，滑动到新月份时触发
+ * @param collapseProgress 折叠进度，0f=展开，1f=折叠
+ * @param modifier 外部布局修饰符
+ */
 @Composable
 fun CalendarPager(
     selectedDate: LocalDate,
@@ -68,15 +79,17 @@ fun CalendarPager(
     }
 }
 
-@Suppress("DEPRECATION")
+@Suppress("DEPRECATION") // monthNumber 无替代 API，kotlinx-datetime 尚未提供新接口
 private fun LocalDate.toYearMonth(): Pair<Int, Int> = Pair(year, monthNumber)
 
+// 页码→年月：偏移量 + 初始月份的绝对月数，再拆分回年月
 private fun pageToYearMonth(page: Int, initial: Pair<Int, Int>): Pair<Int, Int> {
     val offset = page - START_PAGE
     val totalMonths = initial.first * 12 + (initial.second - 1) + offset
     return Pair(totalMonths / 12, totalMonths % 12 + 1)
 }
 
+// 年月→页码：目标与初始的绝对月数差 + 起始页
 private fun yearMonthToPage(yearMonth: Pair<Int, Int>, initial: Pair<Int, Int>): Int {
     val targetTotal = yearMonth.first * 12 + (yearMonth.second - 1)
     val initialTotal = initial.first * 12 + (initial.second - 1)

shared/src/commonMain/kotlin/plus/rua/project/ui/DayCell.kt

@@ -14,6 +14,16 @@ import androidx.compose.ui.draw.clip
 import androidx.compose.ui.text.style.TextAlign
 import kotlinx.datetime.LocalDate
 
+/**
+ * 单个日期单元格，显示日期数字并支持选中/今天/非当月状态。
+ *
+ * @param date 日期
+ * @param isCurrentMonth 是否属于当前显示月份
+ * @param isSelected 是否为选中日期
+ * @param isToday 是否为今天
+ * @param onClick 点击回调
+ * @param modifier 外部布局修饰符
+ */
 @Composable
 fun DayCell(
     date: LocalDate,

shared/src/commonMain/kotlin/plus/rua/project/ui/MonthHeader.kt

@@ -11,6 +11,14 @@ import androidx.compose.ui.Modifier
 import androidx.compose.ui.unit.dp
 import androidx.compose.ui.unit.sp
 
+/**
+ * 月份标题栏，显示"年月"文字和 ISO 周号。
+ *
+ * @param year 年份
+ * @param month 月份（1-12）
+ * @param weekNumber 当前 ISO 周号
+ * @param modifier 外部布局修饰符
+ */
 @Composable
 fun MonthHeader(
     year: Int,

shared/src/commonMain/kotlin/plus/rua/project/ui/WeekPager.kt

@@ -19,8 +19,18 @@ import kotlinx.datetime.LocalDate
 import kotlinx.datetime.minus
 import kotlinx.datetime.plus
 
+/** 无限分页中心页，用于 HorizontalPager 的起始位置 */
 private const val START_PAGE = Int.MAX_VALUE / 2
 
+/**
+ * 周视图分页器，折叠状态下显示选中日期所在周，支持左右滑动切换周。
+ *
+ * @param selectedDate 当前选中日期
+ * @param today 今天的日期
+ * @param onDateClick 日期点击回调
+ * @param onWeekChanged 周切换回调，滑动到新周时触发，参数为该周周一日期
+ * @param modifier 外部布局修饰符
+ */
 @Composable
 fun WeekPager(
     selectedDate: LocalDate,

shared/src/commonMain/kotlin/plus/rua/project/ui/WeekdayHeader.kt

@@ -10,6 +10,11 @@ import androidx.compose.ui.text.style.TextAlign
 
 private val WEEKDAY_LABELS = listOf("一", "二", "三", "四", "五", "六", "日")
 
+/**
+ * 星期标题行，固定显示"一二三四五六日"。
+ *
+ * @param modifier 外部布局修饰符
+ */
 @Composable
 fun WeekdayHeader(modifier: Modifier = Modifier) {
     Row(modifier = modifier.fillMaxWidth()) {