fix(calendars): top-bar filter switch resets scroll; week/month/day headers scroll with the disappearing bar

Two related fixes for the calendar surface:

1. Filter switch leaving the user in the past section. The feed-content
   state already calls sendToTop() when feedKey changes, but the calendar
   feed's LazyColumn never subscribed to the scrollToTop signal — so a
   filter switch (e.g. People List → Global) preserved the previous
   scroll position. Often that landed the user mid-feed in the "Past"
   section of the much larger Global list, looking like "the events
   didn't come back". Added a LazyListState + WatchScrollToTop wiring.

2. Week/month/day headers stayed pinned when the DisappearingScaffold's
   top bar collapsed on scroll. The views had a Column with
   disappearingScaffoldPadding() that reserved a fixed top inset, so when
   the bar slid up the headers stayed put and a visual gap opened. Pulled
   the nav header (and for the week view, the WeekStrip + DaySummaryHeader)
   into the same LazyColumn as the events, with rememberFeedContentPadding
   as contentPadding — now the whole stack scrolls under the bar together.

amethyst/src/main/java/com/vitorpamplona/amethyst/ui/screen/loggedIn/calendars/CalendarDayView.kt

@@ -57,10 +57,12 @@ import com.vitorpamplona.amethyst.commons.model.nip52Calendar.groupByDayKeyExpan
 import com.vitorpamplona.amethyst.commons.ui.feeds.FeedContentState
 import com.vitorpamplona.amethyst.commons.ui.feeds.FeedState
 import com.vitorpamplona.amethyst.model.Note
+import com.vitorpamplona.amethyst.ui.layouts.rememberFeedContentPadding
 import com.vitorpamplona.amethyst.ui.navigation.navs.INav
 import com.vitorpamplona.amethyst.ui.navigation.routes.Route
 import com.vitorpamplona.amethyst.ui.screen.loggedIn.AccountViewModel
 import com.vitorpamplona.amethyst.ui.stringRes
+import com.vitorpamplona.amethyst.ui.theme.FeedPadding
 import java.time.LocalDate
 import java.time.ZoneId
 
@@ -91,58 +93,54 @@ fun CalendarDayView(
     val byDay by remember(notes) { derivedStateOf { groupByDayKeyExpanded(notes) } }
     val dayEvents = byDay[visibleDate.toEpochDay()].orEmpty()
 
-    Column(
-        modifier =
-            Modifier
-                .fillMaxSize()
-                .disappearingScaffoldPadding()
-                .calendarSwipeNavigation(
-                    key = visibleEpochDay,
-                    onSwipeLeft = { visibleEpochDay = visibleDate.plusDays(1).toEpochDay() },
-                    onSwipeRight = { visibleEpochDay = visibleDate.minusDays(1).toEpochDay() },
-                ),
-    ) {
-        CalendarNavigationHeader(
-            title = formatLongDate(visibleDate.atStartOfDay(ZoneId.systemDefault()).toEpochSecond()),
-            prevContentDescription = stringRes(R.string.calendar_nav_previous_day),
-            nextContentDescription = stringRes(R.string.calendar_nav_next_day),
-            onPrev = { visibleEpochDay = visibleDate.minusDays(1).toEpochDay() },
-            onNext = { visibleEpochDay = visibleDate.plusDays(1).toEpochDay() },
-            onToday = { visibleEpochDay = LocalDate.now().toEpochDay() },
-        )
-
-        if (dayEvents.isEmpty()) {
-            CalendarEmptyState(
-                title = stringRes(R.string.calendar_empty_day_title),
-                subtitle = stringRes(R.string.calendar_empty_day_subtitle),
-            )
-            return@Column
-        }
-
-        DayTimeline(dayEvents, visibleEpochDay, nav)
-    }
-}
-
-@Composable
-private fun DayTimeline(
-    dayEvents: List<Note>,
-    visibleEpochDay: Long,
-    nav: INav,
-) {
     val sorted =
         remember(dayEvents) {
             // All-day events bubble to the top (Long.MIN_VALUE), then time-slot events in order.
             dayEvents.sortedBy { it.appointmentView()?.startSeconds ?: Long.MAX_VALUE }
         }
 
-    LazyColumn(modifier = Modifier.fillMaxSize().padding(horizontal = 12.dp)) {
-        items(sorted, key = { it.idHex }) { note ->
-            DayRow(
-                note = note,
-                visibleEpochDay = visibleEpochDay,
-                onClick = { nav.nav(Route.Note(note.idHex)) },
+    // Single LazyColumn — nav header is the first item so it scrolls with the disappearing
+    // top bar instead of staying pinned mid-screen when the bar collapses.
+    LazyColumn(
+        contentPadding = rememberFeedContentPadding(FeedPadding),
+        modifier =
+            Modifier
+                .fillMaxSize()
+                .calendarSwipeNavigation(
+                    key = visibleEpochDay,
+                    onSwipeLeft = { visibleEpochDay = visibleDate.plusDays(1).toEpochDay() },
+                    onSwipeRight = { visibleEpochDay = visibleDate.minusDays(1).toEpochDay() },
+                ),
+    ) {
+        item(key = "day-nav") {
+            CalendarNavigationHeader(
+                title = formatLongDate(visibleDate.atStartOfDay(ZoneId.systemDefault()).toEpochSecond()),
+                prevContentDescription = stringRes(R.string.calendar_nav_previous_day),
+                nextContentDescription = stringRes(R.string.calendar_nav_next_day),
+                onPrev = { visibleEpochDay = visibleDate.minusDays(1).toEpochDay() },
+                onNext = { visibleEpochDay = visibleDate.plusDays(1).toEpochDay() },
+                onToday = { visibleEpochDay = LocalDate.now().toEpochDay() },
             )
-            HorizontalDivider()
+        }
+
+        if (dayEvents.isEmpty()) {
+            item(key = "day-empty") {
+                CalendarEmptyState(
+                    title = stringRes(R.string.calendar_empty_day_title),
+                    subtitle = stringRes(R.string.calendar_empty_day_subtitle),
+                )
+            }
+        } else {
+            items(sorted, key = { it.idHex }) { note ->
+                Column(modifier = Modifier.padding(horizontal = 12.dp)) {
+                    DayRow(
+                        note = note,
+                        visibleEpochDay = visibleEpochDay,
+                        onClick = { nav.nav(Route.Note(note.idHex)) },
+                    )
+                    HorizontalDivider()
+                }
+            }
         }
     }
 }

amethyst/src/main/java/com/vitorpamplona/amethyst/ui/screen/loggedIn/calendars/CalendarFeedView.kt

@@ -25,6 +25,7 @@ import androidx.compose.foundation.layout.fillMaxSize
 import androidx.compose.foundation.layout.padding
 import androidx.compose.foundation.lazy.LazyColumn
 import androidx.compose.foundation.lazy.items
+import androidx.compose.foundation.lazy.rememberLazyListState
 import androidx.compose.material3.HorizontalDivider
 import androidx.compose.material3.MaterialTheme
 import androidx.compose.material3.Text
@@ -44,6 +45,7 @@ import com.vitorpamplona.amethyst.commons.ui.feeds.FeedContentState
 import com.vitorpamplona.amethyst.commons.ui.feeds.FeedState
 import com.vitorpamplona.amethyst.model.Note
 import com.vitorpamplona.amethyst.ui.feeds.RefresheableBox
+import com.vitorpamplona.amethyst.ui.feeds.WatchScrollToTop
 import com.vitorpamplona.amethyst.ui.layouts.rememberFeedContentPadding
 import com.vitorpamplona.amethyst.ui.navigation.navs.INav
 import com.vitorpamplona.amethyst.ui.screen.loggedIn.AccountViewModel
@@ -62,7 +64,7 @@ fun CalendarFeedView(
         val state by feedState.feedContent.collectAsStateWithLifecycle()
 
         when (val s = state) {
-            is FeedState.Loaded -> CalendarFeedLoadedBody(s, accountViewModel, nav, filterAddresses)
+            is FeedState.Loaded -> CalendarFeedLoadedBody(s, feedState, accountViewModel, nav, filterAddresses)
             is FeedState.Empty -> CalendarFeedEmpty()
             is FeedState.Loading -> Box(modifier = Modifier.fillMaxSize())
             is FeedState.FeedError -> CalendarFeedError(s)
@@ -73,6 +75,7 @@ fun CalendarFeedView(
 @Composable
 private fun CalendarFeedLoadedBody(
     loaded: FeedState.Loaded,
+    feedState: FeedContentState,
     accountViewModel: AccountViewModel,
     nav: INav,
     filterAddresses: Set<com.vitorpamplona.quartz.nip01Core.core.Address>?,
@@ -85,7 +88,15 @@ private fun CalendarFeedLoadedBody(
         }
     }
 
+    // Without this the top-bar filter switch fires `sendToTop()`, but the LazyColumn never hears
+    // it — so the scroll position from the previous filter (e.g. mid-way through a tiny People
+    // List) is preserved when the user flips back to Global, leaving the user staring at the
+    // past-events section of a 100-item feed instead of the top.
+    val listState = rememberLazyListState()
+    WatchScrollToTop(feedState, listState)
+
     LazyColumn(
+        state = listState,
         contentPadding = rememberFeedContentPadding(FeedPadding),
         modifier = Modifier.fillMaxSize(),
     ) {

amethyst/src/main/java/com/vitorpamplona/amethyst/ui/screen/loggedIn/calendars/CalendarMonthView.kt

@@ -61,9 +61,11 @@ import com.vitorpamplona.amethyst.commons.model.nip52Calendar.computeMonthGridBa
 import com.vitorpamplona.amethyst.commons.model.nip52Calendar.groupByDayKeyExpanded
 import com.vitorpamplona.amethyst.commons.ui.feeds.FeedContentState
 import com.vitorpamplona.amethyst.commons.ui.feeds.FeedState
+import com.vitorpamplona.amethyst.ui.layouts.rememberFeedContentPadding
 import com.vitorpamplona.amethyst.ui.navigation.navs.INav
 import com.vitorpamplona.amethyst.ui.screen.loggedIn.AccountViewModel
 import com.vitorpamplona.amethyst.ui.stringRes
+import com.vitorpamplona.amethyst.ui.theme.FeedPadding
 import java.time.LocalDate
 import java.time.YearMonth
 import java.time.ZoneId
@@ -102,11 +104,15 @@ fun CalendarMonthView(
 
     var selectedDayKey by rememberSaveable { mutableStateOf<Long?>(null) }
 
-    Column(
+    val selectedEvents = selectedDayKey?.let { eventsByDay[it] }.orEmpty()
+
+    // Single LazyColumn — nav header + weekday header + grid scroll together with the
+    // disappearing top bar so the grid doesn't stay pinned mid-screen when the bar collapses.
+    LazyColumn(
+        contentPadding = rememberFeedContentPadding(FeedPadding),
         modifier =
             Modifier
                 .fillMaxSize()
-                .disappearingScaffoldPadding()
                 .calendarSwipeNavigation(
                     key = visibleYear to visibleMonthValue,
                     onSwipeLeft = {
@@ -119,44 +125,49 @@ fun CalendarMonthView(
                     },
                 ),
     ) {
-        CalendarNavigationHeader(
-            title = formatMonthYear(visibleMonth.year, visibleMonth.monthValue - 1),
-            prevContentDescription = stringRes(R.string.calendar_nav_previous_month),
-            nextContentDescription = stringRes(R.string.calendar_nav_next_month),
-            onPrev = {
-                setVisibleMonth(visibleMonth.minusMonths(1))
-                selectedDayKey = null
-            },
-            onNext = {
-                setVisibleMonth(visibleMonth.plusMonths(1))
-                selectedDayKey = null
-            },
-            onToday = {
-                setVisibleMonth(YearMonth.from(LocalDate.now()))
-                selectedDayKey = null
-            },
-        )
+        item(key = "month-nav") {
+            CalendarNavigationHeader(
+                title = formatMonthYear(visibleMonth.year, visibleMonth.monthValue - 1),
+                prevContentDescription = stringRes(R.string.calendar_nav_previous_month),
+                nextContentDescription = stringRes(R.string.calendar_nav_next_month),
+                onPrev = {
+                    setVisibleMonth(visibleMonth.minusMonths(1))
+                    selectedDayKey = null
+                },
+                onNext = {
+                    setVisibleMonth(visibleMonth.plusMonths(1))
+                    selectedDayKey = null
+                },
+                onToday = {
+                    setVisibleMonth(YearMonth.from(LocalDate.now()))
+                    selectedDayKey = null
+                },
+            )
+        }
 
-        WeekdayHeader()
+        item(key = "month-weekday-header") {
+            WeekdayHeader()
+        }
 
-        MonthGrid(
-            visibleMonth = visibleMonth,
-            today = today,
-            barsByDay = barsByDay,
-            selectedDayKey = selectedDayKey,
-            onDayClick = { dayKey ->
-                selectedDayKey = if (selectedDayKey == dayKey) null else dayKey
-            },
-        )
+        item(key = "month-grid") {
+            MonthGrid(
+                visibleMonth = visibleMonth,
+                today = today,
+                barsByDay = barsByDay,
+                selectedDayKey = selectedDayKey,
+                onDayClick = { dayKey ->
+                    selectedDayKey = if (selectedDayKey == dayKey) null else dayKey
+                },
+            )
+        }
 
-        Spacer(modifier = Modifier.height(8.dp))
+        item(key = "month-grid-spacer") {
+            Spacer(modifier = Modifier.height(8.dp))
+        }
 
-        val selectedEvents = selectedDayKey?.let { eventsByDay[it] }.orEmpty()
         if (selectedEvents.isNotEmpty()) {
-            LazyColumn(modifier = Modifier.fillMaxSize()) {
-                items(selectedEvents, key = { it.idHex }) { note ->
-                    CalendarEventListCard(note, accountViewModel, nav)
-                }
+            items(selectedEvents, key = { it.idHex }) { note ->
+                CalendarEventListCard(note, accountViewModel, nav)
             }
         }
     }

amethyst/src/main/java/com/vitorpamplona/amethyst/ui/screen/loggedIn/calendars/CalendarWeekView.kt

@@ -57,9 +57,11 @@ import com.vitorpamplona.amethyst.commons.model.nip52Calendar.groupByDayKeyExpan
 import com.vitorpamplona.amethyst.commons.ui.feeds.FeedContentState
 import com.vitorpamplona.amethyst.commons.ui.feeds.FeedState
 import com.vitorpamplona.amethyst.model.Note
+import com.vitorpamplona.amethyst.ui.layouts.rememberFeedContentPadding
 import com.vitorpamplona.amethyst.ui.navigation.navs.INav
 import com.vitorpamplona.amethyst.ui.screen.loggedIn.AccountViewModel
 import com.vitorpamplona.amethyst.ui.stringRes
+import com.vitorpamplona.amethyst.ui.theme.FeedPadding
 import java.time.LocalDate
 import java.time.ZoneId
 
@@ -92,11 +94,18 @@ fun CalendarWeekView(
 
     val eventsByDay by remember(notes) { derivedStateOf { groupByDayKeyExpanded(notes) } }
 
-    Column(
+    val selectedDate = weekStart.plusDays(selectedDayIndex.toLong())
+    val dayNotes = eventsByDay[selectedDate.toEpochDay()].orEmpty()
+
+    // Single LazyColumn containing nav + strip + day-summary + events so the whole stack
+    // scrolls together with the [DisappearingScaffold]'s top bar. The previous Column-with-
+    // disappearingScaffoldPadding kept the strip pinned at a fixed offset, so when the top bar
+    // collapsed on scroll the strip stayed put and left a visual gap.
+    LazyColumn(
+        contentPadding = rememberFeedContentPadding(FeedPadding),
         modifier =
             Modifier
                 .fillMaxSize()
-                .disappearingScaffoldPadding()
                 .calendarSwipeNavigation(
                     key = weekStartEpochDay,
                     onSwipeLeft = {
@@ -109,49 +118,54 @@ fun CalendarWeekView(
                     },
                 ),
     ) {
-        CalendarNavigationHeader(
-            title = formatMonthYear(weekStart.year, weekStart.monthValue - 1),
-            prevContentDescription = stringRes(R.string.calendar_nav_previous_week),
-            nextContentDescription = stringRes(R.string.calendar_nav_next_week),
-            onPrev = {
-                weekStartEpochDay = weekStart.minusWeeks(1).toEpochDay()
-                selectedDayIndex = 0
-            },
-            onNext = {
-                weekStartEpochDay = weekStart.plusWeeks(1).toEpochDay()
-                selectedDayIndex = 0
-            },
-            onToday = {
-                weekStartEpochDay = startOfWeek(LocalDate.now()).toEpochDay()
-                selectedDayIndex = 0
-            },
-        )
+        item(key = "week-nav") {
+            CalendarNavigationHeader(
+                title = formatMonthYear(weekStart.year, weekStart.monthValue - 1),
+                prevContentDescription = stringRes(R.string.calendar_nav_previous_week),
+                nextContentDescription = stringRes(R.string.calendar_nav_next_week),
+                onPrev = {
+                    weekStartEpochDay = weekStart.minusWeeks(1).toEpochDay()
+                    selectedDayIndex = 0
+                },
+                onNext = {
+                    weekStartEpochDay = weekStart.plusWeeks(1).toEpochDay()
+                    selectedDayIndex = 0
+                },
+                onToday = {
+                    weekStartEpochDay = startOfWeek(LocalDate.now()).toEpochDay()
+                    selectedDayIndex = 0
+                },
+            )
+        }
 
-        WeekStrip(
-            weekStart = weekStart,
-            today = today,
-            selectedIndex = selectedDayIndex,
-            eventsByDay = eventsByDay,
-            onSelect = { selectedDayIndex = it },
-        )
+        item(key = "week-strip") {
+            WeekStrip(
+                weekStart = weekStart,
+                today = today,
+                selectedIndex = selectedDayIndex,
+                eventsByDay = eventsByDay,
+                onSelect = { selectedDayIndex = it },
+            )
+        }
 
-        Spacer(modifier = Modifier.height(8.dp))
+        item(key = "week-spacer") {
+            Spacer(modifier = Modifier.height(8.dp))
+        }
 
-        val selectedDate = weekStart.plusDays(selectedDayIndex.toLong())
-        val dayNotes = eventsByDay[selectedDate.toEpochDay()].orEmpty()
-
-        DaySummaryHeader(selectedDate)
+        item(key = "week-day-summary") {
+            DaySummaryHeader(selectedDate)
+        }
 
         if (dayNotes.isEmpty()) {
-            CalendarEmptyState(
-                title = stringRes(R.string.calendar_empty_week_title),
-                subtitle = stringRes(R.string.calendar_empty_week_subtitle),
-            )
+            item(key = "week-empty") {
+                CalendarEmptyState(
+                    title = stringRes(R.string.calendar_empty_week_title),
+                    subtitle = stringRes(R.string.calendar_empty_week_subtitle),
+                )
+            }
         } else {
-            LazyColumn(modifier = Modifier.fillMaxSize()) {
-                items(dayNotes, key = { it.idHex }) { note ->
-                    CalendarEventListCard(note, accountViewModel, nav)
-                }
+            items(dayNotes, key = { it.idHex }) { note ->
+                CalendarEventListCard(note, accountViewModel, nav)
             }
         }
     }