Fix drag-to-reschedule for events spanning midnight (#253) (#257)

Dragging an event that crosses midnight now works from either half.

- The tail of an overnight event can be picked up and dragged; the drop takes the clip offset back off, so the event lands where its own start belongs, and the second half can be dragged earlier as well as later.
- Timed blocks are cut square at midnight instead of being rounded off, and a month row draws an event crossing into the next week as one bar rather than two unrelated pills.
- Both halves are previewed while dragging, whichever one is held, and the floating copy carries the time range once.
- A moved chip is seated from its own bar's first column, a clipped-tail drop is confirmed against the slice the grid actually draws, and both halves stay ghosted until the write lands.
- The drop's arithmetic is wall clock throughout, so a DST transition between the event's start and the midnight its tail is cut at no longer shifts the write by an hour.
- A refused drop ticks `abandoned`, so a held copy is let go by one signal instead of by every call site.

Closes #253

Co-authored-by: Jean-Luc Makiola <business@jeanlucmakiola.de>
Reviewed-on: https://codeberg.org/jlmakiola/calendula/pulls/257

app/src/main/java/de/jeanlucmakiola/calendula/ui/CalendarHost.kt

@@ -322,6 +322,7 @@ fun CalendarHost(
             move = reschedule::move,
             inFlight = reschedule.inFlight,
             undoStarted = reschedule.undoStarted,
+            abandoned = reschedule.abandoned,
             edit = onEditEvent,
         )
     }

app/src/main/java/de/jeanlucmakiola/calendula/ui/common/EventChipShape.kt

@@ -0,0 +1,35 @@
+package de.jeanlucmakiola.calendula.ui.common
+
+import androidx.compose.foundation.shape.RoundedCornerShape
+import androidx.compose.ui.unit.dp
+
+/** The corner radius every event chip keeps on each edge the event doesn't cross. */
+val EVENT_CHIP_CORNER = 4.dp
+
+/** An event chip that is cut on no edge — an all-day bar, a floating copy. */
+val EventChipShape = RoundedCornerShape(EVENT_CHIP_CORNER)
+
+/**
+ * A timed block's corners: square on whichever edge the event runs past, so a
+ * cut edge reads as "this carries on" rather than as the event's own end. The
+ * vertical counterpart of [monthBarShape].
+ */
+fun timedBlockShape(continuesBefore: Boolean, continuesAfter: Boolean): RoundedCornerShape =
+    RoundedCornerShape(
+        topStart = if (continuesBefore) 0.dp else EVENT_CHIP_CORNER,
+        topEnd = if (continuesBefore) 0.dp else EVENT_CHIP_CORNER,
+        bottomStart = if (continuesAfter) 0.dp else EVENT_CHIP_CORNER,
+        bottomEnd = if (continuesAfter) 0.dp else EVENT_CHIP_CORNER,
+    )
+
+/**
+ * A month/all-day bar's corners: square on whichever side the event runs past
+ * the row it is drawn in.
+ */
+fun monthBarShape(continuesLeft: Boolean, continuesRight: Boolean): RoundedCornerShape =
+    RoundedCornerShape(
+        topStart = if (continuesLeft) 0.dp else EVENT_CHIP_CORNER,
+        bottomStart = if (continuesLeft) 0.dp else EVENT_CHIP_CORNER,
+        topEnd = if (continuesRight) 0.dp else EVENT_CHIP_CORNER,
+        bottomEnd = if (continuesRight) 0.dp else EVENT_CHIP_CORNER,
+    )

app/src/main/java/de/jeanlucmakiola/calendula/ui/common/EventMoveScope.kt

@@ -45,6 +45,12 @@ class EventMoveScope(
     val inFlight: StateFlow<Boolean>,
     /** Ticks when an undo write begins — see `RescheduleViewModel.undoStarted`. */
     val undoStarted: StateFlow<Int>,
+    /**
+     * Ticks when a drop ends with nothing landing — see
+     * `RescheduleViewModel.abandoned`. [move] answers before the write is
+     * resolved, so this is what tells a held copy to stop waiting.
+     */
+    val abandoned: StateFlow<Int>,
     /** Open an event in the edit form — the pointer-free route to the same change. */
     val edit: (EventInstance) -> Unit,
 ) {
@@ -57,6 +63,8 @@ private val NEVER_IN_FLIGHT = MutableStateFlow(false)
 
 private val NEVER_UNDONE = MutableStateFlow(0)
 
+private val NEVER_ABANDONED = MutableStateFlow(0)
+
 /**
  * Whether a dropped event is still being written — false wherever moving is off.
  * The drag overlays hold a landed block on its target for this window.
@@ -67,6 +75,17 @@ fun moveInFlight(): Boolean {
     return flow.collectAsStateWithLifecycle().value
 }
 
+/**
+ * How many drops have ended with nothing landing. Read as a plain count so a
+ * drag overlay can capture it at the moment of the drop and tell, later, whether
+ * *its own* drop was one of them.
+ */
+@Composable
+fun abandonedMoves(): Int {
+    val flow = LocalEventMove.current?.abandoned ?: NEVER_ABANDONED
+    return flow.collectAsStateWithLifecycle().value
+}
+
 /**
  * Runs [onUndo] when an undo write begins, and never for one that began before
  * this composable came on screen.

app/src/main/java/de/jeanlucmakiola/calendula/ui/common/RescheduleViewModel.kt

@@ -140,6 +140,17 @@ class RescheduleViewModel @Inject constructor(
      */
     val inFlight: StateFlow<Boolean> = _inFlight.asStateFlow()
 
+    private val _abandoned = MutableStateFlow(0)
+
+    /**
+     * Ticks when a drop ends with nothing on the target day: refused outright,
+     * refused before the write, written and failed, or its scope dialog
+     * dismissed. [move] answers before any of that is known, so without this
+     * signal the view that drew the drop held its copy out for the full settle
+     * timeout waiting for a grid that was never going to draw it (#253).
+     */
+    val abandoned: StateFlow<Int> = _abandoned.asStateFlow()
+
     private val _undoStarted = MutableStateFlow(0)
 
     /**
@@ -189,15 +200,19 @@ class RescheduleViewModel @Inject constructor(
 
     /**
      * Take a drop, unless one is already being written. False means nothing will
-     * be written and the caller must let its held copy go now — waiting on
-     * [inFlight] would strand it until the settle timeout instead.
+     * be written; [abandoned] ticks for that refusal too, so a held copy is let
+     * go by the one signal rather than by every caller remembering to.
      */
     fun move(request: MoveRequest): Boolean {
-        if (busy || _scopePrompt.value != null) return false
+        if (busy || _scopePrompt.value != null) {
+            _abandoned.value += 1
+            return false
+        }
         busy = true
         viewModelScope.launch {
             val prepared = prepare(request)
             if (prepared == null) {
+                _abandoned.value += 1
                 busy = false
                 return@launch
             }
@@ -231,6 +246,7 @@ class RescheduleViewModel @Inject constructor(
         pending = null
         busy = false
         _scopePrompt.value = null
+        _abandoned.value += 1
     }
 
     /**
@@ -340,6 +356,7 @@ class RescheduleViewModel @Inject constructor(
         val request = prepared.request
         if (endsBeforeItStarts(prepared, scope)) {
             _outcome.value = MoveOutcome.BlockedSeriesEnd
+            _abandoned.value += 1
             return
         }
         _outcome.value = try {
@@ -375,6 +392,9 @@ class RescheduleViewModel @Inject constructor(
         } catch (e: Exception) {
             MoveOutcome.Failed
         }
+        // Nothing landed, so the copy the view is holding has nothing to fade
+        // into — let it go now rather than at the end of the settle timeout.
+        if (_outcome.value !is MoveOutcome.Moved) _abandoned.value += 1
     }
 
     /**

app/src/main/java/de/jeanlucmakiola/calendula/ui/common/TimelineDrag.kt

@@ -25,6 +25,7 @@ import androidx.compose.runtime.setValue
 import androidx.compose.runtime.withFrameNanos
 import androidx.compose.ui.Modifier
 import androidx.compose.ui.geometry.Offset
+import androidx.compose.ui.graphics.Color
 import androidx.compose.ui.graphics.graphicsLayer
 import androidx.compose.ui.layout.LayoutCoordinates
 import androidx.compose.ui.layout.boundsInRoot
@@ -44,7 +45,11 @@ import de.jeanlucmakiola.calendula.ui.week.TimedBlock
 import de.jeanlucmakiola.floret.identity.rememberReduceMotion
 import de.jeanlucmakiola.floret.locale.currentLocale
 import kotlinx.coroutines.delay
+import kotlinx.coroutines.flow.StateFlow
+import kotlinx.datetime.DateTimeUnit
 import kotlinx.datetime.LocalDate
+import kotlinx.datetime.atStartOfDayIn
+import kotlinx.datetime.plus
 import kotlinx.datetime.LocalDateTime
 import kotlinx.datetime.LocalTime
 import kotlinx.datetime.TimeZone
@@ -66,17 +71,109 @@ private val AUTO_SCROLL_STEP = 16.dp
 data class TimelineDrag(
     val event: EventInstance,
     val date: LocalDate,
+    /**
+     * Where the dragged *block's* top edge now sits, in minutes from [date]'s
+     * midnight. The gesture's own quantity — what snaps, what the haptics tick
+     * on, and what the drop is expressed in. Not the event's start: for the tail
+     * of an event that began the day before, the two are a clip offset apart.
+     */
     val startMin: Int,
-    val endMin: Int,
-    val topLeftInRoot: Offset,
-    val sizePx: IntSize,
+    /** The event's new start, from [date]'s midnight — negative if it began earlier. */
+    val eventStartMin: Int,
+    val eventSpanMin: Int,
+    /** The event as the grid would draw it, one piece per day column it covers. */
+    val pieces: List<TimelineDragPiece>,
 ) {
     /** What the snap haptics key off: one tick per changed slot, not per frame. */
     val slot: Pair<LocalDate, Int> get() = date to startMin
 }
 
-/** Where a finished drag asks its event to go. */
-data class TimelineDrop(val event: EventInstance, val date: LocalDate, val startMin: Int)
+/**
+ * One day column's share of a dragged event, ready to draw. Both halves of an
+ * event crossing midnight are previewed, whichever half the finger picked up:
+ * showing only the held one made the event read as growing rather than moving,
+ * since the day beside it still stood at the block's old extent (#253).
+ */
+data class TimelineDragPiece(
+    val topLeftInRoot: Offset,
+    val sizePx: IntSize,
+    val continuesBefore: Boolean,
+    val continuesAfter: Boolean,
+)
+
+/**
+ * How a run of [spanMin] minutes beginning [eventStartMin] minutes into a day —
+ * negative when it began on an earlier one — falls across day columns, as
+ * offsets from that day. Every slice but the first and last is a whole day, and
+ * the flags say which edges are cuts rather than the event's own ends.
+ *
+ * [within] bounds the day offsets that have a column to draw in, so a very long
+ * event doesn't slice days no one can see.
+ */
+internal fun dragSlices(
+    eventStartMin: Int,
+    spanMin: Int,
+    within: IntRange? = null,
+): List<DragSlice> {
+    val span = spanMin.coerceAtLeast(0)
+    val end = eventStartMin + span
+    val first = eventStartMin.floorDiv(MINUTES_PER_DAY)
+    // A zero-length event still has a block, on the one day it sits in.
+    val last = maxOf((end - 1).floorDiv(MINUTES_PER_DAY), first)
+    val from = maxOf(first, within?.first ?: first)
+    val to = minOf(last, within?.last ?: last)
+    if (from > to) return emptyList()
+    return (from..to).map { day ->
+        val dayStart = day * MINUTES_PER_DAY
+        val sliceStart = maxOf(eventStartMin - dayStart, 0)
+        val sliceEnd = minOf(end - dayStart, MINUTES_PER_DAY)
+        DragSlice(
+            dayOffset = day,
+            startMin = sliceStart,
+            spanMin = sliceEnd - sliceStart,
+            continuesBefore = day > first,
+            continuesAfter = day < last,
+        )
+    }
+}
+
+/**
+ * How far above its day's midnight a block's top edge may be dragged. Zero for
+ * an ordinary block, whose top edge is the event's own start. A tail clipped at
+ * midnight has to go lower: its top edge *is* midnight and stays there however
+ * much earlier the event moves, so pinning it at zero made dragging the second
+ * half earlier a no-op (#253). It may rise until the event's end reaches one
+ * snap step into this day — or by a single step, for a tail too short to afford
+ * even that, which then leaves the day for the one before it.
+ */
+internal fun dragFloorMin(clipOffsetMin: Int, eventSpanMin: Int): Int =
+    if (clipOffsetMin > 0) {
+        minOf(-DRAG_SNAP_MINUTES, DRAG_SNAP_MINUTES + clipOffsetMin - eventSpanMin)
+    } else {
+        0
+    }
+
+/** One day's share of a dragged event, before it is placed on screen. */
+internal data class DragSlice(
+    val dayOffset: Int,
+    val startMin: Int,
+    val spanMin: Int,
+    val continuesBefore: Boolean,
+    val continuesAfter: Boolean,
+)
+
+/**
+ * Where a finished drag asks its event to go. [date]/[startMin] are where the
+ * dragged *block's* top edge landed, which is the event's own start only for a
+ * block that isn't clipped — see [clipOffsetMin] and [startInstant].
+ */
+data class TimelineDrop(
+    val event: EventInstance,
+    val date: LocalDate,
+    val startMin: Int,
+    /** Minutes from the event's start to the dragged block's top edge. */
+    val clipOffsetMin: Int = 0,
+)
 
 /**
  * The timeline's live geometry, republished on every layout. Plain fields rather
@@ -134,12 +231,14 @@ class TimelineDragController {
         private set
 
     /**
-     * Where the settled drop came from, and which event row it belongs to. The
-     * instance id alone can't identify the source block for the length of the
-     * write: the provider regenerates `Instances` rows, so a re-read carrying the
-     * *old* time can arrive under a new instance id.
+     * The event row and start instant the settled drop came from. The instance id
+     * alone can't identify the source for the length of the write: the provider
+     * regenerates `Instances` rows, so a re-read carrying the *old* time can
+     * arrive under a new instance id. Matching the start instant rather than a
+     * single day and slot keeps *both* halves of an event that crosses midnight
+     * ghosted until the write lands (#253).
      */
-    private var settledOrigin: Triple<Long, LocalDate, Int>? by mutableStateOf(null)
+    private var settledOrigin: Pair<Long, Instant>? by mutableStateOf(null)
 
     /** Whether a finger is on a block right now — [settling] is not dragging. */
     var isDragging: Boolean by mutableStateOf(false)
@@ -153,18 +252,42 @@ class TimelineDragController {
     var settledOnGrid: Boolean by mutableStateOf(false)
         private set
 
+    /**
+     * The abandoned-move counter, read at the drop so the mark can't be a
+     * composition behind the tick it is compared against.
+     */
+    var abandonedTicks: StateFlow<Int>? = null
+
+    /** What [abandonedTicks] stood at when the settling drop was let go. */
+    var settledAbandonedMark: Int = 0
+        private set
+
     private var source: TimedBlock? = null
     private var grab = Offset.Zero
     private var pointer = Offset.Zero
 
+    /**
+     * How far the picked-up block's top edge sits past the event's own start —
+     * nonzero only for a block clipped at midnight, which is the tail of an
+     * event that began the day before (#253). The gesture tracks the block the
+     * finger is on; this is what turns where it lands back into an event start.
+     */
+    private var clipOffsetMin = 0
+
     /**
      * The slot the block already occupied when it was picked up — not the same
      * as its start, since the target snaps to the grid (09:07 lifts to 09:00).
      */
     private var originSlot: Pair<LocalDate, Int>? = null
 
-    fun begin(block: TimedBlock, pointerInRoot: Offset, blockInRoot: Offset) {
+    fun begin(
+        block: TimedBlock,
+        clipOffsetMin: Int,
+        pointerInRoot: Offset,
+        blockInRoot: Offset,
+    ) {
         source = block
+        this.clipOffsetMin = clipOffsetMin
         settling = null
         isDragging = true
         liftedInstanceId = block.event.instanceId
@@ -182,6 +305,7 @@ class TimelineDragController {
 
     fun cancel() {
         source = null
+        clipOffsetMin = 0
         isDragging = false
         liftedInstanceId = null
         originSlot = null
@@ -192,32 +316,41 @@ class TimelineDragController {
     }
 
     /**
-     * Whether [block] is the one whose copy is in flight, and so must stay a
-     * ghost: the instance the finger picked up, or once dropped whatever now
-     * sits in the slot it left.
+     * Whether [block] is part of the event whose copy is in flight, and so must
+     * stay a ghost: the instance the finger picked up, or once dropped whatever
+     * the re-read now carries at the time it came from — both halves of it, for
+     * an event that crosses midnight (#253).
      */
-    fun ghosts(block: TimedBlock, date: LocalDate): Boolean {
+    fun ghosts(block: TimedBlock): Boolean {
         if (liftedInstanceId == null) return false
         if (block.event.instanceId == liftedInstanceId) return true
-        val (eventId, originDate, originMin) = settledOrigin ?: return false
-        return block.event.eventId == eventId &&
-            date == originDate &&
-            block.startMin == originMin
+        val (eventId, start) = settledOrigin ?: return false
+        return block.event.eventId == eventId && block.event.start == start
     }
 
     /**
      * What a day column now holds, so a settled drop can tell when the grid has
      * caught up with it. Matched on the landing slot plus either the event row
-     * or its title, since a single-occurrence move writes a new `eventId`.
+     * or its title, since a single-occurrence move writes a new `eventId`. A
+     * blank title matches nothing: every untitled event has one (#253).
      */
     fun noteGrid(date: LocalDate, blocks: List<TimedBlock>) {
         val landed = settling ?: return
-        if (settledOnGrid || landed.date != date) return
+        if (settledOnGrid) return
+        // Where this day would draw it, which for a drop clipped at midnight is
+        // the day's own start rather than the edge the finger held (#253) — and
+        // which for a tail dragged clear of its day is the day before it.
+        val offset = (date.toEpochDays() - landed.date.toEpochDays()).toInt()
+        val slice = dragSlices(landed.eventStartMin, landed.eventSpanMin, offset..offset)
+            .firstOrNull() ?: return
         settledOnGrid = blocks.any { block ->
-            block.startMin == landed.startMin &&
+            block.startMin == slice.startMin &&
                 (
                     block.event.eventId == landed.event.eventId ||
-                        block.event.title == landed.event.title
+                        (
+                            landed.event.title.isNotBlank() &&
+                                block.event.title == landed.event.title
+                            )
                     )
         }
     }
@@ -230,12 +363,14 @@ class TimelineDragController {
     fun finish(): TimelineDrop? {
         val landed = drag
         val origin = originSlot
+        val clipOffset = clipOffsetMin
         cancel()
         if (landed == null || landed.slot == origin) return null
         settling = landed
         liftedInstanceId = landed.event.instanceId
-        settledOrigin = origin?.let { (date, min) -> Triple(landed.event.eventId, date, min) }
-        return TimelineDrop(landed.event, landed.date, landed.startMin)
+        settledOrigin = landed.event.eventId to landed.event.start
+        settledAbandonedMark = abandonedTicks?.value ?: 0
+        return TimelineDrop(landed.event, landed.date, landed.startMin, clipOffset)
     }
 
     /**
@@ -271,28 +406,44 @@ class TimelineDragController {
         val origin = grid.positionInRoot()
         val rawMinutes = (pointer.y - grab.y - origin.y) / hourPx * 60f
         val snapped = (rawMinutes / DRAG_SNAP_MINUTES).roundToInt() * DRAG_SNAP_MINUTES
-        // Clamp the start into the target day; a tail past midnight is fine.
-        val startMin = snapped.coerceIn(0, MINUTES_PER_DAY - DRAG_SNAP_MINUTES)
-        // The event's own length, not the block's: TimedBlock.endMin is clipped
-        // at midnight, which would draw a 22:00–02:00 event as a two-hour copy.
-        val span = (block.event.end - block.event.start).inWholeMinutes.toInt().coerceAtLeast(0)
-        // The column the finger is over on screen, and the day that column shows.
+        val eventSpan = (block.event.end - block.event.start).inWholeMinutes.toInt()
+            .coerceAtLeast(0)
+        val floor = dragFloorMin(clipOffsetMin, eventSpan)
+        val startMin = snapped.coerceIn(floor, MINUTES_PER_DAY - DRAG_SNAP_MINUTES)
+        val eventStartMin = startMin - clipOffsetMin
         val column = ((pointer.x - origin.x) / columnPx).toInt().coerceIn(0, days.lastIndex)
         val dayIndex = if (geometry.isRtl) days.lastIndex - column else column
-        val height = maxOf(span / 60f * hourPx, MIN_EVENT_FRACTION * hourPx)
         drag = TimelineDrag(
             event = block.event,
             date = days[dayIndex],
             startMin = startMin,
-            endMin = startMin + span,
-            topLeftInRoot = Offset(
-                x = origin.x + column * columnPx,
-                y = origin.y + startMin / 60f * hourPx,
-            ),
-            sizePx = IntSize(
-                (columnPx - geometry.columnGapPx).roundToInt(),
-                height.roundToInt(),
-            ),
+            eventStartMin = eventStartMin,
+            eventSpanMin = eventSpan,
+            // Bounded to the columns this timeline actually shows: a day it
+            // doesn't has no piece to draw. The write is unaffected.
+            pieces = dragSlices(
+                eventStartMin,
+                eventSpan,
+                within = -dayIndex..days.lastIndex - dayIndex,
+            ).map { slice ->
+                val day = dayIndex + slice.dayOffset
+                val col = if (geometry.isRtl) days.lastIndex - day else day
+                TimelineDragPiece(
+                    topLeftInRoot = Offset(
+                        x = origin.x + col * columnPx,
+                        y = origin.y + slice.startMin / 60f * hourPx,
+                    ),
+                    sizePx = IntSize(
+                        (columnPx - geometry.columnGapPx).roundToInt(),
+                        maxOf(
+                            slice.spanMin / 60f * hourPx,
+                            MIN_EVENT_FRACTION * hourPx,
+                        ).roundToInt(),
+                    ),
+                    continuesBefore = slice.continuesBefore,
+                    continuesAfter = slice.continuesAfter,
+                )
+            },
         )
     }
 
@@ -334,24 +485,52 @@ fun rememberTimelineDragController(): TimelineDragController {
     val density = LocalDensity.current
     controller.geometry.edgePx = with(density) { AUTO_SCROLL_EDGE.toPx() }
     controller.geometry.stepPx = with(density) { AUTO_SCROLL_STEP.toPx() }
+    controller.abandonedTicks = LocalEventMove.current?.abandoned
     return controller
 }
 
 /**
- * True when [block] actually begins on [day] rather than being the tail of an
- * event that started earlier. A clipped block's top edge is midnight, not the
- * event's start, so dragging it would move the event to a time it never had.
+ * How far this block's top edge sits past its event's start, in minutes — zero
+ * for a block that begins on [day], and the part already run for the tail of an
+ * event that started earlier, whose top edge is midnight rather than the event's
+ * start. Dragging such a tail moves the event by where *its own* top edge lands,
+ * so the offset has to come back off at the drop (#253).
  */
-fun TimedBlock.beginsOn(day: LocalDate, zone: TimeZone): Boolean =
-    event.start.toLocalDateTime(zone).date == day
+fun TimedBlock.clipOffsetMinutes(day: LocalDate, zone: TimeZone): Int {
+    val start = event.start.toLocalDateTime(zone)
+    val days = (day.toEpochDays() - start.date.toEpochDays()).toInt()
+    val minutes = days * MINUTES_PER_DAY + startMin - start.time.toSecondOfDay() / 60
+    return minutes.coerceAtLeast(0)
+}
 
 /**
- * The instant a drop asks for, read in the zone the timeline is drawn in. A drop
- * into a spring-forward gap has no instant of its own; `toInstant` resolves it
- * forward by the missing hour, and the block visibly settles there.
+ * True when the event began before [day] — this block is its tail, cut at
+ * midnight rather than starting where the event does.
  */
-fun TimelineDrop.startInstant(zone: TimeZone): Instant =
-    LocalDateTime(date, LocalTime(startMin / 60, startMin % 60)).toInstant(zone)
+fun TimedBlock.continuesBefore(day: LocalDate, zone: TimeZone): Boolean =
+    event.start < day.atStartOfDayIn(zone)
+
+/** True when the event runs past [day]'s midnight, so this block is cut there. */
+fun TimedBlock.continuesAfter(day: LocalDate, zone: TimeZone): Boolean =
+    event.end > day.plus(1, DateTimeUnit.DAY).atStartOfDayIn(zone)
+
+/**
+ * The instant a drop asks for — the *event's* new start, so the tail of an
+ * overnight event drops back onto the day its own start belongs to. Read in the
+ * zone the timeline is drawn in. A drop into a spring-forward gap has no instant
+ * of its own; `toInstant` resolves it forward by the missing hour, and the block
+ * visibly settles there.
+ */
+fun TimelineDrop.startInstant(zone: TimeZone): Instant {
+    // Wall clock throughout, and past this day at either end: a block's top edge
+    // can be dragged above its midnight and a tail's below the next one, so the
+    // start is resolved as a day plus a minute of it rather than as an offset
+    // from an instant — which would shift by an hour across a DST boundary.
+    val fromMidnight = startMin - clipOffsetMin
+    val day = date.plus(fromMidnight.floorDiv(MINUTES_PER_DAY), DateTimeUnit.DAY)
+    val minute = fromMidnight.mod(MINUTES_PER_DAY)
+    return LocalDateTime(day, LocalTime(minute / 60, minute % 60)).toInstant(zone)
+}
 
 /**
  * A beat after the grid draws the drop, so its own block is under way before the
@@ -384,7 +563,6 @@ fun TimelineDragOverlay(controller: TimelineDragController, modifier: Modifier =
     val use24Hour = LocalUse24HourFormat.current
     val locale = currentLocale()
     val reduceMotion = rememberReduceMotion()
-    val density = LocalDensity.current
     val moveInFlight = moveInFlight()
 
     // Both live here rather than beside the controller: they read [drag], which
@@ -397,9 +575,14 @@ fun TimelineDragOverlay(controller: TimelineDragController, modifier: Modifier =
     // recurring drop's scope dialog is up — and then until the grid draws the
     // drop itself.
     var handingOver by remember(controller.settling) { mutableStateOf(false) }
-    LaunchedEffect(controller.settling, moveInFlight, controller.settledOnGrid) {
+    val abandoned = abandonedMoves()
+    LaunchedEffect(controller.settling, moveInFlight, controller.settledOnGrid, abandoned) {
         if (controller.settling == null || moveInFlight) return@LaunchedEffect
-        delay(if (controller.settledOnGrid) SETTLE_GRACE_MILLIS else SETTLE_TIMEOUT_MILLIS)
+        // Past the mark this drop was let go on, it was abandoned: nothing will
+        // land and there is nothing to wait for.
+        if (abandoned == controller.settledAbandonedMark) {
+            delay(if (controller.settledOnGrid) SETTLE_GRACE_MILLIS else SETTLE_TIMEOUT_MILLIS)
+        }
         handingOver = true
         controller.handOver()
         delay(SETTLE_FADE_MILLIS.toLong())
@@ -428,49 +611,84 @@ fun TimelineDragOverlay(controller: TimelineDragController, modifier: Modifier =
         )
         val fill = eventFill(drag.event.color, dark, soften)
         val title = drag.event.title.ifBlank { stringResource(R.string.event_untitled) }
-        // An end past midnight wraps rather than saturating, so a four-hour
-        // event dragged to 22:00 reads "22:00–02:00" and not "22:00–24:00".
-        val endMin = if (drag.endMin > MINUTES_PER_DAY) {
-            drag.endMin % MINUTES_PER_DAY
-        } else {
-            drag.endMin
-        }
-        val label = "${formatMinuteOfDay(drag.startMin, use24Hour, locale)}–" +
+        // Read off the event rather than the held block, so grabbing either half
+        // of an event that crosses midnight names the same hours. An end past
+        // midnight wraps rather than saturating, so a four-hour event dragged to
+        // 22:00 reads "22:00–02:00" and not "22:00–24:00".
+        val startMin = drag.eventStartMin.mod(MINUTES_PER_DAY)
+        val rawEnd = startMin + drag.eventSpanMin
+        val endMin = if (rawEnd > MINUTES_PER_DAY) rawEnd % MINUTES_PER_DAY else rawEnd
+        val label = "${formatMinuteOfDay(startMin, use24Hour, locale)}–" +
             formatMinuteOfDay(endMin, use24Hour, locale)
-        Box(
-            modifier = Modifier
-                // Absolute: these are root coordinates, and the direction-aware
-                // offset would mirror them across the screen in an RTL layout.
-                .absoluteOffset {
-                    IntOffset(
-                        (drag.topLeftInRoot.x - origin.x).roundToInt(),
-                        (drag.topLeftInRoot.y - origin.y).roundToInt(),
-                    )
-                }
-                .size(
-                    width = with(density) { drag.sizePx.width.toDp() },
-                    height = with(density) { drag.sizePx.height.toDp() },
-                )
-                .padding(horizontal = 1.dp)
-                .graphicsLayer {
-                    scaleX = 1f + 0.02f * lift
-                    scaleY = 1f + 0.02f * lift
-                    shadowElevation = 8.dp.toPx() * lift
-                    alpha = copyAlpha
-                    shape = RoundedCornerShape(4.dp)
-                    clip = false
-                }
-                .background(fill, RoundedCornerShape(4.dp))
-                .padding(horizontal = 4.dp, vertical = 2.dp),
-        ) {
-            Column {
-                Text(
-                    text = title,
-                    style = MaterialTheme.typography.labelMedium,
-                    maxLines = 1,
-                    overflow = TextOverflow.Ellipsis,
-                    color = eventInk(fill, alpha = 0.85f),
+        // The tallest piece carries the range: on the smallest it would be
+        // clipped away, which is exactly the case when a short tail is held.
+        val labelled = drag.pieces.indices.maxByOrNull { drag.pieces[it].sizePx.height }
+        drag.pieces.forEachIndexed { index, piece ->
+            DragCopy(
+                topLeftInRoot = piece.topLeftInRoot,
+                overlayOrigin = origin,
+                sizePx = piece.sizePx,
+                fill = fill,
+                shape = timedBlockShape(piece.continuesBefore, piece.continuesAfter),
+                lift = lift,
+                alpha = copyAlpha,
+                title = title,
+                // Once for the whole event: repeated, it would name it per day.
+                label = label.takeIf { index == labelled },
+            )
+        }
+    }
+}
+
+/** One piece of a dragged block, floating over the calendar. */
+@Composable
+private fun DragCopy(
+    topLeftInRoot: Offset,
+    overlayOrigin: Offset,
+    sizePx: IntSize,
+    fill: Color,
+    shape: RoundedCornerShape,
+    lift: Float,
+    alpha: Float,
+    title: String,
+    label: String?,
+) {
+    val density = LocalDensity.current
+    Box(
+        modifier = Modifier
+            // Absolute: these are root coordinates, and the direction-aware
+            // offset would mirror them across the screen in an RTL layout.
+            .absoluteOffset {
+                IntOffset(
+                    (topLeftInRoot.x - overlayOrigin.x).roundToInt(),
+                    (topLeftInRoot.y - overlayOrigin.y).roundToInt(),
                 )
+            }
+            .size(
+                width = with(density) { sizePx.width.toDp() },
+                height = with(density) { sizePx.height.toDp() },
+            )
+            .padding(horizontal = 1.dp)
+            .graphicsLayer {
+                scaleX = 1f + 0.02f * lift
+                scaleY = 1f + 0.02f * lift
+                shadowElevation = 8.dp.toPx() * lift
+                this.alpha = alpha
+                this.shape = shape
+                clip = false
+            }
+            .background(fill, shape)
+            .padding(horizontal = 4.dp, vertical = 2.dp),
+    ) {
+        Column {
+            Text(
+                text = title,
+                style = MaterialTheme.typography.labelMedium,
+                maxLines = 1,
+                overflow = TextOverflow.Ellipsis,
+                color = eventInk(fill, alpha = 0.85f),
+            )
+            if (label != null) {
                 Text(
                     text = label,
                     style = MaterialTheme.typography.labelSmall,

app/src/main/java/de/jeanlucmakiola/calendula/ui/day/DayScreen.kt

@@ -91,7 +91,10 @@ import de.jeanlucmakiola.calendula.ui.common.NowLine
 import de.jeanlucmakiola.calendula.ui.common.TimelineDragController
 import de.jeanlucmakiola.calendula.ui.common.TimelineDragOverlay
 import de.jeanlucmakiola.calendula.ui.common.TimelineDrop
-import de.jeanlucmakiola.calendula.ui.common.beginsOn
+import de.jeanlucmakiola.calendula.ui.common.clipOffsetMinutes
+import de.jeanlucmakiola.calendula.ui.common.continuesAfter
+import de.jeanlucmakiola.calendula.ui.common.continuesBefore
+import de.jeanlucmakiola.calendula.ui.common.timedBlockShape
 import de.jeanlucmakiola.calendula.ui.common.eventDragAllowed
 import de.jeanlucmakiola.calendula.ui.common.eventMoveAction
 import de.jeanlucmakiola.calendula.ui.common.rememberEventDragSource
@@ -104,6 +107,7 @@ import de.jeanlucmakiola.calendula.ui.common.rememberCalendarPageSwipe
 import de.jeanlucmakiola.floret.identity.rememberReduceMotion
 import de.jeanlucmakiola.calendula.ui.common.next
 import de.jeanlucmakiola.calendula.ui.common.LocalSoftenColors
+import de.jeanlucmakiola.calendula.ui.common.EventChipShape
 import de.jeanlucmakiola.calendula.ui.common.eventFill
 import de.jeanlucmakiola.calendula.ui.common.eventInk
 import de.jeanlucmakiola.calendula.ui.common.declinedDecoration
@@ -351,7 +355,7 @@ private fun DayContent(
                     onEventClick = onEventClick,
                     onCreateAt = onCreateAt,
                     onDrop = { drop ->
-                        val took = move?.move(
+                        move?.move(
                             MoveRequest(
                                 eventId = drop.event.eventId,
                                 beginMillis = drop.event.start.toEpochMilliseconds(),
@@ -359,9 +363,6 @@ private fun DayContent(
                                 target = MoveTarget.Start(drop.startInstant(zone)),
                             ),
                         )
-                        // Refused, so nothing will land: let the copy go now
-                        // rather than hold it out for a settle that never comes.
-                        if (took != true) dragController.release()
                     },
                 )
             }
@@ -519,7 +520,7 @@ private fun AllDayBar(
     val fill = eventFill(event.color, dark, soften)
     Box(
         modifier = modifier
-            .background(fill, RoundedCornerShape(4.dp))
+            .background(fill, EventChipShape)
             .clickable(onClick = onClick)
             .padding(horizontal = 6.dp, vertical = 2.dp)
             .semantics { contentDescription = title },
@@ -744,24 +745,30 @@ private fun EventBlock(
     val fill = eventFill(block.event.color, dark, soften)
     val zone = remember { TimeZone.currentSystemDefault() }
     val moveAction = eventMoveAction(block.event)
-    // A block clipped at the top continues from the previous day: its top edge
-    // is midnight, not the event's start, so dragging it would invent a time.
-    val draggable = eventDragAllowed(block.event) && block.beginsOn(date, zone)
+    val draggable = eventDragAllowed(block.event)
+    // The drop takes this offset back off, so a tail clipped at midnight lands
+    // where the event's own start belongs (#253).
+    val clipOffset = remember(block, date, zone) { block.clipOffsetMinutes(date, zone) }
+    val shape = remember(block, date, zone) {
+        timedBlockShape(block.continuesBefore(date, zone), block.continuesAfter(date, zone))
+    }
     val dragModifier = rememberEventDragSource(
         enabled = draggable,
         key = block.event.instanceId,
-        onPickUp = { pointer, blockRoot, _ -> dragController.begin(block, pointer, blockRoot) },
+        onPickUp = { pointer, blockRoot, _ ->
+            dragController.begin(block, clipOffset, pointer, blockRoot)
+        },
         onMove = dragController::move,
         onDrop = { dragController.finish()?.let(onDrop) },
         onCancel = dragController::cancel,
     )
-    val lifted = draggable && dragController.ghosts(block, date)
+    val lifted = draggable && dragController.ghosts(block)
     val ghost = ghostAlpha(lifted)
     Box(
         modifier = modifier
             // The source stays put as a ghost while its floating copy travels.
             .then(if (ghost < 1f) Modifier.alpha(ghost) else Modifier)
-            .background(fill, RoundedCornerShape(4.dp))
+            .background(fill, shape)
             .clickable(onClick = onClick)
             // After clickable, so it is the inner node and wins the main pass;
             // the tap still works, since a drag consumes the up.

app/src/main/java/de/jeanlucmakiola/calendula/ui/month/MonthDrag.kt

@@ -13,6 +13,8 @@ import androidx.compose.ui.layout.boundsInRoot
 import androidx.compose.ui.layout.positionInRoot
 import androidx.compose.ui.unit.IntSize
 import de.jeanlucmakiola.calendula.domain.EventInstance
+import de.jeanlucmakiola.calendula.ui.common.LocalEventMove
+import kotlinx.coroutines.flow.StateFlow
 import kotlinx.datetime.LocalDate
 import kotlin.math.abs
 
@@ -33,6 +35,8 @@ class MonthRowGeometry(
     val isRtl: Boolean,
     /** What this row currently draws in [lane] of column `col`, or null. */
     val chipAt: (col: Int, lane: Int) -> EventInstance?,
+    /** The column the chip in [lane] of column `col` is drawn from. */
+    val chipStart: (col: Int, lane: Int) -> Int,
 ) {
     /** Root top-left of the chip seated in [lane] of column [col]. */
     fun seat(col: Int, lane: Int): Offset? {
@@ -47,21 +51,43 @@ class MonthRowGeometry(
      * the day isn't in this week, or the chip went into the day's "+N" overflow.
      */
     fun seatOf(event: EventInstance, date: LocalDate): Offset? {
-        val col = days.indexOf(date).takeIf { it >= 0 } ?: return null
-        val lane = (0 until laneCount).firstOrNull { lane ->
-            chipAt(col, lane)?.let { isSameEvent(it, event) } == true
-        } ?: return null
+        val (col, lane) = chipSeat(days, laneCount, chipAt, chipStart, event, date) ?: return null
         return seat(col, lane)
     }
 }
 
+/**
+ * The column and lane a row draws [event]'s chip in, given it covers [date] —
+ * null when the row seats no such chip. The column is the *left end* of the bar
+ * within this row, not [date]'s own: a bar spanning several days is drawn once,
+ * from its first column, so an event dropped onto the second day it covers is
+ * seated a column (or more) to the left of where it landed (#253).
+ */
+internal fun chipSeat(
+    days: List<LocalDate>,
+    laneCount: Int,
+    chipAt: (col: Int, lane: Int) -> EventInstance?,
+    chipStart: (col: Int, lane: Int) -> Int,
+    event: EventInstance,
+    date: LocalDate,
+): Pair<Int, Int>? {
+    val col = days.indexOf(date).takeIf { it >= 0 } ?: return null
+    val lane = (0 until laneCount).firstOrNull { lane ->
+        chipAt(col, lane)?.let { isSameEvent(it, event) } == true
+    } ?: return null
+    return chipStart(col, lane) to lane
+}
+
 /**
  * Whether [chip] is the moved event [moved] as the grid now holds it. Neither id
  * alone will do: re-read instances get new instance ids, and a single-occurrence
- * move writes a new event id — the title survives both.
+ * move writes a new event id — the title survives both. A *blank* title is no
+ * evidence at all, though: every untitled event carries one, so matching on it
+ * made any two of them the same event (#253).
  */
-private fun isSameEvent(chip: EventInstance, moved: EventInstance): Boolean =
-    chip.eventId == moved.eventId || chip.title == moved.title
+internal fun isSameEvent(chip: EventInstance, moved: EventInstance): Boolean =
+    chip.eventId == moved.eventId ||
+        (moved.title.isNotBlank() && chip.title == moved.title)
 
 /** A chip in flight, in root coordinates so it can be drawn in an overlay. */
 data class MonthChipDrag(
@@ -134,6 +160,16 @@ class MonthDragController {
      */
     private var undoable: MonthChipDrag? = null
 
+    /**
+     * The abandoned-move counter, read at the drop so the mark can't be a
+     * composition behind the tick it is compared against.
+     */
+    var abandonedTicks: StateFlow<Int>? = null
+
+    /** What [abandonedTicks] stood at when the settling chip was let go. */
+    var settledAbandonedMark: Int = 0
+        private set
+
     private var event: EventInstance? = null
     private var grabDate: LocalDate? = null
     private var grab = Offset.Zero
@@ -222,6 +258,7 @@ class MonthDragController {
         liftedInstanceId = last.event.instanceId
         settledGhost = true
         settledInRoot = null
+        settledAbandonedMark = abandonedTicks?.value ?: 0
         return true
     }
 
@@ -242,6 +279,7 @@ class MonthDragController {
         liftedInstanceId = landed.event.instanceId
         settledGhost = true
         undoable = settling
+        settledAbandonedMark = abandonedTicks?.value ?: 0
         return MonthChipDrop(landed.event, landed.grabDate, target)
     }
 
@@ -298,6 +336,10 @@ class MonthDragController {
 }
 
 @Composable
-fun rememberMonthDragController(): MonthDragController = remember { MonthDragController() }
+fun rememberMonthDragController(): MonthDragController {
+    val controller = remember { MonthDragController() }
+    controller.abandonedTicks = LocalEventMove.current?.abandoned
+    return controller
+}
 
 val LocalMonthDrag = compositionLocalOf<MonthDragController?> { null }

app/src/main/java/de/jeanlucmakiola/calendula/ui/month/MonthScreen.kt

@@ -95,6 +95,7 @@ import de.jeanlucmakiola.calendula.ui.common.MoveTarget
 import de.jeanlucmakiola.calendula.ui.common.MoveRequest
 import de.jeanlucmakiola.calendula.ui.common.LocalEventMove
 import de.jeanlucmakiola.calendula.ui.common.moveInFlight
+import de.jeanlucmakiola.calendula.ui.common.abandonedMoves
 import de.jeanlucmakiola.calendula.ui.common.OnUndoStarted
 import de.jeanlucmakiola.calendula.ui.common.ghostAlpha
 import de.jeanlucmakiola.calendula.ui.common.DragSnapHaptics
@@ -145,6 +146,8 @@ import de.jeanlucmakiola.calendula.ui.common.declinedDecoration
 import de.jeanlucmakiola.calendula.ui.common.LocalDimCutoff
 import de.jeanlucmakiola.calendula.ui.common.LocalSoftenColors
 import de.jeanlucmakiola.calendula.ui.common.eventAccent
+import de.jeanlucmakiola.calendula.ui.common.EventChipShape
+import de.jeanlucmakiola.calendula.ui.common.monthBarShape
 import de.jeanlucmakiola.calendula.ui.common.eventFill
 import de.jeanlucmakiola.calendula.ui.common.eventInk
 import de.jeanlucmakiola.calendula.ui.common.rememberCurrentMinute
@@ -505,11 +508,14 @@ private fun MonthDragOverlay(controller: MonthDragController) {
     val glide = remember { Animatable(Offset.Zero, Offset.VectorConverter) }
     val glideSpec = MaterialTheme.motionScheme.fastSpatialSpec<Offset>()
     val seat = controller.settledInRoot
-    LaunchedEffect(controller.settling, moveInFlight, seat) {
+    val abandoned = abandonedMoves()
+    LaunchedEffect(controller.settling, moveInFlight, seat, abandoned) {
         val landed = controller.settling
         if (landed == null || moveInFlight) return@LaunchedEffect
         if (seat == null) {
-            delay(MONTH_SETTLE_TIMEOUT_MILLIS)
+            // Past the mark this drop was let go on, it was abandoned and no
+            // seat is ever coming.
+            if (abandoned == controller.settledAbandonedMark) delay(MONTH_SETTLE_TIMEOUT_MILLIS)
         } else {
             if (!gliding) glide.snapTo(landed.topLeftInRoot)
             gliding = true
@@ -563,7 +569,7 @@ private fun MonthDragOverlay(controller: MonthDragController) {
                     scaleY = 1f + 0.04f * lift
                     shadowElevation = 8.dp.toPx() * lift
                     alpha = copyAlpha
-                    shape = RoundedCornerShape(4.dp)
+                    shape = EventChipShape
                     clip = false
                 },
         )
@@ -1919,6 +1925,7 @@ private fun MonthWeekRow(
                     laneCount = MAX_EVENT_ROWS,
                     isRtl = isRtl,
                     chipAt = { col, lane -> week.chipAt(col, lane, MAX_EVENT_ROWS) },
+                    chipStart = { col, lane -> week.chipStartCol(col, lane) },
                 ),
             )
         }
@@ -2310,7 +2317,7 @@ private fun monthChipDragModifier(
             // How many columns the finger crossed — grabbing the middle of a
             // multi-day bar shifts by what it travelled, not to where it landed.
             val delta = (drop.targetDate.toEpochDays() - drop.grabDate.toEpochDays()).toInt()
-            val took = moveScope?.move(
+            moveScope?.move(
                 MoveRequest(
                     eventId = drop.event.eventId,
                     beginMillis = drop.event.start.toEpochMilliseconds(),
@@ -2318,9 +2325,6 @@ private fun monthChipDragModifier(
                     target = MoveTarget.ByDays(delta),
                 ),
             )
-            // Refused, so nothing will land: let the copy go now rather than
-            // hold the chip out for a settle that can never arrive.
-            if (took != true) controller?.release()
         }
     },
     onCancel = { controller?.cancel() },
@@ -2436,12 +2440,7 @@ private fun MonthBar(
     val lifted = monthDrag?.liftedInstanceId == event.instanceId ||
         monthDrag?.isSettledChip(event, days) == true
     val ghost = ghostAlpha(lifted)
-    val shape = RoundedCornerShape(
-        topStart = if (continuesLeft) 0.dp else 4.dp,
-        bottomStart = if (continuesLeft) 0.dp else 4.dp,
-        topEnd = if (continuesRight) 0.dp else 4.dp,
-        bottomEnd = if (continuesRight) 0.dp else 4.dp,
-    )
+    val shape = monthBarShape(continuesLeft, continuesRight)
     Box(
         modifier = (if (dimmed) modifier.alpha(EventDimAlpha) else modifier)
             .then(if (ghost < 1f) Modifier.alpha(ghost) else Modifier)

app/src/main/java/de/jeanlucmakiola/calendula/ui/month/MonthUiState.kt

@@ -84,6 +84,16 @@ fun MonthWeek.chipAt(col: Int, lane: Int, laneCap: Int): EventInstance? {
     return timedByDay[days[col]].orEmpty().take(free.size).getOrNull(index)
 }
 
+/**
+ * The column the chip drawn in lane [lane] of column [col] begins in. A bar is
+ * drawn once, from its own first column, so a chip seated by [chipAt] on the
+ * second day it covers belongs a column (or more) to the left (#253). Answers
+ * [col] for a single-day chip, and for an empty slot no one should be asking
+ * about.
+ */
+fun MonthWeek.chipStartCol(col: Int, lane: Int): Int =
+    spans.firstOrNull { it.lane == lane && col in it.startCol..it.endCol }?.startCol ?: col
+
 /**
  * The events on [day] that [laneEvents] had no lane left for — its exact
  * complement, in the same bars-then-pills order. Returned as events rather than

app/src/main/java/de/jeanlucmakiola/calendula/ui/month/MonthViewModel.kt

@@ -12,6 +12,7 @@ import de.jeanlucmakiola.calendula.domain.EventInstance
 import de.jeanlucmakiola.calendula.domain.FailureReason
 import de.jeanlucmakiola.calendula.ui.week.coversDay
 import de.jeanlucmakiola.calendula.ui.week.layoutAllDay
+import de.jeanlucmakiola.calendula.ui.week.spansMultipleDays
 import kotlinx.coroutines.CoroutineDispatcher
 import kotlinx.coroutines.ExperimentalCoroutinesApi
 import kotlinx.coroutines.flow.MutableStateFlow
@@ -417,8 +418,11 @@ internal fun layoutCalendarWeek(
     zone: TimeZone,
 ): MonthWeek {
     val weekEvents = instances.filter { ev -> days.any { ev.coversDay(it, zone) } }
+    // A bar is decided by the *event*, not by how much of it this row holds: one
+    // crossing midnight into the next week row covers a single day in each, and
+    // counting per row drew it as two unrelated pills (#253).
     val (bars, singles) = weekEvents.partition { ev ->
-        ev.isAllDay || days.count { ev.coversDay(it, zone) } > 1
+        ev.isAllDay || ev.spansMultipleDays(zone)
     }
     val spans = layoutAllDay(bars, days, zone).map { s ->
         MonthSpan(

app/src/main/java/de/jeanlucmakiola/calendula/ui/week/WeekScreen.kt

@@ -100,7 +100,10 @@ import de.jeanlucmakiola.calendula.ui.common.MoveTarget
 import de.jeanlucmakiola.calendula.ui.common.TimelineDragController
 import de.jeanlucmakiola.calendula.ui.common.TimelineDragOverlay
 import de.jeanlucmakiola.calendula.ui.common.TimelineDrop
-import de.jeanlucmakiola.calendula.ui.common.beginsOn
+import de.jeanlucmakiola.calendula.ui.common.clipOffsetMinutes
+import de.jeanlucmakiola.calendula.ui.common.continuesAfter
+import de.jeanlucmakiola.calendula.ui.common.continuesBefore
+import de.jeanlucmakiola.calendula.ui.common.timedBlockShape
 import de.jeanlucmakiola.calendula.ui.common.eventDragAllowed
 import de.jeanlucmakiola.calendula.ui.common.eventMoveAction
 import de.jeanlucmakiola.calendula.ui.common.rememberEventDragSource
@@ -108,6 +111,7 @@ import de.jeanlucmakiola.calendula.ui.common.rememberTimelineDragController
 import de.jeanlucmakiola.calendula.ui.common.startInstant
 import de.jeanlucmakiola.calendula.ui.common.LocalDimCutoff
 import de.jeanlucmakiola.calendula.ui.common.LocalSoftenColors
+import de.jeanlucmakiola.calendula.ui.common.EventChipShape
 import de.jeanlucmakiola.calendula.ui.common.eventFill
 import de.jeanlucmakiola.calendula.ui.common.eventInk
 import de.jeanlucmakiola.calendula.ui.common.NowLine
@@ -387,7 +391,7 @@ private fun WeekContent(
                     onOpenDay = onOpenDay,
                     onCreateAt = onCreateAt,
                     onDrop = { drop ->
-                        val took = move?.move(
+                        move?.move(
                             MoveRequest(
                                 eventId = drop.event.eventId,
                                 beginMillis = drop.event.start.toEpochMilliseconds(),
@@ -395,9 +399,6 @@ private fun WeekContent(
                                 target = MoveTarget.Start(drop.startInstant(zone)),
                             ),
                         )
-                        // Refused, so nothing will land: let the copy go now
-                        // rather than hold it out for a settle that never comes.
-                        if (took != true) dragController.release()
                     },
                 )
             }
@@ -656,7 +657,7 @@ private fun AllDayBar(
     val fill = eventFill(event.color, dark, soften)
     Box(
         modifier = (if (dimmed) modifier.alpha(EventDimAlpha) else modifier)
-            .background(fill, RoundedCornerShape(4.dp))
+            .background(fill, EventChipShape)
             .clickable(onClick = onClick)
             .padding(horizontal = 6.dp, vertical = 2.dp)
             .semantics { contentDescription = title },
@@ -912,24 +913,30 @@ private fun EventBlock(
     val fill = eventFill(block.event.color, dark, soften)
     val zone = remember { TimeZone.currentSystemDefault() }
     val moveAction = eventMoveAction(block.event)
-    // A block clipped at the top continues from the previous day: its top edge
-    // is midnight, not the event's start, so dragging it would invent a time.
-    val draggable = eventDragAllowed(block.event) && block.beginsOn(date, zone)
+    val draggable = eventDragAllowed(block.event)
+    // The drop takes this offset back off, so a tail clipped at midnight lands
+    // where the event's own start belongs (#253).
+    val clipOffset = remember(block, date, zone) { block.clipOffsetMinutes(date, zone) }
+    val shape = remember(block, date, zone) {
+        timedBlockShape(block.continuesBefore(date, zone), block.continuesAfter(date, zone))
+    }
     val dragModifier = rememberEventDragSource(
         enabled = draggable,
         key = block.event.instanceId,
-        onPickUp = { pointer, blockRoot, _ -> dragController.begin(block, pointer, blockRoot) },
+        onPickUp = { pointer, blockRoot, _ ->
+            dragController.begin(block, clipOffset, pointer, blockRoot)
+        },
         onMove = dragController::move,
         onDrop = { dragController.finish()?.let(onDrop) },
         onCancel = dragController::cancel,
     )
-    val lifted = draggable && dragController.ghosts(block, date)
+    val lifted = draggable && dragController.ghosts(block)
     val ghost = ghostAlpha(lifted)
     Box(
         modifier = (if (dimmed) modifier.alpha(EventDimAlpha) else modifier)
             // The source stays put as a ghost while its floating copy travels.
             .then(if (ghost < 1f) Modifier.alpha(ghost) else Modifier)
-            .background(fill, RoundedCornerShape(4.dp))
+            .background(fill, shape)
             .clickable(onClick = onClick)
             // After clickable, so it is the inner node and wins the main pass;
             // the tap still works, since a drag consumes the up.

app/src/main/java/de/jeanlucmakiola/calendula/ui/week/WeekViewModel.kt

@@ -206,6 +206,17 @@ internal fun EventInstance.coversDay(day: LocalDate, zone: TimeZone): Boolean {
     return start < dayEnd && end > dayStart
 }
 
+/**
+ * True if this event touches more than one calendar day in [zone] — an all-day
+ * event covering a range, or a timed one crossing midnight. Occurrences are
+ * contiguous, so covering the day after the first is the whole question.
+ */
+internal fun EventInstance.spansMultipleDays(zone: TimeZone): Boolean {
+    val anchor = if (isAllDay) TimeZone.UTC else zone
+    val secondDay = start.toLocalDateTime(anchor).date.plus(1, DateTimeUnit.DAY)
+    return coversDay(secondDay, zone)
+}
+
 /**
  * Clip [events] to a single [day] and assign lanes so overlapping events render
  * side-by-side. Lane count is computed per overlap-cluster (a maximal run of

app/src/test/java/de/jeanlucmakiola/calendula/ui/common/RescheduleViewModelTest.kt

@@ -494,4 +494,61 @@ class RescheduleViewModelTest {
         assertThat(fake.updatedEvents).isEmpty()
         assertThat(fake.updatedOccurrences).isEmpty()
     }
+
+    @Test
+    fun `a drop that lands nothing says so, since move() already answered yes`(
+        @TempDir tempDir: Path,
+    ) = runTest(dispatcher) {
+        val fake = FakeCalendarDataSource().apply { eventDetailResult = { detail() } }
+        val vm = viewModel(tempDir, fake)
+
+        // Refused in prepare: nowhere to move to.
+        assertThat(vm.move(
+            MoveRequest(
+                eventId = 42L,
+                beginMillis = beginMillis,
+                endMillis = endMillis,
+                target = MoveTarget.Start(Instant.fromEpochMilliseconds(beginMillis)),
+            ),
+        )).isTrue()
+        advanceUntilIdle()
+        assertThat(vm.abandoned.value).isEqualTo(1)
+
+        // Refused by the provider, after the write was attempted.
+        fake.writeError = SecurityException("revoked")
+        vm.move(oneHourLater())
+        advanceUntilIdle()
+        assertThat(vm.outcome.value).isEqualTo(MoveOutcome.WriteDenied)
+        assertThat(vm.abandoned.value).isEqualTo(2)
+    }
+
+    @Test
+    fun `a scope dialog dismissed leaves nothing waiting on the write`(
+        @TempDir tempDir: Path,
+    ) = runTest(dispatcher) {
+        val fake = FakeCalendarDataSource().apply {
+            eventDetailResult = { detail(rrule = "FREQ=WEEKLY") }
+        }
+        val vm = viewModel(tempDir, fake)
+
+        vm.move(oneHourLater())
+        advanceUntilIdle()
+        assertThat(vm.abandoned.value).isEqualTo(0)
+
+        vm.cancelScope()
+        advanceUntilIdle()
+        assertThat(vm.abandoned.value).isEqualTo(1)
+    }
+
+    @Test
+    fun `a written move never counts as abandoned`(@TempDir tempDir: Path) = runTest(dispatcher) {
+        val fake = FakeCalendarDataSource().apply { eventDetailResult = { detail() } }
+        val vm = viewModel(tempDir, fake)
+
+        vm.move(oneHourLater())
+        advanceUntilIdle()
+
+        assertThat(vm.outcome.value).isInstanceOf(MoveOutcome.Moved::class.java)
+        assertThat(vm.abandoned.value).isEqualTo(0)
+    }
 }

app/src/test/java/de/jeanlucmakiola/calendula/ui/common/TimedBlockShapeTest.kt

@@ -0,0 +1,183 @@
+package de.jeanlucmakiola.calendula.ui.common
+
+import com.google.common.truth.Truth.assertThat
+import de.jeanlucmakiola.calendula.domain.EventInstance
+import de.jeanlucmakiola.calendula.ui.week.MINUTES_PER_DAY
+import de.jeanlucmakiola.calendula.ui.week.layoutDay
+import kotlinx.datetime.DateTimeUnit
+import kotlinx.datetime.LocalDate
+import kotlinx.datetime.TimeZone
+import kotlinx.datetime.atTime
+import kotlinx.datetime.plus
+import kotlinx.datetime.toInstant
+import androidx.compose.foundation.shape.CornerSize
+import androidx.compose.ui.unit.dp
+import org.junit.jupiter.api.Test
+
+/**
+ * Which edges a timed block is cut on, and how much of a dragged piece its day
+ * can show (#253).
+ */
+class TimedBlockShapeTest {
+
+    private val zone = TimeZone.UTC
+    private val day1 = LocalDate(2026, 9, 5)
+    private val day2 = day1.plus(1, DateTimeUnit.DAY)
+    private val day3 = day2.plus(1, DateTimeUnit.DAY)
+
+    private fun event(from: LocalDateTimeIsh, to: LocalDateTimeIsh) = EventInstance(
+        instanceId = 1L, eventId = 1L, calendarId = 1L, title = "E",
+        start = from.date.atTime(from.hour, 0).toInstant(zone),
+        end = to.date.atTime(to.hour, 0).toInstant(zone),
+        isAllDay = false, color = 0xFF112233.toInt(), location = null,
+    )
+
+    data class LocalDateTimeIsh(val date: LocalDate, val hour: Int)
+
+    private fun at(date: LocalDate, hour: Int) = LocalDateTimeIsh(date, hour)
+
+    @Test
+    fun `a same-day block is cut on neither edge`() {
+        val ev = event(at(day1, 9), at(day1, 10))
+        val block = layoutDay(listOf(ev), day1, zone).single()
+
+        assertThat(block.continuesBefore(day1, zone)).isFalse()
+        assertThat(block.continuesAfter(day1, zone)).isFalse()
+    }
+
+    @Test
+    fun `an overnight event is cut at the foot of its first day and the head of its second`() {
+        val ev = event(at(day1, 20), at(day2, 8))
+
+        val head = layoutDay(listOf(ev), day1, zone).single()
+        assertThat(head.continuesBefore(day1, zone)).isFalse()
+        assertThat(head.continuesAfter(day1, zone)).isTrue()
+
+        val tail = layoutDay(listOf(ev), day2, zone).single()
+        assertThat(tail.continuesBefore(day2, zone)).isTrue()
+        assertThat(tail.continuesAfter(day2, zone)).isFalse()
+    }
+
+    @Test
+    fun `a day wholly inside a long event is cut on both edges`() {
+        val ev = event(at(day1, 20), at(day3, 8))
+        val middle = layoutDay(listOf(ev), day2, zone).single()
+
+        assertThat(middle.continuesBefore(day2, zone)).isTrue()
+        assertThat(middle.continuesAfter(day2, zone)).isTrue()
+    }
+
+    @Test
+    fun `an event ending exactly at midnight is not cut`() {
+        val ev = event(at(day1, 20), at(day2, 0))
+        val block = layoutDay(listOf(ev), day1, zone).single()
+
+        assertThat(block.continuesAfter(day1, zone)).isFalse()
+    }
+
+    @Test
+    fun `only the cut edges lose their corners`() {
+        val square = 0.dp
+        assertThat(timedBlockShape(continuesBefore = true, continuesAfter = false).topStart)
+            .isEqualTo(CornerSize(square))
+        assertThat(timedBlockShape(continuesBefore = true, continuesAfter = false).bottomStart)
+            .isEqualTo(CornerSize(EVENT_CHIP_CORNER))
+        assertThat(timedBlockShape(continuesBefore = false, continuesAfter = true).topStart)
+            .isEqualTo(CornerSize(EVENT_CHIP_CORNER))
+        assertThat(timedBlockShape(continuesBefore = false, continuesAfter = true).bottomEnd)
+            .isEqualTo(CornerSize(square))
+    }
+
+    private val fourHours = 4 * 60
+
+    @Test
+    fun `an event that fits its day is drawn as one uncut piece`() {
+        val pieces = dragSlices(eventStartMin = 10 * 60, spanMin = fourHours)
+
+        assertThat(pieces).hasSize(1)
+        assertThat(pieces.single().dayOffset).isEqualTo(0)
+        assertThat(pieces.single().spanMin).isEqualTo(fourHours)
+        assertThat(pieces.single().continuesBefore).isFalse()
+        assertThat(pieces.single().continuesAfter).isFalse()
+    }
+
+    @Test
+    fun `dragging the start half re-splits both days as it moves`() {
+        // Held at 22:00: two hours on this day, two on the next.
+        assertThat(dragSlices(22 * 60, fourHours).map { it.spanMin })
+            .containsExactly(2 * 60, 2 * 60).inOrder()
+        // Carried up to 21:00 the first day takes three, so the second day's end
+        // comes up by exactly the hour the first day gained.
+        assertThat(dragSlices(21 * 60, fourHours).map { it.spanMin })
+            .containsExactly(3 * 60, 60).inOrder()
+    }
+
+    @Test
+    fun `dragging the end half splits the same way, one day back`() {
+        // The tail's top edge is at midnight and the event began two hours
+        // earlier, so it starts at -120 relative to the day the finger is on.
+        val pieces = dragSlices(eventStartMin = -2 * 60, spanMin = fourHours)
+
+        assertThat(pieces.map { it.dayOffset }).containsExactly(-1, 0).inOrder()
+        assertThat(pieces.map { it.spanMin }).containsExactly(2 * 60, 2 * 60).inOrder()
+        // The piece on the earlier day ends at midnight; the held one starts there.
+        assertThat(pieces.first().startMin).isEqualTo(22 * 60)
+        assertThat(pieces.first().continuesAfter).isTrue()
+        assertThat(pieces.last().startMin).isEqualTo(0)
+        assertThat(pieces.last().continuesBefore).isTrue()
+    }
+
+    @Test
+    fun `the earlier half shrinks away as the end half is pulled down its own day`() {
+        // Tail top dragged from midnight down to 01:00: one hour left behind.
+        assertThat(dragSlices(-2 * 60 + 60, fourHours).map { it.spanMin })
+            .containsExactly(60, 3 * 60).inOrder()
+        // At 02:00 the event no longer crosses midnight at all.
+        val whole = dragSlices(0, fourHours)
+        assertThat(whole).hasSize(1)
+        assertThat(whole.single().continuesBefore).isFalse()
+    }
+
+    @Test
+    fun `a day wholly inside a long event is cut on both sides`() {
+        val pieces = dragSlices(eventStartMin = 22 * 60, spanMin = 30 * 60)
+
+        assertThat(pieces.map { it.dayOffset }).containsExactly(0, 1, 2).inOrder()
+        assertThat(pieces[1].spanMin).isEqualTo(MINUTES_PER_DAY)
+        assertThat(pieces[1].continuesBefore).isTrue()
+        assertThat(pieces[1].continuesAfter).isTrue()
+    }
+
+    @Test
+    fun `an event ending exactly at midnight takes no piece of the next day`() {
+        val pieces = dragSlices(eventStartMin = 22 * 60, spanMin = 2 * 60)
+
+        assertThat(pieces).hasSize(1)
+        assertThat(pieces.single().continuesAfter).isFalse()
+    }
+
+    @Test
+    fun `a zero-length event still has a piece to draw`() {
+        val pieces = dragSlices(eventStartMin = 9 * 60, spanMin = 0)
+
+        assertThat(pieces).hasSize(1)
+        assertThat(pieces.single().dayOffset).isEqualTo(0)
+        assertThat(pieces.single().startMin).isEqualTo(9 * 60)
+        assertThat(pieces.single().spanMin).isEqualTo(0)
+    }
+
+    @Test
+    fun `only the days there are columns for are sliced`() {
+        // A week's worth of event, previewed on a timeline showing three days
+        // from the one the finger is on.
+        val pieces = dragSlices(0, 7 * MINUTES_PER_DAY, within = 0..2)
+
+        assertThat(pieces.map { it.dayOffset }).containsExactly(0, 1, 2).inOrder()
+        assertThat(pieces.last().continuesAfter).isTrue()
+    }
+
+    @Test
+    fun `an event outside the columns shown is sliced into nothing`() {
+        assertThat(dragSlices(-3 * MINUTES_PER_DAY, 60, within = 0..2)).isEmpty()
+    }
+}

app/src/test/java/de/jeanlucmakiola/calendula/ui/common/TimelineDropTest.kt

@@ -0,0 +1,156 @@
+package de.jeanlucmakiola.calendula.ui.common
+
+import com.google.common.truth.Truth.assertThat
+import de.jeanlucmakiola.calendula.domain.EventInstance
+import de.jeanlucmakiola.calendula.ui.week.TimedBlock
+import de.jeanlucmakiola.calendula.ui.week.layoutDay
+import kotlinx.datetime.DateTimeUnit
+import kotlinx.datetime.LocalDate
+import kotlinx.datetime.TimeZone
+import kotlinx.datetime.atTime
+import kotlinx.datetime.plus
+import kotlinx.datetime.toInstant
+import org.junit.jupiter.api.Test
+
+/**
+ * What a timeline drop asks for, for the head and the tail of an event that
+ * crosses midnight (#253). The tail's top edge is midnight rather than the
+ * event's start, so the drop has to take that offset back off.
+ */
+class TimelineDropTest {
+
+    private val zone = TimeZone.UTC
+    private val sat = LocalDate(2026, 9, 5)
+    private val sun = sat.plus(1, DateTimeUnit.DAY)
+
+    // Sat 5 Sep 20:00 to Sun 6 Sep 08:00.
+    private val overnight = EventInstance(
+        instanceId = 1L,
+        eventId = 1L,
+        calendarId = 1L,
+        title = "Night shift",
+        start = sat.atTime(20, 0).toInstant(zone),
+        end = sun.atTime(8, 0).toInstant(zone),
+        isAllDay = false,
+        color = 0xFF112233.toInt(),
+        location = null,
+    )
+
+    private fun blockOn(day: LocalDate): TimedBlock =
+        layoutDay(listOf(overnight), day, zone).single()
+
+    @Test
+    fun `the head block carries no clip offset`() {
+        val head = blockOn(sat)
+        assertThat(head.startMin).isEqualTo(20 * 60)
+        assertThat(head.clipOffsetMinutes(sat, zone)).isEqualTo(0)
+    }
+
+    @Test
+    fun `the tail block is offset by the part that already ran`() {
+        val tail = blockOn(sun)
+        assertThat(tail.startMin).isEqualTo(0)
+        // 20:00 to midnight is four hours of the event already gone.
+        assertThat(tail.clipOffsetMinutes(sun, zone)).isEqualTo(4 * 60)
+    }
+
+    @Test
+    fun `dropping the head asks for exactly where it landed`() {
+        val target = LocalDate(2026, 9, 2)
+        val drop = TimelineDrop(overnight, target, 20 * 60, clipOffsetMin = 0)
+
+        assertThat(drop.startInstant(zone)).isEqualTo(target.atTime(20, 0).toInstant(zone))
+    }
+
+    @Test
+    fun `dropping the tail moves the event by the days the tail travelled`() {
+        val tail = blockOn(sun)
+        val offset = tail.clipOffsetMinutes(sun, zone)
+        // Dragged three days back, same height in the column: Sun 6 -> Thu 3.
+        val drop = TimelineDrop(overnight, LocalDate(2026, 9, 3), 0, offset)
+
+        // The event began Sat 5 Sep 20:00, so it now begins Wed 2 Sep 20:00 —
+        // the whole event moved three days, and no time of day was invented.
+        assertThat(drop.startInstant(zone))
+            .isEqualTo(LocalDate(2026, 9, 2).atTime(20, 0).toInstant(zone))
+    }
+
+    @Test
+    fun `dragging the tail down the column re-times the event across midnight`() {
+        val offset = blockOn(sun).clipOffsetMinutes(sun, zone)
+        // Tail top pulled from 00:00 to 03:00 on its own day.
+        val drop = TimelineDrop(overnight, sun, 3 * 60, offset)
+
+        assertThat(drop.startInstant(zone)).isEqualTo(sat.atTime(23, 0).toInstant(zone))
+    }
+
+    @Test
+    fun `pulling the tail above its own midnight moves the event earlier`() {
+        val offset = blockOn(sun).clipOffsetMinutes(sun, zone)
+        // The tail's top edge dragged an hour above the midnight it rests on.
+        val drop = TimelineDrop(overnight, sun, -60, offset)
+
+        // Event was Sat 20:00 to Sun 08:00; it now begins an hour earlier.
+        assertThat(drop.startInstant(zone)).isEqualTo(sat.atTime(19, 0).toInstant(zone))
+    }
+
+    @Test
+    fun `a top edge dragged past the next midnight resolves onto the day after`() {
+        val drop = TimelineDrop(overnight, sat, 25 * 60, clipOffsetMin = 0)
+
+        assertThat(drop.startInstant(zone)).isEqualTo(sun.atTime(1, 0).toInstant(zone))
+    }
+
+    @Test
+    fun `a short tail can still be dragged a step earlier`() {
+        // 23:50 to 00:05: five minutes of tail, less than one snap step, which
+        // a floor pinned at midnight left with nowhere to go (#253).
+        assertThat(dragFloorMin(clipOffsetMin = 10, eventSpanMin = 15))
+            .isEqualTo(-DRAG_SNAP_MINUTES)
+    }
+
+    @Test
+    fun `a long tail may rise until its event ends just inside the day`() {
+        // Sat 20:00 to Sun 08:00, held by the Sunday half.
+        assertThat(dragFloorMin(clipOffsetMin = 4 * 60, eventSpanMin = 12 * 60))
+            .isEqualTo(DRAG_SNAP_MINUTES - 8 * 60)
+    }
+
+    @Test
+    fun `an unclipped block cannot be dragged above its own midnight`() {
+        assertThat(dragFloorMin(clipOffsetMin = 0, eventSpanMin = 60)).isEqualTo(0)
+    }
+
+    @Test
+    fun `a drop across a DST boundary keeps the time of day it was let go at`() {
+        // Europe/Berlin springs forward at 02:00 on 29 March 2026, between the
+        // event's start and the midnight its tail is cut at.
+        val berlin = TimeZone.of("Europe/Berlin")
+        val sun = LocalDate(2026, 3, 29)
+        val overnightIntoDst = EventInstance(
+            instanceId = 3L, eventId = 3L, calendarId = 1L, title = "Night shift",
+            start = LocalDate(2026, 3, 28).atTime(22, 0).toInstant(berlin),
+            end = sun.atTime(6, 0).toInstant(berlin),
+            isAllDay = false, color = 0xFF112233.toInt(), location = null,
+        )
+        val tail = layoutDay(listOf(overnightIntoDst), sun, berlin).single()
+        val offset = tail.clipOffsetMinutes(sun, berlin)
+        // Dropped back onto its own slot a week earlier, clear of the boundary.
+        val drop = TimelineDrop(overnightIntoDst, LocalDate(2026, 3, 22), 0, offset)
+
+        assertThat(drop.startInstant(berlin))
+            .isEqualTo(LocalDate(2026, 3, 21).atTime(22, 0).toInstant(berlin))
+    }
+
+    @Test
+    fun `a block that is not clipped is unaffected wherever it sits`() {
+        val plain = EventInstance(
+            instanceId = 2L, eventId = 2L, calendarId = 1L, title = "Standup",
+            start = sat.atTime(9, 0).toInstant(zone),
+            end = sat.atTime(10, 0).toInstant(zone),
+            isAllDay = false, color = 0xFF112233.toInt(), location = null,
+        )
+        val block = layoutDay(listOf(plain), sat, zone).single()
+        assertThat(block.clipOffsetMinutes(sat, zone)).isEqualTo(0)
+    }
+}

app/src/test/java/de/jeanlucmakiola/calendula/ui/month/ChipSeatTest.kt

@@ -0,0 +1,120 @@
+package de.jeanlucmakiola.calendula.ui.month
+
+import com.google.common.truth.Truth.assertThat
+import de.jeanlucmakiola.calendula.domain.EventInstance
+import kotlinx.datetime.DateTimeUnit
+import kotlinx.datetime.LocalDate
+import kotlinx.datetime.atTime
+import kotlinx.datetime.plus
+import kotlinx.datetime.TimeZone
+import kotlinx.datetime.toInstant
+import org.junit.jupiter.api.Test
+
+/**
+ * Where a week row draws a moved chip — what the settling copy glides onto
+ * (#68, #253).
+ */
+class ChipSeatTest {
+
+    private val monday = LocalDate(2026, 6, 8)
+    private val days = (0..6).map { monday.plus(it, DateTimeUnit.DAY) }
+
+    private fun event(id: Long, title: String = "E") = EventInstance(
+        instanceId = id,
+        eventId = id,
+        calendarId = 1L,
+        title = title,
+        start = monday.atTime(9, 0).toInstant(TimeZone.UTC),
+        end = monday.atTime(10, 0).toInstant(TimeZone.UTC),
+        isAllDay = false,
+        color = 0xFF112233.toInt(),
+        location = null,
+    )
+
+    /**
+     * A grid holding [seated] in lane 0 as one bar across [cols], and nothing
+     * else — the seating a [MonthWeek] gives a span.
+     */
+    private fun row(seated: EventInstance, cols: IntRange) = MonthWeek(
+        days = days,
+        spans = listOf(
+            MonthSpan(
+                event = seated,
+                startCol = cols.first,
+                endCol = cols.last,
+                lane = 0,
+                continuesLeft = false,
+                continuesRight = false,
+            ),
+        ),
+        timedByDay = emptyMap(),
+        countByDay = emptyMap(),
+    )
+
+    /** A grid holding one single-day pill per day of [cols], all of [seated]. */
+    private fun pills(seated: EventInstance, cols: IntRange) = MonthWeek(
+        days = days,
+        spans = emptyList(),
+        timedByDay = cols.associate { days[it] to listOf(seated) },
+        countByDay = emptyMap(),
+    )
+
+    private fun seat(week: MonthWeek, event: EventInstance, date: LocalDate) = chipSeat(
+        days = days,
+        laneCount = 3,
+        chipAt = { col, lane -> week.chipAt(col, lane, 3) },
+        chipStart = { col, lane -> week.chipStartCol(col, lane) },
+        event = event,
+        date = date,
+    )
+
+    @Test
+    fun `a single-day chip is seated in its own column`() {
+        val ev = event(1L)
+        assertThat(seat(row(ev, 3..3), ev, days[3])).isEqualTo(3 to 0)
+    }
+
+    @Test
+    fun `a bar is seated from its first column, not the day it was dropped on`() {
+        val ev = event(1L)
+        // Covers Wed–Thu; dropped on the Thursday it now runs into.
+        assertThat(seat(row(ev, 2..3), ev, days[3])).isEqualTo(2 to 0)
+    }
+
+    @Test
+    fun `a bar carried in from the previous week is seated at column zero`() {
+        val ev = event(1L)
+        assertThat(seat(row(ev, 0..4), ev, days[4])).isEqualTo(0 to 0)
+    }
+
+    @Test
+    fun `a row that does not hold the event seats nothing`() {
+        val ev = event(1L)
+        assertThat(seat(row(ev, 2..3), ev, days[5])).isNull()
+        assertThat(seat(row(ev, 2..3), ev, LocalDate(2026, 7, 1))).isNull()
+    }
+
+    @Test
+    fun `a re-read chip is matched by title once its event id has changed`() {
+        // A single-occurrence move writes a new event id; the title survives.
+        val moved = event(1L, title = "Standup")
+        val reRead = event(9L, title = "Standup")
+        assertThat(seat(row(reRead, 3..3), moved, days[3])).isEqualTo(3 to 0)
+    }
+
+    @Test
+    fun `two untitled events are not the same event`() {
+        val moved = event(1L, title = "")
+        val other = event(2L, title = "")
+        assertThat(isSameEvent(other, moved)).isFalse()
+        assertThat(seat(row(other, 3..3), moved, days[3])).isNull()
+    }
+
+    @Test
+    fun `a daily series seats each occurrence in its own column`() {
+        // Every column holds an occurrence of the same event id, so a walk left
+        // by identity would run to the start of the row (#253).
+        val ev = event(1L, title = "Standup")
+        assertThat(seat(pills(ev, 0..6), ev, days[4])).isEqualTo(4 to 0)
+    }
+}

app/src/test/java/de/jeanlucmakiola/calendula/ui/month/MonthLayoutTest.kt

@@ -44,6 +44,19 @@ class MonthLayoutTest {
         location = null,
     )
 
+    /** A timed event running from [date] 20:00 into the next day at [endHour]. */
+    private fun overnight(date: LocalDate, endHour: Int = 8) = EventInstance(
+        instanceId = 7L,
+        eventId = 7L,
+        calendarId = 1L,
+        title = "Night shift",
+        start = at(date, 20),
+        end = at(date.plus(1, DateTimeUnit.DAY), endHour),
+        isAllDay = false,
+        color = 0xFF112233.toInt(),
+        location = null,
+    )
+
     /** All-day events live at UTC midnights with an *exclusive* end. */
     private fun allDay(
         from: LocalDate,
@@ -162,6 +175,43 @@ class MonthLayoutTest {
         assertThat(week.timedByDay[LocalDate(2026, 6, 11)]).isEmpty()
     }
 
+    @Test
+    fun `an event crossing midnight is one bar, not two pills, on both sides of a week seam`() {
+        // Sun 14 Jun 20:00 to Mon 15 Jun 08:00 — the seam of a Monday-anchored
+        // grid: one day in this row, one in the next. Counting per row made each
+        // a standalone pill with nothing saying they were one event (#253).
+        val overnight = overnight(LocalDate(2026, 6, 14))
+        val head = layoutCalendarWeek(weekOf8th, listOf(overnight), zone)
+        assertThat(head.timedByDay.values.flatten()).isEmpty()
+        val headSpan = head.spans.single()
+        assertThat(headSpan.startCol).isEqualTo(6)
+        assertThat(headSpan.endCol).isEqualTo(6)
+        assertThat(headSpan.continuesLeft).isFalse()
+        assertThat(headSpan.continuesRight).isTrue()
+
+        val tailRow = layoutCalendarWeek(
+            weekOf8th.map { it.plus(7, DateTimeUnit.DAY) },
+            listOf(overnight),
+            zone,
+        )
+        assertThat(tailRow.timedByDay.values.flatten()).isEmpty()
+        val tailSpan = tailRow.spans.single()
+        assertThat(tailSpan.startCol).isEqualTo(0)
+        assertThat(tailSpan.endCol).isEqualTo(0)
+        assertThat(tailSpan.continuesLeft).isTrue()
+        assertThat(tailSpan.continuesRight).isFalse()
+    }
+
+    @Test
+    fun `an event ending exactly at midnight stays a single-day pill`() {
+        val untilMidnight = overnight(LocalDate(2026, 6, 10), endHour = 0)
+        val week = layoutCalendarWeek(weekOf8th, listOf(untilMidnight), zone)
+
+        assertThat(week.spans).isEmpty()
+        assertThat(week.timedByDay[LocalDate(2026, 6, 10)]).hasSize(1)
+        assertThat(week.timedByDay[LocalDate(2026, 6, 11)]).isEmpty()
+    }
+
     @Test
     fun `countByDay totals bars and pills on each date`() {
         val span = allDay(LocalDate(2026, 6, 10), LocalDate(2026, 6, 12), id = 1L)