M4: percent-complete, conflict-safe saves & subtask reparent

M3 detail/edit polish:
- "Progress" slider on the edit form writes Tasks.PERCENT_COMPLETE (clamped
  0-100, 5% detents); status stays owned by the complete toggle.
- Conflict-safe saves: updateTask re-checks the provider's last_modified against
  the value captured when the form loaded and throws TaskConflictException; the
  editor offers overwrite-or-cancel instead of clobbering an external change.

M4 subtasks (UI):
- Reparent: a "Parent task" picker files a task under any top-level task in its
  list (or "None" to promote it); candidates stay top-level to keep nesting one
  level deep. Switching list clears the now-invalid parent.
- Tapping a subtask opens its own detail (a new TaskDetail entry, own VM).

Tests: percent clamping, parent-id write, populatedFields reveal logic.
Docs: ROADMAP M2/M3/M4 reconciled to the codebase; CHANGELOG [Unreleased].

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

CHANGELOG.md

@@ -6,6 +6,31 @@ the source of truth for version codes (see Calendula's `docs/RELEASING.md`).
 
 ## [Unreleased]
 
+### Added
+- M3 detail/edit polish: a "Progress" slider (percent-complete, 5% detents,
+  written to `Tasks.PERCENT_COMPLETE`) and conflict-safe saves — `updateTask`
+  re-checks the provider's `last_modified` against the value captured when the
+  form loaded and surfaces an overwrite-or-cancel prompt instead of clobbering an
+  external change (e.g. a DAVx5 sync).
+- M4 subtasks (UI): reparent — a full-width, searchable "Parent task" sheet on
+  the edit form, with candidates grouped by due-date section, files a task under
+  any active top-level task in its list (or "None" to promote it); switching list
+  clears the now-invalid parent. Tapping a subtask in the detail screen opens its
+  own detail, which shows a "Part of …" parent card. On the task list a parent has
+  a dedicated expand button that reveals its children as a nested grouped run,
+  ending with an inline "add a subtask" row (an opt-out toggle is planned for the
+  M6 settings screen).
+- Priority is coloured by level (green / amber / red pastels) on the list, detail,
+  and edit screens.
+
+### Fixed
+- Overview open-counts now count top-level tasks only, so subtasks — and
+  especially open subtasks under a completed parent — no longer inflate a list's
+  "N open" or the smart-list counts.
+- Swipe-to-delete now reveals its red background + icon as you drag (tracking the
+  live direction, not just the settled target), and a floating "Deleted · Undo"
+  chip defers the actual delete so it can be restored.
+
 ## [0.1.0] - 2026-06-18
 
 ### Added

app/src/main/java/de/jeanlucmakiola/floret/data/tasks/Failures.kt

@@ -7,3 +7,10 @@ class ProviderUnavailableException :
 /** A ContentResolver write returned no URI or affected no rows. */
 class TaskWriteFailedException(operation: String) :
     RuntimeException("Task write failed: $operation")
+
+/**
+ * The task changed (e.g. a DAVx5 sync or another app) since the edit form loaded
+ * it, so saving would clobber that change. The UI offers to overwrite or reload.
+ */
+class TaskConflictException(taskId: Long) :
+    RuntimeException("Task $taskId changed since it was loaded")

app/src/main/java/de/jeanlucmakiola/floret/data/tasks/TaskWriteMapper.kt

@@ -17,6 +17,27 @@ object TaskWriteMapper {
         put(Tasks.LIST_ID, form.listId)
         put(Tasks.DESCRIPTION, form.description?.trim()?.ifBlank { null })
         put(Tasks.PRIORITY, form.priority.toICal())
+        // Keep completion in sync with progress whenever the form carries a
+        // percent (the Progress field was used). The provider already auto-
+        // completes at 100% but won't reopen below it — left to itself it strands
+        // a task "done at 75%" — so we set status both ways. COMPLETED is only
+        // cleared on reopen; at 100% we leave it for the provider to fill/keep so
+        // re-saving a finished task doesn't churn its completion timestamp. When
+        // no percent is present the standalone complete toggle stays authoritative.
+        val percent = form.percentComplete?.coerceIn(0, 100)
+        put(Tasks.PERCENT_COMPLETE, percent)
+        when {
+            percent == null -> Unit
+            percent >= 100 -> put(Tasks.STATUS, TasksContract.STATUS_COMPLETED)
+            percent > 0 -> {
+                put(Tasks.STATUS, TasksContract.STATUS_IN_PROCESS)
+                put(Tasks.COMPLETED, null)
+            }
+            else -> {
+                put(Tasks.STATUS, TasksContract.STATUS_NEEDS_ACTION)
+                put(Tasks.COMPLETED, null)
+            }
+        }
         put(Tasks.IS_ALLDAY, if (form.isAllDay) 1 else 0)
         put(Tasks.DTSTART, form.start?.toEpochMilliseconds())
         put(Tasks.DUE, form.due?.toEpochMilliseconds())

app/src/main/java/de/jeanlucmakiola/floret/data/tasks/TasksRepository.kt

@@ -6,6 +6,7 @@ import de.jeanlucmakiola.floret.domain.TaskFilter
 import de.jeanlucmakiola.floret.domain.TaskForm
 import de.jeanlucmakiola.floret.domain.TaskList
 import kotlinx.coroutines.flow.Flow
+import kotlin.time.Instant
 
 /** Whether Floret can use the tasks provider right now. Drives onboarding. */
 enum class ProviderStatus { READY, NEEDS_PERMISSION, NO_PROVIDER }
@@ -21,7 +22,14 @@ interface TasksRepository {
     fun taskDetail(taskId: Long): Flow<TaskDetail?>
 
     suspend fun createTask(form: TaskForm): Long
-    suspend fun updateTask(taskId: Long, form: TaskForm)
+
+    /**
+     * Overwrite [taskId] with [form]. When [expectedLastModified] is non-null, the
+     * task's current `last_modified` is re-checked first and a
+     * [TaskConflictException] is thrown if it differs — i.e. something changed it
+     * since the form loaded. Pass `null` to force the write (overwrite-anyway).
+     */
+    suspend fun updateTask(taskId: Long, form: TaskForm, expectedLastModified: Instant? = null)
     suspend fun setCompleted(taskId: Long, completed: Boolean)
     suspend fun deleteTask(taskId: Long)
     suspend fun createLocalList(name: String, color: Int): Long

app/src/main/java/de/jeanlucmakiola/floret/data/tasks/TasksRepositoryImpl.kt

@@ -22,6 +22,7 @@ import java.time.ZoneId
 import javax.inject.Inject
 import javax.inject.Singleton
 import kotlin.time.Clock
+import kotlin.time.Instant
 
 @Singleton
 class TasksRepositoryImpl @Inject constructor(
@@ -36,7 +37,11 @@ class TasksRepositoryImpl @Inject constructor(
 
     override fun taskDetail(taskId: Long): Flow<TaskDetail?> = observing {
         dataSource.task(taskId)?.let { task ->
-            TaskDetail(task, dataSource.subtasks(taskId).filter { it.taskId != taskId })
+            TaskDetail(
+                task = task,
+                subtasks = dataSource.subtasks(taskId).filter { it.taskId != taskId },
+                parent = task.parentId?.takeIf { it > 0 }?.let { dataSource.task(it) },
+            )
         }
     }
 
@@ -71,8 +76,17 @@ class TasksRepositoryImpl @Inject constructor(
     override suspend fun createTask(form: TaskForm): Long =
         withContext(io) { dataSource.insertTask(form) }
 
-    override suspend fun updateTask(taskId: Long, form: TaskForm) =
-        withContext(io) { dataSource.updateTask(taskId, form) }
+    override suspend fun updateTask(taskId: Long, form: TaskForm, expectedLastModified: Instant?) =
+        withContext(io) {
+            // Conflict-safe overwrite: re-read just before writing and bail if the
+            // provider's last_modified moved since the form captured it (external
+            // sync / another app). A null baseline means "force / overwrite anyway".
+            if (expectedLastModified != null) {
+                val current = dataSource.task(taskId)?.lastModified
+                if (current != null && current != expectedLastModified) throw TaskConflictException(taskId)
+            }
+            dataSource.updateTask(taskId, form)
+        }
 
     override suspend fun setCompleted(taskId: Long, completed: Boolean) =
         withContext(io) { dataSource.setCompleted(taskId, completed) }

app/src/main/java/de/jeanlucmakiola/floret/domain/Models.kt

@@ -67,10 +67,11 @@ data class Task(
     val effectiveColor: Int get() = taskColor ?: listColor
 }
 
-/** Detail bundle: a task plus its direct children. */
+/** Detail bundle: a task, its parent (if it's a subtask), and its direct children. */
 data class TaskDetail(
     val task: Task,
     val subtasks: List<Task>,
+    val parent: Task? = null,
 )
 
 // --- pure provider <-> domain value mapping (unit-testable) ------------------

app/src/main/java/de/jeanlucmakiola/floret/domain/TaskForm.kt

@@ -16,6 +16,8 @@ data class TaskForm(
     val isAllDay: Boolean = false,
     val priority: Priority = Priority.NONE,
     val parentId: Long? = null,
+    /** 0..100 progress; `null` leaves it unset (cleared). */
+    val percentComplete: Int? = null,
     /** Minutes before [due] to fire a reminder; `null` = no reminder. */
     val reminderMinutesBeforeDue: Int? = null,
 ) {
@@ -37,11 +39,13 @@ enum class TaskFormError { BLANK_TITLE, NO_LIST, DUE_BEFORE_START, REMINDER_WITH
  * a setting; the rest unfold on demand. Declaring these as an enum keeps the
  * disclosure generic, so adding a field later is one entry plus its card.
  */
-enum class TaskFormField { Description, Priority, Reminder }
+enum class TaskFormField { Description, Priority, Progress, Parent, Reminder }
 
 /** The optional fields that already carry a value — auto-revealed when editing. */
 fun TaskForm.populatedFields(): Set<TaskFormField> = buildSet {
     if (!description.isNullOrBlank()) add(TaskFormField.Description)
     if (priority != Priority.NONE) add(TaskFormField.Priority)
+    if ((percentComplete ?: 0) > 0) add(TaskFormField.Progress)
+    if (parentId != null && parentId > 0) add(TaskFormField.Parent)
     if (reminderMinutesBeforeDue != null) add(TaskFormField.Reminder)
 }

app/src/main/java/de/jeanlucmakiola/floret/ui/common/PriorityChip.kt

@@ -0,0 +1,109 @@
+package de.jeanlucmakiola.floret.ui.common
+
+import androidx.compose.foundation.BorderStroke
+import androidx.compose.foundation.isSystemInDarkTheme
+import androidx.compose.foundation.layout.Arrangement
+import androidx.compose.foundation.layout.Row
+import androidx.compose.foundation.layout.padding
+import androidx.compose.foundation.layout.size
+import androidx.compose.foundation.shape.RoundedCornerShape
+import androidx.compose.material.icons.Icons
+import androidx.compose.material.icons.rounded.Flag
+import androidx.compose.material3.ExperimentalMaterial3Api
+import androidx.compose.material3.Icon
+import androidx.compose.material3.MaterialTheme
+import androidx.compose.material3.Surface
+import androidx.compose.material3.Text
+import androidx.compose.runtime.Composable
+import androidx.compose.ui.Alignment
+import androidx.compose.ui.Modifier
+import androidx.compose.ui.graphics.Color
+import androidx.compose.ui.graphics.isSpecified
+import androidx.compose.ui.graphics.luminance
+import androidx.compose.ui.unit.dp
+import de.jeanlucmakiola.floret.domain.Priority
+
+/**
+ * Priority has no semantic Material role (M3 only ships `error` for danger), so
+ * we give the ranked levels their own hues — green / amber / red. They're softened
+ * harder than the list-colour [pastelize] (lower saturation, higher value) so the
+ * chips stay gentle and low-key rather than shouting. [Priority.NONE] has no
+ * colour (callers render it neutral).
+ */
+fun priorityFill(priority: Priority, dark: Boolean): Color {
+    val base = when (priority) {
+        Priority.HIGH -> 0xFFE53935.toInt()   // red
+        Priority.MEDIUM -> 0xFFFFB300.toInt() // amber
+        Priority.LOW -> 0xFF43A047.toInt()    // green
+        Priority.NONE -> return Color.Unspecified
+    }
+    val hsv = FloatArray(3)
+    android.graphics.Color.colorToHSV(base, hsv)
+    hsv[1] = if (dark) 0.36f else 0.22f // desaturate toward pastel
+    hsv[2] = if (dark) 0.58f else 0.92f // light, soft fill in light; muted in dark
+    return Color(android.graphics.Color.HSVToColor(hsv))
+}
+
+/**
+ * A coloured status pill for a task's priority: a flag plus the level's [label],
+ * filled in that level's pastel hue. Used read-only in the list and detail
+ * screens (default [selected] = true), and as a selectable option in the edit
+ * form — there [selected] = false shows the hue on the flag with an outlined,
+ * unfilled container, and tapping commits the choice via [onClick].
+ */
+@OptIn(ExperimentalMaterial3Api::class)
+@Composable
+fun PriorityChip(
+    priority: Priority,
+    label: String,
+    modifier: Modifier = Modifier,
+    selected: Boolean = true,
+    showIcon: Boolean = true,
+    onClick: (() -> Unit)? = null,
+) {
+    val dark = isSystemInDarkTheme()
+    val fill = priorityFill(priority, dark)
+    val hasColor = fill.isSpecified
+
+    val container: Color
+    val content: Color
+    val iconTint: Color
+    var border: BorderStroke? = null
+    when {
+        selected && hasColor -> {
+            container = fill
+            content = if (fill.luminance() > 0.5f) Color.Black else Color.White
+            iconTint = content
+        }
+        selected -> { // NONE, selected — neutral fill, no hue to show
+            container = MaterialTheme.colorScheme.surfaceContainerHighest
+            content = MaterialTheme.colorScheme.onSurfaceVariant
+            iconTint = content
+        }
+        else -> { // an unselected option in a picker — outline, hue kept on the flag
+            container = Color.Transparent
+            content = MaterialTheme.colorScheme.onSurfaceVariant
+            iconTint = if (hasColor) fill else MaterialTheme.colorScheme.onSurfaceVariant
+            border = BorderStroke(1.dp, MaterialTheme.colorScheme.outlineVariant)
+        }
+    }
+
+    val body: @Composable () -> Unit = {
+        Row(
+            modifier = Modifier.padding(horizontal = 10.dp, vertical = 5.dp),
+            horizontalArrangement = Arrangement.spacedBy(4.dp),
+            verticalAlignment = Alignment.CenterVertically,
+        ) {
+            if (showIcon) {
+                Icon(Icons.Rounded.Flag, contentDescription = null, tint = iconTint, modifier = Modifier.size(15.dp))
+            }
+            Text(label, style = MaterialTheme.typography.labelMedium, color = content)
+        }
+    }
+    val shape = RoundedCornerShape(50)
+    if (onClick != null) {
+        Surface(onClick = onClick, color = container, shape = shape, border = border, modifier = modifier) { body() }
+    } else {
+        Surface(color = container, shape = shape, border = border, modifier = modifier) { body() }
+    }
+}

app/src/main/java/de/jeanlucmakiola/floret/ui/detail/TaskDetailScreen.kt

@@ -27,6 +27,7 @@ import androidx.compose.material.icons.Icons
 import androidx.compose.material.icons.automirrored.rounded.ArrowBack
 import androidx.compose.material.icons.automirrored.rounded.ListAlt
 import androidx.compose.material.icons.automirrored.rounded.Notes
+import androidx.compose.material.icons.rounded.AccountTree
 import androidx.compose.material.icons.rounded.Add
 import androidx.compose.material.icons.rounded.Check
 import androidx.compose.material.icons.rounded.Checklist
@@ -70,12 +71,12 @@ import de.jeanlucmakiola.floret.R
 import de.jeanlucmakiola.floret.domain.Task
 import de.jeanlucmakiola.floret.domain.TaskDetail
 import de.jeanlucmakiola.floret.ui.common.GroupedSurface
+import de.jeanlucmakiola.floret.ui.common.PriorityChip
 import de.jeanlucmakiola.floret.ui.common.formatDate
 import de.jeanlucmakiola.floret.ui.common.formatTime
 import de.jeanlucmakiola.floret.ui.common.pastelize
 import de.jeanlucmakiola.floret.ui.common.positionOf
 import de.jeanlucmakiola.floret.ui.tasklist.priorityLabel
-import de.jeanlucmakiola.floret.ui.tasklist.priorityTint
 
 /**
  * One task's detail. Each fact is its own tonal card with a leading icon (the
@@ -88,6 +89,7 @@ fun TaskDetailScreen(
     onEdit: () -> Unit,
     onDeleted: () -> Unit,
     onBack: () -> Unit,
+    onOpenTask: (Long) -> Unit,
     modifier: Modifier = Modifier,
     viewModel: TaskDetailViewModel = hiltViewModel(),
 ) {
@@ -136,7 +138,7 @@ fun TaskDetailScreen(
                 onToggle = { viewModel.toggleComplete(s.detail.task) },
                 onToggleSubtask = { viewModel.toggleComplete(it) },
                 onAddSubtask = { viewModel.addSubtask(it) },
-                onOpenSubtask = { /* reserved: subtask navigation lands with the subtasks milestone */ },
+                onOpenTask = onOpenTask,
             )
         }
     }
@@ -149,7 +151,7 @@ private fun DetailBody(
     onToggle: () -> Unit,
     onToggleSubtask: (Task) -> Unit,
     onAddSubtask: (String) -> Unit,
-    onOpenSubtask: (Long) -> Unit,
+    onOpenTask: (Long) -> Unit,
 ) {
     val task = detail.task
     val dark = isSystemInDarkTheme()
@@ -190,6 +192,28 @@ private fun DetailBody(
 
         // One card per fact; gaps between, no shared container (they aren't a group).
         val cards = buildList<@Composable () -> Unit> {
+            // Parent — only when this is a subtask. Conveys that it's filed under
+            // another task (and so doesn't stand alone in the list); taps open it.
+            detail.parent?.let { parent ->
+                add {
+                    DetailCard(
+                        icon = Icons.Rounded.AccountTree,
+                        iconContentDescription = stringResource(R.string.detail_parent),
+                        onClick = { onOpenTask(parent.taskId) },
+                    ) {
+                        Text(
+                            text = stringResource(R.string.detail_part_of),
+                            style = MaterialTheme.typography.bodySmall,
+                            color = MaterialTheme.colorScheme.onSurfaceVariant,
+                        )
+                        Text(
+                            text = parent.title.ifBlank { stringResource(R.string.task_untitled) },
+                            style = MaterialTheme.typography.titleMedium,
+                        )
+                    }
+                }
+            }
+
             // When — the Calendula time card: date primary, time(s) secondary.
             taskWhenLines(task)?.let { (primary, secondary) ->
                 add {
@@ -221,25 +245,28 @@ private fun DetailBody(
                 }
             }
 
-            // Priority — the flag moves to the front, tinted like the list rows.
+            // Priority — a coloured status chip in the level's hue.
             if (task.priority != de.jeanlucmakiola.floret.domain.Priority.NONE) {
                 add {
                     DetailCard(
                         icon = Icons.Rounded.Flag,
-                        iconTint = priorityTint(task.priority),
                         iconContentDescription = stringResource(R.string.detail_priority),
                     ) {
-                        Text(priorityLabel(task.priority), style = MaterialTheme.typography.titleMedium)
+                        PriorityChip(
+                            priority = task.priority,
+                            label = priorityLabel(task.priority),
+                            showIcon = false,
+                        )
                     }
                 }
             }
 
-            // Progress — only meaningful with subtasks. Uses the provider's
-            // percent when set, otherwise the subtask completion ratio.
-            if (detail.subtasks.isNotEmpty()) {
-                val total = detail.subtasks.size
-                val doneCount = detail.subtasks.count { it.isCompleted }
-                val pct = task.percentComplete ?: (doneCount * 100 / total)
+            // Progress — shown when the task carries its own percent or has
+            // subtasks (then the completion ratio fills in if no percent is set).
+            val hasSubtasks = detail.subtasks.isNotEmpty()
+            if ((task.percentComplete ?: 0) > 0 || hasSubtasks) {
+                val pct = task.percentComplete
+                    ?: (detail.subtasks.count { it.isCompleted } * 100 / detail.subtasks.size)
                 add {
                     DetailCard(icon = Icons.Rounded.Percent, iconContentDescription = stringResource(R.string.detail_progress)) {
                         Row(modifier = Modifier.fillMaxWidth(), horizontalArrangement = Arrangement.SpaceBetween) {
@@ -275,7 +302,7 @@ private fun DetailBody(
                     onToggle = { subtasksExpanded = !subtasksExpanded },
                     onToggleSubtask = onToggleSubtask,
                     onAddSubtask = onAddSubtask,
-                    onOpenSubtask = onOpenSubtask,
+                    onOpenSubtask = onOpenTask,
                 )
             }
         }
@@ -436,13 +463,12 @@ private fun DetailCard(
     icon: ImageVector,
     iconContentDescription: String?,
     iconTint: Color = MaterialTheme.colorScheme.onSurfaceVariant,
+    onClick: (() -> Unit)? = null,
     content: @Composable ColumnScope.() -> Unit,
 ) {
-    Surface(
-        color = MaterialTheme.colorScheme.surfaceContainerHigh,
-        shape = RoundedCornerShape(16.dp),
-        modifier = Modifier.fillMaxWidth(),
-    ) {
+    val shape = RoundedCornerShape(16.dp)
+    val color = MaterialTheme.colorScheme.surfaceContainerHigh
+    val body: @Composable () -> Unit = {
         Row(
             modifier = Modifier.padding(16.dp),
             verticalAlignment = Alignment.CenterVertically,
@@ -457,6 +483,11 @@ private fun DetailCard(
             Column(modifier = Modifier.weight(1f), content = content)
         }
     }
+    if (onClick != null) {
+        Surface(onClick = onClick, color = color, shape = shape, modifier = Modifier.fillMaxWidth()) { body() }
+    } else {
+        Surface(color = color, shape = shape, modifier = Modifier.fillMaxWidth()) { body() }
+    }
 }
 
 /**

app/src/main/java/de/jeanlucmakiola/floret/ui/edit/TaskEditScreen.kt

@@ -20,11 +20,16 @@ import androidx.compose.foundation.layout.imePadding
 import androidx.compose.foundation.layout.padding
 import androidx.compose.foundation.layout.size
 import androidx.compose.foundation.layout.width
+import androidx.compose.foundation.ExperimentalFoundationApi
+import androidx.compose.foundation.layout.PaddingValues
+import androidx.compose.foundation.lazy.LazyColumn
+import androidx.compose.foundation.lazy.itemsIndexed
 import androidx.compose.foundation.rememberScrollState
 import androidx.compose.foundation.shape.RoundedCornerShape
 import androidx.compose.foundation.verticalScroll
 import androidx.compose.material.icons.Icons
 import androidx.compose.material.icons.automirrored.rounded.Notes
+import androidx.compose.material.icons.rounded.AccountTree
 import androidx.compose.material.icons.rounded.Add
 import androidx.compose.material.icons.rounded.ArrowDropDown
 import androidx.compose.material.icons.rounded.Checklist
@@ -33,7 +38,9 @@ import androidx.compose.material.icons.rounded.Clear
 import androidx.compose.material.icons.rounded.Close
 import androidx.compose.material.icons.rounded.Flag
 import androidx.compose.material.icons.rounded.Notifications
+import androidx.compose.material.icons.rounded.Percent
 import androidx.compose.material.icons.rounded.Schedule
+import androidx.compose.material.icons.rounded.Search
 import androidx.compose.material3.AlertDialog
 import androidx.compose.material3.Button
 import androidx.compose.material3.DatePicker
@@ -42,10 +49,13 @@ import androidx.compose.material3.ExperimentalMaterial3Api
 import androidx.compose.material3.Icon
 import androidx.compose.material3.IconButton
 import androidx.compose.material3.MaterialTheme
+import androidx.compose.material3.ModalBottomSheet
+import androidx.compose.material3.OutlinedTextField
 import androidx.compose.material3.Scaffold
 import androidx.compose.material3.SegmentedButton
 import androidx.compose.material3.SegmentedButtonDefaults
 import androidx.compose.material3.SingleChoiceSegmentedButtonRow
+import androidx.compose.material3.Slider
 import androidx.compose.material3.Surface
 import androidx.compose.material3.Switch
 import androidx.compose.material3.Text
@@ -54,17 +64,21 @@ import androidx.compose.material3.TimePicker
 import androidx.compose.material3.TopAppBar
 import androidx.compose.material3.TopAppBarDefaults
 import androidx.compose.material3.rememberDatePickerState
+import androidx.compose.material3.rememberModalBottomSheetState
 import androidx.compose.material3.rememberTimePickerState
 import androidx.compose.runtime.Composable
 import androidx.compose.runtime.LaunchedEffect
 import androidx.compose.runtime.getValue
 import androidx.compose.runtime.mutableStateOf
 import androidx.compose.runtime.remember
+import androidx.compose.runtime.rememberCoroutineScope
 import androidx.compose.runtime.saveable.rememberSaveable
 import androidx.compose.runtime.setValue
 import androidx.compose.ui.Alignment
 import androidx.compose.ui.Modifier
 import androidx.compose.ui.graphics.Color
+import androidx.compose.ui.graphics.isSpecified
+import androidx.compose.ui.graphics.luminance
 import androidx.compose.ui.graphics.vector.ImageVector
 import androidx.compose.ui.res.stringResource
 import androidx.compose.ui.text.font.FontWeight
@@ -72,21 +86,31 @@ import androidx.compose.ui.unit.dp
 import androidx.hilt.navigation.compose.hiltViewModel
 import androidx.lifecycle.compose.collectAsStateWithLifecycle
 import de.jeanlucmakiola.floret.R
+import de.jeanlucmakiola.floret.domain.DayWindow
 import de.jeanlucmakiola.floret.domain.Priority
+import de.jeanlucmakiola.floret.domain.Task
 import de.jeanlucmakiola.floret.domain.TaskFormError
 import de.jeanlucmakiola.floret.domain.TaskFormField
 import de.jeanlucmakiola.floret.domain.TaskList
+import de.jeanlucmakiola.floret.domain.TaskSection
+import de.jeanlucmakiola.floret.domain.TaskSections
+import de.jeanlucmakiola.floret.ui.common.GroupedRow
 import de.jeanlucmakiola.floret.ui.common.InlineTextField
 import de.jeanlucmakiola.floret.ui.common.OptionCard
+import de.jeanlucmakiola.floret.ui.common.priorityFill
 import de.jeanlucmakiola.floret.ui.common.formatDate
 import de.jeanlucmakiola.floret.ui.common.formatTime
 import de.jeanlucmakiola.floret.ui.common.localToInstant
 import de.jeanlucmakiola.floret.ui.common.pastelize
+import de.jeanlucmakiola.floret.ui.common.positionOf
 import de.jeanlucmakiola.floret.ui.common.toLocalDate
 import de.jeanlucmakiola.floret.ui.common.toLocalTime
 import de.jeanlucmakiola.floret.ui.tasklist.priorityLabel
 import java.time.LocalTime
+import java.time.ZoneId
 import java.time.ZoneOffset
+import kotlinx.coroutines.launch
+import kotlin.time.Clock
 import kotlin.time.Instant
 
 /**
@@ -160,6 +184,7 @@ private fun EditContent(
 
     var pickerTarget by remember { mutableStateOf<PickerTarget?>(null) }
     var showListPicker by rememberSaveable { mutableStateOf(false) }
+    var showParentPicker by rememberSaveable { mutableStateOf(false) }
     var showReminderPicker by rememberSaveable { mutableStateOf(false) }
     var showFieldPicker by rememberSaveable { mutableStateOf(false) }
 
@@ -297,14 +322,26 @@ private fun EditContent(
                         )
                     }
                     Spacer(Modifier.height(12.dp))
+                    // The M3 single-select segmented row, but the active segment
+                    // takes its priority hue so the choice reads in colour.
                     SingleChoiceSegmentedButtonRow(modifier = Modifier.fillMaxWidth()) {
                         Priority.entries.forEachIndexed { index, priority ->
+                            val fill = priorityFill(priority, dark)
+                            val active = fill.isSpecified
                             SegmentedButton(
                                 selected = state.priority == priority,
                                 onClick = { viewModel.onPriorityChange(priority) },
                                 shape = SegmentedButtonDefaults.itemShape(index, Priority.entries.size),
-                                // Drop the selected-check icon; with four buttons
-                                // its reserved width is what crowds the labels.
+                                colors = SegmentedButtonDefaults.colors(
+                                    activeContainerColor = if (active) fill else MaterialTheme.colorScheme.secondaryContainer,
+                                    activeContentColor = when {
+                                        !active -> MaterialTheme.colorScheme.onSecondaryContainer
+                                        fill.luminance() > 0.5f -> Color.Black
+                                        else -> Color.White
+                                    },
+                                ),
+                                // Drop the selected-check icon; with four buttons its
+                                // reserved width is what crowds the labels.
                                 icon = {},
                             ) {
                                 Text(
@@ -319,6 +356,76 @@ private fun EditContent(
             }
         }
 
+        OptionalFormSection(visible = TaskFormField.Progress in state.visibleFields) {
+            Spacer(Modifier.height(gap))
+            val pct = state.percentComplete ?: 0
+            // Full-width like Priority: the slider needs the card's whole width,
+            // so the label/readout sit on a header row above it.
+            Surface(
+                color = MaterialTheme.colorScheme.surfaceContainerHigh,
+                shape = RoundedCornerShape(16.dp),
+                modifier = Modifier.fillMaxWidth(),
+            ) {
+                Column(modifier = Modifier.padding(16.dp)) {
+                    Row(verticalAlignment = Alignment.CenterVertically) {
+                        Icon(
+                            Icons.Rounded.Percent,
+                            contentDescription = null,
+                            tint = MaterialTheme.colorScheme.onSurfaceVariant,
+                            modifier = Modifier.size(24.dp),
+                        )
+                        Spacer(Modifier.width(16.dp))
+                        Text(
+                            text = stringResource(R.string.edit_progress_label),
+                            style = MaterialTheme.typography.titleMedium,
+                            modifier = Modifier.weight(1f),
+                        )
+                        Text(
+                            text = stringResource(R.string.percent_complete, pct),
+                            style = MaterialTheme.typography.titleMedium,
+                            color = MaterialTheme.colorScheme.onSurfaceVariant,
+                        )
+                    }
+                    Spacer(Modifier.height(4.dp))
+                    Slider(
+                        value = pct.toFloat(),
+                        onValueChange = { viewModel.onPercentChange(it.toInt()) },
+                        valueRange = 0f..100f,
+                        steps = 19, // 5% detents
+                    )
+                }
+            }
+        }
+
+        OptionalFormSection(visible = TaskFormField.Parent in state.visibleFields) {
+            Spacer(Modifier.height(gap))
+            EditCard(
+                icon = Icons.Rounded.AccountTree,
+                iconContentDescription = stringResource(R.string.edit_parent_label),
+                onClick = { showParentPicker = true },
+            ) {
+                Row(verticalAlignment = Alignment.CenterVertically, modifier = Modifier.fillMaxWidth()) {
+                    Column(modifier = Modifier.weight(1f)) {
+                        Text(
+                            text = state.parent?.title?.ifBlank { stringResource(R.string.task_untitled) }
+                                ?: stringResource(R.string.edit_parent_none),
+                            style = MaterialTheme.typography.titleMedium,
+                        )
+                        Text(
+                            text = stringResource(R.string.edit_parent_label),
+                            style = MaterialTheme.typography.bodySmall,
+                            color = MaterialTheme.colorScheme.onSurfaceVariant,
+                        )
+                    }
+                    Icon(
+                        imageVector = Icons.Rounded.ArrowDropDown,
+                        contentDescription = null,
+                        tint = MaterialTheme.colorScheme.onSurfaceVariant,
+                    )
+                }
+            }
+        }
+
         OptionalFormSection(visible = TaskFormField.Reminder in state.visibleFields) {
             Spacer(Modifier.height(gap))
             EditCard(
@@ -391,6 +498,31 @@ private fun EditContent(
         )
     }
 
+    if (showParentPicker) {
+        ParentPickerSheet(
+            candidates = state.parentCandidates,
+            selectedId = state.parentId,
+            onSelect = { viewModel.onParentChange(it); showParentPicker = false },
+            onDismiss = { showParentPicker = false },
+        )
+    }
+
+    if (state.saveConflict) {
+        AlertDialog(
+            onDismissRequest = viewModel::dismissConflict,
+            title = { Text(stringResource(R.string.edit_conflict_title)) },
+            text = { Text(stringResource(R.string.edit_conflict_body)) },
+            confirmButton = {
+                TextButton(onClick = { viewModel.save(force = true) }) {
+                    Text(stringResource(R.string.edit_conflict_overwrite))
+                }
+            },
+            dismissButton = {
+                TextButton(onClick = viewModel::dismissConflict) { Text(stringResource(R.string.dialog_cancel)) }
+            },
+        )
+    }
+
     if (showReminderPicker) {
         ReminderPickerDialog(
             selected = state.reminderMinutesBeforeDue,
@@ -650,6 +782,139 @@ private fun ListPickerDialog(
     )
 }
 
+/**
+ * Pick the task to file this one under, or "None" to keep it top-level. A
+ * full-width modal sheet (not a cramped dialog): a search field filters by title,
+ * and candidates group under the same due-date sections as the task list
+ * (Overdue / Today / Upcoming / No date) so the right one is easy to find in a
+ * long list. Only active tasks are offered (the VM filters closed ones out).
+ */
+@OptIn(ExperimentalMaterial3Api::class, ExperimentalFoundationApi::class)
+@Composable
+private fun ParentPickerSheet(
+    candidates: List<Task>,
+    selectedId: Long?,
+    onSelect: (Long?) -> Unit,
+    onDismiss: () -> Unit,
+) {
+    val sheetState = rememberModalBottomSheetState(skipPartiallyExpanded = true)
+    val scope = rememberCoroutineScope()
+    // Animate the sheet out before reporting the pick, so it doesn't snap shut.
+    fun choose(id: Long?) {
+        scope.launch { sheetState.hide() }.invokeOnCompletion {
+            if (!sheetState.isVisible) onSelect(id)
+        }
+    }
+
+    var query by rememberSaveable { mutableStateOf("") }
+    val filtered = remember(candidates, query) {
+        val q = query.trim()
+        if (q.isEmpty()) candidates else candidates.filter { it.title.contains(q, ignoreCase = true) }
+    }
+    val (todayStart, todayEnd) = remember { DayWindow.today(Clock.System.now(), ZoneId.systemDefault()) }
+    val sections = remember(filtered) { TaskSections.of(filtered, todayStart, todayEnd) }
+
+    ModalBottomSheet(onDismissRequest = onDismiss, sheetState = sheetState) {
+        LazyColumn(
+            modifier = Modifier.fillMaxWidth(),
+            contentPadding = PaddingValues(bottom = 32.dp),
+        ) {
+            item(key = "title") {
+                Text(
+                    text = stringResource(R.string.edit_parent_label),
+                    style = MaterialTheme.typography.titleLarge,
+                    modifier = Modifier.padding(start = 24.dp, end = 24.dp, bottom = 12.dp),
+                )
+            }
+            // The search field pins to the top of the sheet while the list scrolls.
+            stickyHeader(key = "search") {
+                Surface(color = MaterialTheme.colorScheme.surfaceContainerLow, modifier = Modifier.fillMaxWidth()) {
+                    OutlinedTextField(
+                        value = query,
+                        onValueChange = { query = it },
+                        singleLine = true,
+                        leadingIcon = { Icon(Icons.Rounded.Search, contentDescription = null) },
+                        trailingIcon = {
+                            if (query.isNotEmpty()) {
+                                IconButton(onClick = { query = "" }) {
+                                    Icon(Icons.Rounded.Clear, contentDescription = stringResource(R.string.edit_clear))
+                                }
+                            }
+                        },
+                        placeholder = { Text(stringResource(R.string.edit_parent_search)) },
+                        shape = RoundedCornerShape(28.dp),
+                        modifier = Modifier
+                            .fillMaxWidth()
+                            .padding(start = 16.dp, end = 16.dp, top = 4.dp, bottom = 12.dp),
+                    )
+                }
+            }
+            // "None" — promote to top-level. Pinned above the grouped candidates.
+            item(key = "none") {
+                GroupedRow(
+                    title = stringResource(R.string.edit_parent_none),
+                    position = de.jeanlucmakiola.floret.ui.common.Position.Alone,
+                    selected = selectedId == null,
+                    minHeight = 56.dp,
+                    onClick = { choose(null) },
+                    modifier = Modifier.padding(bottom = 4.dp),
+                )
+            }
+
+            if (sections.isEmpty()) {
+                item(key = "empty") {
+                    Text(
+                        text = stringResource(R.string.edit_parent_empty),
+                        style = MaterialTheme.typography.bodyMedium,
+                        color = MaterialTheme.colorScheme.onSurfaceVariant,
+                        modifier = Modifier.padding(horizontal = 28.dp, vertical = 24.dp),
+                    )
+                }
+            }
+
+            sections.forEach { section ->
+                stickyHeader(key = "hdr-${section.section}") {
+                    SheetSectionHeader(parentSectionLabel(section.section))
+                }
+                itemsIndexed(section.tasks, key = { _, t -> t.taskId }) { index, task ->
+                    GroupedRow(
+                        title = task.title.ifBlank { stringResource(R.string.task_untitled) },
+                        position = positionOf(index, section.tasks.size),
+                        summary = task.due?.formatDate(),
+                        selected = task.taskId == selectedId,
+                        minHeight = 56.dp,
+                        onClick = { choose(task.taskId) },
+                    )
+                }
+            }
+        }
+    }
+}
+
+/** Section header inside the parent sheet — opaque so rows scroll cleanly under it. */
+@Composable
+private fun SheetSectionHeader(text: String) {
+    Surface(color = MaterialTheme.colorScheme.surfaceContainerLow, modifier = Modifier.fillMaxWidth()) {
+        Text(
+            text = text,
+            style = MaterialTheme.typography.titleSmall,
+            color = MaterialTheme.colorScheme.onSurfaceVariant,
+            modifier = Modifier.padding(start = 28.dp, end = 28.dp, top = 12.dp, bottom = 6.dp),
+        )
+    }
+}
+
+@Composable
+private fun parentSectionLabel(section: TaskSection): String = stringResource(
+    when (section) {
+        TaskSection.OVERDUE -> R.string.section_overdue
+        TaskSection.TODAY -> R.string.section_today
+        TaskSection.UPCOMING -> R.string.section_upcoming
+        TaskSection.NO_DATE -> R.string.section_no_date
+        TaskSection.COMPLETED -> R.string.section_completed
+    },
+)
+
 @Composable
 private fun ReminderPickerDialog(
     selected: Int?,
@@ -706,12 +971,16 @@ private fun FieldPickerDialog(
 private fun fieldLabel(field: TaskFormField): Int = when (field) {
     TaskFormField.Description -> R.string.field_description
     TaskFormField.Priority -> R.string.edit_priority_label
+    TaskFormField.Progress -> R.string.edit_progress_label
+    TaskFormField.Parent -> R.string.edit_parent_label
     TaskFormField.Reminder -> R.string.edit_reminder_label
 }
 
 private fun fieldIcon(field: TaskFormField): ImageVector = when (field) {
     TaskFormField.Description -> Icons.AutoMirrored.Rounded.Notes
     TaskFormField.Priority -> Icons.Rounded.Flag
+    TaskFormField.Progress -> Icons.Rounded.Percent
+    TaskFormField.Parent -> Icons.Rounded.AccountTree
     TaskFormField.Reminder -> Icons.Rounded.Notifications
 }
 

app/src/main/java/de/jeanlucmakiola/floret/ui/edit/TaskEditViewModel.kt

@@ -5,8 +5,11 @@ import androidx.lifecycle.viewModelScope
 import dagger.hilt.android.lifecycle.HiltViewModel
 import de.jeanlucmakiola.floret.data.prefs.SettingsPrefs
 import de.jeanlucmakiola.floret.data.reminders.ReminderScheduler
+import de.jeanlucmakiola.floret.data.tasks.TaskConflictException
 import de.jeanlucmakiola.floret.data.tasks.TasksRepository
 import de.jeanlucmakiola.floret.domain.Priority
+import de.jeanlucmakiola.floret.domain.Task
+import de.jeanlucmakiola.floret.domain.TaskFilter
 import de.jeanlucmakiola.floret.domain.TaskForm
 import de.jeanlucmakiola.floret.domain.TaskFormError
 import de.jeanlucmakiola.floret.domain.TaskFormField
@@ -36,16 +39,24 @@ data class TaskEditUiState(
     val isAllDay: Boolean = false,
     val priority: Priority = Priority.NONE,
     val parentId: Long? = null,
+    val percentComplete: Int? = null,
     val reminderMinutesBeforeDue: Int? = null,
     val lists: List<TaskList> = emptyList(),
+    /** Top-level tasks in the current list this task can be filed under (reparent). */
+    val parentCandidates: List<Task> = emptyList(),
     /** Optional sections currently shown (core Title / List / When are always on). */
     val visibleFields: Set<TaskFormField> = emptySet(),
     /** Optional sections still tucked behind "More fields". */
     val hiddenFields: List<TaskFormField> = emptyList(),
     val errors: Set<TaskFormError> = emptySet(),
     val saveFailed: Boolean = false,
+    /** The task changed underneath us; the screen asks to overwrite or cancel. */
+    val saveConflict: Boolean = false,
     val saved: Boolean = false,
-)
+) {
+    /** The currently-selected parent task, if this task is filed under one. */
+    val parent: Task? get() = parentCandidates.firstOrNull { it.taskId == parentId }
+}
 
 @HiltViewModel
 class TaskEditViewModel @Inject constructor(
@@ -59,12 +70,16 @@ class TaskEditViewModel @Inject constructor(
 
     private var editingTaskId: Long? = null
 
+    /** `last_modified` captured when the form loaded — the conflict-check baseline. */
+    private var baselineLastModified: Instant? = null
+
     /** Sections shown by default (a setting); the rest unfold via [revealField]. */
     private var defaultFields: Set<TaskFormField> = emptySet()
 
     /** Start a fresh task, optionally pre-selecting a list / parent. */
     fun bindNew(presetListId: Long? = null, parentId: Long? = null) {
         editingTaskId = null
+        baselineLastModified = null
         viewModelScope.launch {
             val settings = settingsPrefs.settings.first()
             defaultFields = settings.defaultEditFields
@@ -80,6 +95,7 @@ class TaskEditViewModel @Inject constructor(
                     listId = defaultList,
                     parentId = parentId,
                     lists = lists,
+                    parentCandidates = loadParents(defaultList, selfId = null),
                 ),
             )
         }
@@ -96,6 +112,7 @@ class TaskEditViewModel @Inject constructor(
                 _state.value = _state.value.copy(loading = false, lists = lists)
                 return@launch
             }
+            baselineLastModified = task.lastModified
             _state.value = withFields(
                 TaskEditUiState(
                     loading = false,
@@ -108,12 +125,26 @@ class TaskEditViewModel @Inject constructor(
                     isAllDay = task.isAllDay,
                     priority = task.priority,
                     parentId = task.parentId,
+                    percentComplete = task.percentComplete,
                     lists = lists,
+                    parentCandidates = loadParents(task.listId, selfId = taskId),
                 ),
             )
         }
     }
 
+    /**
+     * Tasks the edited task can be filed under: active, top-level tasks in
+     * [listId], minus the task itself (a task can't parent itself). Restricting to
+     * top-level keeps the hierarchy one level deep (matching the detail screen),
+     * and to active so you don't file work under something already done/cancelled.
+     */
+    private suspend fun loadParents(listId: Long?, selfId: Long?): List<Task> {
+        if (listId == null) return emptyList()
+        val tasks = runCatching { repository.tasks(TaskFilter.OfList(listId)).first() }.getOrElse { emptyList() }
+        return tasks.filter { !it.isClosed && !it.isSubtask && it.taskId != selfId }
+    }
+
     /** Reveal an optional section (one tap from the "More fields" picker). */
     fun revealField(field: TaskFormField) = update {
         val visible = it.visibleFields + field
@@ -134,14 +165,30 @@ class TaskEditViewModel @Inject constructor(
 
     fun onTitleChange(value: String) = update { it.copy(title = value, errors = emptySet()) }
     fun onDescriptionChange(value: String) = update { it.copy(description = value) }
-    fun onListChange(listId: Long) = update { it.copy(listId = listId, errors = emptySet()) }
+
+    /** Switching list invalidates the parent (it lived in the old list); reload candidates. */
+    fun onListChange(listId: Long) {
+        if (_state.value.listId == listId) return // re-picking the same list keeps the parent
+        update { it.copy(listId = listId, parentId = null, errors = emptySet()) }
+        viewModelScope.launch {
+            val candidates = loadParents(listId, selfId = editingTaskId)
+            update { it.copy(parentCandidates = candidates) }
+        }
+    }
+
     fun onStartChange(value: Instant?) = update { it.copy(start = value) }
     fun onDueChange(value: Instant?) = update { it.copy(due = value) }
     fun onAllDayChange(value: Boolean) = update { it.copy(isAllDay = value) }
     fun onPriorityChange(value: Priority) = update { it.copy(priority = value) }
+    fun onPercentChange(value: Int?) = update { it.copy(percentComplete = value?.coerceIn(0, 100)) }
+    fun onParentChange(parentId: Long?) = update { it.copy(parentId = parentId) }
     fun onReminderChange(minutesBeforeDue: Int?) = update { it.copy(reminderMinutesBeforeDue = minutesBeforeDue) }
 
-    fun save() {
+    /** Dismiss the conflict prompt without saving (the user keeps editing). */
+    fun dismissConflict() = update { it.copy(saveConflict = false) }
+
+    /** [force] = overwrite even if the task changed since it loaded (conflict prompt). */
+    fun save(force: Boolean = false) {
         val current = _state.value
         val form = current.toForm()
         val errors = form.validate()
@@ -152,12 +199,20 @@ class TaskEditViewModel @Inject constructor(
         viewModelScope.launch {
             runCatching {
                 val id = editingTaskId
-                if (id == null) repository.createTask(form) else repository.updateTask(id, form)
+                if (id == null) {
+                    repository.createTask(form)
+                } else {
+                    repository.updateTask(id, form, expectedLastModified = if (force) null else baselineLastModified)
+                }
                 reminderScheduler.sync()
             }.onSuccess {
-                _state.value = _state.value.copy(saved = true, saveFailed = false)
-            }.onFailure {
-                _state.value = _state.value.copy(saveFailed = true)
+                _state.value = _state.value.copy(saved = true, saveFailed = false, saveConflict = false)
+            }.onFailure { error ->
+                _state.value = if (error is TaskConflictException) {
+                    _state.value.copy(saveConflict = true, saveFailed = false)
+                } else {
+                    _state.value.copy(saveFailed = true)
+                }
             }
         }
     }
@@ -177,5 +232,6 @@ private fun TaskEditUiState.toForm(): TaskForm = TaskForm(
     isAllDay = isAllDay,
     priority = priority,
     parentId = parentId,
+    percentComplete = percentComplete,
     reminderMinutesBeforeDue = reminderMinutesBeforeDue,
 )

app/src/main/java/de/jeanlucmakiola/floret/ui/lists/ListsViewModel.kt

@@ -49,16 +49,20 @@ class ListsViewModel @Inject constructor(
 
     private fun buildContent(lists: List<TaskList>, openTasks: List<Task>): ListsUiState.Content {
         val (todayStart, todayEnd) = DayWindow.today(Clock.System.now(), ZoneId.systemDefault())
+        // Count only top-level tasks: a subtask is represented by its parent (and
+        // its progress chip), and an open subtask under a *completed* parent must
+        // not read as an open item here. Mirrors the task list collapsing subtasks.
+        val topLevel = openTasks.filter { !it.isSubtask }
         fun count(smart: SmartList) =
-            openTasks.count { TaskFiltering.matches(it, TaskFilter.Smart(smart), todayStart, todayEnd) }
+            topLevel.count { TaskFiltering.matches(it, TaskFilter.Smart(smart), todayStart, todayEnd) }
 
         val smartCounts = listOf(
             SmartCount(SmartList.TODAY, count(SmartList.TODAY)),
             SmartCount(SmartList.OVERDUE, count(SmartList.OVERDUE)),
             SmartCount(SmartList.UPCOMING, count(SmartList.UPCOMING)),
-            SmartCount(SmartList.ALL, openTasks.size),
+            SmartCount(SmartList.ALL, topLevel.size),
         )
-        val openByList = openTasks.groupingBy { it.listId }.eachCount()
+        val openByList = topLevel.groupingBy { it.listId }.eachCount()
         val groups = lists
             .groupBy { it.accountName }
             .map { (account, accountLists) ->

app/src/main/java/de/jeanlucmakiola/floret/ui/navigation/FloretNavHost.kt

@@ -86,6 +86,9 @@ fun FloretNavHost(modifier: Modifier = Modifier) {
                 onEdit = { nav.navigate(Dest.TaskEdit.buildEdit(taskId)) },
                 onDeleted = { nav.popBackStack() },
                 onBack = { nav.popBackStack() },
+                // A subtask opens its own detail — another entry on the stack, with
+                // its own VM bound to that id (it may have children of its own).
+                onOpenTask = { subtaskId -> nav.navigate(Dest.TaskDetail.build(subtaskId)) },
             )
         }
 

app/src/main/java/de/jeanlucmakiola/floret/ui/tasklist/TaskListScreen.kt

@@ -1,9 +1,15 @@
 package de.jeanlucmakiola.floret.ui.tasklist
 
+import androidx.compose.animation.AnimatedVisibility
 import androidx.compose.animation.core.animateDpAsState
 import androidx.compose.animation.core.animateFloatAsState
+import androidx.compose.animation.fadeIn
+import androidx.compose.animation.fadeOut
+import androidx.compose.animation.slideInVertically
+import androidx.compose.animation.slideOutVertically
 import androidx.compose.foundation.ExperimentalFoundationApi
 import androidx.compose.foundation.background
+import androidx.compose.foundation.text.BasicTextField
 import androidx.compose.foundation.interaction.MutableInteractionSource
 import androidx.compose.foundation.interaction.collectIsPressedAsState
 import androidx.compose.foundation.isSystemInDarkTheme
@@ -33,7 +39,6 @@ import androidx.compose.material.icons.rounded.Check
 import androidx.compose.material.icons.rounded.Checklist
 import androidx.compose.material.icons.rounded.Delete
 import androidx.compose.material.icons.rounded.ExpandMore
-import androidx.compose.material.icons.rounded.Flag
 import androidx.compose.material3.Checkbox
 import androidx.compose.material3.ExperimentalMaterial3Api
 import androidx.compose.material3.ExtendedFloatingActionButton
@@ -46,21 +51,25 @@ import androidx.compose.material3.Surface
 import androidx.compose.material3.SwipeToDismissBox
 import androidx.compose.material3.SwipeToDismissBoxValue
 import androidx.compose.material3.Text
+import androidx.compose.material3.TextButton
 import androidx.compose.material3.TextField
 import androidx.compose.material3.TextFieldDefaults
 import androidx.compose.material3.TopAppBarDefaults
 import androidx.compose.material3.rememberSwipeToDismissBoxState
 import androidx.compose.runtime.Composable
+import androidx.compose.runtime.LaunchedEffect
 import androidx.compose.runtime.getValue
 import androidx.compose.runtime.mutableStateOf
 import androidx.compose.runtime.remember
 import androidx.compose.runtime.saveable.rememberSaveable
 import androidx.compose.runtime.setValue
+import kotlinx.coroutines.delay
 import androidx.compose.ui.Alignment
 import androidx.compose.ui.Modifier
 import androidx.compose.ui.draw.clip
 import androidx.compose.ui.draw.rotate
 import androidx.compose.ui.graphics.Color
+import androidx.compose.ui.graphics.SolidColor
 import androidx.compose.ui.graphics.Shape
 import androidx.compose.ui.input.nestedscroll.nestedScroll
 import androidx.compose.ui.res.stringResource
@@ -81,6 +90,7 @@ import de.jeanlucmakiola.floret.domain.TaskSection
 import de.jeanlucmakiola.floret.domain.TaskSections
 import de.jeanlucmakiola.floret.ui.common.ListNameChip
 import de.jeanlucmakiola.floret.ui.common.Position
+import de.jeanlucmakiola.floret.ui.common.PriorityChip
 import de.jeanlucmakiola.floret.ui.common.formatDateTime
 import de.jeanlucmakiola.floret.ui.common.pastelize
 import de.jeanlucmakiola.floret.ui.common.positionOf
@@ -107,6 +117,22 @@ fun TaskListScreen(
     val scrollBehavior = TopAppBarDefaults.exitUntilCollapsedScrollBehavior()
     val listName = (state as? TaskListUiState.Content)?.listName
 
+    // Swipe-delete hides the row at once, then a floating "Deleted · Undo" chip
+    // gives an undo window: Undo restores it, otherwise the delete commits. A
+    // second delete while a chip is up commits the first (its window is over).
+    var undoTarget by remember { mutableStateOf<Task?>(null) }
+    val onRequestDelete: (Task) -> Unit = { task ->
+        undoTarget?.let { viewModel.commitDelete(it.taskId) }
+        viewModel.markPendingDelete(task)
+        undoTarget = task
+    }
+    LaunchedEffect(undoTarget) {
+        val target = undoTarget ?: return@LaunchedEffect
+        delay(4_000)
+        viewModel.commitDelete(target.taskId)
+        if (undoTarget?.taskId == target.taskId) undoTarget = null
+    }
+
     Scaffold(
         modifier = modifier.nestedScroll(scrollBehavior.nestedScrollConnection),
         topBar = {
@@ -131,10 +157,63 @@ fun TaskListScreen(
             )
         },
     ) { inner ->
+        Box(modifier = Modifier.fillMaxSize()) {
             when (val s = state) {
                 TaskListUiState.Loading -> Unit // brief; avoids a flash before first emission
                 TaskListUiState.Failure -> CenteredMessage(stringResource(R.string.task_list_failure), inner)
-            is TaskListUiState.Content -> TaskListBody(s, filter, inner, onOpenTask, viewModel)
+                is TaskListUiState.Content -> TaskListBody(s, filter, inner, onOpenTask, onRequestDelete, viewModel)
+            }
+            UndoChip(
+                visible = undoTarget != null,
+                onUndo = {
+                    undoTarget?.let { viewModel.undoDelete(it.taskId) }
+                    undoTarget = null
+                },
+                modifier = Modifier
+                    .align(Alignment.BottomCenter)
+                    .padding(bottom = inner.calculateBottomPadding() + 24.dp),
+            )
+        }
+    }
+}
+
+/**
+ * A compact floating "snackchip" for an undoable delete — a rounded pill (not a
+ * full-width snackbar) sized to its content, sliding up from the bottom centre.
+ */
+@Composable
+private fun UndoChip(visible: Boolean, onUndo: () -> Unit, modifier: Modifier = Modifier) {
+    AnimatedVisibility(
+        visible = visible,
+        enter = slideInVertically { it } + fadeIn(),
+        exit = slideOutVertically { it } + fadeOut(),
+        modifier = modifier,
+    ) {
+        Surface(
+            color = MaterialTheme.colorScheme.surfaceContainerHighest,
+            contentColor = MaterialTheme.colorScheme.onSurface,
+            shape = RoundedCornerShape(50),
+            shadowElevation = 6.dp,
+        ) {
+            Row(
+                verticalAlignment = Alignment.CenterVertically,
+                modifier = Modifier.padding(start = 20.dp, end = 8.dp, top = 6.dp, bottom = 6.dp),
+                horizontalArrangement = Arrangement.spacedBy(12.dp),
+            ) {
+                Text(
+                    text = stringResource(R.string.task_deleted),
+                    style = MaterialTheme.typography.bodyMedium,
+                )
+                TextButton(
+                    onClick = onUndo,
+                    contentPadding = PaddingValues(horizontal = 16.dp, vertical = 6.dp),
+                ) {
+                    Text(
+                        text = stringResource(R.string.undo),
+                        style = MaterialTheme.typography.labelLarge,
+                    )
+                }
+            }
         }
     }
 }
@@ -146,6 +225,7 @@ private fun TaskListBody(
     filter: TaskFilter,
     inner: PaddingValues,
     onOpenTask: (Long) -> Unit,
+    onRequestDelete: (Task) -> Unit,
     viewModel: TaskListViewModel,
 ) {
     val (todayStart, todayEnd) = remember { DayWindow.today(Clock.System.now(), ZoneId.systemDefault()) }
@@ -165,6 +245,12 @@ private fun TaskListBody(
     val showListName = filter is TaskFilter.Smart
     // Completed tasks collapse away by default to keep the active list in focus.
     var completedExpanded by rememberSaveable { mutableStateOf(false) }
+    // Parents the user expanded to reveal their subtasks inline. Children are
+    // grouped from the same flat task set the list already holds.
+    var expandedParents by rememberSaveable { mutableStateOf(emptySet<Long>()) }
+    val childrenByParent = remember(state.tasks) {
+        state.tasks.filter { it.isSubtask }.groupBy { it.parentId!! }
+    }
 
     LazyColumn(
         modifier = Modifier.fillMaxSize(),
@@ -200,17 +286,82 @@ private fun TaskListBody(
                 }
             }
             if (!collapsible || completedExpanded) {
-                itemsIndexed(section.tasks, key = { _, t -> t.taskId }) { index, task ->
-                    TaskRow(
-                        task = task,
-                        position = positionOf(index, section.tasks.size),
-                        showListName = showListName,
-                        subtaskDone = task.subtaskDone,
-                        subtaskTotal = task.subtaskTotal,
-                        onToggle = { viewModel.toggleComplete(task) },
-                        onDelete = { viewModel.delete(task) },
-                        onClick = { onOpenTask(task.taskId) },
+                // Flatten the section into one grouped run: each parent, followed
+                // by its subtasks when expanded. Each row's corners then come from
+                // its place in the whole run (positionOf below) — so the children
+                // read as a grouped list nested in the list's grouped list:
+                // full-width, connecting to the parent above (small top corners),
+                // and the run rounds off (full corners) only at its genuine ends.
+                val rows = buildList {
+                    val topLevel = section.tasks
+                    topLevel.forEachIndexed { p, task ->
+                        val children = childrenByParent[task.taskId].orEmpty()
+                        // Only expandable when we hold every child: true in a real
+                        // list, but a smart list may omit children due on other
+                        // days, and a half-shown set would mislead.
+                        val canExpand = task.subtaskTotal > 0 && children.size == task.subtaskTotal
+                        val isExpanded = canExpand && task.taskId in expandedParents
+                        // Top-level tasks keep their own connected run — full top
+                        // only on the first, full bottom only on the last — so the
+                        // task after an expanded one stays mid-run (small top). An
+                        // expanded parent's bottom opens (small) to meet its subtasks.
+                        val parentPosition = cornerPosition(
+                            topFull = p == 0,
+                            bottomFull = if (isExpanded) false else p == topLevel.lastIndex,
                         )
+                        add(RenderRow(ListRow.Parent(task, canExpand, isExpanded), parentPosition))
+                        if (isExpanded) {
+                            // Subtasks connect up to the parent (small top) and to
+                            // each other; the inline add row below closes the group,
+                            // so every subtask is mid-run (small top + bottom).
+                            children.sortedBy { it.isCompleted }.forEach { sub ->
+                                add(RenderRow(ListRow.Sub(sub), cornerPosition(topFull = false, bottomFull = false)))
+                            }
+                            // The add row rounds the group off (full bottom),
+                            // independent of whatever top-level task follows.
+                            add(RenderRow(ListRow.AddSub(task), cornerPosition(topFull = false, bottomFull = true)))
+                        }
+                    }
+                }
+                itemsIndexed(rows, key = { _, r -> r.row.key }) { index, r ->
+                    val lastInRun = index == rows.lastIndex
+                    when (val row = r.row) {
+                        is ListRow.Parent -> TaskRow(
+                            task = row.task,
+                            position = r.position,
+                            lastInRun = lastInRun,
+                            showListName = showListName,
+                            subtaskDone = row.task.subtaskDone,
+                            subtaskTotal = row.task.subtaskTotal,
+                            expanded = row.expanded,
+                            onToggleExpand = if (row.expandable) {
+                                {
+                                    expandedParents = if (row.task.taskId in expandedParents) {
+                                        expandedParents - row.task.taskId
+                                    } else {
+                                        expandedParents + row.task.taskId
+                                    }
+                                }
+                            } else {
+                                null
+                            },
+                            onToggle = { viewModel.toggleComplete(row.task) },
+                            onDelete = { onRequestDelete(row.task) },
+                            onClick = { onOpenTask(row.task.taskId) },
+                        )
+                        is ListRow.Sub -> SubtaskRow(
+                            task = row.task,
+                            position = r.position,
+                            lastInRun = lastInRun,
+                            onToggle = { viewModel.toggleComplete(row.task) },
+                            onClick = { onOpenTask(row.task.taskId) },
+                        )
+                        is ListRow.AddSub -> AddSubtaskRow(
+                            position = r.position,
+                            lastInRun = lastInRun,
+                            onAdd = { viewModel.quickAddSubtask(row.parent, it) },
+                        )
+                    }
                 }
             }
         }
@@ -269,9 +420,12 @@ private fun InlineAdd(onAdd: (String) -> Unit) {
 private fun TaskRow(
     task: Task,
     position: Position,
+    lastInRun: Boolean,
     showListName: Boolean,
     subtaskDone: Int,
     subtaskTotal: Int,
+    expanded: Boolean,
+    onToggleExpand: (() -> Unit)?,
     onToggle: () -> Unit,
     onDelete: () -> Unit,
     onClick: () -> Unit,
@@ -279,23 +433,28 @@ private fun TaskRow(
     val dismissState = rememberSwipeToDismissBoxState(
         confirmValueChange = { value ->
             when (value) {
-                SwipeToDismissBoxValue.StartToEnd -> { onToggle(); false } // toggle, snap back
-                SwipeToDismissBoxValue.EndToStart -> { onDelete(); true }  // delete, dismiss
+                // Both snap back: complete toggles status; delete hands off to the
+                // undo flow, which removes the row from the data. Never *confirm*
+                // the dismiss — a terminal dismissed state strands a stale
+                // background bar and won't re-arm when the row is restored.
+                SwipeToDismissBoxValue.StartToEnd -> { onToggle(); false }
+                SwipeToDismissBoxValue.EndToStart -> { onDelete(); false }
                 SwipeToDismissBoxValue.Settled -> false
             }
         },
     )
-    val gap = when (position) {
-        Position.Top, Position.Middle -> Modifier.padding(bottom = 2.dp)
-        Position.Bottom, Position.Alone -> Modifier
-    }
+    // A small gap below every row but the run's last — including a group-ending
+    // Bottom that's followed by a fresh card, so the two groups read apart.
+    val gap = if (lastInRun) Modifier else Modifier.padding(bottom = 2.dp)
 
     SwipeToDismissBox(
         state = dismissState,
         modifier = Modifier.fillMaxWidth().padding(horizontal = 16.dp).then(gap),
-        backgroundContent = { SwipeBackground(dismissState.targetValue, task.isCompleted) },
+        // dismissDirection (not targetValue) tracks the live drag, so the colour +
+        // icon reveal as you swipe rather than only once the threshold is crossed.
+        backgroundContent = { SwipeBackground(dismissState.dismissDirection, task.isCompleted) },
     ) {
-        TaskRowContent(task, position, showListName, subtaskDone, subtaskTotal, onToggle, onClick)
+        TaskRowContent(task, position, showListName, subtaskDone, subtaskTotal, expanded, onToggleExpand, onToggle, onClick)
     }
 }
 
@@ -307,6 +466,8 @@ private fun TaskRowContent(
     showListName: Boolean,
     subtaskDone: Int,
     subtaskTotal: Int,
+    expanded: Boolean,
+    onToggleExpand: (() -> Unit)?,
     onToggle: () -> Unit,
     onClick: () -> Unit,
 ) {
@@ -317,7 +478,8 @@ private fun TaskRowContent(
     val dark = isSystemInDarkTheme()
     val due = task.due?.formatDateTime(task.isAllDay)
     val listName = task.listName?.takeIf { showListName && it.isNotBlank() }
-    val hasSupporting = due != null || listName != null || subtaskTotal > 0
+    val hasSupporting = due != null || listName != null || subtaskTotal > 0 ||
+        task.priority != Priority.NONE
 
     Surface(
         onClick = onClick,
@@ -368,6 +530,9 @@ private fun TaskRowContent(
                         horizontalArrangement = Arrangement.spacedBy(8.dp),
                         itemVerticalAlignment = Alignment.CenterVertically,
                     ) {
+                        if (task.priority != Priority.NONE) {
+                            PriorityChip(task.priority, priorityLabel(task.priority))
+                        }
                         if (due != null) {
                             Text(
                                 text = due,
@@ -380,21 +545,16 @@ private fun TaskRowContent(
                     }
                 }
             }
-            priorityFlag(task.priority)?.let { flag ->
-                Spacer(Modifier.width(8.dp))
-                flag()
+            // Trailing area is only ever the expand control, so the row's right
+            // edge stays put whether or not the task has children (priority now
+            // rides in the supporting chip row instead of a shifting trailing flag).
+            if (onToggleExpand != null) {
+                SubtaskExpandButton(expanded = expanded, onToggle = onToggleExpand)
             }
         }
     }
 }
 
-/** A flag tinted by priority, or nothing for [Priority.NONE]. */
-@Composable
-private fun priorityFlag(priority: Priority): (@Composable () -> Unit)? {
-    if (priority == Priority.NONE) return null
-    return { Icon(Icons.Rounded.Flag, contentDescription = priorityLabel(priority), tint = priorityTint(priority)) }
-}
-
 /** A small neutral pill showing subtask progress, e.g. "3 / 5". */
 @Composable
 private fun SubtaskCountChip(done: Int, total: Int) {
@@ -422,13 +582,186 @@ private fun SubtaskCountChip(done: Int, total: Int) {
     }
 }
 
-/** Shared priority colour so the flag reads the same in the list and the detail view. */
+/**
+ * The inline "add a subtask" row that closes an expanded group — a [BasicTextField]
+ * aligned with the subtask titles (leading + where the checkbox sits), submitting
+ * on the tick or the IME action. Same grouped-card segment as the rows around it.
+ */
+@OptIn(ExperimentalMaterial3Api::class)
 @Composable
-internal fun priorityTint(priority: Priority): Color = when (priority) {
-    Priority.NONE -> MaterialTheme.colorScheme.onSurfaceVariant
-    Priority.HIGH -> MaterialTheme.colorScheme.error
-    Priority.MEDIUM -> MaterialTheme.colorScheme.tertiary
-    Priority.LOW -> MaterialTheme.colorScheme.onSurfaceVariant
+private fun AddSubtaskRow(
+    position: Position,
+    lastInRun: Boolean,
+    onAdd: (String) -> Unit,
+) {
+    var text by remember { mutableStateOf("") }
+    fun submit() {
+        if (text.isNotBlank()) {
+            onAdd(text.trim())
+            text = ""
+        }
+    }
+    val gap = if (lastInRun) Modifier else Modifier.padding(bottom = 2.dp)
+    Surface(
+        shape = cardShape(position, 22.dp, 6.dp),
+        // Same tone as the subtask rows it closes, so the group reads as one unit.
+        color = MaterialTheme.colorScheme.surfaceContainer,
+        modifier = Modifier.fillMaxWidth().padding(horizontal = 16.dp).then(gap),
+    ) {
+        Row(
+            modifier = Modifier.fillMaxWidth().heightIn(min = 52.dp).padding(start = 12.dp, end = 8.dp),
+            verticalAlignment = Alignment.CenterVertically,
+        ) {
+            Spacer(Modifier.width(5.dp)) // the parents' colour-bar slot, kept for alignment
+            Box(modifier = Modifier.size(48.dp), contentAlignment = Alignment.Center) {
+                Icon(
+                    imageVector = Icons.Rounded.Add,
+                    contentDescription = null,
+                    tint = MaterialTheme.colorScheme.onSurfaceVariant,
+                )
+            }
+            Spacer(Modifier.width(4.dp))
+            BasicTextField(
+                value = text,
+                onValueChange = { text = it },
+                singleLine = true,
+                textStyle = MaterialTheme.typography.bodyLarge.copy(color = MaterialTheme.colorScheme.onSurface),
+                cursorBrush = SolidColor(MaterialTheme.colorScheme.primary),
+                keyboardOptions = androidx.compose.foundation.text.KeyboardOptions(imeAction = ImeAction.Done),
+                keyboardActions = androidx.compose.foundation.text.KeyboardActions(onDone = { submit() }),
+                modifier = Modifier.weight(1f),
+                decorationBox = { inner ->
+                    if (text.isEmpty()) {
+                        Text(
+                            text = stringResource(R.string.add_subtask_hint),
+                            style = MaterialTheme.typography.bodyLarge,
+                            color = MaterialTheme.colorScheme.onSurfaceVariant,
+                        )
+                    }
+                    inner()
+                },
+            )
+            if (text.isNotBlank()) {
+                IconButton(onClick = ::submit) {
+                    Icon(
+                        Icons.Rounded.Check,
+                        contentDescription = stringResource(R.string.cd_add_task),
+                        tint = MaterialTheme.colorScheme.primary,
+                    )
+                }
+            }
+        }
+    }
+}
+
+/** The trailing expand/collapse control for a parent row — a rotating chevron. */
+@Composable
+private fun SubtaskExpandButton(expanded: Boolean, onToggle: () -> Unit) {
+    val rotation by animateFloatAsState(if (expanded) 180f else 0f, label = "subtaskExpand")
+    IconButton(onClick = onToggle) {
+        Icon(
+            imageVector = Icons.Rounded.ExpandMore,
+            contentDescription = stringResource(
+                if (expanded) R.string.cd_collapse_subtasks else R.string.cd_expand_subtasks,
+            ),
+            tint = MaterialTheme.colorScheme.onSurfaceVariant,
+            modifier = Modifier.rotate(rotation),
+        )
+    }
+}
+
+/** A visual row in a flattened section run: a top-level task, or one of its subtasks. */
+private sealed interface ListRow {
+    val key: Long
+
+    data class Parent(val task: Task, val expandable: Boolean, val expanded: Boolean) : ListRow {
+        override val key: Long get() = task.taskId
+    }
+
+    data class Sub(val task: Task) : ListRow {
+        override val key: Long get() = task.taskId
+    }
+
+    /** The inline "add a subtask" row that closes an expanded group. */
+    data class AddSub(val parent: Task) : ListRow {
+        // Negative so it never collides with a real (positive) provider task id.
+        override val key: Long get() = -parent.taskId
+    }
+}
+
+/** A flattened row paired with the grouped-card corners it should render with. */
+private data class RenderRow(val row: ListRow, val position: Position)
+
+/**
+ * Map independent top/bottom corner choices to a [Position]. `full` = the big
+ * outer corner radius (a run's start/end); otherwise the small connecting radius.
+ * Letting each edge be chosen on its own lets a subtask group round off (full
+ * bottom) while the next top-level task keeps a small top and stays mid-run.
+ */
+private fun cornerPosition(topFull: Boolean, bottomFull: Boolean): Position = when {
+    topFull && bottomFull -> Position.Alone
+    topFull -> Position.Top
+    bottomFull -> Position.Bottom
+    else -> Position.Middle
+}
+
+/**
+ * One subtask row inside an expanded parent: a full-width grouped-card segment
+ * (same tonal surface, corners-from-[position], press-morph as the task rows), so
+ * it's part of the same grouped run. The only difference is a leading indent
+ * before the checkbox to convey nesting — the card width is preserved.
+ */
+@OptIn(ExperimentalMaterial3Api::class)
+@Composable
+private fun SubtaskRow(
+    task: Task,
+    position: Position,
+    lastInRun: Boolean,
+    onToggle: () -> Unit,
+    onClick: () -> Unit,
+) {
+    val interaction = remember { MutableInteractionSource() }
+    val pressed by interaction.collectIsPressedAsState()
+    val full by animateDpAsState(if (pressed) 36.dp else 22.dp, label = "subFullCorner")
+    val small by animateDpAsState(if (pressed) 36.dp else 6.dp, label = "subSmallCorner")
+    val gap = if (lastInRun) Modifier else Modifier.padding(bottom = 2.dp)
+    Surface(
+        onClick = onClick,
+        shape = cardShape(position, full, small),
+        // A step below the parents' surfaceContainerHigh so the subtask group
+        // reads as a distinct, recessive tone — the nesting cue alongside shape.
+        color = MaterialTheme.colorScheme.surfaceContainer,
+        interactionSource = interaction,
+        modifier = Modifier.fillMaxWidth().padding(horizontal = 16.dp).then(gap),
+    ) {
+        Row(
+            modifier = Modifier
+                .fillMaxWidth()
+                .heightIn(min = 56.dp)
+                .padding(start = 12.dp, end = 16.dp, top = 6.dp, bottom = 6.dp),
+            verticalAlignment = Alignment.CenterVertically,
+        ) {
+            // No colour bar — that absence (with the grouped nesting) marks the row
+            // as a subtask. Reserve the bar's 5dp so the checkbox still lines up
+            // with the parent rows' checkboxes rather than indenting.
+            Spacer(Modifier.width(5.dp))
+            Checkbox(checked = task.isCompleted, onCheckedChange = { onToggle() })
+            Spacer(Modifier.width(4.dp))
+            Text(
+                text = task.title.ifBlank { stringResource(R.string.task_untitled) },
+                style = MaterialTheme.typography.bodyLarge,
+                maxLines = 2,
+                overflow = TextOverflow.Ellipsis,
+                textDecoration = if (task.isCompleted) TextDecoration.LineThrough else null,
+                color = if (task.isCompleted) {
+                    MaterialTheme.colorScheme.onSurfaceVariant
+                } else {
+                    MaterialTheme.colorScheme.onSurface
+                },
+                modifier = Modifier.weight(1f),
+            )
+        }
+    }
 }
 
 /** The colored reveal behind a swiping row: complete on the left, delete on the right. */

app/src/main/java/de/jeanlucmakiola/floret/ui/tasklist/TaskListViewModel.kt

@@ -46,6 +46,9 @@ class TaskListViewModel @Inject constructor(
 
     private val filter = MutableStateFlow<TaskFilter?>(null)
 
+    /** Tasks swiped to delete but not yet committed — hidden until the undo lapses. */
+    private val pendingDeletes = MutableStateFlow<Set<Long>>(emptySet())
+
     val state: StateFlow<TaskListUiState> =
         filter.filterNotNull()
             .flatMapLatest { f ->
@@ -58,7 +61,15 @@ class TaskListViewModel @Inject constructor(
                     is TaskFilter.Smart ->
                         tasks.map { TaskListUiState.Content(it) }
                 }
-                content
+                // Drop rows pending an undoable delete so the row vanishes on swipe
+                // while the actual provider delete waits for the snackbar to commit.
+                combine(content, pendingDeletes) { st, pending ->
+                    if (st is TaskListUiState.Content) {
+                        st.copy(tasks = st.tasks.filter { it.taskId !in pending })
+                    } else {
+                        st
+                    }
+                }
                     .onStart { emit(TaskListUiState.Loading) }
                     .catch { emit(TaskListUiState.Failure) }
             }
@@ -70,8 +81,24 @@ class TaskListViewModel @Inject constructor(
         runCatching { repository.setCompleted(task.taskId, !task.isCompleted) }
     }
 
-    fun delete(task: Task) = viewModelScope.launch {
-        runCatching { repository.deleteTask(task.taskId) }
+    /** Swipe-delete: hide the row now; the screen's snackbar commits or restores it. */
+    fun markPendingDelete(task: Task) {
+        pendingDeletes.value = pendingDeletes.value + task.taskId
+    }
+
+    /** Undo — stop hiding the task; it returns to the list. */
+    fun undoDelete(taskId: Long) {
+        pendingDeletes.value = pendingDeletes.value - taskId
+    }
+
+    /**
+     * Commit the delete once the undo window passes. The id stays in the pending
+     * set: the task is gone from the provider so it can't reappear, and removing
+     * it could briefly un-hide the row before the provider change propagates.
+     */
+    fun commitDelete(taskId: Long) = viewModelScope.launch {
+        if (taskId !in pendingDeletes.value) return@launch
+        runCatching { repository.deleteTask(taskId) }
     }
 
     /** Inline "add task" — title only, into [listId]. */
@@ -79,4 +106,14 @@ class TaskListViewModel @Inject constructor(
         if (title.isBlank() || listId <= 0L) return@launch
         runCatching { repository.createTask(TaskForm(title = title, listId = listId)) }
     }
+
+    /** Inline "add subtask" from an expanded list group — files it under [parent]. */
+    fun quickAddSubtask(parent: Task, title: String) = viewModelScope.launch {
+        if (title.isBlank() || parent.listId <= 0L) return@launch
+        runCatching {
+            repository.createTask(
+                TaskForm(title = title.trim(), listId = parent.listId, parentId = parent.taskId),
+            )
+        }
+    }
 }

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

@@ -29,9 +29,14 @@
 
     <!-- Task list: inline add + swipe -->
     <string name="add_task_hint">Add a task</string>
+    <string name="add_subtask_hint">Add a subtask</string>
     <string name="cd_add_task">Add task</string>
     <string name="cd_complete">Complete</string>
     <string name="cd_reopen">Reopen</string>
+    <string name="task_deleted">Deleted</string>
+    <string name="undo">Undo</string>
+    <string name="cd_expand_subtasks">Show subtasks</string>
+    <string name="cd_collapse_subtasks">Hide subtasks</string>
 
     <!-- Sections (due-date buckets) -->
     <string name="section_overdue">Overdue</string>
@@ -55,6 +60,8 @@
     <string name="detail_priority">Priority</string>
     <string name="detail_progress">Progress</string>
     <string name="detail_subtasks">Subtasks</string>
+    <string name="detail_parent">Parent task</string>
+    <string name="detail_part_of">Part of</string>
     <string name="percent_complete">%1$d%%</string>
 
     <!-- Task edit -->
@@ -63,6 +70,11 @@
     <string name="edit_due_label">Due</string>
     <string name="edit_all_day">All day</string>
     <string name="edit_priority_label">Priority</string>
+    <string name="edit_progress_label">Progress</string>
+    <string name="edit_parent_label">Parent task</string>
+    <string name="edit_parent_none">None (top-level)</string>
+    <string name="edit_parent_search">Search tasks</string>
+    <string name="edit_parent_empty">No matching tasks in this list.</string>
     <string name="edit_reminder_label">Reminder</string>
     <string name="edit_set">Set</string>
     <string name="edit_clear">Clear</string>
@@ -72,6 +84,11 @@
     <string name="close">Close</string>
     <string name="dialog_cancel">Cancel</string>
 
+    <!-- Save conflict -->
+    <string name="edit_conflict_title">Task changed elsewhere</string>
+    <string name="edit_conflict_body">This task was updated somewhere else (a sync or another app) since you opened it. Overwrite those changes with your edits?</string>
+    <string name="edit_conflict_overwrite">Overwrite</string>
+
     <!-- Reminder offsets -->
     <string name="reminder_none">None</string>
     <string name="reminder_at_due">At time of task</string>

app/src/test/java/de/jeanlucmakiola/floret/data/tasks/TaskWriteMapperTest.kt

@@ -28,6 +28,50 @@ class TaskWriteMapperTest {
         assertThat(values[Tasks.TZ]).isEqualTo("Europe/Berlin")
     }
 
+    @Test
+    fun `percent complete is written and clamped to 0-100`() {
+        val values = TaskWriteMapper.taskValues(
+            TaskForm(title = "x", listId = 1L, percentComplete = 140),
+            tzId = "UTC",
+        )
+        assertThat(values[Tasks.PERCENT_COMPLETE]).isEqualTo(100)
+
+        val unset = TaskWriteMapper.taskValues(TaskForm(title = "x", listId = 1L), tzId = "UTC")
+        assertThat(unset[Tasks.PERCENT_COMPLETE]).isNull()
+    }
+
+    @Test
+    fun `progress keeps completion in sync both ways`() {
+        // 100% completes the task (timestamp left to the provider / existing value).
+        val done = TaskWriteMapper.taskValues(
+            TaskForm(title = "x", listId = 1L, percentComplete = 100),
+            tzId = "UTC",
+        )
+        assertThat(done[Tasks.STATUS]).isEqualTo(TasksContract.STATUS_COMPLETED)
+        assertThat(done.containsKey(Tasks.COMPLETED)).isFalse()
+
+        // Below 100% reopens it and clears the completion timestamp.
+        val reopened = TaskWriteMapper.taskValues(
+            TaskForm(title = "x", listId = 1L, percentComplete = 75),
+            tzId = "UTC",
+        )
+        assertThat(reopened[Tasks.STATUS]).isEqualTo(TasksContract.STATUS_IN_PROCESS)
+        assertThat(reopened[Tasks.COMPLETED]).isNull()
+
+        // No percent in the form ⇒ status is left to the complete toggle.
+        val untouched = TaskWriteMapper.taskValues(TaskForm(title = "x", listId = 1L), tzId = "UTC")
+        assertThat(untouched.containsKey(Tasks.STATUS)).isFalse()
+    }
+
+    @Test
+    fun `parent id is written so a task can be filed under another`() {
+        val values = TaskWriteMapper.taskValues(
+            TaskForm(title = "x", listId = 1L, parentId = 7L),
+            tzId = "UTC",
+        )
+        assertThat(values[Tasks.PARENT_ID]).isEqualTo(7L)
+    }
+
     @Test
     fun `all-day task clears the timezone`() {
         val form = TaskForm(

app/src/test/java/de/jeanlucmakiola/floret/domain/TaskFormTest.kt

@@ -35,4 +35,13 @@ class TaskFormTest {
         val errors = TaskForm(title = "x", listId = 1, reminderMinutesBeforeDue = 10).validate()
         assertThat(errors).contains(TaskFormError.REMINDER_WITHOUT_DUE)
     }
+
+    @Test
+    fun `progress and parent auto-reveal only when they carry a value`() {
+        assertThat(TaskForm(title = "x", listId = 1).populatedFields()).isEmpty()
+        assertThat(TaskForm(title = "x", listId = 1, percentComplete = 0, parentId = 0).populatedFields())
+            .isEmpty()
+        assertThat(TaskForm(title = "x", listId = 1, percentComplete = 30, parentId = 9).populatedFields())
+            .containsExactly(TaskFormField.Progress, TaskFormField.Parent)
+    }
 }

docs/ROADMAP.md

@@ -11,9 +11,12 @@ Status legend: ✅ done · 🚧 in progress · ⬜ not started
 ## Current state (one line)
 
 The full non-visual stack ("backoffice") over the OpenTasks `TaskContract`
-provider is **done and unit-tested**; the Material 3 Expressive UI is being
-built screen by screen on top of it. App builds, gates on provider/permission,
-and navigates lists → task list → detail / edit through base screen scaffolds.
+provider is **done and unit-tested**, and the Material 3 Expressive UI is built
+through **M4**: lists → task list (swipe gestures, inline add, smart-list section
+headers) → detail / edit with full CRUD, date-time pickers, priority,
+percent-complete, conflict-safe saves, per-task reminders, and subtask
+create + reparent. Remaining work is M5 (notification / exact-alarm onboarding,
+default reminder UI) and M6 (Settings screen, Glance widget, i18n, release).
 
 ---
 
@@ -39,38 +42,81 @@ The complete non-visual stack:
 - JVM unit tests across mappers, filtering, sorting, form, value mapping, and
   day windows.
 
-### 🚧 M2 — Screens: lists, task list, complete & CRUD
-Replace the functional scaffold with the real Material 3 Expressive UI, screen
-by screen, against the already-built ViewModels.
+### ✅ M2 — Screens: lists, task list, complete & CRUD
+The real Material 3 Expressive UI, built screen by screen against the M1
+ViewModels.
 - ✅ Provider/permission onboarding gate (`RootScreen`).
 - ✅ Lists overview (`ListsScreen`) — smart lists + user lists grouped by account.
 - ✅ Navigation host wiring (`FloretNavHost` + `Dest` route table: lists → task
   list → detail / edit, each binding its M1 ViewModel from route args).
-- 🚧 Task list screen — base scaffold lands (checkbox rows, toggle-complete, open
-  / new-task nav). Remaining: swipe-to-complete / -delete, inline add field,
-  section headers for smart lists.
-- 🚧 Detail + edit screens — base scaffolds land (detail shows title /
-  description / subtasks with edit+delete; edit has title / description / save).
-  Remaining: full CRUD fields and local-list creation wired to the UI.
+- ✅ Task list screen — checkbox rows + toggle-complete, swipe-to-complete /
+  -delete (`SwipeToDismissBox`), inline add field (`InlineAdd` → `quickAdd`),
+  smart-list section headers (`TaskSections`).
+- ✅ Detail + edit screens — detail shows title / description / subtasks with
+  edit+delete; edit has the full CRUD form (title, description, save) wired to a
+  list picker.
 
-### ⬜ M3 — Detail / edit polish
-Task detail and edit screens: due/start date-time pickers, priority,
-percent-complete, conflict-safe saves (re-check before overwrite), smart-list
-section presentation.
+### ✅ M3 — Detail / edit polish
+- ✅ Due / start date-time pickers (`DateTimePickerFlow` in `TaskEditScreen`).
+- ✅ Priority — coloured by level: green / amber / red pastels (`priorityFill`;
+  M3 has no priority role, only `error`). A shared `ui/common/PriorityChip` on the
+  list and detail screens, and the edit form's M3 segmented selector tints its
+  active segment in the chosen level's hue.
+- ✅ Smart-list section presentation (`TaskSections` headers on the task list).
+- ✅ Percent-complete field — optional "Progress" slider (5% detents) on the edit
+  form; writes `Tasks.PERCENT_COMPLETE` (clamped 0–100, status left to the
+  complete toggle).
+- ✅ Conflict-safe saves — `updateTask` re-checks `last_modified` against the
+  value captured when the form loaded and throws `TaskConflictException`; the
+  editor offers overwrite-or-cancel instead of clobbering an external change.
 
-### ⬜ M4 — Subtasks (UI)
-`RELATED-TO` hierarchy in the UI: indentation, create subtask, reparent. The
-data layer already reads `parentId`; this is the trickiest UI piece.
+### ✅ M4 — Subtasks (UI)
+`RELATED-TO` hierarchy in the UI. The data layer already reads `parentId`.
+- ✅ Create subtask (`AddSubtaskField` → `TaskDetailViewModel.addSubtask` sets
+  `parentId`); subtasks render as a grouped section in the detail screen. Tapping
+  a subtask opens its own detail (a new `TaskDetail` entry, so it can have
+  children too), and the subtask's detail shows a tappable "Part of …" parent
+  card so it never reads as a stray standalone task.
+- ✅ Inline expansion on the task list — a parent row has a dedicated expand
+  button (trailing chevron, separate from the count chip). Each section flattens
+  into one grouped run (parents + their expanded children) and corners are chosen
+  per-edge (`cornerPosition`): top-level tasks keep their own run, an expanded
+  parent opens its bottom to its children, and the child group rounds off on its
+  last segment while the next top-level task stays mid-run. Children are
+  full-width, set a step down in tone (`surfaceContainer` vs the parents'
+  `surfaceContainerHigh`) and with no colour bar (checkbox stays aligned). An expanded group ends with an inline "add a subtask"
+  row (always on for now; an opt-out toggle lands with the M6 settings screen).
+  Offered only where the list holds all the children (a real list; smart lists
+  that omit off-day children stay collapsed). `TaskDetail.parent` carries the
+  parent for the detail card.
+- ✅ Reparent — a full-width, searchable "Parent task" sheet on the edit form
+  groups active candidates by due-date section (Overdue / Today / Upcoming / No
+  date) and files a task under any top-level task in its list (or "None" to
+  promote it); switching list clears the now-invalid parent. Candidates stay
+  active + top-level to keep nesting one level deep, matching the detail screen.
 
-### ⬜ M5 — Reminders onboarding & polish
-The engine exists (M1). Remaining: the `POST_NOTIFICATIONS` + exact-alarm
-onboarding flow, per-task / default reminder-offset settings UI, and
-end-to-end verification on device.
+### 🚧 M5 — Reminders onboarding & polish
+The engine exists (M1: `ReminderScheduler` + boot / provider-change re-sync,
+`DueReminderReceiver`, `TaskNotifier`).
+- ✅ Per-task reminder-offset UI (`ReminderPickerDialog` → `TaskForm`
+  `reminderMinutesBeforeDue`).
+- ⬜ `POST_NOTIFICATIONS` + exact-alarm onboarding flow — currently only graceful
+  runtime checks (`TaskNotifier.canPost`, `canScheduleExactAlarms`), no
+  user-facing gate.
+- ⬜ Default reminder-offset settings UI — `SettingsPrefs`/`SettingsViewModel`
+  back it, but no Composable exposes it.
+- ⬜ End-to-end verification on device.
 
-### ⬜ M6 — Settings, widget, i18n, release
-Settings screen (theme / dynamic-color / language, default list, default
-reminder), Glance task-list widget, translations, finalize F-Droid metadata,
-confirm CI release flow.
+### 🚧 M6 — Settings, widget, i18n, release
+- ✅ F-Droid metadata scaffolded (`fdroid-metadata/`).
+- ⬜ Settings screen — `SettingsViewModel` exists but no `SettingsScreen`
+  Composable and it is not in the nav graph (only used by `MainActivity` for
+  app-level theming). Needs theme / dynamic-color / language, default list,
+  default reminder, and the opt-out toggle for the task list's inline
+  add-a-subtask row (on by default since M4).
+- ⬜ Glance task-list widget — deps present in `build.gradle.kts`, zero impl.
+- ⬜ Translations — only `res/values/` (English); no `values-XX`.
+- ⬜ Finalize F-Droid metadata, confirm CI release flow.
 
 ### ⬜ Posture B (separate track, later)
 Add a `:provider` module bundling the Apache-2.0 `opentasks-provider`;