Minimum QRB filter; the station map follows the station filters (#21) (#132)

* Add a minimum QRB filter to the station filter bar (#21)

Next to "Show only QRB [km] <=" the bar gets "Show only QRB [km] >": it
hides every station up to the entered distance. With both switched on the
list keeps a range, min < QRB <= max. The minimum is exclusive, as the
issue asks, so the two filters split the list without overlap at the same
value. A station without a known QRB is hidden while either is on, as the
maximum already did. The value lives in the bar for the running session
only, like the maximum, and the station map follows through activeFilters.

The distance check moves from the controller predicate into
StationFilterState.acceptsQrb so it can be tested; the maximum keeps its
behaviour (null or > max is hidden).

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

* Document the minimum QRB filter (#21)

Changelog v1.50 under New, the filter tables of the user interface pages,
the distance filter section of the feature pages, and the station filter
page of the website.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

* Let the first filter bar row wrap instead of clipping (#21)

With both QRB filters the first row of the station filter bar no longer
fits a narrow station pane, and as a plain Row it cut the bearing buttons
off at the right edge. It is a FlowRow now. Reset, the QRB pair, the QTF
controls and the bearings each move to the next line as one group; the
QRB pair and the bearings only break up inside their group when even the
group is wider than the pane. Separators in the wrapping row have a fixed
height, because a flow row line has no intrinsic height to fill.

A screen test at 300 dp checks that every bearing button, both QRB labels
and fields and the QTF label are displayed and end inside the bar.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

* Refuse NaN, Infinity and negatives in the QRB filter fields (#21)

toDoubleOrNull also reads "NaN" and "Infinity": a pasted "Infinity" as
the minimum hid every station, "NaN" let every one through, and the
maximum field had the same hole before. Both QRB fields now go through
parseQrbKm, which takes only finite, non-negative distances; anything
else leaves the field at its last valid value.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

* Let the station map follow the station filters (#21)

The Compose map built its markers from all station rows, so no filter
reached it, although its status line reported "filtered view active".
The JavaFX map, up to beta-v1.50.0-beta-001, took the sorted, filtered
list (StationMapBridge.refreshNow), so this is a regression of the
Compose port that never shipped. The markers now come from the rows the
list shows, and the filter is a key of the remembered markers so a
filter change redraws them. A selected station that a filter hides gets
no marker, as in the JavaFX map.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

* Filter again on redraw; no path analysis for a hidden station (#21)

DataTableState.visibleRows caches the filtered rows, and forceRedraw only
bumped contentRevision. The filter reads fields that change in place
(QRB, worked and QRV flags, last activity), so a redraw could hand back
rows filtered before the change -- in the list and, since the map draws
the same rows, on the map. forceRedraw now drops the cache, and
visibleRows reads contentRevision so a reader recomputes after it. In the
running application the user-list refresh also sets a new row filter,
which dropped the cache before; this makes the redraw itself sufficient.

A selected station without a marker -- hidden by a filter, or without a
locator -- no longer starts a path analysis: the map used to set
"Loading" with an empty target and send the request. The analysis is
cleared instead, and the effect re-runs when the station's marker
appears or disappears.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

---------

Co-authored-by: Claude Opus 5.5 <noreply@anthropic.com>

app-desktop/src/main/kotlin/kst4contest/view/compose/DataTableState.kt

@@ -275,7 +275,14 @@ class DataTableState<T>(
     var contentRevision by mutableStateOf(0)
         private set
 
+    /**
+     * Redraws the rows and filters them again. The filter reads mutable row fields (a
+     * station's QRB, worked and QRV flags, its last activity), so a cached [visibleRows]
+     * from before the change could keep a row the filter now excludes, or hide one it
+     * now lets through -- in the list and in the station map, which draws the same rows.
+     */
     fun forceRedraw() {
+        invalidateOrder()
         contentRevision++
     }
 
@@ -299,6 +306,7 @@ class DataTableState<T>(
              */
             val currentRows = rows
             val currentFilter = rowFilter
+            contentRevision // read for the subscription: forceRedraw drops the cache
             val currentColumn = sortedColumnId
             val ascending = sortAscending
 

app-desktop/src/main/kotlin/kst4contest/view/compose/StationFilterBar.kt

@@ -48,11 +48,19 @@ fun StationFilterBar(
         modifier = modifier.fillMaxWidth().padding(horizontal = 2.dp, vertical = 1.dp),
         verticalArrangement = Arrangement.spacedBy(1.dp),
     ) {
-        // ROW 1: Reset | QRB | QTF + bearings
-        Row(
-            modifier = Modifier.fillMaxWidth().height(IntrinsicSize.Min),
+        /*
+         * ROW 1: Reset | QRB max + min | QTF | bearings
+         *
+         * It wraps (#21): with both QRB filters the line no longer fits a narrow station
+         * pane, and a plain row cut the bearing buttons off at the right edge. Each group
+         * stays together on its line; only the QRB pair and the bearings may break up
+         * inside their group when even that group is wider than the pane.
+         */
+        FlowRow(
+            modifier = Modifier.fillMaxWidth(),
             horizontalArrangement = Arrangement.spacedBy(4.dp),
-            verticalAlignment = Alignment.CenterVertically,
+            verticalArrangement = Arrangement.spacedBy(1.dp),
+            itemVerticalAlignment = Alignment.CenterVertically,
         ) {
             // Reset filters
             FilterButton(strings.filterReset, on = false, isAccent = true) {
@@ -60,65 +68,105 @@ fun StationFilterBar(
                 onChanged()
             }
 
-            VerticalSeparator()
-
-            // QRB checkbox + field
-            CompactCheckbox(
-                checked = filters.maxQrbEnabled,
-                onCheckedChange = {
-                    filters.maxQrbEnabled = it
-                    onChanged()
-                },
-            )
-            Text(strings.filterShowOnlyQrb, style = MaterialTheme.typography.bodySmall)
-            CompactTextField(
-                value = if (filters.maxQrbKm.rem(1) == 0.0) filters.maxQrbKm.toInt().toString() else filters.maxQrbKm.toString(),
-                onValueChange = {
-                    val parsed = it.toDoubleOrNull()
-                    if (parsed != null) {
-                        filters.maxQrbKm = parsed
-                        if (filters.maxQrbEnabled) onChanged()
-                    } else if (it.isEmpty()) {
-                        filters.maxQrbKm = 0.0
-                        if (filters.maxQrbEnabled) onChanged()
+            // QRB maximum + minimum (#21): together they make a range, so they stay one group
+            FilterGroup {
+                GroupSeparator()
+                FlowRow(
+                    horizontalArrangement = Arrangement.spacedBy(4.dp),
+                    verticalArrangement = Arrangement.spacedBy(1.dp),
+                    itemVerticalAlignment = Alignment.CenterVertically,
+                ) {
+                    FilterGroup {
+                        CompactCheckbox(
+                            checked = filters.maxQrbEnabled,
+                            onCheckedChange = {
+                                filters.maxQrbEnabled = it
+                                onChanged()
+                            },
+                        )
+                        Text(strings.filterShowOnlyQrb, style = MaterialTheme.typography.bodySmall)
+                        CompactTextField(
+                            value = if (filters.maxQrbKm.rem(1) == 0.0) filters.maxQrbKm.toInt().toString() else filters.maxQrbKm.toString(),
+                            onValueChange = {
+                                val parsed = parseQrbKm(it)
+                                if (parsed != null) {
+                                    filters.maxQrbKm = parsed
+                                    if (filters.maxQrbEnabled) onChanged()
+                                } else if (it.isEmpty()) {
+                                    filters.maxQrbKm = 0.0
+                                    if (filters.maxQrbEnabled) onChanged()
+                                }
+                            },
+                            modifier = Modifier.width(50.dp)
+                        )
                     }
-                },
-                modifier = Modifier.width(50.dp)
-            )
-
-            VerticalSeparator()
-
-            // QTF checkbox + field + bearings
-            CompactCheckbox(
-                checked = filters.qtfEnabled,
-                onCheckedChange = {
-                    filters.qtfEnabled = it
-                    onChanged()
-                },
-            )
-            Text(strings.filterShowOnlyQtf, style = MaterialTheme.typography.bodySmall)
-            CompactTextField(
-                value = if (filters.qtfDegrees.rem(1) == 0.0) filters.qtfDegrees.toInt().toString() else filters.qtfDegrees.toString(),
-                onValueChange = {
-                    val parsed = it.toDoubleOrNull()
-                    if (parsed != null) {
-                        filters.qtfDegrees = parsed
-                        filters.bearing = null
-                        if (filters.qtfEnabled) onChanged()
-                    } else if (it.isEmpty()) {
-                        filters.qtfDegrees = 0.0
-                        filters.bearing = null
-                        if (filters.qtfEnabled) onChanged()
+                    FilterGroup {
+                        CompactCheckbox(
+                            checked = filters.minQrbEnabled,
+                            onCheckedChange = {
+                                filters.minQrbEnabled = it
+                                onChanged()
+                            },
+                        )
+                        Text(strings.filterShowOnlyQrbAbove, style = MaterialTheme.typography.bodySmall)
+                        CompactTextField(
+                            value = if (filters.minQrbKm.rem(1) == 0.0) filters.minQrbKm.toInt().toString() else filters.minQrbKm.toString(),
+                            onValueChange = {
+                                val parsed = parseQrbKm(it)
+                                if (parsed != null) {
+                                    filters.minQrbKm = parsed
+                                    if (filters.minQrbEnabled) onChanged()
+                                } else if (it.isEmpty()) {
+                                    filters.minQrbKm = 0.0
+                                    if (filters.minQrbEnabled) onChanged()
+                                }
+                            },
+                            modifier = Modifier.width(50.dp)
+                        )
                     }
-                },
-                modifier = Modifier.width(50.dp)
-            )
-            Text("± BW/2", style = MaterialTheme.typography.bodySmall)
+                }
+            }
 
-            Bearing.entries.forEach { bearing ->
-                FilterButton(bearing.name, on = filters.bearing == bearing) {
-                    filters.toggleBearing(bearing)
-                    onChanged()
+            // QTF checkbox + field
+            FilterGroup {
+                GroupSeparator()
+                CompactCheckbox(
+                    checked = filters.qtfEnabled,
+                    onCheckedChange = {
+                        filters.qtfEnabled = it
+                        onChanged()
+                    },
+                )
+                Text(strings.filterShowOnlyQtf, style = MaterialTheme.typography.bodySmall)
+                CompactTextField(
+                    value = if (filters.qtfDegrees.rem(1) == 0.0) filters.qtfDegrees.toInt().toString() else filters.qtfDegrees.toString(),
+                    onValueChange = {
+                        val parsed = it.toDoubleOrNull()
+                        if (parsed != null) {
+                            filters.qtfDegrees = parsed
+                            filters.bearing = null
+                            if (filters.qtfEnabled) onChanged()
+                        } else if (it.isEmpty()) {
+                            filters.qtfDegrees = 0.0
+                            filters.bearing = null
+                            if (filters.qtfEnabled) onChanged()
+                        }
+                    },
+                    modifier = Modifier.width(50.dp)
+                )
+                Text("± BW/2", style = MaterialTheme.typography.bodySmall)
+            }
+
+            // Bearings
+            FlowRow(
+                horizontalArrangement = Arrangement.spacedBy(4.dp),
+                verticalArrangement = Arrangement.spacedBy(1.dp),
+            ) {
+                Bearing.entries.forEach { bearing ->
+                    FilterButton(bearing.name, on = filters.bearing == bearing) {
+                        filters.toggleBearing(bearing)
+                        onChanged()
+                    }
                 }
             }
         }
@@ -235,6 +283,31 @@ private fun FilterButton(label: String, on: Boolean, isAccent: Boolean = false,
     }
 }
 
+/** Controls that belong together and move to the next line of a wrapping row as one. */
+@Composable
+private fun FilterGroup(content: @Composable () -> Unit) {
+    Row(
+        horizontalArrangement = Arrangement.spacedBy(4.dp),
+        verticalAlignment = Alignment.CenterVertically,
+    ) {
+        content()
+    }
+}
+
+/**
+ * The group divider for a wrapping row. A fixed height, because [VerticalSeparator] fills
+ * the row's intrinsic height, which a line of a flow row does not offer.
+ */
+@Composable
+private fun GroupSeparator() {
+    Box(
+        modifier = Modifier
+            .width(Density.HAIRLINE)
+            .height(18.dp)
+            .background(MaterialTheme.colorScheme.outline),
+    )
+}
+
 /** Thin vertical separator matching JavaFX's group dividers. */
 @Composable
 private fun VerticalSeparator() {

app-desktop/src/main/kotlin/kst4contest/view/compose/StationFilterState.kt

@@ -18,6 +18,7 @@ enum class StationFilter {
     NEW_BANDS,
     AIRSCOUT_NEXT_5_MIN,
     MAX_QRB,
+    MIN_QRB,
     QTF,
     SEARCH_TEXT,
     HIDE_INACTIVE,
@@ -33,6 +34,17 @@ enum class StationFilter {
     HIDE_WORKED_3,
 }
 
+/**
+ * What a QRB field of the filter bar makes of the text typed into it: a distance in km, or
+ * `null` when the text is none.
+ *
+ * `toDouble` alone also reads "NaN" and "Infinity", and a pasted "Infinity" as the minimum
+ * hid every station while "NaN" let every one through. A negative distance means nothing
+ * either. All of these are refused, so the field keeps its last valid value (#21).
+ */
+internal fun parseQrbKm(text: String): Double? =
+    text.toDoubleOrNull()?.takeIf { it.isFinite() && it >= 0.0 }
+
 /** The bands the "hide worked" row offers, under the labels the bar shows. */
 enum class WorkedBandFilter(val label: String, val filter: StationFilter, val modelBand: kst4contest.model.Band) {
     B_50("50", StationFilter.HIDE_WORKED_50, kst4contest.model.Band.B_50),
@@ -99,6 +111,16 @@ class StationFilterState {
     /** Only meaningful while [maxQrbEnabled]; a distance alone filters nothing. */
     var maxQrbKm: Double by mutableStateOf(0.0)
 
+    var minQrbEnabled: Boolean
+        get() = isOn(StationFilter.MIN_QRB)
+        set(value) = switch(StationFilter.MIN_QRB, value)
+
+    /**
+     * Only meaningful while [minQrbEnabled]. Exclusive: a station exactly this far away is
+     * hidden, so that "QRB > 300" and "QRB <= 300" split the list without overlap (#21).
+     */
+    var minQrbKm: Double by mutableStateOf(0.0)
+
     var qtfEnabled: Boolean
         get() = isOn(StationFilter.QTF)
         set(value) = switch(StationFilter.QTF, value)
@@ -130,6 +152,23 @@ class StationFilterState {
 
     fun isOn(filter: StationFilter): Boolean = switched[filter] == true
 
+    /**
+     * Whether a station [qrb] km away passes the distance filters that are switched on.
+     *
+     * Both on make a range: `min < qrb <= max`. A station without a known distance is
+     * hidden as soon as either is on — `null` is unknown, not zero, and an unknown distance
+     * can be in neither range.
+     */
+    fun acceptsQrb(qrb: Double?): Boolean {
+        val max = isOn(StationFilter.MAX_QRB)
+        val min = isOn(StationFilter.MIN_QRB)
+        if (!max && !min) return true
+        if (qrb == null) return false
+        if (max && qrb > maxQrbKm) return false
+        if (min && qrb <= minQrbKm) return false
+        return true
+    }
+
     fun setHideWorkedOn(band: WorkedBandFilter, hide: Boolean) = switch(band.filter, hide)
 
     fun isHideWorkedOn(band: WorkedBandFilter): Boolean = isOn(band.filter)

app-desktop/src/main/kotlin/kst4contest/view/compose/map/StationMapWindow.kt

@@ -129,7 +129,19 @@ object StationMapWindow {
             val antennaBeamWidthDeg = mainWindowState.prefs.stn_antennaBeamWidthDeg
             val maxQrbKm = mainWindowState.prefs.stn_maxQRBDefault
 
-            val markers by remember(mainWindowState.stations.rows, mainWindowState.stations.contentRevision, selectedMember, mainWindowState.activeBands) {
+            /*
+             * The markers are the stations the list shows, not all of them (#21): the
+             * JavaFX map took the sorted, filtered list (StationMapBridge.refreshNow), and
+             * the status line below already says "filtered view active". A selected
+             * station that a filter hides gets no marker either, as it did there.
+             */
+            val markers by remember(
+                mainWindowState.stations.rows,
+                mainWindowState.stations.rowFilter,
+                mainWindowState.stations.contentRevision,
+                selectedMember,
+                mainWindowState.activeBands,
+            ) {
                 derivedStateOf {
                     val builder = MapCallsignRawSnapshotBuilder()
                     val activeBands = mainWindowState.activeBands
@@ -140,7 +152,7 @@ object StationMapWindow {
                     }
 
                     builder.buildSnapshots(
-                        mainWindowState.stations.rows,
+                        mainWindowState.stations.visibleRows,
                         selectedMember,
                         bandSet
                     )
@@ -152,17 +164,29 @@ object StationMapWindow {
             // Read through updated state so a caller passing a new lambda is never served a stale one.
             val currentPathAnalysis by rememberUpdatedState(pathAnalysis)
 
-            LaunchedEffect(selectedMember) {
+            /*
+             * Whether the selected station has a marker. A filter can hide it (#21), and a
+             * station without a locator never has one; then there is nothing to analyse.
+             */
+            val selectedHasMarker = selectedMember != null &&
+                markers.any { it.callSignRaw() == selectedMember.callSignRaw }
+
+            LaunchedEffect(selectedMember, selectedHasMarker) {
                 if (selectedMember == null) {
                     pathAnalysisResult = null
                     return@LaunchedEffect
                 }
-                
+
+                val selectedSnapshot = markers.find { it.callSignRaw() == selectedMember.callSignRaw }
+                if (selectedSnapshot == null) {
+                    // No marker: no request, and no "Loading" for a station the map does not show.
+                    pathAnalysisResult = null
+                    return@LaunchedEffect
+                }
+
                 val analysis = currentPathAnalysis()
                 if (analysis != null) {
-                    val selectedSnapshot = markers.find { it.callSignRaw() == selectedMember.callSignRaw }
-                    
-                    if (selectedSnapshot != null && selectedSnapshot.hasUsablePosition()) {
+                    if (selectedSnapshot.hasUsablePosition()) {
                         /*
                          * Pan to the station and leave the zoom alone. The Leaflet map
                          * did exactly this (focusCallsignRaw) and touched the zoom only
@@ -183,8 +207,8 @@ object StationMapWindow {
 
                     pathAnalysisResult = PathAnalysisResult.loading(
                         prefs.stn_loginLocatorMainCat,
-                        selectedSnapshot?.locator6() ?: "",
-                        selectedSnapshot?.callSignRaw() ?: ""
+                        selectedSnapshot.locator6(),
+                        selectedSnapshot.callSignRaw()
                     )
                     
                     analysis.request(selectedMember, selectedSnapshot) { result ->