Fix track detail sheet expansion; fix tack detection sensitivity

Sheet: set isDraggable=false so scrolling the event list doesn't push
the sheet up over the map. Top 50% stays map, bottom 50% stays list.

Tack detector: replaced 5-index skip (~5 s at 1 Hz) with a 45-second
timestamp gap. Also tightened STABILITY_MAX from 30° to 20° to reduce
false positives from GPS heading noise.

https://claude.ai/code/session_01YUbuZNDAoLea4cf9UGQ9qn

2 files changed, 9 insertions, 8 deletions

diff --git a/android-app/app/src/main/kotlin/org/terst/nav/track/TackDetector.kt b/android-app/app/src/main/kotlin/org/terst/nav/track/TackDetector.kt
index 6616acf..3c3385c 100644
--- a/android-app/app/src/main/kotlin/org/terst/nav/track/TackDetector.kt
+++ b/android-app/app/src/main/kotlin/org/terst/nav/track/TackDetector.kt
@@ -3,20 +3,20 @@ package org.terst.nav.track
 import kotlin.math.abs
 
 object TackDetector {
-    private const val HALF_WIN = 2
-    private const val MIN_DELTA = 60.0
-    private const val MAX_DELTA = 140.0
-    private const val SKIP_AFTER = 5
-    private const val STABILITY_MAX = 30.0
+    private const val HALF_WIN      = 2
+    private const val MIN_DELTA     = 60.0
+    private const val MAX_DELTA     = 140.0
+    private const val STABILITY_MAX = 20.0
+    private const val MIN_GAP_MS    = 45_000L   // 45 s minimum between tacks
 
     fun detectTacks(points: List<TrackPoint>): List<TackEvent> {
         if (points.size < 2 * HALF_WIN + 1) return emptyList()
 
         val results = mutableListOf<TackEvent>()
-        var nextCandidate = 0
+        var lastTackMs = Long.MIN_VALUE
 
         for (i in HALF_WIN until points.size - HALF_WIN) {
-            if (i < nextCandidate) continue
+            if (points[i].timestampMs - lastTackMs < MIN_GAP_MS) continue
 
             val spreadBefore = abs(angleDiff(points[i - 2].cogDeg, points[i - 1].cogDeg))
             val spreadAfter  = abs(angleDiff(points[i + 1].cogDeg, points[i + 2].cogDeg))
@@ -28,7 +28,7 @@ object TackDetector {
 
             if (delta in MIN_DELTA..MAX_DELTA) {
                 results += TackEvent(i, points[i].lat, points[i].lon, cogBefore, cogAfter)
-                nextCandidate = i + SKIP_AFTER
+                lastTackMs = points[i].timestampMs
             }
         }
         return results
diff --git a/android-app/app/src/main/kotlin/org/terst/nav/track/TrackDetailSheet.kt b/android-app/app/src/main/kotlin/org/terst/nav/track/TrackDetailSheet.kt
index 627ce89..98205fd 100644
--- a/android-app/app/src/main/kotlin/org/terst/nav/track/TrackDetailSheet.kt
+++ b/android-app/app/src/main/kotlin/org/terst/nav/track/TrackDetailSheet.kt
@@ -75,6 +75,7 @@ class TrackDetailSheet : BottomSheetDialogFragment() {
             isFitToContents = false
             halfExpandedRatio = 0.5f
             skipCollapsed = true
+            isDraggable = false
             state = BottomSheetBehavior.STATE_HALF_EXPANDED
         }
         dialog?.window?.setDimAmount(0.2f)