From 7cf5286bfbc2c2085083f78874d586fa1f5f6c02 Mon Sep 17 00:00:00 2001
From: callebtc <93376500+callebtc@users.noreply.github.com>
Date: Wed, 26 Aug 2026 17:28:17 +0200
Subject: [PATCH] Fix slow Wear scroll intent detection

---
 .../java/com/bitchat/watch/ui/ChatScaffold.kt | 60 ++++++++++------
 .../bitchat/watch/ui/ChatAutoScrollTest.kt    | 72 ++++++++++++++++---
 2 files changed, 104 insertions(+), 28 deletions(-)

diff --git a/wear/src/main/java/com/bitchat/watch/ui/ChatScaffold.kt b/wear/src/main/java/com/bitchat/watch/ui/ChatScaffold.kt
index 15b18436..f304446e 100644
--- a/wear/src/main/java/com/bitchat/watch/ui/ChatScaffold.kt
+++ b/wear/src/main/java/com/bitchat/watch/ui/ChatScaffold.kt
@@ -50,6 +50,7 @@ import com.bitchat.watch.ui.theme.ChatVisualTokens
 import com.bitchat.watch.ui.theme.LocalBitchatPalette
 import kotlinx.coroutines.flow.Flow
 import kotlinx.coroutines.flow.first
+import kotlin.math.sign
 
 /**
  * The shared chat body for global chat and DM threads, following the classic messenger
@@ -95,6 +96,7 @@ fun ChatScaffold(
     val controlsVisible = remember { mutableStateOf(true) }
     LaunchedEffect(columnState) {
         var lastPosition = -1
+        var scrollIntent = ChatScrollIntentState()
         snapshotFlow {
             val first = columnState.layoutInfo.visibleItems.firstOrNull()
             ChatScrollSnapshot(
@@ -103,21 +105,13 @@ fun ChatScaffold(
                 position = (first?.index ?: 0) * 100_000 + (first?.offset ?: 0)
             )
         }.collect { snapshot ->
-            followNewest = updatedFollowNewest(
-                current = followNewest,
+            scrollIntent = updatedChatScrollIntent(
+                current = scrollIntent,
                 snapshot = snapshot,
                 previousPosition = lastPosition
             )
-            if (!snapshot.canScrollForward) {
-                controlsVisible.value = true
-            } else if (lastPosition >= 0) {
-                when {
-                    snapshot.position > lastPosition + CHAT_SCROLL_DIRECTION_THRESHOLD_PX ->
-                        controlsVisible.value = true
-                    snapshot.position < lastPosition - CHAT_SCROLL_DIRECTION_THRESHOLD_PX ->
-                        controlsVisible.value = false
-                }
-            }
+            followNewest = scrollIntent.followsNewest
+            controlsVisible.value = scrollIntent.controlsVisible
             lastPosition = snapshot.position
         }
     }
@@ -173,16 +167,42 @@ internal data class ChatScrollSnapshot(
     val position: Int
 )
 
-internal fun updatedFollowNewest(
-    current: Boolean,
+internal data class ChatScrollIntentState(
+    val followsNewest: Boolean = true,
+    val controlsVisible: Boolean = true,
+    val accumulatedDeltaPx: Int = 0
+)
+
+internal fun updatedChatScrollIntent(
+    current: ChatScrollIntentState,
     snapshot: ChatScrollSnapshot,
     previousPosition: Int
-): Boolean = when {
-    !snapshot.canScrollForward -> true
-    snapshot.isScrollInProgress &&
-        previousPosition >= 0 &&
-        snapshot.position < previousPosition - CHAT_SCROLL_DIRECTION_THRESHOLD_PX -> false
-    else -> current
+): ChatScrollIntentState {
+    if (!snapshot.canScrollForward) return ChatScrollIntentState()
+    if (!snapshot.isScrollInProgress || previousPosition < 0) return current
+
+    val delta = snapshot.position - previousPosition
+    val accumulatedDelta = when {
+        delta == 0 -> current.accumulatedDeltaPx
+        current.accumulatedDeltaPx == 0 ||
+            current.accumulatedDeltaPx.sign == delta.sign ->
+            current.accumulatedDeltaPx + delta
+        else -> delta
+    }
+    val movedAway = accumulatedDelta <= -CHAT_SCROLL_DIRECTION_THRESHOLD_PX
+    val movedTowardNewest = accumulatedDelta >= CHAT_SCROLL_DIRECTION_THRESHOLD_PX
+
+    return current.copy(
+        followsNewest = current.followsNewest && !movedAway,
+        controlsVisible = when {
+            movedAway -> false
+            movedTowardNewest -> true
+            else -> current.controlsVisible
+        },
+        // Keep sub-threshold movement across discrete rotary events. Once intent is clear,
+        // start a fresh accumulator so reversing direction gets the same threshold treatment.
+        accumulatedDeltaPx = if (movedAway || movedTowardNewest) 0 else accumulatedDelta
+    )
 }
 
 internal suspend fun scrollToNewestAfterItemsMeasured(
diff --git a/wear/src/test/java/com/bitchat/watch/ui/ChatAutoScrollTest.kt b/wear/src/test/java/com/bitchat/watch/ui/ChatAutoScrollTest.kt
index ad7c687a..7b2d13b9 100644
--- a/wear/src/test/java/com/bitchat/watch/ui/ChatAutoScrollTest.kt
+++ b/wear/src/test/java/com/bitchat/watch/ui/ChatAutoScrollTest.kt
@@ -12,8 +12,8 @@ class ChatAutoScrollTest {
 
     @Test
     fun `new scroll range from appended message keeps follow intent`() {
-        val updated = updatedFollowNewest(
-            current = true,
+        val updated = updatedChatScrollIntent(
+            current = ChatScrollIntentState(),
             snapshot = ChatScrollSnapshot(
                 canScrollForward = true,
                 isScrollInProgress = false,
@@ -22,13 +22,13 @@ class ChatAutoScrollTest {
             previousPosition = 100
         )
 
-        assertEquals(true, updated)
+        assertEquals(ChatScrollIntentState(), updated)
     }
 
     @Test
     fun `user scroll away disables follow until list reaches newest again`() {
-        val browsingHistory = updatedFollowNewest(
-            current = true,
+        val browsingHistory = updatedChatScrollIntent(
+            current = ChatScrollIntentState(),
             snapshot = ChatScrollSnapshot(
                 canScrollForward = true,
                 isScrollInProgress = true,
@@ -36,9 +36,10 @@ class ChatAutoScrollTest {
             ),
             previousPosition = 100
         )
-        assertFalse(browsingHistory)
+        assertFalse(browsingHistory.followsNewest)
+        assertFalse(browsingHistory.controlsVisible)
 
-        val dockedAgain = updatedFollowNewest(
+        val dockedAgain = updatedChatScrollIntent(
             current = browsingHistory,
             snapshot = ChatScrollSnapshot(
                 canScrollForward = false,
@@ -47,7 +48,62 @@ class ChatAutoScrollTest {
             ),
             previousPosition = 60
         )
-        assertEquals(true, dockedAgain)
+        assertEquals(ChatScrollIntentState(), dockedAgain)
+    }
+
+    @Test
+    fun `slow scroll away accumulates intent across sub-threshold updates`() {
+        var state = ChatScrollIntentState()
+        var previousPosition = 100
+
+        listOf(94, 88, 82, 76).forEach { position ->
+            state = updatedChatScrollIntent(
+                current = state,
+                snapshot = ChatScrollSnapshot(
+                    canScrollForward = true,
+                    isScrollInProgress = true,
+                    position = position
+                ),
+                previousPosition = previousPosition
+            )
+            previousPosition = position
+            state = updatedChatScrollIntent(
+                current = state,
+                snapshot = ChatScrollSnapshot(
+                    canScrollForward = true,
+                    isScrollInProgress = false,
+                    position = position
+                ),
+                previousPosition = previousPosition
+            )
+        }
+
+        assertFalse(state.followsNewest)
+        assertFalse(state.controlsVisible)
+        assertEquals(0, state.accumulatedDeltaPx)
+    }
+
+    @Test
+    fun `slow scroll toward newest reveals controls without restoring follow early`() {
+        var state = ChatScrollIntentState(followsNewest = false, controlsVisible = false)
+        var previousPosition = 60
+
+        listOf(66, 72, 78, 84).forEach { position ->
+            state = updatedChatScrollIntent(
+                current = state,
+                snapshot = ChatScrollSnapshot(
+                    canScrollForward = true,
+                    isScrollInProgress = true,
+                    position = position
+                ),
+                previousPosition = previousPosition
+            )
+            previousPosition = position
+        }
+
+        assertFalse(state.followsNewest)
+        assertEquals(true, state.controlsVisible)
+        assertEquals(0, state.accumulatedDeltaPx)
     }
 
     @Test