fix: keep zap/reaction card inner content on the card's tint

The embedded note and comment inside the lightning / nutzap / onchain-zap
and reaction activity cards were handed the parent feed / MultiSetCard
background state, so they drew black (the app background) or flashed the
new-note highlight instead of letting the card's orange (or like-tinted)
wash show through.

ActivityCardFrame now exposes a stable transparent background state to its
content for the inner note and comment to draw on; the hand-built onchain
card uses a matching local state. Nothing inside the card's layout changes
background from the feed anymore.

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01GEUsgVr5e31qYeqNSjgHif

amethyst/src/main/java/com/vitorpamplona/amethyst/ui/note/types/ActivityCard.kt

@@ -36,6 +36,9 @@ import androidx.compose.foundation.shape.RoundedCornerShape
 import androidx.compose.material3.MaterialTheme
 import androidx.compose.material3.Text
 import androidx.compose.runtime.Composable
+import androidx.compose.runtime.MutableState
+import androidx.compose.runtime.mutableStateOf
+import androidx.compose.runtime.remember
 import androidx.compose.ui.Alignment
 import androidx.compose.ui.Modifier
 import androidx.compose.ui.draw.clip
@@ -57,12 +60,20 @@ val LikeTint = Color(0xFFCA395F)
  * Gradient card frame shared by the reaction / zap / nutzap / onchain-zap
  * renderings, mirroring the onchain card's look: rounded corners and a soft
  * top-to-bottom wash of the kind's tint.
+ *
+ * The content lambda receives a stable [transparentCardBackground] state to hand
+ * down to the embedded note and comment: everything inside the card sits on the
+ * orange (or like-tinted) wash, so inner content must draw transparent and let
+ * that wash show through. Passing the parent feed / MultiSetCard background here
+ * instead would paint the inner note black (the app background) or flash it with
+ * the new-note highlight, breaking the card's solid tint.
  */
 @Composable
 fun ActivityCardFrame(
     tint: Color,
-    content: @Composable ColumnScope.() -> Unit,
+    content: @Composable ColumnScope.(transparentCardBackground: MutableState<Color>) -> Unit,
 ) {
+    val transparentCardBackground = remember { mutableStateOf<Color>(Color.Transparent) }
     Box(
         modifier =
             Modifier
@@ -78,7 +89,9 @@ fun ActivityCardFrame(
                     ),
                 ).padding(horizontal = 12.dp, vertical = 10.dp),
     ) {
-        Column(verticalArrangement = Arrangement.spacedBy(8.dp), content = content)
+        Column(verticalArrangement = Arrangement.spacedBy(8.dp)) {
+            content(transparentCardBackground)
+        }
     }
 }
 

amethyst/src/main/java/com/vitorpamplona/amethyst/ui/note/types/Nutzap.kt

@@ -61,7 +61,7 @@ fun RenderNutzap(
     val recipientKey = nutzapEvent.linkedPubKeys().firstOrNull()
     val orange = MaterialTheme.colorScheme.bitcoinColor
 
-    ActivityCardFrame(orange) {
+    ActivityCardFrame(orange) { cardBackground ->
         ActivityHeaderRow(
             tint = orange,
             pillLabel = "CASHU",
@@ -89,12 +89,12 @@ fun RenderNutzap(
                 },
         )
 
-        RenderZappedPost(note, quotesLeft, backgroundColor, accountViewModel, nav)
+        RenderZappedPost(note, quotesLeft, cardBackground, accountViewModel, nav)
 
         ActivityAmountRow(showAmount(BigDecimal(nutzapEvent.claimedSatsTotal())), orange)
 
         nutzapEvent.content.ifBlank { null }?.let {
-            CrossfadeToDisplayComment(it, backgroundColor, nav, accountViewModel)
+            CrossfadeToDisplayComment(it, cardBackground, nav, accountViewModel)
         }
     }
 }

amethyst/src/main/java/com/vitorpamplona/amethyst/ui/note/types/OnchainZapEvent.kt

@@ -105,6 +105,12 @@ fun RenderOnchainZap(
 
     val orange = MaterialTheme.colorScheme.bitcoinColor
 
+    // The embedded note sits on the orange wash, so it must draw transparent and
+    // let that show through. Handing it the parent feed / MultiSetCard background
+    // instead would paint it black (the app background) or flash it with the
+    // new-note highlight, breaking the card's solid tint.
+    val cardBackground = remember { mutableStateOf<Color>(Color.Transparent) }
+
     // Async chain lookup so we can show a real "Confirmed at block N" or
     // "In mempool…" pill rather than a sender-claimed status. Null = backend
     // not configured, or fetch failed — we just show the sender-claimed sats
@@ -143,7 +149,7 @@ fun RenderOnchainZap(
                 nav = nav,
             )
 
-            RenderZappedPost(note, quotesLeft, backgroundColor, accountViewModel, nav)
+            RenderZappedPost(note, quotesLeft, cardBackground, accountViewModel, nav)
 
             AmountRow(sats = sats, orange = orange)
 

amethyst/src/main/java/com/vitorpamplona/amethyst/ui/note/types/Reaction.kt

@@ -50,7 +50,7 @@ fun RenderReaction(
 ) {
     val reactionType = note.event?.content ?: ""
 
-    ActivityCardFrame(LikeTint) {
+    ActivityCardFrame(LikeTint) { cardBackground ->
         ActivityHeaderRow(
             tint = LikeTint,
             pillLabel = "REACTION",
@@ -77,6 +77,6 @@ fun RenderReaction(
                 },
         )
 
-        RenderZappedPost(note, quotesLeft, backgroundColor, accountViewModel, nav)
+        RenderZappedPost(note, quotesLeft, cardBackground, accountViewModel, nav)
     }
 }

amethyst/src/main/java/com/vitorpamplona/amethyst/ui/note/types/ZapEvent.kt

@@ -127,7 +127,7 @@ fun RenderLnZapCard(
 ) {
     val orange = MaterialTheme.colorScheme.bitcoinColor
 
-    ActivityCardFrame(orange) {
+    ActivityCardFrame(orange) { cardBackground ->
         ActivityHeaderRow(
             tint = orange,
             pillLabel = "LIGHTNING",
@@ -150,12 +150,12 @@ fun RenderLnZapCard(
                 },
         )
 
-        RenderZappedPost(note, quotesLeft, backgroundColor, accountViewModel, nav)
+        RenderZappedPost(note, quotesLeft, cardBackground, accountViewModel, nav)
 
         card.amount?.let { ActivityAmountRow(it, orange) }
 
         card.comment?.let {
-            CrossfadeToDisplayComment(it, backgroundColor, nav, accountViewModel)
+            CrossfadeToDisplayComment(it, cardBackground, nav, accountViewModel)
         }
     }
 }