feat(desktop): blur NIP-36 content-warning notes with tap-to-reveal

Generalize SpamCheckedNoteRender to also gate sensitive content: a note tagged
content-warning / NSFW renders behind a collapsed scrim (reason + 'Show') unless
the account opted into 'always show sensitive content'. Reuses the same
per-note rememberSaveable reveal + forceReveal as the spam collapse.

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

desktopApp/src/jvmMain/kotlin/com/vitorpamplona/amethyst/desktop/ui/note/SpamCheckedNoteRender.kt

@@ -20,6 +20,15 @@
  */
 package com.vitorpamplona.amethyst.desktop.ui.note
 
+import androidx.compose.foundation.layout.Column
+import androidx.compose.foundation.layout.Row
+import androidx.compose.foundation.layout.fillMaxWidth
+import androidx.compose.foundation.layout.padding
+import androidx.compose.foundation.shape.RoundedCornerShape
+import androidx.compose.material3.MaterialTheme
+import androidx.compose.material3.Surface
+import androidx.compose.material3.Text
+import androidx.compose.material3.TextButton
 import androidx.compose.runtime.Composable
 import androidx.compose.runtime.collectAsState
 import androidx.compose.runtime.getValue
@@ -27,6 +36,9 @@ import androidx.compose.runtime.mutableStateOf
 import androidx.compose.runtime.remember
 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.unit.dp
 import com.vitorpamplona.amethyst.commons.model.Note
 import com.vitorpamplona.amethyst.commons.moderation.HashtagSpamCheck
 import com.vitorpamplona.amethyst.commons.moderation.LocalHashtagSpamSettings
@@ -34,8 +46,12 @@ import com.vitorpamplona.amethyst.commons.moderation.LocalSpamExemptKeys
 import com.vitorpamplona.amethyst.commons.moderation.displayedEvent
 import com.vitorpamplona.amethyst.commons.ui.note.CollapsedSpamNote
 import com.vitorpamplona.amethyst.desktop.cache.DesktopLocalCache
+import com.vitorpamplona.amethyst.desktop.model.LocalDesktopIAccount
 import com.vitorpamplona.quartz.nip01Core.core.Event
 import com.vitorpamplona.quartz.nip01Core.tags.hashtags.countHashtags
+import com.vitorpamplona.quartz.nip36SensitiveContent.contentWarningReason
+import com.vitorpamplona.quartz.nip36SensitiveContent.isSensitiveOrNSFW
+import kotlinx.coroutines.flow.MutableStateFlow
 
 /**
  * Wraps a note render in the hashtag-spam check.
@@ -80,24 +96,73 @@ fun SpamCheckedNoteRender(
             )
         }
 
+    // NIP-36 content warning: blur sensitive content unless the account opted
+    // into "always show sensitive content".
+    val account = LocalDesktopIAccount.current
+    val showSensitiveFlow = remember(account) { account?.showSensitiveContentSetting ?: MutableStateFlow(null) }
+    val showSensitive by showSensitiveFlow.collectAsState()
+    val isSensitive = remember(noteIdHex, displayedEvent) { displayedEvent?.isSensitiveOrNSFW() == true }
+
     var revealed by rememberSaveable(noteIdHex) { mutableStateOf(false) }
 
-    if (!forceReveal && isSpam && !revealed && displayedEvent != null) {
-        val authorPubkey = displayedEvent.pubKey
-        val author = localCache?.getUserIfExists(authorPubkey)
-        val displayName = author?.toBestDisplayName() ?: authorPubkey.take(8)
-        val avatarUrl = author?.profilePicture()
-        val hashtagCount = displayedEvent.tags.countHashtags()
-        CollapsedSpamNote(
-            authorPubkeyHex = authorPubkey,
-            authorDisplayName = displayName,
-            authorAvatarUrl = avatarUrl,
-            hashtagCount = hashtagCount,
-            threshold = threshold,
-            onReveal = { revealed = true },
-        )
-    } else {
-        normal()
+    when {
+        forceReveal || revealed -> normal()
+        isSpam && displayedEvent != null -> {
+            val authorPubkey = displayedEvent.pubKey
+            val author = localCache?.getUserIfExists(authorPubkey)
+            val displayName = author?.toBestDisplayName() ?: authorPubkey.take(8)
+            val avatarUrl = author?.profilePicture()
+            val hashtagCount = displayedEvent.tags.countHashtags()
+            CollapsedSpamNote(
+                authorPubkeyHex = authorPubkey,
+                authorDisplayName = displayName,
+                authorAvatarUrl = avatarUrl,
+                hashtagCount = hashtagCount,
+                threshold = threshold,
+                onReveal = { revealed = true },
+            )
+        }
+        isSensitive && showSensitive != true && displayedEvent != null -> {
+            CollapsedContentWarning(
+                reason = displayedEvent.contentWarningReason(),
+                onReveal = { revealed = true },
+            )
+        }
+        else -> normal()
+    }
+}
+
+/**
+ * Collapsed placeholder for a NIP-36 content-warning note. Mirrors the
+ * spam-collapse reveal affordance: the body stays hidden behind a scrim with the
+ * warning reason until the user taps "Show".
+ */
+@Composable
+private fun CollapsedContentWarning(
+    reason: String?,
+    onReveal: () -> Unit,
+) {
+    Surface(
+        shape = RoundedCornerShape(8.dp),
+        color = MaterialTheme.colorScheme.surfaceVariant,
+        modifier = Modifier.fillMaxWidth().padding(vertical = 4.dp),
+    ) {
+        Row(
+            verticalAlignment = Alignment.CenterVertically,
+            modifier = Modifier.fillMaxWidth().padding(12.dp),
+        ) {
+            Column(modifier = Modifier.weight(1f)) {
+                Text("Sensitive content", style = MaterialTheme.typography.titleSmall)
+                if (!reason.isNullOrBlank()) {
+                    Text(
+                        reason,
+                        style = MaterialTheme.typography.bodySmall,
+                        color = MaterialTheme.colorScheme.onSurfaceVariant,
+                    )
+                }
+            }
+            TextButton(onClick = onReveal) { Text("Show") }
+        }
     }
 }