feat(mobile): show message timestamps in chat bubbles

- Add relative timestamp display below each message bubble
- Show time only (HH:mm) for today's messages
- Show day + time (EEE HH:mm) for messages within 7 days
- Show date + time (d MMM HH:mm) for older messages
- Subtle styling: small font, reduced opacity
- Implemented for both Android (Compose) and iOS/macOS (SwiftUI)

apps/android/app/src/main/java/com/clawdbot/android/ui/chat/ChatMessageViews.kt

@@ -38,32 +38,49 @@ import com.clawdbot.android.tools.ToolDisplayRegistry
 import kotlinx.coroutines.Dispatchers
 import kotlinx.coroutines.withContext
 import androidx.compose.ui.platform.LocalContext
+import java.text.SimpleDateFormat
+import java.util.Date
+import java.util.Locale
 
 @Composable
 fun ChatMessageBubble(message: ChatMessage) {
   val isUser = message.role.lowercase() == "user"
+  val timestampText = remember(message.timestampMs) { formatTimestamp(message.timestampMs) }
 
-  Row(
+  Column(
     modifier = Modifier.fillMaxWidth(),
-    horizontalArrangement = if (isUser) Arrangement.End else Arrangement.Start,
+    horizontalAlignment = if (isUser) Alignment.End else Alignment.Start,
   ) {
-    Surface(
-      shape = RoundedCornerShape(16.dp),
-      tonalElevation = 0.dp,
-      shadowElevation = 0.dp,
-      color = Color.Transparent,
-      modifier = Modifier.fillMaxWidth(0.92f),
+    Row(
+      modifier = Modifier.fillMaxWidth(),
+      horizontalArrangement = if (isUser) Arrangement.End else Arrangement.Start,
     ) {
-      Box(
-        modifier =
-          Modifier
-            .background(bubbleBackground(isUser))
-            .padding(horizontal = 12.dp, vertical = 10.dp),
+      Surface(
+        shape = RoundedCornerShape(16.dp),
+        tonalElevation = 0.dp,
+        shadowElevation = 0.dp,
+        color = Color.Transparent,
+        modifier = Modifier.fillMaxWidth(0.92f),
       ) {
-        val textColor = textColorOverBubble(isUser)
-        ChatMessageBody(content = message.content, textColor = textColor)
+        Box(
+          modifier =
+            Modifier
+              .background(bubbleBackground(isUser))
+              .padding(horizontal = 12.dp, vertical = 10.dp),
+        ) {
+          val textColor = textColorOverBubble(isUser)
+          ChatMessageBody(content = message.content, textColor = textColor)
+        }
       }
     }
+    if (timestampText != null) {
+      Text(
+        text = timestampText,
+        style = MaterialTheme.typography.labelSmall,
+        color = MaterialTheme.colorScheme.onSurfaceVariant.copy(alpha = 0.6f),
+        modifier = Modifier.padding(horizontal = 4.dp, vertical = 2.dp),
+      )
+    }
   }
 }
 
@@ -250,3 +267,35 @@ fun ChatCodeBlock(code: String, language: String?) {
     )
   }
 }
+
+private fun formatTimestamp(timestampMs: Long?): String? {
+  if (timestampMs == null || timestampMs <= 0) return null
+  val now = System.currentTimeMillis()
+  val diff = now - timestampMs
+  val date = Date(timestampMs)
+
+  // If today, show only time (e.g., "14:32")
+  // If yesterday or within 7 days, show day + time (e.g., "Mon 14:32")
+  // Otherwise, show date + time (e.g., "15 Jan 14:32")
+  val dayMs = 24 * 60 * 60 * 1000L
+  val weekMs = 7 * dayMs
+
+  return when {
+    diff < dayMs && isSameDay(timestampMs, now) -> {
+      SimpleDateFormat("HH:mm", Locale.getDefault()).format(date)
+    }
+    diff < weekMs -> {
+      SimpleDateFormat("EEE HH:mm", Locale.getDefault()).format(date)
+    }
+    else -> {
+      SimpleDateFormat("d MMM HH:mm", Locale.getDefault()).format(date)
+    }
+  }
+}
+
+private fun isSameDay(ts1: Long, ts2: Long): Boolean {
+  val cal1 = java.util.Calendar.getInstance().apply { timeInMillis = ts1 }
+  val cal2 = java.util.Calendar.getInstance().apply { timeInMillis = ts2 }
+  return cal1.get(java.util.Calendar.YEAR) == cal2.get(java.util.Calendar.YEAR) &&
+    cal1.get(java.util.Calendar.DAY_OF_YEAR) == cal2.get(java.util.Calendar.DAY_OF_YEAR)
+}

apps/shared/ClawdbotKit/Sources/ClawdbotChatUI/ChatMessageViews.swift

@@ -141,18 +141,47 @@ struct ChatMessageBubble: View {
     let userAccent: Color?
 
     var body: some View {
-        ChatMessageBody(
-            message: self.message,
-            isUser: self.isUser,
-            style: self.style,
-            markdownVariant: self.markdownVariant,
-            userAccent: self.userAccent)
-            .frame(maxWidth: ChatUIConstants.bubbleMaxWidth, alignment: self.isUser ? .trailing : .leading)
-            .frame(maxWidth: .infinity, alignment: self.isUser ? .trailing : .leading)
-            .padding(.horizontal, 2)
+        VStack(alignment: self.isUser ? .trailing : .leading, spacing: 2) {
+            ChatMessageBody(
+                message: self.message,
+                isUser: self.isUser,
+                style: self.style,
+                markdownVariant: self.markdownVariant,
+                userAccent: self.userAccent)
+                .frame(maxWidth: ChatUIConstants.bubbleMaxWidth, alignment: self.isUser ? .trailing : .leading)
+            if let timestampText = self.formattedTimestamp {
+                Text(timestampText)
+                    .font(.caption2)
+                    .foregroundStyle(.secondary.opacity(0.6))
+                    .padding(.horizontal, 4)
+            }
+        }
+        .frame(maxWidth: .infinity, alignment: self.isUser ? .trailing : .leading)
+        .padding(.horizontal, 2)
     }
 
     private var isUser: Bool { self.message.role.lowercased() == "user" }
+
+    private var formattedTimestamp: String? {
+        guard let ts = self.message.timestamp, ts > 0 else { return nil }
+        let date = Date(timeIntervalSince1970: ts / 1000.0)
+        let now = Date()
+        let calendar = Calendar.current
+        let dayDiff = calendar.dateComponents([.day], from: date, to: now).day ?? 0
+
+        let formatter = DateFormatter()
+        formatter.locale = Locale.current
+
+        if calendar.isDateInToday(date) {
+            formatter.dateFormat = "HH:mm"
+        } else if dayDiff < 7 {
+            formatter.dateFormat = "EEE HH:mm"
+        } else {
+            formatter.dateFormat = "d MMM HH:mm"
+        }
+
+        return formatter.string(from: date)
+    }
 }
 
 @MainActor