Ensure unique timestamps for chat messages to prevent collisions and fix date formatting in chat-box UI.

backend/src/main/java/com/alttd/altitudeweb/controllers/chat/ChatMessage.java

@@ -2,6 +2,7 @@ package com.alttd.altitudeweb.controllers.chat;
 
 import lombok.Builder;
 import lombok.Getter;
+import lombok.Setter;
 
 import java.time.Instant;
 import java.util.UUID;
@@ -11,7 +12,8 @@ import java.util.UUID;
 public class ChatMessage {
 
     private final UUID uuid;
-    private final Instant timestamp;
+    @Setter
+    private Instant timestamp;
     private final String server;
     //TODO [Stijn] [2026-07-18]: Handle channel types
     //private final String channel;

backend/src/main/java/com/alttd/altitudeweb/controllers/chat/ChatMessageMapper.java

@@ -4,16 +4,18 @@ import com.alttd.altitudeweb.database.chat.ChatLogDao;
 import com.alttd.altitudeweb.model.ChatMessageDto;
 import com.fasterxml.jackson.core.JsonProcessingException;
 import com.fasterxml.jackson.databind.ObjectMapper;
+import com.fasterxml.jackson.databind.SerializationFeature;
 import com.fasterxml.jackson.datatype.jsr310.JavaTimeModule;
 import lombok.experimental.UtilityClass;
 
-import java.time.Instant;
 import java.util.UUID;
 
 @UtilityClass
 public class ChatMessageMapper {
     private static final ObjectMapper OBJECT_MAPPER = new ObjectMapper()
-            .registerModule(new JavaTimeModule());
+            .registerModule(new JavaTimeModule())
+            .enable(SerializationFeature.WRITE_DATES_AS_TIMESTAMPS)
+            .disable(SerializationFeature.WRITE_DATE_TIMESTAMPS_AS_NANOSECONDS);
 
     public ChatMessage fromDto(ChatMessageDto dto) {
         return ChatMessage.builder()

backend/src/main/java/com/alttd/altitudeweb/services/chat/ChatService.java

@@ -30,6 +30,7 @@ public class ChatService {
     private String[] allowedServers;
     private final NavigableMap<Instant, ChatMessage> chatMessages = new TreeMap<>();
     private final EventPublisher eventPublisher;
+    private long lastMillis = 0;
 
     @Scheduled(cron = "0 * * * * *")
     public void clearOldMessages() {
@@ -50,7 +51,8 @@ public class ChatService {
                     try {
                         sqlSession.getMapper(ChatLogMapper.class)
                                 .getChatLogs(Instant.now().minus(Duration.ofHours(1)).toEpochMilli())
-                                .stream().map(ChatMessageMapper::fromDao)
+                                .stream()
+                                .map(ChatMessageMapper::fromDao)
                                 .forEach(this::putChatMessage);
                     } catch (Exception e) {
                         log.error("Failed to load history count", e);
@@ -58,7 +60,19 @@ public class ChatService {
                 });
     }
 
+    private synchronized void setUniqueTimestamp(ChatMessage chatMessage) {
+        long timestamp = chatMessage.getTimestamp().toEpochMilli();
+        if (timestamp == lastMillis) {
+            timestamp += 1;
+        } else {
+            return;
+        }
+        lastMillis = timestamp;
+        chatMessage.setTimestamp(Instant.ofEpochMilli(timestamp));
+    }
+
     private void putChatMessage(ChatMessage chatMessage) {
+        setUniqueTimestamp(chatMessage);
         chatMessages.put(chatMessage.getTimestamp(), chatMessage);
     }
 

frontend/src/app/pages/altitude/chat/components/chat/chat-box.component.html

@@ -2,7 +2,7 @@
   @for (message of messages(); track message.timestamp) {
     <p class="message">
       <span class="date-time" [class.blocked]="!message.notBlocked">
-        [{{ message.timestamp * 1000 | date: 'mediumTime' }}]
+        [{{ message.timestamp | date: 'mediumTime' }}]
       </span>
       <mini-message [node]="message.messageJson"></mini-message>
     </p>