fix(chat-messages): store current scroll height

Author: robertwilde

playwright/snapshots/static.spec.ts-snapshots/si-chat-messages--si-chat-container-element-examples-chromium-dark-linux.png

@@ -55,6 +55,7 @@ export class SiChatContainerComponent implements AfterContentInit, OnDestroy {
   private scrollDebounceMs = 7; // ~144fps
   private resizeObserver: ResizeObserver | undefined;
   private contentObserver: MutationObserver | undefined;
+  private lastScrollHeight = 0;
 
   /**
    * The color variant to apply to the container.
@@ -145,9 +146,15 @@ export class SiChatContainerComponent implements AfterContentInit, OnDestroy {
     }
 
     this.resizeObserver = new ResizeObserver(() => {
-      this.debouncedScrollToBottom();
+      const element = container.nativeElement;
+      const currentScrollHeight = element.scrollHeight;
+      if (currentScrollHeight > this.lastScrollHeight) {
+        this.debouncedScrollToBottom();
+      }
+      this.lastScrollHeight = currentScrollHeight;
     });
 
+    this.lastScrollHeight = container.nativeElement.scrollHeight;
     this.resizeObserver.observe(container.nativeElement);
   }
 

playwright/snapshots/static.spec.ts-snapshots/si-chat-messages--si-chat-container-element-examples-chromium-light-linux.png

@@ -1,5 +1,5 @@
 <div class="si-layout-fixed-height w-100 h-100">
-  <si-chat-container #chatContainer colorVariant="base-0" noAutoScroll>
+  <si-chat-container #chatContainer colorVariant="base-0">
     @for (message of messages(); track message) {
       @if (message.type === 'user') {
         <si-user-message