diff --git a/js/global_scope_js.js b/js/global_scope_js.js
index e808c473..29d2d8bd 100644
--- a/js/global_scope_js.js
+++ b/js/global_scope_js.js
@@ -31,13 +31,13 @@ function removeLastClick() {
 }
 
 function handleMorphdomUpdate(text) {
-  // Track closed blocks
-  const closedBlocks = new Set();
+  // Track open blocks
+  const openBlocks = new Set();
   document.querySelectorAll(".thinking-block").forEach(block => {
     const blockId = block.getAttribute("data-block-id");
-    // If block exists and is not open, add to closed set
-    if (blockId && !block.hasAttribute("open")) {
-      closedBlocks.add(blockId);
+    // If block exists and is open, add to open set
+    if (blockId && block.hasAttribute("open")) {
+      openBlocks.add(blockId);
     }
   });
 
@@ -72,13 +72,15 @@ function handleMorphdomUpdate(text) {
           }
         }
 
-        // For thinking blocks, respect closed state
+        // For thinking blocks, assume closed by default
         if (fromEl.classList && fromEl.classList.contains("thinking-block") &&
-            toEl.classList && toEl.classList.contains("thinking-block")) {
+           toEl.classList && toEl.classList.contains("thinking-block")) {
           const blockId = toEl.getAttribute("data-block-id");
-          // If this block was closed by user, keep it closed
-          if (blockId && closedBlocks.has(blockId)) {
-            toEl.removeAttribute("open");
+          // Remove open attribute by default
+          toEl.removeAttribute("open");
+          // If this block was explicitly opened by user, keep it open
+          if (blockId && openBlocks.has(blockId)) {
+            toEl.setAttribute("open", "");
           }
         }
 
diff --git a/modules/html_generator.py b/modules/html_generator.py
index c5252c26..67d15b6e 100644
--- a/modules/html_generator.py
+++ b/modules/html_generator.py
@@ -167,7 +167,7 @@ def convert_to_markdown(string, message_id=None):
         title_text = "Thinking..." if is_streaming else "Thought"
 
         thinking_block = f'''
-        <details class="thinking-block" data-block-id="{block_id}" data-streaming="{str(is_streaming).lower()}" open>
+        <details class="thinking-block" data-block-id="{block_id}" data-streaming="{str(is_streaming).lower()}">
             <summary class="thinking-header">
                 <svg class="thinking-icon" width="16" height="16" viewBox="0 0 16 16" fill="none" xmlns="http://www.w3.org/2000/svg">
                     <path d="M8 1.33334C4.31868 1.33334 1.33334 4.31868 1.33334 8.00001C1.33334 11.6813 4.31868 14.6667 8 14.6667C11.6813 14.6667 14.6667 11.6813 14.6667 8.00001C14.6667 4.31868 11.6813 1.33334 8 1.33334Z" stroke="currentColor" stroke-width="1.33" stroke-linecap="round" stroke-linejoin="round"/>