diff --git a/static/messages.js b/static/messages.js
index 2d5e24b72..037a5eae2 100644
--- a/static/messages.js
+++ b/static/messages.js
@@ -2551,6 +2551,15 @@ function attachLiveStream(activeSid, streamId, uploaded=[], options={}){
       if(!byIdx.has(idx)) byIdx.set(idx,[]);
       byIdx.get(idx).push(row);
     };
+    // Pre-index S.toolCalls by assistant_msg_idx for O(m+n) lookup
+    const toolsByIdx=new Map();
+    if(S.toolCalls) for(const tc of S.toolCalls){
+      const ti=typeof tc.toolIdx==='number'? tc.toolIdx : parseInt(tc.assistant_msg_idx,10);
+      if(Number.isFinite(ti)){
+        if(!toolsByIdx.has(ti)) toolsByIdx.set(ti,[]);
+        toolsByIdx.get(ti).push(tc);
+      }
+    }
     let encounter=0;
     for(let idx=turnStart+1;idx<lastAsstIndex;idx+=1){
       const message=messages[idx];
@@ -2575,12 +2584,10 @@ function attachLiveStream(activeSid, streamId, uploaded=[], options={}){
         if(tid) seenToolIds.add(tid);
       }
       // Merge S.toolCalls for this index, dedup by tool id
-      const toolCalls=Array.isArray(S.toolCalls)?S.toolCalls:[];
-      for(const tool of toolCalls){
+      for(const tool of (toolsByIdx.get(idx)||[])){
         if(!tool||typeof tool!=='object') continue;
         const toolIdx=Number(tool.assistant_msg_idx);
         if(!Number.isFinite(toolIdx)||toolIdx!==idx) continue;
-        if(toolIdx<=turnStart||toolIdx>=lastAsstIndex) continue;
         const row=_anchorSceneToolRowFromCall(tool,0,idx);
         const tid=row.tool_call_id||(row.tool&&row.tool.id);
         if(tid&&seenToolIds.has(tid)) continue;
diff --git a/tests/test_live_to_final_anchor_visible_order.py b/tests/test_live_to_final_anchor_visible_order.py
index 3803537b9..b01d96e43 100644
--- a/tests/test_live_to_final_anchor_visible_order.py
+++ b/tests/test_live_to_final_anchor_visible_order.py
@@ -709,8 +709,9 @@ def test_settled_anchor_scene_persists_the_full_assistant_turn_not_only_tail():
     assert "messages.slice(turnStart+1,lastAsstIndex+1)" in complete
     assert "message.reasoning||message._reasoning||message.reasoning_content||message.thinking" in reasoning_text
     assert "const reasoning=_anchorSceneMessageReasoningText(message);" in rows_by_message
-    assert "const toolCalls=Array.isArray(S.toolCalls)?S.toolCalls:[]" in rows_by_message
-    assert "toolIdx<=turnStart||toolIdx>=lastAsstIndex" in rows_by_message
+    assert "const toolsByIdx=new Map();" in rows_by_message
+    assert "if(S.toolCalls) for(const tc of S.toolCalls){" in rows_by_message
+    assert "for(const tool of (toolsByIdx.get(idx)||[]))" in rows_by_message
     assert "_anchorSceneToolRowFromCall(tool,0,idx)" in rows_by_message