From ec3584e7c25efa023ba906ee0a8ee9e5a3be7578 Mon Sep 17 00:00:00 2001
From: Ian <chess123mate@yahoo.ca>
Date: Mon, 3 Aug 2026 15:32:25 -0400
Subject: [PATCH] Fix

---
 src/graph.luau | 20 +++++++++++++++++---
 todo.md        |  1 +
 2 files changed, 18 insertions(+), 3 deletions(-)

diff --git a/src/graph.luau b/src/graph.luau
index f96bf4e..38d2bfc 100644
--- a/src/graph.luau
+++ b/src/graph.luau
@@ -228,15 +228,29 @@ local function remove_dependency_counts(node) -- to be called when updating a no
     for i = 1, #node do
         local child = node[i]
         if not node.owner then continue end -- we won't be updating this anyway
-        node_deps_left[child] -= 1
-        remove_dependency_counts(child)
+        local deps_left = node_deps_left[child]
+        if deps_left > 1 then
+            node_deps_left[child] = deps_left - 1
+        else
+            node_deps_left[child] = 0
+            -- only recurse if we're removing the last dependency *and* if we aren't planning on updating it
+            if not in_queue[child] then
+                remove_dependency_counts(child)
+            end
+        end
     end
 end
 
 local function queue_children_for_update<T>(node: SourceNode<T>)
     for i = 1, #node do
         local child = node[i]
-        node_deps_left[child] -= 1
+        local deps_left = node_deps_left[child]
+        if deps_left then
+            node_deps_left[child] = deps_left - 1
+        else
+            -- This can happen if child adds parent as a new dependency after the initial update
+            node_deps_left[child] = 0
+        end
         if not in_queue[child] then
             in_queue[child] = true
             update_queue_n += 1
diff --git a/todo.md b/todo.md
index 499fbb8..2142d7b 100644
--- a/todo.md
+++ b/todo.md
@@ -1,3 +1,4 @@
 # todo
 
 - improve error traces
+- prevent redundant re-eval of nodes in complex graphs after a node adds a dependency mid-update