diff --git a/comfy_execution/caching.py b/comfy_execution/caching.py
index 4cf2c3516..3a04f8651 100644
--- a/comfy_execution/caching.py
+++ b/comfy_execution/caching.py
@@ -461,18 +461,18 @@ class CacheKeySetInputSignature(CacheKeySet):
         signature.append(await self.get_immediate_node_signature(dynprompt, node_id, order_mapping))
         for ancestor_id in ancestors:
             signature.append(await self.get_immediate_node_signature(dynprompt, ancestor_id, order_mapping))
-        return _signature_to_hashable(signature)
+        return tuple(signature)
 
     async def get_immediate_node_signature(self, dynprompt, node_id, ancestor_order_mapping):
         """Build the immediate cache-signature fragment for a node.
 
         Link inputs are reduced to ancestor references here. Non-link values
-        are canonicalized or failed closed before being appended so the outer
-        node-signature pass never recurses into live prompt input containers.
+        are canonicalized or failed closed before being appended so the final
+        node signature is assembled from already-hashable fragments.
         """
         if not dynprompt.has_node(node_id):
             # This node doesn't exist -- we can't cache it.
-            return [float("NaN")]
+            return (float("NaN"),)
         node = dynprompt.get_node(node_id)
         class_type = node["class_type"]
         class_def = nodes.NODE_CLASS_MAPPINGS[class_type]
@@ -487,7 +487,7 @@ class CacheKeySetInputSignature(CacheKeySet):
                 signature.append((key,("ANCESTOR", ancestor_index, ancestor_socket)))
             else:
                 signature.append((key, to_hashable(inputs[key])))
-        return signature
+        return tuple(signature)
 
     # This function returns a list of all ancestors of the given node. The order of the list is
     # deterministic based on which specific inputs the ancestor is connected by.
diff --git a/tests/execution/test_caching.py b/tests/execution/test_caching.py
index f5851c980..192c3102e 100644
--- a/tests/execution/test_caching.py
+++ b/tests/execution/test_caching.py
@@ -42,11 +42,11 @@ def test_get_immediate_node_signature_canonicalizes_non_link_inputs(monkeypatch)
     keyset = caching.CacheKeySetInputSignature(dynprompt, [], _StubIsChangedCache())
     signature = asyncio.run(keyset.get_immediate_node_signature(dynprompt, "1", {}))
 
-    assert signature == [
+    assert signature == (
         "TestCacheNode",
         None,
         ("value", ("list", (1, ("dict", (("nested", ("list", (2, 3))),))))),
-    ]
+    )
 
 
 def test_get_immediate_node_signature_fails_closed_for_opaque_non_link_input(monkeypatch):
@@ -69,7 +69,7 @@ def test_get_immediate_node_signature_fails_closed_for_opaque_non_link_input(mon
     keyset = caching.CacheKeySetInputSignature(dynprompt, [], _StubIsChangedCache())
     signature = asyncio.run(keyset.get_immediate_node_signature(dynprompt, "1", {}))
 
-    assert signature[:2] == ["TestCacheNode", None]
+    assert signature[:2] == ("TestCacheNode", None)
     assert signature[2][0] == "value"
     assert type(signature[2][1]) is caching.Unhashable
 
@@ -87,17 +87,77 @@ def test_get_node_signature_never_visits_raw_non_link_input(monkeypatch):
 
     monkeypatch.setitem(caching.nodes.NODE_CLASS_MAPPINGS, "TestCacheNode", _StubNode)
     monkeypatch.setattr(caching, "NODE_CLASS_CONTAINS_UNIQUE_ID", {})
-
-    original_impl = caching._signature_to_hashable_impl
-
-    def guarded_impl(obj, *args, **kwargs):
-        if obj is live_value:
-            raise AssertionError("raw non-link input reached outer signature canonicalizer")
-        return original_impl(obj, *args, **kwargs)
-
-    monkeypatch.setattr(caching, "_signature_to_hashable_impl", guarded_impl)
+    monkeypatch.setattr(
+        caching,
+        "_signature_to_hashable",
+        lambda *_args, **_kwargs: (_ for _ in ()).throw(
+            AssertionError("outer signature canonicalizer should not run")
+        ),
+    )
 
     keyset = caching.CacheKeySetInputSignature(dynprompt, [], _StubIsChangedCache())
     signature = asyncio.run(keyset.get_node_signature(dynprompt, "1"))
 
     assert isinstance(signature, tuple)
+
+
+def test_get_node_signature_keeps_deep_canonicalized_input_fragment(monkeypatch):
+    live_value = 1
+    for _ in range(8):
+        live_value = [live_value]
+    expected = caching.to_hashable(live_value)
+
+    dynprompt = _StubDynPrompt(
+        {
+            "1": {
+                "class_type": "TestCacheNode",
+                "inputs": {"value": live_value},
+            }
+        }
+    )
+
+    monkeypatch.setitem(caching.nodes.NODE_CLASS_MAPPINGS, "TestCacheNode", _StubNode)
+    monkeypatch.setattr(caching, "NODE_CLASS_CONTAINS_UNIQUE_ID", {})
+
+    keyset = caching.CacheKeySetInputSignature(dynprompt, [], _StubIsChangedCache())
+    signature = asyncio.run(keyset.get_node_signature(dynprompt, "1"))
+
+    assert isinstance(signature, tuple)
+    assert signature[0][2][0] == "value"
+    assert signature[0][2][1] == expected
+
+
+def test_get_node_signature_keeps_large_precanonicalized_fragment(monkeypatch):
+    live_value = object()
+    canonical_fragment = ("tuple", tuple(("list", (index, index + 1)) for index in range(256)))
+    dynprompt = _StubDynPrompt(
+        {
+            "1": {
+                "class_type": "TestCacheNode",
+                "inputs": {"value": live_value},
+            }
+        }
+    )
+
+    monkeypatch.setitem(caching.nodes.NODE_CLASS_MAPPINGS, "TestCacheNode", _StubNode)
+    monkeypatch.setattr(caching, "NODE_CLASS_CONTAINS_UNIQUE_ID", {})
+    monkeypatch.setattr(
+        caching,
+        "to_hashable",
+        lambda value, max_nodes=caching._MAX_SIGNATURE_CONTAINER_VISITS: (
+            canonical_fragment if value is live_value else caching.Unhashable()
+        ),
+    )
+    monkeypatch.setattr(
+        caching,
+        "_signature_to_hashable",
+        lambda *_args, **_kwargs: (_ for _ in ()).throw(
+            AssertionError("outer signature canonicalizer should not run")
+        ),
+    )
+
+    keyset = caching.CacheKeySetInputSignature(dynprompt, [], _StubIsChangedCache())
+    signature = asyncio.run(keyset.get_node_signature(dynprompt, "1"))
+
+    assert isinstance(signature, tuple)
+    assert signature[0][2] == ("value", canonical_fragment)