From e07e739f70b18b167d12b550523bcebe9fc8bfcf Mon Sep 17 00:00:00 2001
From: Vardhman Gupta <vardhmangupta2004@gmail.com>
Date: Thu, 1 Oct 2026 16:16:23 +0530
Subject: [PATCH] fix(graph): preserve existing node ntype and props in
 add_node

Closes #271.

- Update GraphStore.add_node to use if_not_exists for ntype and props.
- Prevent add_edge and link_docs placeholder node initialization from erasing pre-existing entity metadata.
- Add unit tests verifying node metadata preservation across edge additions, doc linkages, and partial updates.
---
 src/dynavec/graph.py           | 42 ++++++++++++++++++++++++----------
 tests/test_graph_properties.py | 39 +++++++++++++++++++++++++++++++
 2 files changed, 69 insertions(+), 12 deletions(-)

diff --git a/src/dynavec/graph.py b/src/dynavec/graph.py
index ab289a8..37d5e86 100644
--- a/src/dynavec/graph.py
+++ b/src/dynavec/graph.py
@@ -188,20 +188,38 @@ def _node_pk(ns: str, entity_id: str) -> str:
     def add_node(
         self, ns: str, entity_id: str, ntype: str | None = None, props: Props | None = None
     ) -> None:
+        set_clauses = [
+            "kind = if_not_exists(kind, :k)",
+            "ns = if_not_exists(ns, :ns)",
+            "entity_id = if_not_exists(entity_id, :eid)",
+            "edges = if_not_exists(edges, :empty_list)",
+            "docs = if_not_exists(docs, :empty_list)",
+        ]
+        values: dict[str, Any] = {
+            ":k": "node",
+            ":ns": ns,
+            ":eid": entity_id,
+            ":empty_list": [],
+        }
+
+        if ntype is not None:
+            set_clauses.append("ntype = :t")
+            values[":t"] = ntype
+        else:
+            set_clauses.append("ntype = if_not_exists(ntype, :null)")
+            values[":null"] = None
+
+        if props is not None:
+            set_clauses.append("props = :p")
+            values[":p"] = props
+        else:
+            set_clauses.append("props = if_not_exists(props, :empty_map)")
+            values[":empty_map"] = {}
+
         self._table.update_item(
             Key={"pk": self._node_pk(ns, entity_id)},
-            UpdateExpression=(
-                "SET kind = :k, ns = :ns, entity_id = :eid, ntype = :t, props = :p, "
-                "edges = if_not_exists(edges, :empty), docs = if_not_exists(docs, :empty)"
-            ),
-            ExpressionAttributeValues={
-                ":k": "node",
-                ":ns": ns,
-                ":eid": entity_id,
-                ":t": ntype,
-                ":p": props or {},
-                ":empty": [],
-            },
+            UpdateExpression="SET " + ", ".join(set_clauses),
+            ExpressionAttributeValues=values,
         )
 
     @retry()
diff --git a/tests/test_graph_properties.py b/tests/test_graph_properties.py
index bd34d52..18ab68f 100644
--- a/tests/test_graph_properties.py
+++ b/tests/test_graph_properties.py
@@ -127,3 +127,42 @@ def test_graph_add_edge_forwards_weight_props_and_bidirectional_values():
         ("tenant", "source", "connects", "target", 3.5, props),
         ("tenant", "target", "connects", "source", 3.5, props),
     ]
+
+
+def test_add_edge_and_link_docs_preserve_existing_node_metadata(store):
+    store.add_node("ns", "alice", ntype="Person", props={"role": "Admin", "dept": "Eng"})
+    store.add_node("ns", "bob", ntype="Person", props={"role": "Dev", "dept": "Design"})
+
+    store.add_edge("ns", "alice", "manages", "bob", weight=1.0)
+
+    alice_node = store.get_node("ns", "alice")
+    bob_node = store.get_node("ns", "bob")
+
+    assert alice_node["ntype"] == "Person"
+    assert alice_node["props"] == {"role": "Admin", "dept": "Eng"}
+    assert len(alice_node["edges"]) == 1
+
+    assert bob_node["ntype"] == "Person"
+    assert bob_node["props"] == {"role": "Dev", "dept": "Design"}
+
+    store.link_docs("ns", "alice", ["doc-1", "doc-2"])
+    alice_node_after_link = store.get_node("ns", "alice")
+
+    assert alice_node_after_link["ntype"] == "Person"
+    assert alice_node_after_link["props"] == {"role": "Admin", "dept": "Eng"}
+    assert alice_node_after_link["docs"] == ["doc-1", "doc-2"]
+
+
+def test_add_node_partial_update_preserves_unspecified_attributes(store):
+    store.add_node("ns", "user", ntype="Person", props={"age": Decimal("30")})
+
+    store.add_node("ns", "user", props={"age": Decimal("31"), "city": "NYC"})
+    node = store.get_node("ns", "user")
+    assert node["ntype"] == "Person"
+    assert node["props"] == {"age": Decimal("31"), "city": "NYC"}
+
+    store.add_node("ns", "user", ntype="Admin")
+    node_after_ntype = store.get_node("ns", "user")
+    assert node_after_ntype["ntype"] == "Admin"
+    assert node_after_ntype["props"] == {"age": Decimal("31"), "city": "NYC"}
+