fix(extract): nested types get a contains edge from the enclosing type (#2040)

In _extract_generic's class branch the `contains` edge was hard-coded to source
from the file node, so a nested class/object/trait attached to the file instead
of its enclosing type across ~19 languages (only C# even flagged the node with
is_nested_type, and still emitted no edge to the parent). The edge now sources
from parent_class_nid when set, else the file node — keeping the containment
tree connected (file -> Outer -> Inner). A `!= class_nid` guard avoids a
self-loop when same-name nesting collides ids (class ids omit the enclosing
name). The C# is_nested_type flag is retained (load-bearing for cross-file
resolution). Methods were already parent-sourced and are unaffected.

graphify/extractors/engine.py

@@ -2371,7 +2371,19 @@ def _extract_generic(
                 metadata = {"is_nested_type": True}
             add_node(class_nid, class_name, line, metadata=metadata)
             callable_def_nids.add(class_nid)  # a class is callable (constructor)
-            add_edge(file_nid, class_nid, "contains", line)
+            # A nested class/object/trait is contained by its ENCLOSING type, not
+            # the file (#2040). parent_class_nid is threaded down the walk for
+            # every language and is always a real class-like node (never a
+            # namespace — namespace handlers pass it through unchanged), so it is
+            # a valid edge source. The `!= class_nid` guard avoids a self-loop
+            # when same-name nesting (`class Foo: class Foo`) collides ids, since
+            # class ids omit the enclosing type name. Top-level types (parent
+            # None) still source from the file, keeping the containment tree
+            # connected: file -> Outer -> Inner.
+            if parent_class_nid and parent_class_nid != class_nid:
+                add_edge(parent_class_nid, class_nid, "contains", line)
+            else:
+                add_edge(file_nid, class_nid, "contains", line)
 
             # TS/JS decorators on the class and its members (@Component, @Injectable,
             # @Input, @Inject, @Entity, …). Decorators live only in class subtrees.

tests/test_languages.py

@@ -553,6 +553,39 @@ def test_java_enum_and_annotation_declarations_are_type_nodes(tmp_path):
     assert definitions["Audited"].get("source_file") == str(source)
 
 
+def test_nested_types_contained_by_enclosing_type(tmp_path):
+    """#2040: a nested class/object/trait's `contains` edge sources from its
+    ENCLOSING type, not the file node; top-level types still source from the file
+    (keeping the tree connected: file -> Outer -> Inner)."""
+    # Java inner class
+    j = tmp_path / "Outer.java"
+    j.write_text("class Outer {\n  class Inner { void m() {} }\n}\n")
+    cj = _edge_labels(extract_java(j), "contains")
+    assert ("Outer.java", "Outer") in cj      # top-level still file-sourced
+    assert ("Outer", "Inner") in cj           # nested sourced from enclosing type
+    assert ("Outer.java", "Inner") not in cj  # NOT from the file (the bug)
+
+    # Scala nested class + object (the issue's repro shape)
+    s = tmp_path / "Outer.scala"
+    s.write_text("class Outer {\n  class Inner\n  object Obj\n}\n")
+    cs = _edge_labels(extract_scala(s), "contains")
+    assert ("Outer.scala", "Outer") in cs
+    assert ("Outer", "Inner") in cs
+    assert ("Outer", "Obj") in cs
+    assert ("Outer.scala", "Inner") not in cs
+
+
+def test_csharp_nested_type_gets_containment_edge(tmp_path):
+    """#2040 for C#: the nested type now gets a real `contains` edge from its
+    enclosing type (the is_nested_type flag it already carried is retained and
+    covered by test_csharp_type_resolution)."""
+    c = tmp_path / "N.cs"
+    c.write_text("namespace N {\n  class Outer {\n    class Inner {}\n  }\n}\n")
+    cc = _edge_labels(extract_csharp(c), "contains")
+    assert ("Outer", "Inner") in cc
+    assert ("N.cs", "Inner") not in cc
+
+
 def test_csharp_field_type_references_have_field_context():
     r = extract_csharp(FIXTURES / "sample.cs")
     refs = _references(r)