From 1247bae63535895801a681dc94ca17cee6c5bad6 Mon Sep 17 00:00:00 2001
From: Synvoya <16019863+Synvoya@users.noreply.github.com>
Date: Sun, 12 Jul 2026 12:11:22 +1000
Subject: [PATCH] fix(extract): emit inherits edge for Python parameterized
 bases

The Python heritage handler in _extract_generic only matched bare
`identifier` bases in a class's `superclasses` list. A parameterized
base -- `class Repo(Base[int])`, `class C(Generic[T])` -- parses as a
`subscript` node whose `value` field is the actual base type and whose
`[...]` holds only type parameters. That node type fell through the
identifier-only check, so every generic base silently lost its
`inherits` edge.

Unwrap a `subscript` base to its `value` before the identifier check,
so parameterized bases point their heritage edge at the base type.
Bare-identifier bases are unaffected. Qualified (`attribute`) bases
remain handled by the cross-file symbol resolver and are out of scope
here.

Regression test in tests/test_languages.py fails before, passes after.
---
 graphify/extractors/engine.py | 12 ++++++++++--
 tests/test_languages.py       | 28 ++++++++++++++++++++++++++++
 2 files changed, 38 insertions(+), 2 deletions(-)

diff --git a/graphify/extractors/engine.py b/graphify/extractors/engine.py
index 90c95cc49..013e8923a 100644
--- a/graphify/extractors/engine.py
+++ b/graphify/extractors/engine.py
@@ -2344,8 +2344,16 @@ def walk(node, parent_class_nid: str | None = None) -> None:
                 args = node.child_by_field_name("superclasses")
                 if args:
                     for arg in args.children:
-                        if arg.type == "identifier":
-                            base = _read_text(arg, source)
+                        base_node = arg
+                        # A parameterized base (`Base[T]`, `Generic[T]`,
+                        # `Repo[User]`) parses as a `subscript` whose `value`
+                        # field is the actual base type; the `[...]` holds only
+                        # type parameters. Unwrap to the value so the heritage
+                        # edge points at the base instead of being dropped.
+                        if base_node.type == "subscript":
+                            base_node = base_node.child_by_field_name("value") or base_node
+                        if base_node.type == "identifier":
+                            base = _read_text(base_node, source)
                             base_nid = ensure_named_node(base, line)
                             add_edge(class_nid, base_nid, "inherits", line)
 
diff --git a/tests/test_languages.py b/tests/test_languages.py
index f610fbc40..a08480662 100644
--- a/tests/test_languages.py
+++ b/tests/test_languages.py
@@ -3,6 +3,7 @@
 from pathlib import Path
 import pytest
 from graphify.extract import (
+    extract_python,
     extract_java, extract_c, extract_cpp, extract_ruby,
     extract_csharp, extract_kotlin, extract_scala, extract_php,
     extract_swift, extract_go, extract_julia, extract_js, extract_fortran,
@@ -333,6 +334,33 @@ def test_ruby_inherits_edge():
     assert found, "TimeoutApiClient should have inherits edge to ApiClient"
 
 
+# ── Python ──────────────────────────────────────────────────────────────────
+
+def test_python_parameterized_base_inherits_edge(tmp_path):
+    """`class C(Base[T])` must still emit an inherits edge to the base type.
+
+    The Python heritage handler only matched bare `identifier` bases in the
+    `superclasses` list. A parameterized base parses as a `subscript` node
+    (its `value` field is the base type; the `[...]` holds only type params),
+    so it fell through and the heritage edge was silently dropped -- every
+    `Generic[T]` / `Repo[User]` base lost its `inherits` edge.
+    """
+    source = tmp_path / "heritage.py"
+    source.write_text(
+        "class Base: pass\n"
+        "class Mixin: pass\n"
+        "class Repo(Base[int]): pass\n"
+        "class Multi(Mixin, Base[str]): pass\n"
+    )
+    result = extract_python(source)
+    inherits = _edge_labels(result, "inherits")
+    # Parameterized base must resolve to the base type, not be dropped.
+    assert ("Repo", "Base") in inherits
+    assert ("Multi", "Base") in inherits
+    # Bare-identifier bases must keep working (regression guard).
+    assert ("Multi", "Mixin") in inherits
+
+
 # ── C# ───────────────────────────────────────────────────────────────────────
 
 def test_csharp_no_error():