fix(ruby): emit inherits edge for class superclass

`class Dog < Animal` exposes the base in the `superclass` field, but the
inheritance handler in `_extract_generic` had branches for
java/kotlin/c#/scala/cpp/php/swift/python and none for Ruby, so every Ruby
`inherits` edge was silently dropped (contains/methods/calls unaffected).

Add a Ruby branch that reads the `superclass` field, handling both a bare
`constant` (`< Animal`) and a `scope_resolution` (`< Foo::Bar` -> Bar).
Adds a subclass to the Ruby fixture and a regression test.

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

graphify/extract.py

@@ -3426,6 +3426,37 @@ def _extract_generic(
                                             add_edge(class_nid, target, "references", line,
                                                      context="generic_arg")
 
+            # Ruby: `class Dog < Animal` puts the base class in the `superclass`
+            # field (a `<` token followed by a constant or scope_resolution).
+            # There was no Ruby branch, so every Ruby inherits edge was dropped.
+            if config.ts_module == "tree_sitter_ruby":
+                sup = node.child_by_field_name("superclass")
+                if sup is not None:
+                    base = ""
+                    for sub in sup.children:
+                        if sub.type == "constant":
+                            base = _read_text(sub, source)
+                            break
+                        if sub.type == "scope_resolution":
+                            consts = [c for c in sub.children if c.type == "constant"]
+                            if consts:
+                                base = _read_text(consts[-1], source)
+                            break
+                    if base:
+                        base_nid = _make_id(stem, base)
+                        if base_nid not in seen_ids:
+                            base_nid = _make_id(base)
+                            if base_nid not in seen_ids:
+                                nodes.append({
+                                    "id": base_nid,
+                                    "label": base,
+                                    "file_type": "code",
+                                    "source_file": "",
+                                    "source_location": "",
+                                })
+                                seen_ids.add(base_nid)
+                        add_edge(class_nid, base_nid, "inherits", line)
+
             # C#-specific: inheritance / interface implementation via base_list
             if config.ts_module == "tree_sitter_c_sharp":
                 csharp_type_params = _csharp_type_parameters_in_scope(node, source)

tests/fixtures/sample.rb

@@ -22,6 +22,12 @@ class ApiClient
   end
 end
 
+class TimeoutApiClient < ApiClient
+  def fetch(path, method)
+    super
+  end
+end
+
 def parse_response(raw)
   JSON.parse(raw)
 end

tests/test_languages.py

@@ -299,6 +299,22 @@ def test_ruby_finds_function():
     assert any("parse_response" in l for l in _labels(r))
 
 
+def test_ruby_inherits_edge():
+    """`class Sub < Base` must emit an inherits edge.
+
+    Ruby exposes the base class in the `superclass` field, but there was no
+    Ruby branch in the inheritance handler, so the edge was silently dropped.
+    """
+    r = extract_ruby(FIXTURES / "sample.rb")
+    node_by_id = {n["id"]: n["label"] for n in r["nodes"]}
+    found = any(
+        "TimeoutApiClient" in node_by_id.get(e["source"], "")
+        and node_by_id.get(e["target"], "") == "ApiClient"
+        for e in r["edges"] if e["relation"] == "inherits"
+    )
+    assert found, "TimeoutApiClient should have inherits edge to ApiClient"
+
+
 # ── C# ───────────────────────────────────────────────────────────────────────
 
 def test_csharp_no_error():