fix(extract): emit Kotlin enum entries as nodes with case_of edges (#1700 Kotlin half, #1738)

Kotlin enum entries weren't extracted: the walker never descended into the enum
body (`enum_class_body` wasn't in _KOTLIN_CONFIG.body_fallback_child_types, so
_find_body returned None). Add `enum_class_body` to the fallback body types and a
`_kotlin_extra_walk` (dispatched for tree_sitter_kotlin, mirroring the Java/Swift
handling) that emits each enum_entry as a node with a `case_of` edge to the enum.

Re-applied from PR #1738 (@ivanzhl) onto the post-#1737 module layout: the walk
engine now lives in graphify/extractors/engine.py while _KOTLIN_CONFIG stays in
extract.py. Closes the Kotlin half of #1700 (Java was #1719).

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

graphify/extract.py

@@ -772,7 +772,7 @@ _KOTLIN_CONFIG = LanguageConfig(
     # older forks use `simple_identifier`. Accept both so the extractor
     # works across grammar generations.
     name_fallback_child_types=("simple_identifier", "identifier"),
-    body_fallback_child_types=("function_body", "class_body"),
+    body_fallback_child_types=("function_body", "class_body", "enum_class_body"),
     function_boundary_types=frozenset({"function_declaration"}),
     import_handler=_import_kotlin,
 )

graphify/extractors/engine.py

@@ -1768,6 +1768,33 @@ def _java_extra_walk(node, source: bytes, file_nid: str, stem: str, str_path: st
         return True
     return False
 
+
+def _kotlin_extra_walk(node, source: bytes, file_nid: str, stem: str, str_path: str,
+                       nodes: list, edges: list, seen_ids: set, function_bodies: list,
+                       parent_class_nid: str | None, add_node_fn, add_edge_fn,
+                       walk_fn) -> bool:
+    """Handle enum_entry for Kotlin. Returns True if handled (#1700 Kotlin half)."""
+    if node.type == "enum_entry" and parent_class_nid:
+        name_node = None
+        for child in node.children:
+            if child.type in ("simple_identifier", "identifier"):
+                name_node = child
+                break
+        if name_node is None:
+            return True
+        const_name = _read_text(name_node, source)
+        line = node.start_point[0] + 1
+        const_nid = _make_id(parent_class_nid, const_name)
+        add_node_fn(const_nid, const_name, line)
+        add_edge_fn(parent_class_nid, const_nid, "case_of", line)
+        for child in node.children:
+            if child.type == "class_body":
+                for member in child.children:
+                    walk_fn(member, parent_class_nid=const_nid)
+        return True
+    return False
+
+
 def _read_csharp_type_name(node, source: bytes) -> tuple[str, bool, str] | None:
     """Resolve a C# type name, whether it was qualified, and its qualifier prefix."""
     if node is None:
@@ -3299,6 +3326,12 @@ def _extract_generic(
                                 parent_class_nid, add_node, add_edge, walk):
                 return
 
+        if config.ts_module == "tree_sitter_kotlin":
+            if _kotlin_extra_walk(node, source, file_nid, stem, str_path,
+                                  nodes, edges, seen_ids, function_bodies,
+                                  parent_class_nid, add_node, add_edge, walk):
+                return
+
         if config.ts_module == "tree_sitter_ruby":
             if _ruby_extra_walk(node, source, file_nid, stem, str_path,
                                 nodes, edges, seen_ids, function_bodies,

tests/fixtures/sample.kt

@@ -41,3 +41,9 @@ fun createClient(baseUrl: String): HttpClient {
     val config = Config(baseUrl, 30)
     return HttpClient(config)
 }
+
+enum class ChatType {
+    NORMAL,
+    GROUP,
+    SYSTEM
+}

tests/test_languages.py

@@ -615,6 +615,14 @@ def test_kotlin_finds_function():
     r = extract_kotlin(FIXTURES / "sample.kt")
     assert any("createClient" in l for l in _labels(r))
 
+def test_kotlin_enum_entries_have_case_of_edge():
+    # #1700 (Kotlin half): enum entries must be nodes with case_of edges to the enum.
+    r = extract_kotlin(FIXTURES / "sample.kt")
+    labels = _labels(r)
+    assert "NORMAL" in labels and "GROUP" in labels and "SYSTEM" in labels
+    assert ("ChatType", "NORMAL") in _edge_labels(r, "case_of")
+    assert ("ChatType", "SYSTEM") in _edge_labels(r, "case_of")
+
 def test_kotlin_emits_in_file_calls():
     """Regression test for the call-walker `simple_identifier` /
     `identifier` rename — see graphify-kmp's PythonParityTest."""