fix(parser): track keyword argument callback references

code_review_graph/parser.py

@@ -12194,13 +12194,17 @@ def _ref_from_arguments(
     ) -> None:
         """Extract REFERENCES from identifier arguments (callbacks)."""
         for ch in args_node.children:
-            if ch.type == "identifier":
-                name = ch.text.decode("utf-8", errors="replace")
-                self._emit_reference_if_known(
-                    name, language, file_path, caller, edges,
-                    import_map, defined_names,
-                    line=ch.start_point[0] + 1,
-                )
+            reference_node = ch
+            if ch.type == "keyword_argument" and language == "python":
+                reference_node = ch.child_by_field_name("value")
+            if reference_node is None or reference_node.type != "identifier":
+                continue
+            name = reference_node.text.decode("utf-8", errors="replace")
+            self._emit_reference_if_known(
+                name, language, file_path, caller, edges,
+                import_map, defined_names,
+                line=reference_node.start_point[0] + 1,
+            )
 
     def _extract_solidity_constructs(
         self,

tests/fixtures/sample_callback_refs.py

@@ -1,8 +1,8 @@
 """Fixture for issue #363: function references in callback positions.
 
-Each `*_callback` function is passed as a bare-identifier argument to
-another call. They are never invoked with parens, so without REFERENCES
-edge tracking they would be flagged as dead code.
+Each `*_callback` function is passed as an argument to another call, either
+directly or as a keyword value. They are never invoked with parens, so without
+REFERENCES edge tracking they would be flagged as dead code.
 """
 from concurrent.futures import ThreadPoolExecutor
 
@@ -19,6 +19,10 @@ def map_callback(item):
     return item * 2
 
 
+def keyword_callback(args):
+    return args
+
+
 def trigger_executor():
     with ThreadPoolExecutor() as executor:
         future = executor.submit(executor_callback)
@@ -33,3 +37,7 @@ def trigger_filter():
 def trigger_map():
     items = [1, 2, 3]
     return list(map(map_callback, items))
+
+
+def register_keyword_callback(parser):
+    parser.set_defaults(func=keyword_callback)

tests/test_parser.py

@@ -823,7 +823,7 @@ def test_vitest_tested_by_edges(self):
             f"All edges: {[(e.kind, e.source, e.target) for e in edges]}"
         )
 
-    # --- Python callback REFERENCES (#363) ---
+    # --- Python callback REFERENCES (#363, #840) ---
     # Functions passed as bare-identifier arguments (executor.submit(fn),
     # filter(fn, xs), map(fn, xs), df.apply(fn), ...) should produce
     # REFERENCES edges so dead-code detection does not flag them as unused.
@@ -842,6 +842,13 @@ def test_python_callback_references_emitted(self):
                 f"{ref_target_names}"
             )
 
+    def test_python_keyword_callback_reference_emitted(self):
+        """A function passed as a keyword-argument value should produce a reference."""
+        nodes, edges = self.parser.parse_file(FIXTURES / "sample_callback_refs.py")
+        refs = [e for e in edges if e.kind == "REFERENCES"]
+        ref_target_names = {e.target.rsplit("::", 1)[-1] for e in refs}
+        assert "keyword_callback" in ref_target_names
+
     def test_python_callback_references_not_treated_as_dead(self):
         """End-to-end: with REFERENCES edges in place, find_dead_code
         should not flag callback functions as dead."""
@@ -862,7 +869,10 @@ def test_python_callback_references_not_treated_as_dead(self):
                 dead = find_dead_code(store)
                 dead_names = {d["name"] for d in dead}
                 for callback in (
-                    "executor_callback", "filter_callback", "map_callback",
+                    "executor_callback",
+                    "filter_callback",
+                    "map_callback",
+                    "keyword_callback",
                 ):
                     assert callback not in dead_names, (
                         f"{callback} was flagged as dead but is used as a "