fix(python): count x.prop += v as a read of the property

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01B8gwEpjajiWHVW3c9smuKf

graphify/extractors/engine.py

@@ -1829,13 +1829,14 @@ def _same_node(a, b) -> bool:
 
 
 def _python_attribute_is_store(node) -> bool:
-    """`x.a = ...`, `x.a += ...`, `for x.a in ...`, `del x.a`: not a read of `a`."""
+    """`x.a = ...`, `for x.a in ...`, `del x.a`: not a read of `a`. `x.a += ...`
+    is: it reads `a` (the getter runs) before it writes it."""
     child, parent = node, node.parent
     while parent is not None and parent.type in ("pattern_list", "tuple_pattern", "list_pattern"):
         child, parent = parent, parent.parent
     if parent is None:
         return False
-    if parent.type in ("assignment", "augmented_assignment", "for_statement", "for_in_clause"):
+    if parent.type in ("assignment", "for_statement", "for_in_clause"):
         return _same_node(parent.child_by_field_name("left"), child)
     return parent.type == "delete_statement"
 

tests/test_python_property_reads.py

@@ -80,6 +80,15 @@ def test_fields_method_references_and_stores_are_not_reads(tmp_path: Path):
     assert not any(e[0] == "poke()" and e[3] == "property_read" for e in edges), edges
 
 
+def test_augmented_assignment_reads_the_property(tmp_path: Path):
+    # `r.text += x` runs the getter before the setter.
+    edges = _edges(tmp_path, {
+        "resp.py": _RESPONSE,
+        "use.py": "from resp import Response\n\n\ndef extend():\n    r = Response()\n    r.text += 'x'\n",
+    })
+    assert ("extend()", "Response", ".text()", "property_read") in edges
+
+
 def test_underscored_field_does_not_reach_the_property_without_underscore(tmp_path: Path):
     # `_items` and `items` fold to one key in the resolver; the read names `_items`.
     edges = _edges(tmp_path, {