fix: use native GraphRAG renderer on macOS

presentation/graph/graph_renderer.py

@@ -237,7 +237,7 @@ class GraphRenderer(QWidget):
     # ---- prewarm / scan lifecycle -------------------------------------------------- #
     def prewarm(self) -> None:
         """Pay for the graph view before it is clicked on, not during."""
-        if not HAS_WEB_ENGINE or self.web is not None:
+        if self.web is not None:
             return
         self._ensure_web()
         if self._graph is None and self.path_edit.text().strip():

presentation/shared/web_engine_support.py

@@ -27,7 +27,14 @@ def _frozen_onefile() -> bool:
         return True
 
 
+# QtWebEngine is noisy and unreliable on the macOS runtime we support (GPU/
+# helper-process failures leave the stacked view blank). The native Qt graph is
+# already available and avoids that failure path entirely.
+HAS_WEB_ENGINE = False
+
 try:  # WebEngine + WebChannel are optional PySide6 add-ons
+    if sys.platform == "darwin":
+        raise ImportError("use native graph renderer on macOS")
     from PySide6.QtWebEngineWidgets import QWebEngineView  # noqa: F401
     from PySide6.QtWebChannel import QWebChannel  # noqa: F401
     HAS_WEB_ENGINE = not _frozen_onefile()