fix(plugins): share one cached handoff runtime and use version 0.3.2

integrations/agent-plugin-core/tests/test_conformance.py

@@ -115,9 +115,12 @@ def test_handoff_packaging_rejects_missing_and_drifted_runtime(tmp_path: Path) -
         target.parent.mkdir(parents=True, exist_ok=True)
         target.write_text("", encoding="utf-8")
     for name in HANDOFF_RUNTIME_FILES:
-        (dist / name).write_bytes((PLUGIN_ROOT / "python" / name).read_bytes())
+        (dist / name).write_bytes((PLUGIN_ROOT / ("python" if name.endswith(".py") else "build") / name).read_bytes())
     assert verify_artifact("opencode", tmp_path, required)["status"] == "passed"
 
+    (dist / "claude_to_codex.py").write_text("# obsolete bundled engine\n", encoding="utf-8")
+    assert "duplicated handoff engine" in verify_artifact("opencode", tmp_path, required)["output"]
+    (dist / "claude_to_codex.py").unlink()
     (dist / "session_handoff.py").write_text("# stale importer\n", encoding="utf-8")
     assert "differs from shared source" in verify_artifact("opencode", tmp_path, required)["output"]
     (dist / "session_handoff.py").unlink()