feat: strengthen BSP and PSP validation and handoff

skills/firmware-lowlevel-psp-development/scripts/psp/test_psp_project_guard.py

@@ -111,6 +111,22 @@ def main() -> int:
         assert audited["passed"] is True, audited
         assert audited["repository_unchanged"] is True
 
+        no_reference = create_empty_project(psp_root, "NO-REFERENCE")
+        empty_manifest = root / "evidence" / "empty-manifest.json"
+        empty_prepared = psp_project_guard.prepare(
+            None, no_reference, empty_manifest, [], False, psp_root
+        )
+        empty_staging = Path(empty_prepared["staging"])
+        assert list(empty_staging.iterdir()) == []
+        assert json.loads(empty_manifest.read_text(encoding="utf-8"))["reference"] is None
+        (empty_staging / "psp.json").write_text('{"project":"NO-REFERENCE"}', encoding="utf-8")
+        empty_report = root / "evidence" / "empty-verify.json"
+        assert psp_project_guard.verify(empty_manifest, ["psp.json"], [], empty_report)["passed"]
+        psp_project_guard.finalize(empty_manifest, empty_report)
+        assert psp_project_guard.audit_final(empty_manifest, ["psp.json"], [], None)["passed"]
+        assert (no_reference / ".git").is_dir()
+        assert (no_reference / "psp.json").is_file()
+
         missing = psp_root / "MISSING"
         expect_guard_error(
             lambda: psp_project_guard.prepare(