diff --git a/scripts/disk-gc-plan.py b/scripts/disk-gc-plan.py
index 4130815..b3fa42a 100755
--- a/scripts/disk-gc-plan.py
+++ b/scripts/disk-gc-plan.py
@@ -59,6 +59,12 @@ def load_report_only_guests(contract_path: pathlib.Path) -> list[dict]:
             guests = data.get("report_only_guests") or []
             if not isinstance(guests, list):
                 raise SystemExit("report_only_guests must be a list")
+            for guest in guests:
+                if not isinstance(guest, dict) or not _keys(guest):
+                    raise SystemExit(
+                        "report_only_guests entry has no recognizable identity key "
+                        f"(expected one of: {', '.join(IDENTITY_FIELDS)}): {guest!r}"
+                    )
             return guests
     raise SystemExit(
         f"no authoritative report_only_guests block found in {contract_path}"
diff --git a/tests/test_disk_gc_report_only.py b/tests/test_disk_gc_report_only.py
index bde9df2..f3b4e48 100644
--- a/tests/test_disk_gc_report_only.py
+++ b/tests/test_disk_gc_report_only.py
@@ -102,6 +102,28 @@ def test_unidentified_threat_fails_closed(tmp_path):
     assert plan[0]["reason"], plan
 
 
+def test_exclusion_entry_without_identity_fails_closed(tmp_path):
+    """A mis-typed exclusion entry must break the run, never silently disable the gate."""
+    contract = tmp_path / "broken.prose.md"
+    contract.write_text(
+        "```yaml\n"
+        "report_only_guests:\n"
+        "  - node: storepve\n"
+        "    reason: \"typo - no guest identity\"\n"
+        "```\n"
+    )
+    scan_file = tmp_path / "scan.json"
+    scan_file.write_text(json.dumps([{"ct": 111, "usage_pct": 97}]))
+    proc = subprocess.run(
+        [sys.executable, str(PLAN), "--scan", str(scan_file),
+         "--contract", str(contract), "--json"],
+        capture_output=True, text=True,
+    )
+    assert proc.returncode != 0, proc.stdout
+    assert "gc-executor" not in proc.stdout
+    assert "identity" in proc.stderr.lower(), proc.stderr
+
+
 def _plan_with_contract(scan, contract_text, tmp_path, name):
     contract = tmp_path / name
     contract.write_text(contract_text)