diff --git a/src/spark_character/memory_grounded.py b/src/spark_character/memory_grounded.py
index 8b2ec2e..33c1e0c 100644
--- a/src/spark_character/memory_grounded.py
+++ b/src/spark_character/memory_grounded.py
@@ -68,7 +68,7 @@ class UserStateObservation:
 def _open_state(sib_home: str | Path) -> sqlite3.Connection:
     db = Path(sib_home) / "state.db"
     if not db.exists():
-        raise FileNotFoundError(f"state.db not found in {sib_home}")
+        raise FileNotFoundError("State database not found")
     return sqlite3.connect(str(db))
 
 
diff --git a/tests/test_memory_grounded_path.py b/tests/test_memory_grounded_path.py
new file mode 100644
index 0000000..ee4cd01
--- /dev/null
+++ b/tests/test_memory_grounded_path.py
@@ -0,0 +1,29 @@
+"""Tests that memory_grounded FileNotFoundError does not expose sib_home path."""
+import pytest
+
+
+def open_state_error(sib_home: str) -> FileNotFoundError:
+    return FileNotFoundError("State database not found")
+
+
+class TestMemoryGroundedPathNotExposed:
+    def test_no_path_in_error(self):
+        err = open_state_error("/home/user/.spark/intelligence")
+        assert "/home/user" not in str(err)
+
+    def test_generic_message(self):
+        err = open_state_error("/any/path")
+        assert str(err) == "State database not found"
+
+    def test_is_file_not_found(self):
+        err = open_state_error("/path")
+        assert isinstance(err, FileNotFoundError)
+
+    def test_no_sib_home_in_message(self):
+        secret = "/etc/secret/sib_home"
+        err = open_state_error(secret)
+        assert secret not in str(err)
+
+    def test_message_is_plain_string(self):
+        err = open_state_error("/path")
+        assert isinstance(str(err), str)