diff --git a/src/agent_env/providers/env_state/env_state_provider.py b/src/agent_env/providers/env_state/env_state_provider.py
index f0e1ff93..a82b1c68 100644
--- a/src/agent_env/providers/env_state/env_state_provider.py
+++ b/src/agent_env/providers/env_state/env_state_provider.py
@@ -377,7 +377,9 @@ def get_init_script(environment_names: list[str]) -> str:
         SELECT schemaname, tablename
         FROM pg_tables
         WHERE schemaname = _schema_name
-          AND tablename != '_changelog'
+          -- Names starting with an underscore are a service's internal tables
+          -- (file bytes, caches), not domain rows; _changelog itself is one.
+          AND tablename NOT LIKE '\\_%'
     LOOP
         EXECUTE format(
             'DROP TRIGGER IF EXISTS _changelog_trigger ON %I.%I',
diff --git a/tst/integration/env/envs/service_db_changelog_test.py b/tst/integration/env/envs/service_db_changelog_test.py
index 8ab477ad..337696cc 100644
--- a/tst/integration/env/envs/service_db_changelog_test.py
+++ b/tst/integration/env/envs/service_db_changelog_test.py
@@ -128,3 +128,30 @@ def test_changelog_row_id_composite_pk(pg_conn):
         f"WHERE schema_name='{schema}' AND table_name='daily' ORDER BY id DESC LIMIT 1",
     )[0][0]
     assert json.loads(row_id) == {"user_id": "u_jin", "day": "2025-11-05"}
+
+
+def test_internal_tables_get_no_changelog_trigger(pg_conn):
+    """A service's internal tables (a leading underscore, like _changelog) hold no
+    domain rows: the installer skips them, so a blob written there is not copied
+    into changed_fields while the domain table beside it is still audited."""
+    schema = "files_svc"
+    _exec(pg_conn, LocalPostgresStateProvider.get_init_script([schema]))
+    _exec(pg_conn, f'CREATE TABLE "{schema}".documents (id text PRIMARY KEY, title text)')
+    _exec(pg_conn, f'CREATE TABLE "{schema}"._files (path text PRIMARY KEY, content bytea)')
+    _exec(pg_conn, f"SELECT public._install_changelog_triggers('{schema}')")
+
+    _exec(pg_conn, f"INSERT INTO \"{schema}\".documents VALUES ('d1', 'brief')")
+    _exec(pg_conn, f"INSERT INTO \"{schema}\"._files VALUES ('a/brief.pdf', '\\x255044462d')")
+
+    rows = _rows(
+        pg_conn,
+        "SELECT table_name, operation FROM public._changelog "
+        f"WHERE schema_name='{schema}' ORDER BY id",
+    )
+    assert rows == [("documents", "INSERT")]
+    triggers = _rows(
+        pg_conn,
+        "SELECT event_object_table FROM information_schema.triggers "
+        f"WHERE trigger_schema='{schema}' AND trigger_name='_changelog_trigger'",
+    )
+    assert {t[0] for t in triggers} == {"documents"}
diff --git a/tst/unit/providers/env_state/test_env_state_provider.py b/tst/unit/providers/env_state/test_env_state_provider.py
index bac759bf..741e1579 100644
--- a/tst/unit/providers/env_state/test_env_state_provider.py
+++ b/tst/unit/providers/env_state/test_env_state_provider.py
@@ -180,6 +180,10 @@ def test_get_init_script_changelog_components():
     for op in ("TG_OP = 'INSERT'", "TG_OP = 'DELETE'", "TG_OP = 'UPDATE'"):
         assert op in script
     assert "_install_changelog_triggers(_schema_name TEXT)" in script
+    # Internal tables (a leading underscore, like _changelog itself) carry no
+    # domain rows and get no trigger.
+    assert "tablename NOT LIKE '\\_%'" in script
+    assert "tablename != '_changelog'" not in script
     assert "WHERE schemaname = _schema_name" in script