feat(2): mattermost-lts P4 data-integrity overlay (ops.py postgres ci_marker seed + test_install/upgrade/backup/restore) — verifying recipe's PGDATA-dir restore brings the marker back

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

tests/mattermost-lts/ops.py

@@ -0,0 +1,46 @@
+"""mattermost-lts — pre-op seed hooks (Phase 1e HC3). The orchestrator runs these BEFORE each op; the
+matching test_<op>.py asserts post-op (assertion-only). The marker is a dedicated `ci_marker` row in
+postgres (mattermost's own schema migrations don't touch it), written via psql in the `db` service
+(POSTGRES_USER=mattermost, POSTGRES_DB=mattermost, password /run/secrets/postgres_password). The
+recipe's `db` service is backupbot-labelled (pg_dump pre-hook + the whole PGDATA dir at
+backup.path=/var/lib/postgresql/data/), so the marker rides the backup→restore cycle."""
+
+import os
+import sys
+
+sys.path.insert(0, os.path.join(os.path.dirname(__file__), "..", "..", "runner"))
+from harness import lifecycle  # noqa: E402
+
+
+def _psql(domain, sql):
+    cmd = (
+        "PGPASSWORD=$(cat /run/secrets/postgres_password) "
+        f'psql -U mattermost -d mattermost -tAc "{sql}"'
+    )
+    return lifecycle.exec_in_app(domain, ["sh", "-c", cmd], service="db").strip()
+
+
+def _seed(domain, value):
+    _psql(
+        domain,
+        "CREATE TABLE IF NOT EXISTS ci_marker(v text); DELETE FROM ci_marker; "
+        f"INSERT INTO ci_marker VALUES('{value}');",
+    )
+    assert _psql(domain, "SELECT v FROM ci_marker;") == value
+
+
+def pre_upgrade(domain, meta):
+    _seed(domain, "upgrade-survives")
+
+
+def pre_backup(domain, meta):
+    _seed(domain, "original")
+
+
+def pre_restore(domain, meta):
+    # drop the marker table (diverge from the backup) so a successful restore is observable
+    _psql(domain, "DROP TABLE ci_marker;")
+    assert _psql(domain, "SELECT to_regclass('public.ci_marker');") in (
+        "",
+        "NULL",
+    ), "drop did not take"