Implement approval engine production readiness

Assistant: codex
Assistant-Model: gpt-5.6-sol
Assistant-Session: 01a05e2e-805b-7042-a750-71f473bceea2

tests/test_storage.py

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+import os
+import sqlite3
+from pathlib import Path
+
+import pytest
+
+from approval_engine.errors import Conflict, StoreUnavailable
+from approval_engine.store import Engine, LATEST_SCHEMA_VERSION
+from tests.conftest import FROZEN, approve
+
+
+def test_production_open_refuses_unmigrated_database(tmp_path):
+    path = tmp_path / "approval.sqlite"
+    sqlite3.connect(path).close()
+    with pytest.raises(StoreUnavailable, match="run approval-engine migrate"):
+        Engine(path, clock=lambda: FROZEN, auto_migrate=False)
+
+
+def test_migrate_then_open_without_auto_migrate(tmp_path):
+    path = tmp_path / "approval.sqlite"
+    migrated = Engine(path, clock=lambda: FROZEN)
+    migrated.close()
+    production = Engine(path, clock=lambda: FROZEN, auto_migrate=False)
+    status = production.storage_status(integrity=True)
+    assert status["schema_version"] == LATEST_SCHEMA_VERSION
+    assert status["schema_current"] is True
+    assert status["persistent"] is True
+    assert status["ok"] is True
+    production.close()
+
+
+def test_online_backup_is_mode_0600_and_restorable(tmp_path):
+    source = tmp_path / "approval.sqlite"
+    backup = tmp_path / "approval.backup.sqlite"
+    engine = Engine(source, clock=lambda: FROZEN)
+    obj = approve(engine)
+    result = engine.backup(backup)
+    assert result["integrity"] == "ok"
+    assert os.stat(backup).st_mode & 0o777 == 0o600
+    restored = Engine(backup, clock=lambda: FROZEN, auto_migrate=False)
+    assert restored.get(obj.id).id == obj.id
+    assert restored.storage_status(integrity=True)["ok"] is True
+    restored.close()
+    engine.close()
+
+
+def test_backup_refuses_overwrite(tmp_path):
+    source = tmp_path / "approval.sqlite"
+    target = tmp_path / "existing.sqlite"
+    target.write_text("do not overwrite")
+    engine = Engine(source, clock=lambda: FROZEN)
+    with pytest.raises(Conflict, match="already exists"):
+        engine.backup(target)
+    assert target.read_text() == "do not overwrite"
+    engine.close()