Add enterprise appliance experience Phase 1 foundation

tests/backend/test_migrations.py

@@ -0,0 +1,31 @@
+import sqlite3
+
+from ._source import load_symbols
+
+
+def _migration_namespace():
+    return load_symbols("SCHEMA_VERSION", "_column_names", "run_migrations")
+
+
+def test_migration_is_idempotent_and_creates_operation_contract():
+    db = sqlite3.connect(":memory:")
+    db.execute("CREATE TABLE audit_log (id INTEGER PRIMARY KEY, detail TEXT)")
+    ns = _migration_namespace()
+    assert ns["run_migrations"](db) == 1
+    assert ns["run_migrations"](db) == 1
+    columns = {row[1] for row in db.execute("PRAGMA table_info(operations)")}
+    assert {"id", "correlation_id", "kind", "state", "idempotency_key", "recovery_actions"} <= columns
+    assert "correlation_id" in {row[1] for row in db.execute("PRAGMA table_info(audit_log)")}
+
+
+def test_newer_schema_is_rejected_without_mutation():
+    db = sqlite3.connect(":memory:")
+    db.execute("CREATE TABLE schema_metadata (key TEXT PRIMARY KEY, value TEXT NOT NULL)")
+    db.execute("INSERT INTO schema_metadata VALUES ('schema_version','999')")
+    ns = _migration_namespace()
+    try:
+        ns["run_migrations"](db)
+    except RuntimeError as exc:
+        assert "newer than supported" in str(exc)
+    else:
+        raise AssertionError("newer schema was accepted")