Lukas
a44f1ef35b
Replace non-atomic db.executescript() with explicit transaction control. Wrap each migration's DDL statements and schema_migrations insert in a single BEGIN IMMEDIATE ... COMMIT transaction to ensure atomicity. Changes: - Add _parse_migration_statements() to split migration scripts into individual statements while handling comments and string literals - Update _apply_migration() to wrap all statements in a single explicit transaction with rollback on error - Ensure _get_current_schema_version() uses execute() instead of executescript() - Add 9 new tests for migration atomicity and statement parsing - Update Backend-Development.md with migration authoring guidelines If a crash occurs between DDL execution and schema_migrations insert, the next startup will re-apply the entire migration atomically, preventing partial migrations and data corruption. Test coverage: 98% on db.py (up from 55%) Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>