Function write_backup_pair 

pub async fn write_backup_pair(
    scope_dir: &Path,
    table: &str,
    schema_yaml_path: &Path,
    db_path: &Path,
) -> Result<(), MiniAppError>

Creates a backup pair (YAML + SQLite DB snapshot) for a table.

The pair is written to {scope_dir}/_backup/{table}.{unix_secs}.yaml and {scope_dir}/_backup/{table}.{unix_secs}.db. The _backup directory is created if it does not exist.

The YAML file is copied verbatim from schema_yaml_path. The DB file is created via rusqlite::Connection::backup("main", …, None) using a fresh read-only connection (the existing Store connection is not touched).

A PRAGMA wal_checkpoint(TRUNCATE) is attempted before the backup to ensure the WAL is flushed. If the checkpoint fails it is logged as a warning and the backup continues regardless (rusqlite’s backup API handles WAL-mode databases internally).

Arguments

• scope_dir: the .mini-app/<scope>/ root directory for this table.
• table: the logical table name (used as filename prefix).
• schema_yaml_path: path to the schema.yaml file to back up.
• db_path: path to the SQLite database file to back up.

Returns

Ok(()) on success.

Errors

• MiniAppError::Backup if the timestamp cannot be determined, the backup directory cannot be created, the YAML copy fails, or the SQLite backup fails.
• MiniAppError::Backup if the spawn_blocking task panics.