Constant MIGRATION_SQL 

pub const MIGRATION_SQL: &str = "\
CREATE TABLE IF NOT EXISTS sync_cursors (
    device_id TEXT PRIMARY KEY,
    last_seq INTEGER NOT NULL
);

CREATE TABLE IF NOT EXISTS sync_state (
    key TEXT PRIMARY KEY,
    value TEXT NOT NULL
);

CREATE TABLE IF NOT EXISTS cloud_outbox (
    id INTEGER PRIMARY KEY AUTOINCREMENT,
    operation TEXT NOT NULL CHECK (operation IN ('upload', 'delete')),
    file_id TEXT NOT NULL,
    cloud_key TEXT NOT NULL,
    source_path TEXT,
    created_at TEXT NOT NULL,
    min_seq INTEGER,
    UNIQUE(operation, cloud_key)
);
";

SQL that creates coven’s bookkeeping tables. The host applies this alongside its own schema migration. Idempotent (IF NOT EXISTS).