Function run_connectors 

async fn run_connectors(
    config: &Config,
    connectors: &[&dyn Connector],
    full: bool,
    dry_run: bool,
    since: Option<String>,
    until: Option<String>,
    limit: Option<usize>,
    progress: Option<&dyn SyncProgressReporter>,
) -> Result<()>

Core sync engine: scans connectors sequentially, ingests items.

Scans are run sequentially since connectors hold references. Each connector’s items flow through the standard checkpoint → filter → upsert → chunk → embed pipeline.