Function project_sync 

pub async fn project_sync(
    api_a: &dyn GatewayApi,
    api_b: &dyn GatewayApi,
    project: &str,
    selection: &SyncSelection,
    delete: bool,
    profile_a: &str,
    profile_b: &str,
) -> Result<ProjectSyncResult, CoreError>

ign project sync A B --project NAME — the guarded promotion. Order is the contract: export A then B → resolve the selection (explicit --resource paths must exist in A unless --delete wants them removed from B; --all_changed rides the diff) → splice A’s member bytes into B’s zip via the surgery helpers (replace_member’s descriptor-merge landing rules ride free — 05-07’s put-new hazard is handled) → optional remove_member passes for deletions → validate_import + ONE overwrite-import into B. B’s root project.json is never touched (only resource members splice). An EMPTY effective selection performs NO import (zero writes) and reports empty lists.