Function resolve_pipeline_and_ingest 

async fn resolve_pipeline_and_ingest(
    log_state: LogState,
    query_ctx: QueryContext,
    headers: &HeaderMap,
    pipeline_name: Option<String>,
    version: Option<String>,
    requests: Vec<PipelineIngestRequest>,
    tag_columns: HashMap<String, HashSet<String>>,
) -> Response

Shared tail of /event and /raw: resolves the pipeline (identity default; overridable via param/header, with an optional ?version= pin), enables tag promotion + metadata-first primary-key ordering for the identity path only, runs the ingest, and maps the outcome to a HEC response.