drop_with_schema_from_on_graphql_validation_plugin_hook.md

hive-router-plan-executor	major
hive-router	patch

Drop with_schema from the on_graphql_validation plugin hook

Remove OnGraphQLValidationStartHookPayload::with_schema. Replacing only the validation schema was unsafe because parsing, introspection, normalization, planning, demand control, execution, coprocessors, and schema-aware caches continued using the request's original supergraph.

Plugins that need a request-specific schema should construct and retain an Arc<Supergraph>, then select it in on_http_request:

fn on_http_request<'req>(
    &'req self,
    payload: OnHttpRequestHookPayload<'req>,
) -> OnHttpRequestHookResult<'req> {
    payload.set_supergraph(self.supergraph_for_request(&payload));
    payload.proceed()
}

Build each variant with Supergraph::from_sdl or Supergraph::from_document outside the request hot path and reuse the same Arc<Supergraph>. The router snapshots the selected supergraph and applies it to the complete request pipeline.

See plugin_examples/replace_schema for overriding a configured default and plugin_examples/feature_flags for plugin-only supergraph selection.