Module plugin_aggregates 

Cross-crate registry of plugin-registered aggregate function names.

The Cypher AST’s crate::ast::Expr::is_aggregate uses a hardcoded list of built-in aggregate names (count, sum, min, …) to decide whether a FunctionCall routes through the planner’s aggregate translation. Plugin-registered aggregates (M9 uni.plugin.declareAggregate and any other uni_plugin::traits::aggregate::AggregatePluginFn source) are not in that list, so a Cypher query like RETURN myAgg(n.value) would otherwise fall through to scalar UDF resolution and fail.

Rather than thread a PluginRegistry reference through every AST query, plugin registrars publish each aggregate’s lowercased qname into this process-wide set at registration time. The AST consults it inside is_aggregate; the planner’s own copy of the hardcoded list (in uni-query/src/query/planner.rs::is_aggregate_function_name) does the same.

Lifecycle

Entries are added but never removed today (M9 declared aggregates cannot be dropped while in-flight queries reference them). When dropDeclared infrastructure matures past M11, a counterpart unregister_plugin_aggregate will follow.

Functions

is_known_plugin_aggregate

Return true if name (case-insensitive) was previously registered via register_plugin_aggregate.

register_plugin_aggregate

Register a fully-qualified aggregate name ("namespace.local") so the Cypher planner routes calls to it through the aggregate translation path instead of scalar UDF resolution.