Crate uni_plugin_custom 

Meta-plugin (apoc.custom.declare* analogue) for uni-db.

This crate ships a built-in plugin whose procedures (uni.plugin.declareFunction, declareProcedure, declareAggregate, declareTrigger) accept Cypher source and persist new plugin registrations alongside the framework’s uni_plugin::PluginRegistry.

M9 status (this commit)

Completed M9 deliverables:

• uni.plugin.declareFunction — fully wired. Parses the Cypher expression body at declare time, persists the DeclaredPlugin record via persistence::Persistence, and registers a synthetic uni_plugin::traits::scalar::ScalarPluginFn into the shared PluginRegistry.
• uni.plugin.declareProcedure, declareAggregate, declareTrigger — registered as Cypher-callable procedures. Their declarations are persisted and reachable via uni.plugin.listDeclared; full body execution rides on downstream host APIs (ProcedureHost::execute_inner_query for procedures; trigger/aggregate body invocation follows the M11 capability work).
• uni.plugin.listDeclared / dropDeclared — extended for cascade-aware drops.
• Reactivation — declarations are reloaded into the registry on CustomPlugin::new when constructed with a non-empty persistence backend.
• Capability inheritance — declarations capture the declaring principal id; the registrar enforces capability gating at registration time via the synthetic plugin’s manifest.

Persistence

Proposal §9.7 anchors the persistence schema in a Cypher-visible system label _DeclaredPlugin. Writing to that label from inside a procedure requires write-enabled uni_plugin::traits::procedure::ProcedureHost execution, which does not yet exist (the host’s execute_inner_query is read-only and does not bind parameters — see crates/uni-query/src/query/executor/procedure_host.rs).

M9 ships persistence behind a persistence::Persistence trait with a JSON-sidecar implementation that preserves the exact DeclaredPlugin shape from §9.7. The cutover to system-label persistence — once write-enabled host execution lands — is a drop-in replacement of the backend; no schema, store, or procedure code changes.

Re-exports

pub use crate::persistence::JsonFilePersistence;

pub use crate::persistence::NullPersistence;

pub use crate::persistence::Persistence;

pub use crate::persistence::PersistenceError;

Modules

persistence

Persistence backends for declared-plugin records.

procedures

M9-shipped procedures fronting the declared-plugin store.

Structs

CustomPlugin

Top-level meta-plugin handle.

DeclaredAggregateFn

A Cypher-declared aggregate function.

DeclaredPlugin

Persistent record of a declared plugin (written to uni_system.declared_plugins per proposal §9.7 — currently shipped via JSON sidecar; see crate docs).

DeclaredPluginStore

In-memory store for declared plugins.

DeclaredScalarFn

A scalar function declared from Cypher via uni.plugin.declareFunction.

Enums

CustomError

Errors raised by the meta-plugin.

Traits

ProcedureBodySynthesizer

Host callback that turns a declared-procedure record into an executable uni_plugin::traits::procedure::ProcedurePlugin.

Functions

install_aggregate_into_registry

Compile a declared-aggregate record into a DeclaredAggregateFn and register it into registry under a synthetic plugin id derived from the qname’s namespace.