stripping schema nulls from stems

GEMINI.md

@@ -80,6 +80,7 @@ The Merger provides an automated, high-performance graph synchronization engine
 *   **Hierarchical Table Inheritance**: The Punc system uses distributed table inheritance (e.g. `person` inherits `user` inherits `organization` inherits `entity`). The Merger splits the incoming JSON payload and performs atomic row updates across *all* relevant tables in the lineage map.
 *   **The Archive Paradigm**: Data is never deleted in the Punc system. The Merger securely enforces referential integrity by toggling the `archived` Boolean flag on the base `entity` table rather than issuing SQL `DELETE` commands.
 *   **Change Tracking & Reactivity**: The Merger diffs the incoming JSON against the existing database row (utilizing static, `DashMap`-cached `lk_` SELECT string templates). Every detected change is recorded into the `agreego.change` audit table, tracking the user mapping. It then natively uses `pg_notify` to broadcast a completely flat row-level diff out to the Go WebSocket server for O(1) routing.
+*   **Intelligent Nested Notifications (Reactive Hydration)**: When the Merger detects that a Foreign Key column (e.g., `customer_id` on an `order`) has been explicitly modified, it automatically queries the newly pointed-to entity (e.g., `person`) and bundles its full JSON payload directly inside the parent's `pg_notify` broadcast. This guarantees that downstream caching clients (like the Dart UI) seamlessly receive the exact required subgraph to hydrate their relational widgets instantly, eliminating the need for N+1 HTTP fetches or extraneous notification lookups. This only triggers when the parent entity actively owns the relationship column and the value materially changes.
 *   **Many-to-Many Graph Edge Management**: Operates seamlessly with the global `agreego.relationship` table, allowing the system to represent and merge arbitrary reified M:M relationships directionally between any two entities.
 *   **Sparse Updates**: Empty JSON strings `""` are directly bound as explicit SQL `NULL` directives to clear data, whilst omitted (missing) properties skip UPDATE execution entirely, ensuring partial UI submissions do not wipe out sibling fields.
 *   **Unified Return Structure**: To eliminate UI hydration race conditions and multi-user duplication, `jspg_merge` explicitly strips the response graph and returns only the root `{ "id": "uuid" }` (or an array of IDs for list insertions). External APIs can then explicitly call read APIs to fetch the resulting graph, while the UI relies 100% implicitly on the flat `pg_notify` pipeline for reactive state synchronization.