docs: add comments explaining why VectorFilter exists for pgvector columns

VectorFilter provides equality/distinct operators for vector columns on Filter types.
While similarity search is done via condition types (embeddingNearby), connection-filter
may still auto-generate a filter for vector columns. Without this mapping, those fields
would be silently omitted from the generated SDK.

Author: pyramation

graphql/codegen/src/core/codegen/orm/input-types-generator.ts

@@ -322,7 +322,10 @@ const SCALAR_FILTER_CONFIGS: ScalarFilterConfig[] = [
     operators: ['equality', 'distinct', 'inArray', 'comparison', 'inet'],
   },
   { name: 'FullTextFilter', tsType: 'string', operators: ['fulltext'] },
-  // Vector filter (for pgvector embedding fields)
+  // VectorFilter: equality/distinct operators for vector columns on Filter types.
+  // Similarity search uses condition types (embeddingNearby), not filters, but
+  // connection-filter may still generate a filter for vector columns. This ensures
+  // the generated type uses number[] rather than being silently omitted.
   { name: 'VectorFilter', tsType: 'number[]', operators: ['equality', 'distinct'] },
   // List filters (for array fields like string[], int[], uuid[])
   {

graphql/codegen/src/core/codegen/scalars.ts

@@ -39,7 +39,7 @@ export const SCALAR_TS_MAP: Record<string, string> = {
   TsVector: 'string',
   TsQuery: 'string',
 
-  // Vector types (pgvector)
+  // Vector types (pgvector) — serialized as [Float] in GraphQL
   Vector: 'number[]',
 
   // File upload
@@ -61,6 +61,11 @@ export const SCALAR_FILTER_MAP: Record<string, string> = {
   BigFloat: 'BigFloatFilter',
   BitString: 'BitStringFilter',
   InternetAddress: 'InternetAddressFilter',
+  // VectorFilter provides equality/distinct operators (isNull, equalTo, etc.) for vector
+  // columns on Filter types. While similarity search is done via condition types
+  // (e.g., embeddingNearby on ContactCondition), postgraphile-plugin-connection-filter
+  // may still auto-generate a filter type for vector columns. Without this mapping,
+  // those fields would be silently omitted from the generated SDK.
   Vector: 'VectorFilter',
   FullText: 'FullTextFilter',
   Interval: 'StringFilter',