fix(sql-orm-client): namespace-aware through resolver after TML-2605 rebase

Main's namespace work (TML-2605) removed the unboundTable helper the
resolver relied on and made runtime SQL namespace-qualified. Resolve the
junction via resolveTableForContract so requiredPayloadColumns reads the
correct table and the resolved namespaceId is carried on the descriptor.

Consolidate ResolvedThrough onto ContractRelationThrough (export the
latter from @prisma-next/contract) and surface the junction namespaceId,
addressing Will's review on #678 (collection-contract.ts:201
'Needs namespace' + 'Duplicate of ContractRelationThrough?').

Signed-off-by: Alexey Orlenko's AI Agent <robot@aqrln.net>

Author: tensordreams

packages/1-framework/0-foundation/contract/src/exports/types.ts

@@ -30,6 +30,7 @@ export type {
   ContractReferenceRelation,
   ContractRelation,
   ContractRelationOn,
+  ContractRelationThrough,
   ContractValueObject,
   ContractVariantEntry,
   EmbedRelationKeys,

packages/3-extensions/sql-orm-client/src/collection-contract.ts

@@ -1,6 +1,7 @@
 import {
   type Contract,
   type ContractFieldType,
+  type ContractRelationThrough,
   type CrossReference,
   domainModelsAtDefaultNamespace,
 } from '@prisma-next/contract/types';
@@ -198,11 +199,9 @@ export function getCompleteColumnToFieldMap(
   return cached;
 }
 
-interface ResolvedThrough {
-  readonly table: string;
-  readonly parentColumns: readonly string[];
-  readonly childColumns: readonly string[];
-  readonly targetColumns: readonly string[];
+interface ResolvedThrough extends ContractRelationThrough {
+  /** Namespace of the junction table, resolved from storage. */
+  readonly namespaceId?: string;
   readonly requiredPayloadColumns: readonly string[];
 }
 
@@ -276,10 +275,10 @@ function resolveThrough(
     ...castAs<readonly string[]>(parentColumns),
     ...castAs<readonly string[]>(childColumns),
   ]);
-  const junctionTable = unboundTable(contract, table);
+  const resolvedJunction = resolveTableForContract(contract, table);
   const requiredPayloadColumns: string[] = [];
-  if (junctionTable) {
-    for (const [colName, col] of Object.entries(junctionTable.columns)) {
+  if (resolvedJunction) {
+    for (const [colName, col] of Object.entries(resolvedJunction.table.columns)) {
       if (!fkColumnSet.has(colName) && !col.nullable && col.default === undefined) {
         requiredPayloadColumns.push(colName);
       }
@@ -292,6 +291,7 @@ function resolveThrough(
     childColumns: castAs<readonly string[]>(childColumns),
     targetColumns: castAs<readonly string[]>(targetColumns),
     requiredPayloadColumns,
+    ...(resolvedJunction !== undefined ? { namespaceId: resolvedJunction.namespaceId } : {}),
   };
 }
 

packages/3-extensions/sql-orm-client/test/collection-contract.test.ts

@@ -476,6 +476,7 @@ describe('resolveModelRelations() through descriptor', () => {
       childColumns: ['child_id'],
       targetColumns: ['id'],
       requiredPayloadColumns: [],
+      namespaceId: 'public',
     });
   });