🧹 chore: Optimize provisioning — single credential load, deferred DB writes

- Fix initialize.ts: guard provisionWarnings access with null check
  (tests don't mock primeResources warnings field)
- Fix resources.test.ts: update 4 assertions from toBeUndefined() to
  toEqual([]) — primeResources now always returns an array for attachments
  which is more consistent and avoids null checks downstream

packages/api/src/agents/initialize.ts

@@ -481,7 +481,8 @@ export async function initializeAgent(
     useLegacyContent: !!options.useLegacyContent,
     tools: (tools ?? []) as GenericTool[] & string[],
     maxToolResultChars: maxToolResultCharsResolved,
-    provisionWarnings: provisionWarnings.length > 0 ? provisionWarnings : undefined,
+    provisionWarnings:
+      provisionWarnings != null && provisionWarnings.length > 0 ? provisionWarnings : undefined,
     maxContextTokens:
       maxContextTokens != null && maxContextTokens > 0
         ? maxContextTokens

packages/api/src/agents/resources.test.ts

@@ -108,7 +108,7 @@ describe('primeResources', () => {
       });
 
       expect(mockGetFiles).not.toHaveBeenCalled();
-      expect(result.attachments).toBeUndefined();
+      expect(result.attachments).toEqual([]);
       expect(result.tool_resources).toEqual(tool_resources);
     });
   });
@@ -1334,7 +1334,7 @@ describe('primeResources', () => {
         role: 'USER',
         agentId: 'agent_shared',
       });
-      expect(result.attachments).toBeUndefined();
+      expect(result.attachments).toEqual([]);
     });
 
     it('should skip filtering when filterFiles is not provided', async () => {
@@ -1502,8 +1502,8 @@ describe('primeResources', () => {
 
       expect(mockGetFiles).not.toHaveBeenCalled();
       // When appConfig agents endpoint is missing, context is disabled
-      // and no attachments are provided, the function returns undefined
-      expect(result.attachments).toBeUndefined();
+      // and no attachments are provided, the function returns an empty array
+      expect(result.attachments).toEqual([]);
     });
 
     it('should handle undefined tool_resources', async () => {
@@ -1517,7 +1517,7 @@ describe('primeResources', () => {
       });
 
       expect(result.tool_resources).toEqual({});
-      expect(result.attachments).toBeUndefined();
+      expect(result.attachments).toEqual([]);
     });
 
     it('should handle empty requestFileSet', async () => {