fix(audit): null actor FK when the user lookup throws

Address Greptile P1: the catch branch left the original actorId, so a system
actor like 'admin-api' (or a since-deleted user) would FK-violate the insert and
lose the row when the existence lookup errored. Mirror the not-found branch —
null the FK with a readable label — so the audit row always persists.

Author: waleedlatif1

packages/audit/src/log.test.ts

@@ -318,12 +318,12 @@ describe('recordAudit', () => {
       )
     })
 
-    it('inserts without actor info when lookup fails', async () => {
+    it('nulls the actor FK when the lookup throws so the insert cannot FK-violate', async () => {
       dbChainMockFns.limit.mockRejectedValue(new Error('DB down'))
 
       recordAudit({
         workspaceId: 'ws-1',
-        actorId: 'user-1',
+        actorId: 'admin-api',
         action: AuditAction.KNOWLEDGE_BASE_CREATED,
         resourceType: AuditResourceType.KNOWLEDGE_BASE,
       })
@@ -333,8 +333,8 @@ describe('recordAudit', () => {
       expect(dbChainMockFns.select).toHaveBeenCalledTimes(1)
       expect(dbChainMockFns.values).toHaveBeenCalledWith(
         expect.objectContaining({
-          actorId: 'user-1',
-          actorName: undefined,
+          actorId: null,
+          actorName: 'Admin API',
           actorEmail: undefined,
         })
       )

packages/audit/src/log.ts

@@ -87,7 +87,12 @@ async function insertAuditLog(params: AuditLogParams): Promise<void> {
         actorId = null
       }
     } catch (error) {
+      // The lookup couldn't confirm the user exists, so null the FK to guarantee
+      // the insert can't violate it (e.g. a system actor like 'admin-api', or a
+      // since-deleted user). The label still identifies the actor.
       logger.warn('Failed to resolve actor info', { error, actorId })
+      actorName = actorId === 'admin-api' ? 'Admin API' : 'System'
+      actorId = null
     }
   }