fix: allow null parentAgentId in agent schemas and projections

packages/server/src/server/agent/agent-projections.ts

@@ -84,7 +84,7 @@ export function toAgentPayload(
     pendingPermissions: sanitizePendingPermissions(agent.pendingPermissions),
     persistence: sanitizePersistenceHandle(agent.persistence),
     title: options?.title ?? null,
-    parentAgentId: agent.parentAgentId,
+    parentAgentId: agent.parentAgentId ?? null,
   };
 
   const usage = sanitizeUsage(agent.lastUsage);

packages/server/src/server/messages.ts

@@ -251,7 +251,7 @@ export const AgentSnapshotPayloadSchema = z.object({
   requiresAttention: z.boolean().optional(),
   attentionReason: z.enum(["finished", "error", "permission"]).nullable().optional(),
   attentionTimestamp: z.string().nullable().optional(),
-  parentAgentId: z.string().optional(),
+  parentAgentId: z.string().nullable().optional(),
 });
 
 export type AgentSnapshotPayload = z.infer<typeof AgentSnapshotPayloadSchema>;