🪪 fix: Enforce Conversation Ownership Checks in Remote Agent Controllers (#12263)

* 🔒 fix: Validate conversation ownership in remote agent API endpoints

Add user-scoped ownership checks for client-supplied conversation IDs
in OpenAI-compatible and Open Responses controllers to prevent
cross-tenant file/message loading via IDOR.

* 🔒 fix: Harden ownership checks against type confusion and unhandled errors

- Add typeof string validation before getConvo to block NoSQL operator
  injection (e.g. { "$gt": "" }) bypassing the ownership check
- Move ownership checks inside try/catch so DB errors produce structured
  JSON error responses instead of unhandled promise rejections
- Add string type validation for conversation_id and previous_response_id
  in the upstream TS request validators (defense-in-depth)

* 🧪 test: Add coverage for conversation ownership validation in remote agent APIs

- Fix broken getConvo mock in openai.spec.js (was missing entirely)
- Add tests for: owned conversation, unowned (404), non-string type (400),
  absent conversation_id (skipped), and DB error (500) — both controllers

packages/api/src/agents/openai/service.ts

@@ -289,6 +289,14 @@ export function validateRequest(body: unknown): ChatCompletionValidationResult {
     }
   }
 
+  if (request.conversation_id !== undefined && typeof request.conversation_id !== 'string') {
+    return { valid: false, error: 'conversation_id must be a string' };
+  }
+
+  if (request.parent_message_id !== undefined && typeof request.parent_message_id !== 'string') {
+    return { valid: false, error: 'parent_message_id must be a string' };
+  }
+
   return { valid: true, request: request as unknown as ChatCompletionRequest };
 }
 

packages/api/src/agents/responses/service.ts

@@ -84,6 +84,13 @@ export function validateResponseRequest(body: unknown): RequestValidationResult
     }
   }
 
+  if (
+    request.previous_response_id !== undefined &&
+    typeof request.previous_response_id !== 'string'
+  ) {
+    return { valid: false, error: 'previous_response_id must be a string' };
+  }
+
   return { valid: true, request: request as unknown as ResponseRequest };
 }