Updates to the documentation about the id_random legacy.

documentation/GUIDE__AE_API_V3_for_Frontend.md

@@ -68,6 +68,30 @@ Modify data in the system.
     *   **Header:** `x-ae-ignore-extra-fields: true`
     *   **Behavior:** When set to `true`, the backend will automatically strip any fields from the payload that are not defined in the object's model before attempting to save to the database.
 
+### D. ID Fields in Responses (Vision ID Convention)
+
+> [!IMPORTANT]
+> **V3 responses always use random string IDs — never database integers.**
+
+After a successful `POST` create or any `GET`, the response contains:
+
+| Field | Type | Use |
+| :--- | :--- | :--- |
+| `{obj_type}_id` | `string` | **Primary public ID.** Use this for subsequent `PATCH` calls and UI routing. |
+| `{obj_type}_id_random` | `string` | Legacy alias. Same value as `{obj_type}_id`. Present for backward compat only. |
+
+**Example — create then immediately PATCH:**
+```ts
+const created = await postArchiveContent(archiveId, payload);
+const newId = created.data.archive_content_id; // random string e.g. "xK9mP3qRtL2"
+
+// Use it directly in the PATCH URL — no lookup needed
+await patchArchiveContent(newId, { name: 'Updated Name' });
+// PATCH /v3/crud/archive/{archive_id}/archive_content/{newId}
+```
+
+> **Note on `_id_random` suffix:** The `{obj_type}_id_random` field is a legacy artifact from the pre-Vision model. Once you confirm `{obj_type}_id` is a random string (length 11–22), you do not need `_id_random` as a fallback. New code should only read `{obj_type}_id`.
+
 ---
 
 ## 4. V3 Uniform Lookup System