The problem with using `serde(flatten)` on Turn status is that it
conditionally serializes the `error` field, which is not the pattern we
want in API v2 where all fields on an object should always be returned.
```
#[derive(Serialize, Deserialize, Debug, Clone, PartialEq, JsonSchema, TS)]
#[serde(rename_all = "camelCase")]
#[ts(export_to = "v2/")]
pub struct Turn {
pub id: String,
/// Only populated on a `thread/resume` response.
/// For all other responses and notifications returning a Turn,
/// the items field will be an empty list.
pub items: Vec<ThreadItem>,
#[serde(flatten)]
pub status: TurnStatus,
}
#[derive(Serialize, Deserialize, Debug, Clone, PartialEq, JsonSchema, TS)]
#[serde(tag = "status", rename_all = "camelCase")]
#[ts(tag = "status", export_to = "v2/")]
pub enum TurnStatus {
Completed,
Interrupted,
Failed { error: TurnError },
InProgress,
}
```
serializes to:
```
{
"id": "turn-123",
"items": [],
"status": "completed"
}
{
"id": "turn-123",
"items": [],
"status": "failed",
"error": {
"message": "Tool timeout",
"codexErrorInfo": null
}
}
```
Instead we want:
```
{
"id": "turn-123",
"items": [],
"status": "completed",
"error": null
}
{
"id": "turn-123",
"items": [],
"status": "failed",
"error": {
"message": "Tool timeout",
"codexErrorInfo": null
}
}
```