This PR honors the `history.max_bytes` configuration parameter by
trimming `history.jsonl` whenever it grows past the configured limit.
While appending new entries we retain the newest record, drop the oldest
lines to stay within the byte budget, and serialize the compacted file
back to disk under the same lock to keep writers safe.
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
}
}
```
