Add sorting/backwardsCursor to thread/list and new thread/turns/list api (#17305)

To improve performance of UI loads from the app, add two main
improvements:
1. The `thread/list` api now gets a `sortDirection` request field and a
`backwardsCursor` to the response, which lets you paginate forwards and
backwards from a window. This lets you fetch the first few items to
display immediately while you paginate to fill in history, then can
paginate "backwards" on future loads to catch up with any changes since
the last UI load without a full reload of the entire data set.
2. Added a new `thread/turns/list` api which also has sortDirection and
backwardsCursor for the same behavior as `thread/list`, allowing you the
same small-fetch for immediate display followed by background fill-in
and resync catchup.

codex-rs/core/src/lib.rs

@@ -157,6 +157,7 @@ pub use rollout::RolloutRecorder;
 pub use rollout::RolloutRecorderParams;
 pub use rollout::SESSIONS_SUBDIR;
 pub use rollout::SessionMeta;
+pub use rollout::SortDirection;
 pub use rollout::ThreadItem;
 pub use rollout::ThreadSortKey;
 pub use rollout::ThreadsPage;

codex-rs/core/src/personality_migration.rs

@@ -79,6 +79,7 @@ async fn has_threads(store: &LocalThreadStore, archived: bool) -> io::Result<boo
             page_size: 1,
             cursor: None,
             sort_key: ThreadSortKey::CreatedAt,
+            sort_direction: codex_thread_store::SortDirection::Desc,
             allowed_sources: Vec::new(),
             model_providers: None,
             archived,

codex-rs/core/src/realtime_context.rs

@@ -6,6 +6,7 @@ use codex_exec_server::LOCAL_FS;
 use codex_git_utils::resolve_root_git_project_for_trust;
 use codex_protocol::models::ResponseItem;
 use codex_thread_store::ListThreadsParams;
+use codex_thread_store::SortDirection;
 use codex_thread_store::StoredThread;
 use codex_thread_store::ThreadSortKey;
 use codex_thread_store::ThreadStore;
@@ -132,6 +133,7 @@ async fn load_recent_threads(sess: &Session) -> Vec<StoredThread> {
             page_size: MAX_RECENT_THREADS,
             cursor: None,
             sort_key: ThreadSortKey::UpdatedAt,
+            sort_direction: SortDirection::Desc,
             allowed_sources: Vec::new(),
             model_providers: None,
             archived: false,

codex-rs/core/src/rollout.rs

@@ -7,6 +7,7 @@ pub use codex_rollout::RolloutRecorder;
 pub use codex_rollout::RolloutRecorderParams;
 pub use codex_rollout::SESSIONS_SUBDIR;
 pub use codex_rollout::SessionMeta;
+pub use codex_rollout::SortDirection;
 pub use codex_rollout::ThreadItem;
 pub use codex_rollout::ThreadSortKey;
 pub use codex_rollout::ThreadsPage;