[codex] Migrate thread turns list to thread store (#19280)

- migrate `thread/turns/list` to ThreadStore. Uses ThreadStore for most
data now but merges in the in-memory state from thread manager
- keep v2 `thread/list` pathless-store friendly by converting
`StoredThread` directly to API `Thread`
- add regression coverage for pathless store history/listing

codex-rs/thread-store/src/local/list_threads.rs

@@ -1,8 +1,15 @@
+use std::collections::HashMap;
+use std::collections::HashSet;
+
+use codex_protocol::ThreadId;
 use codex_rollout::RolloutConfig;
 use codex_rollout::RolloutRecorder;
+use codex_rollout::find_thread_names_by_ids;
 use codex_rollout::parse_cursor;
 
 use super::LocalThreadStore;
+use super::helpers::distinct_thread_metadata_title;
+use super::helpers::set_thread_name_from_title;
 use super::helpers::stored_thread_from_rollout_item;
 use crate::ListThreadsParams;
 use crate::SortDirection;
@@ -46,7 +53,7 @@ pub(super) async fn list_threads(
         .as_ref()
         .and_then(|cursor| serde_json::to_value(cursor).ok())
         .and_then(|value| value.as_str().map(str::to_owned));
-    let items = page
+    let mut items = page
         .items
         .into_iter()
         .filter_map(|item| {
@@ -58,6 +65,35 @@ pub(super) async fn list_threads(
         })
         .collect::<Vec<_>>();
 
+    let thread_ids = items
+        .iter()
+        .map(|thread| thread.thread_id)
+        .collect::<HashSet<_>>();
+    let mut names = HashMap::<ThreadId, String>::with_capacity(thread_ids.len());
+    if let Some(state_db_ctx) = store.state_db().await {
+        for &thread_id in &thread_ids {
+            let Ok(Some(metadata)) = state_db_ctx.get_thread(thread_id).await else {
+                continue;
+            };
+            if let Some(title) = distinct_thread_metadata_title(&metadata) {
+                names.insert(thread_id, title);
+            }
+        }
+    }
+    if names.len() < thread_ids.len()
+        && let Ok(legacy_names) =
+            find_thread_names_by_ids(store.config.codex_home.as_path(), &thread_ids).await
+    {
+        for (thread_id, title) in legacy_names {
+            names.entry(thread_id).or_insert(title);
+        }
+    }
+    for thread in &mut items {
+        if let Some(title) = names.get(&thread.thread_id).cloned() {
+            set_thread_name_from_title(thread, title);
+        }
+    }
+
     Ok(ThreadPage { items, next_cursor })
 }