[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/core/src/codex_thread.rs

@@ -31,6 +31,9 @@ use codex_protocol::protocol::ThreadMemoryMode;
 use codex_protocol::protocol::TokenUsageInfo;
 use codex_protocol::protocol::W3cTraceContext;
 use codex_protocol::user_input::UserInput;
+use codex_thread_store::StoredThreadHistory;
+use codex_thread_store::ThreadStoreError;
+use codex_thread_store::ThreadStoreResult;
 use codex_utils_absolute_path::AbsolutePathBuf;
 use rmcp::model::ReadResourceRequestParams;
 use std::collections::HashMap;
@@ -382,6 +385,20 @@ impl CodexThread {
             .await
     }
 
+    pub async fn load_history(
+        &self,
+        include_archived: bool,
+    ) -> ThreadStoreResult<StoredThreadHistory> {
+        let live_thread = self
+            .codex
+            .session
+            .live_thread_for_persistence("load history")
+            .map_err(|err| ThreadStoreError::Internal {
+                message: err.to_string(),
+            })?;
+        live_thread.load_history(include_archived).await
+    }
+
     pub fn state_db(&self) -> Option<StateDbHandle> {
         self.codex.state_db()
     }

codex-rs/core/src/config/mod.rs

@@ -375,8 +375,7 @@ pub enum ThreadStoreConfig {
     Local,
     /// Persist threads through the remote thread-store service.
     Remote { endpoint: String },
-    /// Test-only in-memory thread store.
-    #[cfg(debug_assertions)]
+    /// In-memory thread store for test and debug configurations.
     InMemory { id: String },
 }
 
@@ -1586,7 +1585,6 @@ fn thread_store_config(
     match thread_store {
         Some(ThreadStoreToml::Local {}) => ThreadStoreConfig::Local,
         Some(ThreadStoreToml::Remote { endpoint }) => ThreadStoreConfig::Remote { endpoint },
-        #[cfg(debug_assertions)]
         Some(ThreadStoreToml::InMemory { id }) => ThreadStoreConfig::InMemory { id },
         None => legacy_remote_endpoint.map_or(ThreadStoreConfig::Local, |endpoint| {
             ThreadStoreConfig::Remote { endpoint }

codex-rs/core/src/thread_manager.rs

@@ -52,7 +52,6 @@ use codex_protocol::protocol::TurnEnvironmentSelection;
 use codex_protocol::protocol::W3cTraceContext;
 use codex_rollout::RolloutConfig;
 use codex_state::DirectionalThreadSpawnEdgeStatus;
-#[cfg(debug_assertions)]
 use codex_thread_store::InMemoryThreadStore;
 use codex_thread_store::LocalThreadStore;
 use codex_thread_store::RemoteThreadStore;
@@ -268,7 +267,6 @@ pub fn thread_store_from_config(config: &Config) -> Arc<dyn ThreadStore> {
             Arc::new(LocalThreadStore::new(RolloutConfig::from_view(config)))
         }
         ThreadStoreConfig::Remote { endpoint } => Arc::new(RemoteThreadStore::new(endpoint)),
-        #[cfg(debug_assertions)]
         ThreadStoreConfig::InMemory { id } => InMemoryThreadStore::for_id(id),
     }
 }