Extract turn executor from codex orchestrator

Keep the turn loop in codex.rs as the orchestrator and move prompt preparation, tool router assembly, and sampling/tool execution into a dedicated turn_executor module.

Co-authored-by: Codex <noreply@openai.com>

codex-rs/core/src/codex_tests.rs

@@ -10,9 +10,16 @@ use crate::config_loader::Sourced;
 use crate::exec::ExecToolCallOutput;
 use crate::function_tool::FunctionCallError;
 use crate::mcp_connection_manager::ToolInfo;
+use crate::mcp_connection_manager::filter_codex_apps_mcp_tools_only;
+use crate::mcp_connection_manager::filter_mcp_tools_by_name;
 use crate::models_manager::model_info;
 use crate::shell::default_user_shell;
+use crate::stream_events_utils::HandleOutputCtx;
+use crate::stream_events_utils::handle_output_item_done;
+use crate::tools::ToolRouter;
 use crate::tools::format_exec_output_str;
+use crate::tools::parallel::ToolCallRuntime;
+use crate::turn_executor::AssistantMessageStreamParsers;
 
 use codex_protocol::ThreadId;
 use codex_protocol::models::FunctionCallOutputBody;
@@ -25,6 +32,7 @@ use codex_protocol::permissions::FileSystemSpecialPath;
 use codex_protocol::protocol::ReadOnlyAccess;
 use codex_protocol::protocol::SandboxPolicy;
 use codex_protocol::request_permissions::PermissionGrantScope;
+use codex_utils_stream_parser::ProposedPlanSegment;
 use tracing::Span;
 
 use crate::protocol::CompactedItem;
@@ -45,7 +53,6 @@ use crate::rollout::recorder::RolloutRecorderParams;
 use crate::state::TaskKind;
 use crate::tasks::SessionTask;
 use crate::tasks::SessionTaskContext;
-use crate::tools::ToolRouter;
 use crate::tools::context::FunctionToolOutput;
 use crate::tools::context::ToolInvocation;
 use crate::tools::context::ToolPayload;

codex-rs/core/src/lib.rs

@@ -114,6 +114,7 @@ pub mod state_db;
 pub mod terminal;
 mod tools;
 pub mod turn_diff_tracker;
+mod turn_executor;
 mod turn_metadata;
 mod turn_timing;
 pub use rollout::ARCHIVED_SESSIONS_SUBDIR;