docs(roadmap): 更新 Phase 4b 状态为已完成

src/agent.rs

@@ -22,4 +22,5 @@ pub use builder::AgentBuilder;
 pub use error::AgentError;
 pub use runtime::{AgentConfig, RuntimeBundle};
 pub use session::AgentSession;
-pub use task::{Plan, Step, StepStatus};
+pub use task::{Plan, PlanParser, Step, StepStatus, TaskAgent};
+pub use task::JsonPlanParser;