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docs/architecture/runtime.md

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+# Runtime 架构
+
+Agent Runtime 负责生命周期管理，不直接承担所有业务能力。
+
+核心对象：
+
+- Agent
+- Session
+- Run
+- Task
+- Plan
+- Step
+- ToolCall
+- Observation
+- Memory
+- Result
+
+生命周期：
+
+```mermaid
+stateDiagram-v2
+    [*] --> Created
+    Created --> Running
+    Running --> Waiting
+    Waiting --> Running
+    Running --> Completed
+    Running --> Failed
+    Failed --> Retrying
+    Retrying --> Running
+    Completed --> [*]
+```