docs: update agent and UI protocol documentation

- Update api-endpoints.md with new agent endpoints
- Update run-agent-input.md with new input schemas
- Update sse-events.md with new event types
- Update ui-schema.md with schema changes

docs/protocols/agent/sse-events.md

@@ -84,7 +84,7 @@ data: <json>
   "type": "STEP_STARTED",
   "threadId": "...",
   "runId": "...",
-  "stepName": "worker" | "memory"
+  "stepName": "router" | "worker" | "memory"
 }
 ```
 
@@ -95,7 +95,7 @@ data: <json>
   "type": "STEP_FINISHED",
   "threadId": "...",
   "runId": "...",
-  "stepName": "worker" | "memory"
+  "stepName": "router" | "worker" | "memory"
 }
 ```
 
@@ -111,7 +111,7 @@ data: <json>
   "messageId": "...",
   "toolCallId": "...",
   "toolCallName": "...",
-  "stage": "worker"
+  "stage": "worker" | "memory"
 }
 ```
 
@@ -126,7 +126,7 @@ data: <json>
   "toolCallId": "...",
   "toolCallName": "...",
   "args": {},
-  "stage": "worker"
+  "stage": "worker" | "memory"
 }
 ```
 
@@ -140,7 +140,7 @@ data: <json>
   "messageId": "...",
   "toolCallId": "...",
   "toolCallName": "...",
-  "stage": "worker"
+  "stage": "worker" | "memory"
 }
 ```
 
@@ -153,7 +153,7 @@ data: <json>
   "runId": "...",
   "messageId": "...",
   "role": "tool",
-  "stage": "worker",
+  "stage": "worker" | "memory",
   "tool_name": "...",
   "tool_call_id": "...",
   "tool_call_args": {},
@@ -184,7 +184,7 @@ data: <json>
   "runId": "...",
   "messageId": "...",
   "role": "assistant",
-  "stage": "worker",
+  "stage": "worker" | "memory",
   "status": "success" | "partial_success" | "failed",
   "answer": "...",
   "key_points": [],
@@ -323,3 +323,9 @@ cost = uncached_prompt_tokens * input_cost_per_token
   - `ui_schema`
 
 这部分命名属于当前后端实现约束，文档与实现保持一致。
+
+## 8) 可见性与上下文装载说明
+
+- 持久化消息使用单字段 `visibility_mask`（位掩码）控制 consumer 可见性。
+- `/history` 仅投影 `ui.history` 可见消息。
+- 运行时上下文按当前 stage 对应 consumer 位过滤装载，不依赖前端展示可见性。