feat(agentcli): 运行结果 incomplete 语义与契约文档

RunResult 增加 Outcome/Reason；触顶标记 incomplete:max_steps；
WebSocket finish 区分 incomplete 与 fatal error。补充 ai-agent docs 13 与挂点索引。

backend/pkg/agentcli/core/agent.go

@@ -78,6 +78,9 @@ type RunResult struct {
 	Output      string
 	History     []llm.Message // system 之后的对话历史
 	TotalTokens int
+	// Outcome/Reason 对齐三产品契约（completed/incomplete/...） // Logan.Li
+	Outcome string
+	Reason  string
 }
 
 // Config Agent 运行配置 // Logan.Li
@@ -237,8 +240,7 @@ func (a *Agent) Run(ctx context.Context, query, serverInfo string, prior []llm.M
 			a.emit(Event{Type: EventDone, Phase: PhaseDone, Answer: answer, Tokens: a.totalTokens})
 			a.triggerEvolve(ctx, query, serverInfo, answer, toolRecords, true, start)
 			return &RunResult{
-				Success: true, Output: answer,
-				History: a.extractHistory(messages), TotalTokens: a.totalTokens,
+			Success: true, Output: answer, Outcome: "completed", History: a.extractHistory(messages), TotalTokens: a.totalTokens,
 			}, nil
 		}
 
@@ -255,12 +257,13 @@ func (a *Agent) Run(ctx context.Context, query, serverInfo string, prior []llm.M
 		consecutiveFailures = a.updateConsecutiveFailures(observations, consecutiveFailures) + failInc
 	}
 
-	// 达到最大轮次
-	msg := fmt.Sprintf("达到最大迭代次数(%d)，任务未能完成。可能任务过于复杂或需要更多步骤。", a.config.MaxIterations)
+	// 达到最大轮次 → incomplete:max_steps（契约 13） // Logan.Li
+	msg := fmt.Sprintf("incomplete:max_steps: 达到最大迭代次数(%d)，任务未完成。可加大预算或 continueTask 续跑。", a.config.MaxIterations)
 	a.emit(Event{Type: EventError, Phase: PhaseError, Message: msg, Tokens: a.totalTokens})
 	a.triggerEvolve(ctx, query, serverInfo, "", toolRecords, false, start)
 	return &RunResult{
-		Success: false, History: a.extractHistory(messages), TotalTokens: a.totalTokens,
+		Success: false, Output: msg, History: a.extractHistory(messages), TotalTokens: a.totalTokens,
+		Outcome: "incomplete", Reason: "max_steps",
 	}, fmt.Errorf("%s", msg)
 }