Make stopped work actionable and retain detailed execution errors

Why: A budget-stopped task retained a promise to generate a final result, while readable card errors need the full diagnosis in the execution record.

Evidence: Continuation-promise and missing-error-record regressions failed on the prior implementation; the full Backend suite now passes.

Impact: Terminal next steps require user action, stopped work has clear labels, and precise subagent errors persist outside the default task summary.

Refs: Independent A04 model assessment; approved R08 and R10

internal/runmgr/background_card_test.go

@@ -160,6 +160,10 @@ func TestBackgroundCardLifecycleOnFailure(t *testing.T) {
 	if statusLabel != core.TaskSummaryStatusFailed {
 		t.Fatalf("status kv = %q, want %q", statusLabel, core.TaskSummaryStatusFailed)
 	}
+	failed, err := c.mgr.st.GetRunByID(card.SourceRunID)
+	if err != nil || failed.Error == nil || failed.Error.Message != runner.err.Error() {
+		t.Fatalf("failure details were lost from the execution record: %+v %v", failed.Error, err)
+	}
 }
 
 func TestBackgroundCardCreateUsesL1SkeletonNotRawTask(t *testing.T) {

internal/runmgr/runmgr.go

@@ -1800,6 +1800,9 @@ func (m *Manager) finishChild(rc *runCtx, runner runtime.Runner, emitResult bool
 	child.Status = status
 	child.Phase = core.PhaseDone
 	child.Usage = &usage
+	if execErr != nil {
+		child.Error = &core.ErrorPart{Code: "run.subagent_failed", Message: execErr.Error()}
+	}
 	m.st.UpdateRun(&child)
 	if emitResult {
 		m.emit(child.ConversationID, child.ID, core.EvAgentResult, payload)

internal/runmgr/task_projection.go

@@ -169,6 +169,7 @@ func (m *Manager) finishTaskProjection(b taskBinding, payload core.AgentResultPa
 		}
 		s.DeliveryState = "available"
 		s.Conclusion = taskResultConclusion(payload)
+		s.NextStep = "核验已有结果和未决事项，再选择后续工作"
 		s.CheckpointKeys = nil
 		if runErr != nil {
 			s.ExecutionState = "failed"
@@ -179,7 +180,11 @@ func (m *Manager) finishTaskProjection(b taskBinding, payload core.AgentResultPa
 			if len(s.Findings) > 0 {
 				s.OutcomeCompleteness = "partial"
 			}
-			s.Conclusion = "执行失败：" + runErr.Error()
+			s.NextStep = "核对已有发现和材料；需要继续处理时重新提出请求"
+			s.Conclusion = "执行失败，任务已停止；请核验已有发现和材料限制"
+			if strings.Contains(runErr.Error(), "budget_exceeded") {
+				s.Conclusion = "达到本次处理额度，执行已停止；已有发现已保留"
+			}
 		}
 		if s.Conclusion == "" {
 			s.Conclusion = "没有可用结果摘要"
@@ -212,8 +217,15 @@ func (m *Manager) finishTaskProjection(b taskBinding, payload core.AgentResultPa
 				}
 			}
 		}
-		s.Phase = core.TaskPhase{ID: s.ExecutionState, Label: "处理结束", ObservedAt: time.Now().UTC()}
-		s.Focus = "处理结束"
+		label := "处理结束"
+		if s.ExecutionState == "failed" {
+			label = "执行已停止"
+		}
+		if s.ExecutionState == "interrupted" {
+			label = "任务已中断"
+		}
+		s.Phase = core.TaskPhase{ID: s.ExecutionState, Label: label, ObservedAt: time.Now().UTC()}
+		s.Focus = label
 		s.LastActivityAt = time.Now().UTC()
 		s.LastMeaningfulUpdateAt = s.LastActivityAt
 		if e := s.Validate(); e != nil {

internal/runmgr/task_projection_test.go

@@ -3,12 +3,33 @@ package runmgr
 import (
 	"agent-system-backend/internal/cardsvc"
 	core "agent-system-core"
+	"errors"
 	"os"
 	"path/filepath"
 	"strings"
 	"testing"
 )
 
+func TestFailedTaskDoesNotPromiseAutomaticContinuation(t *testing.T) {
+	c := checkpointEnvironment(t)
+	if err := c.mgr.mutateTask(c.task, func(s *core.TaskSnapshot) error {
+		s.NextStep = "输出最终结构化整理结果"
+		return nil
+	}); err != nil {
+		t.Fatal(err)
+	}
+	if err := c.mgr.finishTaskProjection(c.task, core.AgentResultPayload{}, errors.New("budget_exceeded: run token budget exhausted")); err != nil {
+		t.Fatal(err)
+	}
+	card, err := c.mgr.st.GetCard(c.run.Owner, c.task.cardID)
+	if err != nil {
+		t.Fatal(err)
+	}
+	if card.Task.Phase.ID != "failed" || card.Task.Phase.Label != "执行已停止" || strings.Contains(card.Task.NextStep, "输出最终") || strings.Contains(card.Task.Conclusion, "budget_exceeded") {
+		t.Fatalf("stopped task retained a process promise: %+v", card.Task)
+	}
+}
+
 func TestTaskConclusionSkipsProcessText(t *testing.T) {
 	c, _ := newCardSpawnEnv(t, &gateRunner{parts: []core.Part{{Type: core.PartText, Process: true, Text: "我先检查知识库。"}, {Type: core.PartText, Text: "日期仍待裁定，预算审批尚未完成。"}}})
 	c.mgr.runner = noopRunner{}