feat(agent): 云端 Agent - 增加上下文预算、任务事实与终态恢复保障

backend/internal/model/task_execution.go

@@ -0,0 +1,34 @@
+package model
+
+import "time"
+
+const (
+	TaskCancellationUserRequest     = "user_request"
+	TaskCancellationParentCancelled = "parent_cancelled"
+	TaskCancellationParentFailed    = "parent_failed"
+	TaskCancellationWorkerContext   = "worker_context"
+)
+
+// TaskExecutionDiagnostic records execution facts independently of the node's
+// presentation state. SafeMessage is suitable for users and model context.
+type TaskExecutionDiagnostic struct {
+	Code              string `json:"code"`
+	Phase             string `json:"phase"`
+	FieldPath         string `json:"fieldPath,omitempty"`
+	TaskSubmitted     bool   `json:"taskSubmitted"`
+	SubmissionOutcome string `json:"submissionOutcome"`
+	RetryClass        string `json:"retryClass"`
+	SafeMessage       string `json:"safeMessage"`
+	DiagnosticID      string `json:"diagnosticId"`
+	WritebackOutcome  string `json:"writebackOutcome,omitempty"`
+	WritebackReason   string `json:"writebackReason,omitempty"`
+	WritebackNodeID   string `json:"writebackNodeId,omitempty"`
+	WritebackMessage  string `json:"writebackMessage,omitempty"`
+}
+
+type TaskCancellationIntent struct {
+	Source      string
+	ActorID     string
+	RequestedAt time.Time
+	Diagnostic  TaskExecutionDiagnostic
+}