feat: add durable relative task delays and outage recovery regression

pulse/service/service.go

@@ -64,6 +64,9 @@ func NormalizeSubmit(in SubmitInput) (SubmitInput, error) {
 	if in.TaskTimeoutMS > 30*24*60*60*1000 {
 		return in, fault.Invalid("task_timeout_ms exceeds 30 days")
 	}
+	if in.DelayMS >= in.TaskTimeoutMS || (in.DelayMS != 0 && in.AvailableAt != nil) {
+		return in, fault.Invalid("delay_ms must be less than task_timeout_ms and cannot be combined with available_at")
+	}
 	if in.RecoverySafety == "" {
 		in.RecoverySafety = pulse.RecoveryReconcileOnly
 	}

pulse/service/service_test.go

@@ -24,7 +24,14 @@ func TestSubmitNormalizationAndBounds(t *testing.T) {
 		"unbounded attempts":      func(v *SubmitInput) { v.Retry.MaxAttempts = 101 },
 		"unknown recovery policy": func(v *SubmitInput) { v.RecoverySafety = "UNKNOWN" },
 		"excess timeout":          func(v *SubmitInput) { v.TaskTimeoutMS = 30*86400000 + 1 },
-		"sub-microsecond time":    func(v *SubmitInput) { now := time.Date(2026, 1, 1, 0, 0, 0, 1, time.UTC); v.AvailableAt = &now },
+		"delay equals deadline":   func(v *SubmitInput) { v.DelayMS = 86400000 },
+		"delay overflow":          func(v *SubmitInput) { v.DelayMS = ^uint64(0) },
+		"both timing modes": func(v *SubmitInput) {
+			now := time.Now().UTC().Truncate(time.Microsecond)
+			v.AvailableAt = &now
+			v.DelayMS = 1
+		},
+		"sub-microsecond time": func(v *SubmitInput) { now := time.Date(2026, 1, 1, 0, 0, 0, 1, time.UTC); v.AvailableAt = &now },
 	} {
 		t.Run(name, func(t *testing.T) {
 			in := base
@@ -34,6 +41,10 @@ func TestSubmitNormalizationAndBounds(t *testing.T) {
 			}
 		})
 	}
+	base.DelayMS = 86400000 - 1
+	if out, err := NormalizeSubmit(base); err != nil || out.DelayMS != base.DelayMS || out.AvailableAt != nil {
+		t.Fatal("relative delay was resolved before database acceptance", err)
+	}
 	for _, key := range []string{"", strings.Repeat("a", 129), "with space", "带中文", "line\n"} {
 		if ValidateKey(key) == nil {
 			t.Fatal("accepted invalid key")

pulse/service/types.go

@@ -29,7 +29,9 @@ type SubmitInput struct {
 	ConcurrencyKey string `json:"concurrency_key,omitempty"`
 	// Priority 冻结优先级，0至9，每级30秒排序优势，不改变最早执行时间。
 	Priority int16 `json:"priority,omitempty"`
-	// AvailableAt 最早执行时间；为空表示受理后即可进入派发范围。
+	// DelayMS 相对首次受理数据库时间的等待毫秒数；零为不延迟，非零不能与 AvailableAt 同用。
+	DelayMS uint64 `json:"delay_ms,omitempty"`
+	// AvailableAt 最早执行时间；为空且 DelayMS 为零表示受理后即可进入派发范围。
 	AvailableAt *time.Time `json:"available_at,omitempty"`
 	// StartDeadlineAt 最晚开始时间；为空表示使用任务总截止时间。
 	StartDeadlineAt *time.Time `json:"start_deadline_at,omitempty"`