feat(backthink): 后台自主思考（heartbeat+事件触发 + 打扰决策 fail-closed + 主动推送活跃→IM 兜底 + 限制 + 思考记录）

internal/services/backthink/trigger.go

@@ -0,0 +1,55 @@
+package backthink
+
+import (
+	"fmt"
+
+	"git.yeij.top/AskaEth/Cyrene_v2/internal/bus"
+	"git.yeij.top/AskaEth/Cyrene_v2/internal/iot"
+)
+
+// Bus subjects the service subscribes to for event-triggered thinking. They are
+// the contract defined by design/12 §1: an IoT state change, a reminder firing,
+// or a generic system event.
+const (
+	// SubjectReminderTrigger is the bus subject on which reminders fire.
+	SubjectReminderTrigger = "reminder.trigger"
+	// SubjectSystemEvent is the bus subject for generic system events.
+	SubjectSystemEvent = "system.event"
+)
+
+// Trigger describes what woke a thinking pass: the source subsystem, a
+// human-readable summary and the event's estimated importance.
+type Trigger struct {
+	Source  string
+	Summary string
+	Import  Importance
+}
+
+// heartbeatTrigger is the periodic, low-importance trigger. Low importance means
+// the pass rarely interrupts the user, honouring "默认不发送 chat 类型消息".
+func heartbeatTrigger() Trigger {
+	return Trigger{Source: "heartbeat", Summary: "periodic autonomous reflection", Import: ImportanceLow}
+}
+
+// triggerForEvent maps a bus event to a Trigger. An IoT device change is treated
+// as normal importance, a reminder firing as high importance, and a generic
+// system event as normal importance.
+func triggerForEvent(e bus.Event) Trigger {
+	switch e.Subject {
+	case iot.DeviceUpdateSubject:
+		if d, ok := e.Payload.(iot.DeviceUpdate); ok {
+			return Trigger{
+				Source:  e.Subject,
+				Summary: fmt.Sprintf("device %s (%s) %s", d.Device.ID, d.Device.Type, d.Action),
+				Import:  ImportanceNormal,
+			}
+		}
+		return Trigger{Source: e.Subject, Summary: e.Subject, Import: ImportanceNormal}
+	case SubjectReminderTrigger:
+		return Trigger{Source: e.Subject, Summary: e.Subject, Import: ImportanceHigh}
+	case SubjectSystemEvent:
+		return Trigger{Source: e.Subject, Summary: e.Subject, Import: ImportanceNormal}
+	default:
+		return Trigger{Source: e.Subject, Summary: e.Subject, Import: ImportanceNormal}
+	}
+}