feat(backthink): 事件驱动主动消息绕过PushGate——IoT等事件该发就发(heartbeat仍受60min节流)

- trigger.go: 新增 TriggerKind(TriggerHeartbeat/TriggerEvent) + Trigger.Kind 标记触发来源
- push.go: PushRequest.TriggerKind 分流——event 跳过 gate.Allow/RecordPush(该发就发)，heartbeat 仍受 60min≤1/冷却/分类限频；PushResult.Bypassed 标记 + detail=event_bypass 区分
- backthink.go: think() 传 TriggerKind + 过同事件去重门
- event_dedup.go(新): 同事件(Source+Summary)去重防刷，无 60min 节流；不同事件/心跳后重置链
- 测试: event 连续 3 次全推 bypass / heartbeat 第2次 rate_limited / event 不消耗心跳限 / 同事件去重
- build/vet/test 全绿 + windows/darwin 交叉编译通过

internal/services/backthink/backthink.go

@@ -12,10 +12,12 @@
 // Each pass produces a conclusion, then consults Decide to judge whether the user
 // should be interrupted at all (event importance / time-of-day / user state such
 // as heart rate, sleep, work, busy / boredom). When it is worth interrupting the
-// push goes to the active client first and falls back to the IM bridge, bounded
-// by the proactive-push rate limit of DevDocs/design/11 §6. Every pass is
-// persisted to SQLite via Store so the M9/M10 monitor panel can render the
-// background-thinking page (design/12 §4).
+// push goes to the active client first and falls back to the IM bridge. The
+// proactive-push rate gate of DevDocs/design/11 §6 governs the periodic heartbeat
+// only; an event-driven push bypasses it (owner mandate: "该发就发") subject to
+// same-event dedup (see event_dedup.go). Every pass is persisted to SQLite via
+// Store so the M9/M10 monitor panel can render the background-thinking page
+// (design/12 §4).
 //
 // The package is concurrency-safe: a mutex guards the lifecycle state, the
 // injected store/pusher/thinker are required to be concurrency-safe by contract,
@@ -110,6 +112,11 @@ type Backthink struct {
 	cancel  context.CancelFunc
 	subs    []func()
 	wg      sync.WaitGroup
+
+	// eventMu guards the same-event dedup guard (event_dedup.go). It is separate
+	// from the lifecycle lock so a dedup decision never blocks a sink swap.
+	eventMu      sync.Mutex
+	lastEventKey string
 }
 
 // New builds a Backthink from cfg and deps, applying defaults and validating the
@@ -356,10 +363,18 @@ func (b *Backthink) think(parent context.Context, tr Trigger) {
 
 	pushRes := PushResult{Route: RouteNone, Detail: b.interruptReason(push, at, state, tr.Import, lastActivity, hasActivity)}
 	if shouldPush {
-		pushRes = b.currentPusher().Push(cctx, PushRequest{
-			Message:     b.buildProactiveMessage(message, channelHint),
-			ChannelHint: channelHint,
-		})
+		// Same-event dedup: a repeating identical event is suppressed after the
+		// first push (防刷), while a genuinely new event still goes out. Heartbeats
+		// are never deduped (they reset the chain) and stay gate-governed.
+		if b.eventRedundant(tr) {
+			pushRes = PushResult{Route: RouteNone, Detail: "duplicate event push suppressed"}
+		} else {
+			pushRes = b.currentPusher().Push(cctx, PushRequest{
+				Message:     b.buildProactiveMessage(message, channelHint),
+				ChannelHint: channelHint,
+				TriggerKind: tr.Kind,
+			})
+		}
 	}
 
 	b.record(Record{
@@ -371,7 +386,7 @@ func (b *Backthink) think(parent context.Context, tr Trigger) {
 	})
 
 	if shouldPush {
-		b.log.Info("backthink proactive push", "source", tr.Source, "route", pushRes.Route, "pushed", pushRes.Pushed, "reason", pushRes.Detail)
+		b.log.Info("backthink proactive push", "source", tr.Source, "route", pushRes.Route, "pushed", pushRes.Pushed, "bypass", pushRes.Bypassed, "reason", pushRes.Detail)
 	} else {
 		b.log.Debug("backthink did not interrupt", "source", tr.Source, "reason", pushRes.Detail)
 	}