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_test.go

@@ -3,6 +3,7 @@ package backthink
 import (
 	"context"
 	"errors"
+	"strings"
 	"testing"
 	"time"
 
@@ -308,3 +309,66 @@ func TestBackthink_Stop_UnsubscribesBus(t *testing.T) {
 		t.Fatalf("thinker calls grew after stop (bus not unsubscribed): %d -> %d", before, got)
 	}
 }
+
+// TestBackthink_EventPush_DedupSameEvent verifies the same-event dedup guard: a
+// repeating identical event (same source + summary) is suppressed after the first
+// push (防刷), while a genuinely different event still goes out. The duplicate is
+// recorded as suppressed (route none), not delivered.
+func TestBackthink_EventPush_DedupSameEvent(t *testing.T) {
+	t.Parallel()
+	thinker := &mockThinker{text: "washing finished, clothes ready"}
+	pusher := &mockPusher{result: PushResult{Pushed: true, Route: RouteActiveClient}}
+	b, _ := newBackthink(t, Config{}, Deps{
+		Thinker: thinker,
+		State:   &mockState{state: UserState{}},
+		Pusher:  pusher,
+		Now:     func() time.Time { return dayAt() },
+	})
+
+	ev := triggerForEvent(bus.Event{Subject: iot.DeviceUpdateSubject, Payload: iot.DeviceUpdate{
+		Device: iot.Device{ID: "washer", Type: "sensor"}, Action: "finished",
+	}})
+
+	b.think(context.Background(), ev) // first: pushes
+	b.think(context.Background(), ev) // second: same event -> suppressed
+	b.think(context.Background(), ev) // third: same event -> suppressed
+
+	if got := pusher.count(); got != 1 {
+		t.Fatalf("pusher calls = %d, want 1 (repeating same event deduped)", got)
+	}
+	recs, err := b.List(context.Background(), 10)
+	if err != nil {
+		t.Fatalf("List: %v", err)
+	}
+	if len(recs) < 3 {
+		t.Fatalf("len(recs) = %d, want at least 3 (one per think)", len(recs))
+	}
+	// Newest first: the two most recent records are the suppressed duplicates.
+	for i := 0; i < 2; i++ {
+		if recs[i].PushResult.Pushed || recs[i].PushResult.Route != RouteNone {
+			t.Fatalf("recs[%d] = %+v, want suppressed duplicate", i, recs[i].PushResult)
+		}
+		if !strings.Contains(recs[i].PushResult.Detail, "duplicate") {
+			t.Fatalf("recs[%d].Detail = %q, want it to mention duplicate", i, recs[i].PushResult.Detail)
+		}
+	}
+	// The third-most-recent record is the first (delivered) push.
+	if !recs[2].PushResult.Pushed || recs[2].PushResult.Route != RouteActiveClient {
+		t.Fatalf("recs[2] = %+v, want the first delivered push", recs[2].PushResult)
+	}
+
+	// A genuinely different event resets the chain and goes out.
+	ev2 := triggerForEvent(bus.Event{Subject: iot.DeviceUpdateSubject, Payload: iot.DeviceUpdate{
+		Device: iot.Device{ID: "dryer", Type: "sensor"}, Action: "finished",
+	}})
+	b.think(context.Background(), ev2)
+	if got := pusher.count(); got != 2 {
+		t.Fatalf("pusher calls after a different event = %d, want 2", got)
+	}
+	// After the different event, the original identical event is no longer a
+	// consecutive duplicate, so it pushes again — the guard only dedups consecutively.
+	b.think(context.Background(), ev)
+	if got := pusher.count(); got != 3 {
+		t.Fatalf("pusher calls after an intervening different event = %d, want 3", got)
+	}
+}