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/push_test.go

@@ -237,3 +237,76 @@ func TestRateGate_KindWindowLimitsSameFlavor(t *testing.T) {
 		t.Fatal("same flavor after the kind window should be allowed")
 	}
 }
+
+// TestPusher_EventBypassesGate verifies an event-driven push skips the PushGate:
+// with a limit of 1 push per window, three consecutive event pushes are ALL
+// delivered (owner mandate "该发就发"), each marked Bypassed and each advancing
+// no cooldown/kind window.
+func TestPusher_EventBypassesGate(t *testing.T) {
+	t.Parallel()
+	active := &mockActive{n: 1}
+	p := newPusher(active, nil, newRateGate(1, time.Minute, 0, 0, discardLog()), discardLog())
+	req := PushRequest{Message: adapter.UnifiedMessage{Content: "洗衣机洗好了"}, TriggerKind: TriggerEvent}
+
+	first := p.Push(context.Background(), req)
+	second := p.Push(context.Background(), req)
+	third := p.Push(context.Background(), req)
+
+	if !first.Pushed || !first.Bypassed {
+		t.Fatalf("first event push = %+v, want delivered + Bypassed", first)
+	}
+	if !second.Pushed || !second.Bypassed {
+		t.Fatalf("second event push = %+v, want delivered + Bypassed (gate bypassed)", second)
+	}
+	if !third.Pushed || !third.Bypassed {
+		t.Fatalf("third event push = %+v, want delivered + Bypassed (gate bypassed)", third)
+	}
+	if active.calls != 3 {
+		t.Fatalf("active calls = %d, want 3 (events are not rate-capped)", active.calls)
+	}
+}
+
+// TestPusher_HeartbeatStillRateLimited verifies a heartbeat-driven push stays
+// gate-governed: with a limit of 1 push per window, the first passes and the
+// second is refused as rate_limited, never Bypassed.
+func TestPusher_HeartbeatStillRateLimited(t *testing.T) {
+	t.Parallel()
+	active := &mockActive{n: 1}
+	p := newPusher(active, nil, newRateGate(1, time.Minute, 0, 0, discardLog()), discardLog())
+	req := PushRequest{Message: adapter.UnifiedMessage{Content: "想跟你说声晚安"}, TriggerKind: TriggerHeartbeat}
+
+	first := p.Push(context.Background(), req)
+	second := p.Push(context.Background(), req)
+
+	if !first.Pushed || first.Bypassed {
+		t.Fatalf("first heartbeat push = %+v, want delivered non-bypassed", first)
+	}
+	if second.Pushed || second.Route != RouteRateLimited || second.Bypassed {
+		t.Fatalf("second heartbeat push = %+v, want rate_limited non-bypassed", second)
+	}
+	if active.calls != 1 {
+		t.Fatalf("active calls = %d, want 1 (heartbeat still gated)", active.calls)
+	}
+}
+
+// TestPusher_EventBypass_DoesNotAdvanceGate verifies an event-driven push does not
+// consume the heartbeat limit: after an event push, a following heartbeat push
+// still gets its own full allowance.
+func TestPusher_EventBypass_DoesNotAdvanceGate(t *testing.T) {
+	t.Parallel()
+	active := &mockActive{n: 1}
+	p := newPusher(active, nil, newRateGate(1, time.Minute, 0, 0, discardLog()), discardLog())
+
+	ev := p.Push(context.Background(), PushRequest{Message: adapter.UnifiedMessage{Content: "洗衣机洗好了"}, TriggerKind: TriggerEvent})
+	hb := p.Push(context.Background(), PushRequest{Message: adapter.UnifiedMessage{Content: "想跟你说声晚安"}, TriggerKind: TriggerHeartbeat})
+
+	if !ev.Pushed || !ev.Bypassed {
+		t.Fatalf("event push = %+v, want delivered + Bypassed", ev)
+	}
+	if !hb.Pushed || hb.Bypassed {
+		t.Fatalf("heartbeat push after an event = %+v, want delivered non-bypassed (event did not consume the gate)", hb)
+	}
+	if active.calls != 2 {
+		t.Fatalf("active calls = %d, want 2", active.calls)
+	}
+}