feat: 公共平台最小化打扰(design/12 §6)——5条策略: 分级+轻思考+限流+审查剔噪

降噪A(策略一/二/五):
- channelbridge/light.go: 非owner分级门——小事件当系统消息登记(不进loop)、非owner轻响应(她判断回/不回,规则优先mention/关键词+轻LLM兜底fail-closed静默)
- backthink 触发降噪: SubjectSystemEvent 低价值不唤醒thinking(仅高价值/owner才think), iot/reminder不受影响
- quiet hours: 安静时段非owner无信号静默,被@才回(非硬性静默); config QUIET_START/END_HOUR 单源共用

限流B(策略三/四):
- adapter/flowgate.go: per-adapter 滑窗限流器+总上限+审查剔噪闸门(Admit两连:速率+上限/审查), owner私聊绕过
- channelbridge/flowgate.go: onMessage入站最前挂闸, 超限/被剔不占worker槽; 审查模型NewLLMReviewer复用model.Adapter(仅>80%阈值触发+跨分钟节流,失败回退FIFO,绝不判身份)
- config: ChannelAccount 加 GroupMsgPerMin(默认6)/MsgPerMin/MaxMessages(默认50), CHANNELS_JSON每账号, 向后兼容
- 被剔消息走OnRejected审计不静默丢

main wire接线: 加modelAdapter字段+Review注入(reviewFor nil-safe,无LLM回退FIFO)
全仓 go build/vet/test 绿(53包)+交叉编译, 零新依赖, 前端无涉

cmd/cyrene/channels.go

@@ -110,13 +110,19 @@ type namedAdapter struct {
 	denyGroups  []string
 	allowUsers  []string
 	denyUsers   []string
+	// flow limits (design/12 §6 策略三/四). They are always surfaced through
+	// Config() so the bridge can build a per-account ingress gate; the bridge maps
+	// the zero default to the protective values and a negative value to "off".
+	groupMsgPerMin int
+	msgPerMin      int
+	maxMessages    int
 }
 
 func (n *namedAdapter) Name() string { return n.name }
 
 func (n *namedAdapter) Config() map[string]any {
 	cfg := n.PlatformAdapter.Config()
-	out := make(map[string]any, len(cfg)+4)
+	out := make(map[string]any, len(cfg)+7)
 	for k, v := range cfg {
 		out[k] = v
 	}
@@ -124,6 +130,9 @@ func (n *namedAdapter) Config() map[string]any {
 	out["denyGroups"] = n.denyGroups
 	out["allowUsers"] = n.allowUsers
 	out["denyUsers"] = n.denyUsers
+	out["groupMsgPerMin"] = n.groupMsgPerMin
+	out["msgPerMin"] = n.msgPerMin
+	out["maxMessages"] = n.maxMessages
 	return out
 }
 
@@ -182,6 +191,9 @@ func buildAccountAdapter(platform string, acct config.ChannelAccount, log *slog.
 		denyGroups:      acct.DenyGroups,
 		allowUsers:      acct.AllowUsers,
 		denyUsers:       acct.DenyUsers,
+		groupMsgPerMin:  acct.GroupMsgPerMin,
+		msgPerMin:       acct.MsgPerMin,
+		maxMessages:     acct.MaxMessages,
 	}, nil
 }
 

cmd/cyrene/wire.go

@@ -76,6 +76,7 @@ type app struct {
 	log           *slog.Logger
 	db            *sql.DB
 	bus           bus.Bus
+	modelAdapter  model.Adapter
 	personas      *personareg.Registry
 	caps          *registry.Registry
 	dispatcher    *tool.Dispatcher
@@ -263,6 +264,9 @@ func (a *app) wireRuntime() error {
 		a.log.Warn("llm adapter unavailable", "error", aerr)
 		adapter = nil
 	}
+	// Keep the model adapter for cross-function use (e.g. the channel-bridge
+	// review model that prunes low-value messages, design/12 §6 策略四).
+	a.modelAdapter = adapter
 	router := model.NewRouter(model.DefaultModelForProvider(a.cfg.LLM),
 		model.WithVisionModel(a.cfg.LLM.VisionModel))
 
@@ -484,11 +488,16 @@ func (a *app) wireChannels() error {
 	}
 
 	bridge, berr := channelbridge.New(channelbridge.Options{
-		Log:      logger.WithSource(a.log, "services/channelbridge"),
-		Loop:     a.loop,
-		Sessions: a.sessions,
-		Owner:    a.owner,
-		History:  a.history,
+		Log:            logger.WithSource(a.log, "services/channelbridge"),
+		Loop:           a.loop,
+		Sessions:       a.sessions,
+		Owner:          a.owner,
+		History:        a.history,
+		QuietStartHour: a.cfg.Background.QuietStartHour,
+		QuietEndHour:   a.cfg.Background.QuietEndHour,
+		// Optional review model prunes low-value queued messages near the per-adapter
+		// cap (design/12 §6 策略四). Nil adapter → the gate falls back to FIFO evict.
+		Review: reviewFor(a.modelAdapter, logger.WithSource(a.log, "services/channelbridge/review")),
 	})
 	if berr != nil {
 		return fmt.Errorf("channel bridge: %w", berr)
@@ -652,3 +661,13 @@ func resolveSQLitePath(cfg *config.Config, dataDir string) string {
 	}
 	return p
 }
+
+// reviewFor builds the channel-bridge review model (design/12 §6 策略四), or nil
+// when no model adapter is available so the gate falls back to FIFO eviction — the
+// reviewer is never invoked with a nil adapter (which would panic on .Chat).
+func reviewFor(llm model.Adapter, log *slog.Logger) adapter.Reviewer {
+	if llm == nil {
+		return nil
+	}
+	return channelbridge.NewLLMReviewer(llm, log)
+}