feat(backthink/admin): ③b — rag/delete 真实现 + D1 推送出口钩子(自建优先→个推兜底) + api-reference 补 D2/D3/D5 补丁

- B5: POST /admin/rag/delete 真做(DeleteDocument→DeleteProject 级联删章节+索引清理, owner+审计, 200/404/500, 500降级兜底); users/iot scenarios+rules 诚实501(无用户表/IoT场景规则模型, 消息写明缺什么, 不伪造), 锁住 501+not_implemented
- D1: backthink/push_outlet.go PushExporter{Export}; pushOutlet 自建HTTP(2xx=送达, token仅Authorization头+error脱敏)优先→Getui兜底(未接入, 诚实日志'getui not integrated'+(false,nil)); backthink.Deps.Exporter → pusher.withExporter, Push 在WS/IM后 exportAsync(detached+5s超时, 失败仅日志, 不破坏现有投递, 限流不上报); config PushOutletConfig(PUSH_EXPORTER_* + GETUI_*占位)
- 前端 Rag.tsx/api.ts 删除后 reload + 类型; Docs/api-client v0.31 + api-reference(#23 owner/200-404, §8.4, 端点表PATCH/DELETE messages + pinned + messages?q=)
- 测试(push_outlet/admin_rag_delete/admin_honest501/knowledge store), 后端+前端build全绿+3平台交叉编译
- 刻意: Getui SDK 未接入(无SDK不硬造), 主人自建服务填 PUSH_EXPORTER_URL/TOKEN 即可

internal/services/backthink/push.go

@@ -128,20 +128,34 @@ type Pusher interface {
 
 // pusher is the concrete Pusher: it consults the gate, then routes the message to
 // exactly one target — the active client for a "web" hint, otherwise the IM bridge.
+// After the local delivery it mirrors the message to the optional push outlet
+// (self-hosted service → Getui fallback) without blocking that delivery.
 type pusher struct {
-	active ActiveClient
-	im     IMAdapter
-	gate   PushGate
-	log    *slog.Logger
+	active   ActiveClient
+	im       IMAdapter
+	gate     PushGate
+	exporter PushExporter
+	log      *slog.Logger
+	// exportDone, when non-nil, receives one value after each asynchronous export
+	// completes. It exists so tests can deterministically observe the hook; the
+	// send is non-blocking, so a full channel never stalls the exporter.
+	exportDone chan struct{}
 }
 
 // newPusher builds a Pusher from the optional active-client sink, IM sink and
 // rate gate. Any of them may be nil; a nil target simply makes that route
-// unavailable.
+// unavailable. The push outlet is attached separately with withExporter.
 func newPusher(active ActiveClient, im IMAdapter, gate PushGate, log *slog.Logger) *pusher {
 	return &pusher{active: active, im: im, gate: gate, log: log}
 }
 
+// withExporter attaches the push outlet hook and returns the pusher for fluent
+// use. A nil exporter leaves the hook disabled.
+func (p *pusher) withExporter(exporter PushExporter) *pusher {
+	p.exporter = exporter
+	return p
+}
+
 // Push implements Pusher: it applies the rate gate, then routes the message to a
 // single target. A "web" hint reaches the active web/native client; every other
 // hint ("im", "auto", or a concrete platform) goes over the IM bridge once, where
@@ -192,6 +206,11 @@ func (p *pusher) Push(ctx context.Context, req PushRequest) PushResult {
 	if res.Pushed && p.gate != nil && !eventDriven {
 		p.gate.RecordPush(kind)
 	}
+	// D1: mirror the proactive message to the external push outlet (self-hosted
+	// unified push service → Getui fallback). Fire-and-forget: a slow or failing
+	// outlet never delays or breaks the local delivery above, and a rate-limited
+	// push returned before reaching here.
+	p.exportAsync(msg)
 	res = annotateHint(res, req.ChannelHint)
 	if eventDriven {
 		res.Bypassed = true
@@ -200,6 +219,33 @@ func (p *pusher) Push(ctx context.Context, req PushRequest) PushResult {
 	return res
 }
 
+// exportAsync reports msg to the push outlet on a detached, bounded goroutine so
+// the proactive path never blocks on the outlet. A nil exporter (hook disabled)
+// or a nil outlet result is a no-op; a delivery miss or error is only logged.
+func (p *pusher) exportAsync(msg adapter.UnifiedMessage) {
+	if p.exporter == nil {
+		return
+	}
+	timeout := defaultExportTimeout
+	go func() {
+		ctx, cancel := context.WithTimeout(context.Background(), timeout)
+		defer cancel()
+		delivered, err := p.exporter.Export(ctx, msg)
+		switch {
+		case err != nil:
+			p.log.Warn("push outlet export failed", "error", err)
+		case !delivered:
+			p.log.Info("push outlet did not deliver", "hint", "getui fallback not integrated")
+		}
+		if p.exportDone != nil {
+			select {
+			case p.exportDone <- struct{}{}:
+			default:
+			}
+		}
+	}()
+}
+
 // pushActive delivers only to the active web/native client.
 func (p *pusher) pushActive(ctx context.Context, msg adapter.UnifiedMessage) PushResult {
 	if p.active != nil {