Expose a runnable backend without giving the ingress layer secrets

The backend can now be inspected through a loopback-only gateway while the database-aware API remains on the internal data network. A governed synthetic demo proves readiness, pgvector retrieval, reranking, and citation output through real HTTP without invoking cloud models.

Constraint: The previously exposed Bailian key is compromised and cannot be used for live validation

Constraint: The API must be locally reachable while retaining no internet egress

Rejected: Attach the API directly to the ingress network | a real socket test proved that configuration still had egress

Rejected: Publish a port from the internal-only network | Docker Desktop did not expose the host port

Confidence: high

Scope-risk: moderate

Reversibility: clean

Directive: Keep model and database credentials out of the gateway; do not relax the fixed demo identity/profile filters

Tested: make verify; 63 pytest tests; strict mypy; Ruff; Secret scan; Compose config; three backend image builds; API/DB/gateway healthy; migration exit 0; Swagger browser check; live/ready/meta/status/search HTTP; 20/20/20 index; API egress ENETUNREACH; empty gateway mounts and business environment

Not-tested: Live Bailian calls require a newly rotated key; full generated-answer flow and React UI are not implemented

docs/05-stage1-runbook.md

@@ -21,7 +21,7 @@ bash scripts/init-local-secrets.sh
 离线模式使用确定性的 1024 维 feature-hash 向量和词法重排器，只验证数据治理、批处理、迁移、向量写入、权限过滤、检索、重排和幂等性，不把它当成真实模型质量。
 
 ```bash
-docker compose up -d --build db migrate
+docker compose up -d --build gateway
 docker compose --profile tools run --rm seed-demo-offline
 docker compose --profile tools run --rm seed-demo-offline
 ```
@@ -44,6 +44,28 @@ Seed 的实际流程是：
 7. 对 Top K 候选重排并输出虚构问题的 Hit@3；
 8. 相同输入再次执行使用相同 ID 和幂等 upsert，不增加行数。
 
+### 2.1 查看后端运行效果
+
+内部 API 只连接 `internal` data 网络，只挂载 app 数据库 Secret，不连接外网，也不挂载百炼 Key。无 Secret、无数据库凭证的 gateway 同时连接 ingress 与 data 网络，并且仅发布到本机回环地址 `127.0.0.1:8000`。两个容器都以数值非 root 用户运行，根文件系统只读，并移除 Linux capabilities。
+
+```bash
+curl http://127.0.0.1:8000/health/live
+curl http://127.0.0.1:8000/health/ready
+curl http://127.0.0.1:8000/api/v1/demo/status
+curl -X POST http://127.0.0.1:8000/api/v1/demo/search \
+  -H 'Content-Type: application/json' \
+  --data '{"query":"花岗斑岩铜矿化特征","top_k":3}'
+```
+
+预期结果：
+
+- readiness 返回 `database=ok`；
+- demo status 返回 chunks/vectors/searchable = 20/20/20；
+- search 只返回 `synthetic-demo` 数据集中的合成标题、批准后的片段、页码、分数和不透明 citation ID；
+- Swagger 位于 <http://127.0.0.1:8000/docs>。
+
+该接口是 Stage 1 的离线可见效果，不调用百炼，也不代表完整问答生成链或 React 前端已经完成。
+
 ## 3. 真实百炼能力探测
 
 完成旧 Key 轮换后：