M0：灵台 Kernel 骨架（事件溯源/命台席位/瀑布总线/插件注册）与神识客户端边界，新增 POST /runs 占位闭环与测试，Alembic 基线合并为单一起点

backend/app/shenshi_client/client.py

@@ -0,0 +1,93 @@
+"""神识客户端：灵台唯一的模型出口边界。
+
+两种实现可互换（Protocol）：
+- ``HttpShenshiClient``：经 HTTP+SSE 调用 Go 神识服务（SHENSHI_BASE_URL 配置时启用）；
+- ``EchoShenshi``：进程内回声桩，逐字回流输入，供本地开发与测试在无神识时跑通端到端。
+
+领域模块禁止绕过本边界 import Provider SDK（docs/architecture/service-boundaries.md §4）。
+"""
+
+from __future__ import annotations
+
+import json
+from collections.abc import AsyncIterator
+from typing import Protocol
+
+import httpx
+
+from app.shenshi_client.types import ShenshiChatRequest, ShenshiDelta, ShenshiError
+
+
+class ShenshiClient(Protocol):
+    """神识数据面契约：流式对话补全。"""
+
+    def stream_chat(self, request: ShenshiChatRequest) -> AsyncIterator[ShenshiDelta]: ...
+
+
+class EchoShenshi:
+    """进程内回声桩：把最后一条用户消息按固定粒度切分回流。
+
+    只用于 M0 骨架验证（登录 → 占位 Run → SSE 端到端），不模拟任何 Provider 行为。
+    """
+
+    chunk_size = 8
+
+    async def stream_chat(self, request: ShenshiChatRequest) -> AsyncIterator[ShenshiDelta]:
+        prompt = next((m.content for m in reversed(request.messages) if m.role == "user"), "")
+        text = f"【回声桩】{prompt}"
+        for i in range(0, len(text), self.chunk_size):
+            yield ShenshiDelta(delta=text[i : i + self.chunk_size])
+        yield ShenshiDelta(
+            finish_reason="stop",
+            usage_prompt_tokens=max(len(prompt) // 4, 1),
+            usage_completion_tokens=max(len(text) // 4, 1),
+        )
+
+
+class HttpShenshiClient:
+    """HTTP+SSE 神识客户端。
+
+    认证：服务令牌经 ``Authorization: Bearer`` 透传（管理面 RBAC 不在此层）。
+    流解析：``data:`` 帧为 ShenshiDelta JSON，``[DONE]`` 结束；非 2xx 映射 ShenshiError。
+    """
+
+    def __init__(self, base_url: str, service_token: str, timeout: float = 120.0) -> None:
+        self._base_url = base_url.rstrip("/")
+        self._headers = {"Authorization": f"Bearer {service_token}"} if service_token else {}
+        self._timeout = timeout
+
+    async def stream_chat(self, request: ShenshiChatRequest) -> AsyncIterator[ShenshiDelta]:
+        payload = request.model_dump(mode="json")
+        assert payload.get("stream") is True  # 数据面当前只有流式形态
+        async with httpx.AsyncClient(trust_env=False, timeout=self._timeout) as client:
+            async with client.stream(
+                "POST",
+                f"{self._base_url}/v1/chat/completions",
+                json=payload,
+                headers=self._headers,
+            ) as response:
+                if response.status_code >= 400:
+                    body = (await response.aread()).decode("utf-8", errors="replace")
+                    code = f"HJ-2{max(response.status_code - 400, 0):03d}"
+                    try:
+                        detail = json.loads(body)
+                        code = detail.get("error", {}).get("code", code)
+                        body = detail.get("error", {}).get("message", body)
+                    except json.JSONDecodeError:
+                        pass
+                    raise ShenshiError(code, body)
+                async for line in response.aiter_lines():
+                    if not line.startswith("data:"):
+                        continue
+                    data = line[len("data:") :].strip()
+                    if data == "[DONE]":
+                        return
+                    if data:
+                        yield ShenshiDelta.model_validate_json(data)
+
+
+def build_shenshi_client(base_url: str, service_token: str) -> ShenshiClient:
+    """按配置装配客户端：未配置神识地址时降级为回声桩（M0 骨架形态）。"""
+    if base_url:
+        return HttpShenshiClient(base_url, service_token)
+    return EchoShenshi()