rebuild(llm): add audited model connectivity tests

next/backend/llm/gateway.py

@@ -49,6 +49,8 @@ class ModelRuntimeAccess(Protocol):
 class ModelPoolAccess(Protocol):
     def runtime_config(self) -> ModelRuntimeAccess: ...
 
+    def runtime_model(self, model_id: int) -> ModelRecordAccess: ...
+
     def decrypt_api_key(self, record: ModelRecordAccess) -> str: ...
 
 
@@ -237,6 +239,57 @@ class LLMGateway:
         code, message = _safe_error(last_error)
         raise LLMGatewayError(code, message)
 
+    def test_model(self, principal: PrincipalAccess, model_id: int) -> dict[str, object]:
+        try:
+            record = self._model_pool.runtime_model(model_id)
+        except BusinessError as exc:
+            raise LLMGatewayError("model_not_found", "模型不存在。") from exc
+        now = datetime.now(SHANGHAI)
+        request_id = uuid.uuid4().hex
+        call = LLMCall(
+            request_id=request_id,
+            user_id=principal.user.id,
+            feature="model_connectivity",
+            prompt_version="system:model-connectivity:v1",
+            business_id=f"model:{model_id}",
+            started_at=now,
+            usage_date=now.date().isoformat(),
+            input_chars=15,
+            quota_exempt=True,
+            profiles=(
+                LLMProfile(
+                    model_id=record.id,
+                    role="primary",
+                    base_url=record.base_url,
+                    model_identifier=record.model_identifier,
+                    api_key=self._model_pool.decrypt_api_key(record),
+                ),
+            ),
+        )
+        with self._database.transaction() as connection:
+            self._repository.reserve(
+                connection,
+                request_id=request_id,
+                user_id=principal.user.id,
+                feature=call.feature,
+                business_id=call.business_id,
+                prompt_version=call.prompt_version,
+                started_at=now.isoformat(timespec="seconds"),
+                input_chars=call.input_chars,
+            )
+        started = time.perf_counter()
+        for _event in self.stream(
+            call,
+            [{"role": "user", "content": "连接测试，只回复：连接成功"}],
+        ):
+            pass
+        return {
+            "connected": True,
+            "message": "连接成功",
+            "duration_ms": round((time.perf_counter() - started) * 1000),
+            "request_id": request_id,
+        }
+
     def _finish_attempt(
         self,
         attempt_id: int,