feat: rebuild as multi-user web agent

agent_platform/runtime/provider.py

@@ -0,0 +1,77 @@
+from __future__ import annotations
+
+from typing import Any
+
+import httpx
+
+from agent_platform.config import Settings
+
+
+def completions_url(base_url: str) -> str:
+    base = base_url.rstrip("/")
+    if base.endswith("/v1"):
+        return f"{base}/chat/completions"
+    return f"{base}/v1/chat/completions"
+
+
+class ModelProvider:
+    def __init__(self, settings: Settings, client: httpx.AsyncClient | None = None) -> None:
+        self.settings = settings
+        self.client = client or httpx.AsyncClient(
+            timeout=httpx.Timeout(settings.model_timeout_seconds),
+            limits=httpx.Limits(max_connections=50, max_keepalive_connections=20),
+        )
+        self._owns_client = client is None
+
+    @property
+    def headers(self) -> dict[str, str]:
+        return {
+            "Authorization": f"Bearer {self.settings.model_api_key}",
+            "Content-Type": "application/json",
+        }
+
+    async def close(self) -> None:
+        if self._owns_client:
+            await self.client.aclose()
+
+    async def complete(
+        self,
+        *,
+        model: str,
+        messages: list[dict[str, Any]],
+        tools: list[dict[str, Any]] | None = None,
+        temperature: float | None = None,
+    ) -> dict[str, Any]:
+        payload: dict[str, Any] = {
+            "model": model,
+            "messages": messages,
+            "stream": False,
+        }
+        if tools:
+            payload["tools"] = tools
+            payload["tool_choice"] = "auto"
+        if temperature is not None:
+            payload["temperature"] = temperature
+        response = await self.client.post(
+            completions_url(self.settings.model_api_base_url),
+            headers=self.headers,
+            json=payload,
+        )
+        response.raise_for_status()
+        data = response.json()
+        if not data.get("choices"):
+            raise RuntimeError("Model provider returned no choices")
+        return data
+
+    async def forward(self, payload: dict[str, Any]) -> httpx.Response:
+        request = self.client.build_request(
+            "POST",
+            completions_url(self.settings.model_api_base_url),
+            headers=self.headers,
+            json=payload,
+        )
+        response = await self.client.send(request, stream=bool(payload.get("stream")))
+        if response.status_code >= 400:
+            await response.aread()
+            response.raise_for_status()
+        return response