feat(v2 managed agents): add SandboxAdapter Protocol + error types

litellm/managed_agents/adapters/base.py

@@ -0,0 +1,105 @@
+"""Sandbox adapter protocol for managed agents v2.
+
+Each sandbox provider (today: only opencode) implements this protocol. The
+endpoint handlers in `litellm/managed_agents/router.py` resolve an adapter
+via `registry.get_adapter(sandbox_type)` and use it to translate sandbox-
+agnostic public-API calls into provider-specific HTTP requests.
+
+The Protocol exists for typing only — concrete adapters (e.g.
+`OpencodeAdapter`) are regular classes whose method signatures match.
+
+Adapters are stateless: every call carries the `sandbox_url` and provider
+session id. The handler does all DB work; the adapter only translates HTTP.
+"""
+
+from typing import AsyncIterator, Optional, Protocol, Tuple
+
+from litellm.managed_agents.types import MessageRow
+
+
+class SandboxUnreachableError(Exception):
+    """Raised by adapter HTTP calls on connect/timeout failures.
+
+    Endpoint handlers translate this to a 504 response with body
+    `{"detail":{"error":"Sandbox unreachable"}}` per contract §7.
+    """
+
+
+class SandboxBadGatewayError(Exception):
+    """Raised when the sandbox responds but the body is malformed.
+
+    Endpoint handlers translate this to a 502 response with body
+    `{"detail":{"error":"Bad gateway"}}` per contract §7.
+    """
+
+
+class SandboxAdapter(Protocol):
+    """Protocol every sandbox adapter must implement.
+
+    Concrete adapters do NOT need to inherit from this class — duck typing
+    is enough. The Protocol is here so callers can type-annotate adapter
+    handles and so static type checkers can verify each concrete adapter
+    matches the contract.
+    """
+
+    async def send_message(
+        self,
+        sandbox_url: str,
+        opencode_session_id: str,
+        content: str,
+        model: Optional[str],
+    ) -> None:
+        """Forward a user message to the sandbox.
+
+        Translates to `POST <sandbox_url>/session/<oc_sid>/prompt_async` for
+        the opencode adapter. The sandbox returns 204; the caller is
+        responsible for writing the user `MessageRow` separately. Raises
+        `SandboxUnreachableError` on connect/timeout failures.
+        """
+        ...
+
+    async def list_messages(
+        self,
+        sandbox_url: str,
+        opencode_session_id: str,
+        our_session_id: str,
+        limit: int = 50,
+    ) -> list[MessageRow]:
+        """Fetch the message history for a session, normalized to our shape.
+
+        Translates to `GET <sandbox_url>/session/<oc_sid>/message` for the
+        opencode adapter. Each provider message is run through normalization
+        before being returned. Raises `SandboxUnreachableError` on
+        connect/timeout failures and `SandboxBadGatewayError` on malformed
+        responses.
+        """
+        ...
+
+    async def stream_events(
+        self,
+        sandbox_url: str,
+        opencode_session_id: str,
+        our_session_id: str,
+    ) -> AsyncIterator[Tuple[str, dict]]:
+        """Subscribe to the sandbox event bus and yield normalized events.
+
+        First yield is always `("connected", {"session_id": our_session_id})`
+        (synthesized — not from the upstream bus). Subsequent yields are the
+        normalized `(event_type, data_dict)` tuples per contract §7. Events
+        not in the translation table are dropped. Raises
+        `SandboxUnreachableError` on connect/timeout failures.
+        """
+        ...
+
+    async def delete(
+        self,
+        sandbox_url: str,
+        opencode_session_id: str,
+    ) -> None:
+        """Best-effort delete of the upstream sandbox session.
+
+        Translates to `DELETE <sandbox_url>/session/<oc_sid>` for the
+        opencode adapter. Errors are logged and swallowed — sandbox
+        teardown is also enforced by idle/timeout in the provider.
+        """
+        ...