feat: copy SandboxBackendProtocol from deepagents to reduce coupling (#897)

- Add local protocol.py with SandboxBackendProtocol, ExecuteResponse, WriteResult, EditResult
- Update server.py to import from local protocol instead of deepagents
- Reduces dependency coupling between open-swe and deepagents

Co-authored-by: Cursor <cursoragent@cursor.com>

apps/agent/agent/protocol.py

@@ -0,0 +1,96 @@
+"""Protocol definitions for sandbox backends.
+
+This module defines the SandboxBackendProtocol that sandbox implementations
+must follow. Copied from deepagents to reduce coupling.
+"""
+
+from dataclasses import dataclass
+from typing import Protocol, runtime_checkable
+
+
+@dataclass
+class ExecuteResponse:
+    """Result of code execution.
+
+    Simplified schema optimized for LLM consumption.
+    """
+
+    output: str
+    """Combined stdout and stderr output of the executed command."""
+
+    exit_code: int | None = None
+    """The process exit code. 0 indicates success, non-zero indicates failure."""
+
+    truncated: bool = False
+    """Whether the output was truncated due to backend limitations."""
+
+
+@runtime_checkable
+class SandboxBackendProtocol(Protocol):
+    """Protocol for sandbox backends that support shell command execution.
+
+    Designed for backends running in isolated environments (containers, VMs,
+    remote hosts).
+
+    This is a minimal protocol for type checking - actual implementations
+    come from deepagents.
+    """
+
+    @property
+    def id(self) -> str:
+        """Unique identifier for the sandbox backend instance."""
+        ...
+
+    def execute(self, command: str) -> ExecuteResponse:
+        """Execute a command in the sandbox.
+
+        Args:
+            command: Full shell command string to execute.
+
+        Returns:
+            ExecuteResponse with combined output, exit code, and truncation flag.
+        """
+        ...
+
+    async def aexecute(self, command: str) -> ExecuteResponse:
+        """Async version of execute."""
+        ...
+
+    def read(self, file_path: str, offset: int = 0, limit: int = 2000) -> str:
+        """Read file content with line numbers."""
+        ...
+
+    async def aread(self, file_path: str, offset: int = 0, limit: int = 2000) -> str:
+        """Async version of read."""
+        ...
+
+    def write(self, file_path: str, content: str) -> "WriteResult":
+        """Write content to a new file."""
+        ...
+
+    def edit(
+        self,
+        file_path: str,
+        old_string: str,
+        new_string: str,
+        replace_all: bool = False,
+    ) -> "EditResult":
+        """Perform exact string replacements in an existing file."""
+        ...
+
+
+@dataclass
+class WriteResult:
+    """Result from backend write operations."""
+
+    error: str | None = None
+    path: str | None = None
+
+
+@dataclass
+class EditResult:
+    """Result from backend edit operations."""
+
+    error: str | None = None
+    path: str | None = None
+    occurrences: int | None = None

apps/agent/agent/server.py

@@ -26,7 +26,7 @@ warnings.filterwarnings("ignore", message=".*Pydantic V1.*", category=UserWarnin
 
 # Now safe to import agent (which imports LangChain modules)
 from deepagents import create_deep_agent
-from deepagents.backends.sandbox import SandboxBackendProtocol
+from .protocol import SandboxBackendProtocol
 
 # Local import for encryption
 from langchain_anthropic import ChatAnthropic