Implement LocalSandbox fallback for HF Spaces

src/infrastructure/sandbox/docker_manager.py

@@ -75,10 +75,51 @@ class DockerSandbox(SandboxService):
         except Exception as e:
             return f"Error reading file: {e}"
 
-# Singleton for simplicity
-# Note: In a real deployment, we'd handle docker connection errors gracefully
+import subprocess
+import os
+
+class LocalSandbox(SandboxService):
+    """Fallback sandbox that runs commands locally when Docker is unavailable"""
+    async def start_session(self, session_id: str) -> None:
+        # No-op for local execution
+        pass
+
+    async def stop_session(self, session_id: str) -> None:
+        # No-op for local execution
+        pass
+
+    async def execute_shell(self, session_id: str, command: str) -> str:
+        try:
+            # Run command in a subprocess
+            result = subprocess.run(
+                command, 
+                shell=True, 
+                capture_output=True, 
+                text=True, 
+                timeout=30
+            )
+            output = result.stdout
+            if result.stderr:
+                output += f"\nStderr: {result.stderr}"
+            return output
+        except Exception as e:
+            return f"Error executing command: {e}"
+
+    async def read_file(self, session_id: str, path: str) -> str:
+        try:
+            if os.path.exists(path):
+                with open(path, 'r', encoding='utf-8') as f:
+                    return f.read()
+            else:
+                return f"Error: File not found at {path}"
+        except Exception as e:
+            return f"Error reading file: {e}"
+
+# Singleton initialization with fallback
 try:
     docker_sandbox = DockerSandbox()
-except Exception:
-    print("Warning: Docker not available. Sandbox features will fail.")
-    docker_sandbox = None
+    # Test connection
+    docker_sandbox.client.ping()
+except Exception as e:
+    print(f"Docker not available ({e}). Falling back to LocalSandbox.")
+    docker_sandbox = LocalSandbox()