Allow attaching to existing sessions without reinitializing the runtime (#4329)

Co-authored-by: tofarr <tofarr@gmail.com>

openhands/server/session/conversation.py

@@ -0,0 +1,36 @@
+from openhands.core.config import AppConfig
+from openhands.events.stream import EventStream
+from openhands.runtime import get_runtime_cls
+from openhands.runtime.runtime import Runtime
+from openhands.security import SecurityAnalyzer, options
+from openhands.storage.files import FileStore
+
+
+class Conversation:
+    sid: str
+    file_store: FileStore
+    event_stream: EventStream
+    runtime: Runtime
+
+    def __init__(
+        self,
+        sid: str,
+        file_store: FileStore,
+        config: AppConfig,
+    ):
+        self.sid = sid
+        self.config = config
+        self.file_store = file_store
+        self.event_stream = EventStream(sid, file_store)
+        if config.security.security_analyzer:
+            self.security_analyzer = options.SecurityAnalyzers.get(
+                config.security.security_analyzer, SecurityAnalyzer
+            )(self.event_stream)
+
+        runtime_cls = get_runtime_cls(self.config.runtime)
+        self.runtime = runtime_cls(
+            config=config,
+            event_stream=self.event_stream,
+            sid=self.sid,
+            attach_to_existing=True,
+        )

openhands/server/session/manager.py

@@ -6,7 +6,9 @@ from fastapi import WebSocket
 
 from openhands.core.config import AppConfig
 from openhands.core.logger import openhands_logger as logger
+from openhands.events.stream import session_exists
 from openhands.runtime.utils.shutdown_listener import should_continue
+from openhands.server.session.conversation import Conversation
 from openhands.server.session.session import Session
 from openhands.storage.files import FileStore
 
@@ -44,6 +46,11 @@ class SessionManager:
             return None
         return self._sessions.get(sid)
 
+    def attach_to_conversation(self, sid: str) -> Conversation | None:
+        if not session_exists(sid, self.file_store):
+            return None
+        return Conversation(sid, file_store=self.file_store, config=self.config)
+
     async def send(self, sid: str, data: dict[str, object]) -> bool:
         """Sends data to the client."""
         session = self.get_session(sid)