Create AgentServerErrorEvent for server-level errors

Create a new AgentServerErrorEvent class in the agent server models to
distinguish server-level errors (like MCP connection failures, WebSocket
errors) from conversation-level errors. This provides better semantic
separation - ConversationErrorEvent is for conversation runtime failures
while AgentServerErrorEvent is for infrastructure/server issues.

The sockets.py now uses AgentServerErrorEvent instead of ConversationErrorEvent
when sending error events over the WebSocket connection.

Co-authored-by: openhands <openhands@all-hands.dev>

Author: openhands-agent

openhands-agent-server/openhands/agent_server/models.py

@@ -7,11 +7,12 @@
 from pydantic import BaseModel, Discriminator, Field, Tag, field_validator
 
 from openhands.agent_server.utils import OpenHandsUUID, utc_now
-from openhands.sdk import LLM, Agent, Event, ImageContent, Message, TextContent
+from openhands.sdk import LLM, Agent, ImageContent, Message, TextContent
 from openhands.sdk.agent.acp_agent import ACPAgent
 from openhands.sdk.conversation.conversation_stats import ConversationStats
 from openhands.sdk.conversation.secret_registry import SecretRegistry
 from openhands.sdk.conversation.state import ConversationExecutionStatus
+from openhands.sdk.event.base import Event
 from openhands.sdk.hooks import HookConfig
 from openhands.sdk.llm.utils.metrics import MetricsSnapshot
 from openhands.sdk.plugin import PluginSource
@@ -31,6 +32,19 @@
 from openhands.sdk.workspace.base import BaseWorkspace
 
 
+class AgentServerErrorEvent(Event):
+    """Event emitted by the agent server when a server-level error occurs.
+
+    This event is used for errors that originate from the agent server itself,
+    such as MCP connection failures, WebSocket errors, or other infrastructure
+    issues. Unlike ConversationErrorEvent which is for conversation-level failures,
+    this event indicates a problem with the server environment.
+    """
+
+    code: str = Field(description="Code for the error - typically an error type")
+    detail: str = Field(description="Details about the error")
+
+
 ACPEnabledAgent = Annotated[
     Annotated[Agent, Tag("Agent")] | Annotated[ACPAgent, Tag("ACPAgent")],
     Discriminator(kind_of),

openhands-agent-server/openhands/agent_server/sockets.py

@@ -26,10 +26,13 @@
     get_default_conversation_service,
 )
 from openhands.agent_server.event_router import normalize_datetime_to_server_timezone
-from openhands.agent_server.models import BashEventBase, ExecuteBashRequest
+from openhands.agent_server.models import (
+    AgentServerErrorEvent,
+    BashEventBase,
+    ExecuteBashRequest,
+)
 from openhands.agent_server.pub_sub import Subscriber
 from openhands.sdk import Event, Message
-from openhands.sdk.event.conversation_error import ConversationErrorEvent
 from openhands.sdk.utils.paging import page_iterator
 
 
@@ -211,7 +214,7 @@ async def events_socket(
                 # Tell the client about this so they can decide what to do next
                 logger.exception("error_in_subscription", stack_info=True)
                 try:
-                    error_event = ConversationErrorEvent(
+                    error_event = AgentServerErrorEvent(
                         source="environment",
                         code=e.__class__.__name__,
                         detail=str(e),
@@ -293,7 +296,7 @@ async def bash_events_socket(
                 # Tell the client about this so they can decide what to do next
                 logger.exception("error_in_bash_event_subscription", stack_info=True)
                 try:
-                    error_event = ConversationErrorEvent(
+                    error_event = AgentServerErrorEvent(
                         source="environment",
                         code=e.__class__.__name__,
                         detail=str(e),