From e38178fd13790acda1c663c5747a4c82e810438c Mon Sep 17 00:00:00 2001
From: 29448 <29448@users.noreply.github.com>
Date: Thu, 9 Apr 2026 17:38:38 +0800
Subject: [PATCH] fix(web,mcp): gracefully degrade when MCP loading fails in
 Web UI worker

When an MCP server fails to connect (e.g., due to a port conflict),
the Web UI session worker previously crashed entirely, causing
messages to get stuck in thinking state indefinitely.

Changes:
- In `_agent_loop()`, catch `MCPRuntimeError` during
  `wait_for_background_mcp_loading()` and log a warning instead of
  letting the exception crash the agent loop.
- In `_read_loop()`, when an unexpected exception occurs, clear
  `_in_flight_prompt_ids` and emit an error status so the
  frontend can recover instead of leaving prompts stuck in
  thinking state.

Fixes #1766
---
 src/kimi_cli/soul/kimisoul.py      | 3 +++
 src/kimi_cli/web/runner/process.py | 2 ++
 2 files changed, 5 insertions(+)

diff --git a/src/kimi_cli/soul/kimisoul.py b/src/kimi_cli/soul/kimisoul.py
index 9365c11b9..dee575f1b 100644
--- a/src/kimi_cli/soul/kimisoul.py
+++ b/src/kimi_cli/soul/kimisoul.py
@@ -64,6 +64,7 @@
 from kimi_cli.soul.message import check_message, system, system_reminder, tool_result_to_message
 from kimi_cli.soul.slash import registry as soul_slash_registry
 from kimi_cli.soul.toolset import KimiToolset
+from kimi_cli.exception import MCPRuntimeError
 from kimi_cli.tools.dmail import NAME as SendDMail_NAME
 from kimi_cli.tools.utils import ToolRejectedError
 from kimi_cli.utils.logging import logger
@@ -683,6 +684,8 @@ async def _agent_loop(self) -> TurnOutcome:
                 wire_send(MCPLoadingBegin())
             try:
                 await self.wait_for_background_mcp_loading()
+            except MCPRuntimeError as e:
+                logger.warning("MCP loading failed, continuing without MCP tools: {}", e)
             finally:
                 if loading:
                     wire_send(StatusUpdate(mcp_status=self._mcp_status_snapshot()))
diff --git a/src/kimi_cli/web/runner/process.py b/src/kimi_cli/web/runner/process.py
index 91bfe7eb0..c0f2ff3b3 100644
--- a/src/kimi_cli/web/runner/process.py
+++ b/src/kimi_cli/web/runner/process.py
@@ -355,6 +355,8 @@ async def _read_loop(self) -> None:
             raise
         except Exception as e:
             logger.warning(f"Unexpected error in read loop: {e.__class__.__name__} {e}")
+            self._in_flight_prompt_ids.clear()
+            await self._emit_status("error", reason="read_loop_error", detail=str(e))
 
     async def _handle_out_message(self, message: JSONRPCOutMessage) -> None:
         """Handle outbound message from worker."""