From 8d4cc3fbba13f1825d1903c38c0ee39061852bdf Mon Sep 17 00:00:00 2001
From: dtapps <li.gc@icloud.com>
Date: Thu, 30 Apr 2026 22:56:40 +0800
Subject: [PATCH] fix(agent): make MCP initialization failure non-fatal

When all MCP servers fail to connect (e.g., network unreachable),
the agent loop would exit immediately, leaving the application in a
zombie state where the gateway is running but no messages can be
processed.

Changes:
- Downgrade MCP init failure from fatal error to warning in Run(),
  ProcessDirectWithChannel(), ProcessHeartbeat(), and Continue()
- Add 30s timeout to HTTP client used for SSE/HTTP MCP transports
  to prevent indefinite blocking on unreachable servers

The agent now continues operating without MCP tools when servers are
unavailable, rather than becoming completely unresponsive.
---
 pkg/agent/agent.go         |  3 ++-
 pkg/agent/agent_message.go |  6 ++++--
 pkg/agent/steering.go      |  4 ++--
 pkg/mcp/manager.go         | 17 ++++++++++++-----
 4 files changed, 20 insertions(+), 10 deletions(-)

diff --git a/pkg/agent/agent.go b/pkg/agent/agent.go
index 2c456dca7..5b2d6878f 100644
--- a/pkg/agent/agent.go
+++ b/pkg/agent/agent.go
@@ -132,7 +132,8 @@ func (al *AgentLoop) Run(ctx context.Context) error {
 		return err
 	}
 	if err := al.ensureMCPInitialized(ctx); err != nil {
-		return err
+		logger.WarnCF("agent", "MCP initialization failed, continuing without MCP tools",
+			map[string]any{"error": err.Error()})
 	}
 
 	idleTicker := time.NewTicker(100 * time.Millisecond)
diff --git a/pkg/agent/agent_message.go b/pkg/agent/agent_message.go
index 96b0b0817..37dbb4190 100644
--- a/pkg/agent/agent_message.go
+++ b/pkg/agent/agent_message.go
@@ -48,7 +48,8 @@ func (al *AgentLoop) ProcessDirectWithChannel(
 		return "", err
 	}
 	if err := al.ensureMCPInitialized(ctx); err != nil {
-		return "", err
+		logger.WarnCF("agent", "MCP initialization failed, processing without MCP tools",
+			map[string]any{"error": err.Error()})
 	}
 
 	msg := bus.InboundMessage{
@@ -73,7 +74,8 @@ func (al *AgentLoop) ProcessHeartbeat(
 		return "", err
 	}
 	if err := al.ensureMCPInitialized(ctx); err != nil {
-		return "", err
+		logger.WarnCF("agent", "MCP initialization failed, processing heartbeat without MCP tools",
+			map[string]any{"error": err.Error()})
 	}
 
 	agent := al.GetRegistry().GetDefaultAgent()
diff --git a/pkg/agent/steering.go b/pkg/agent/steering.go
index 2efa7bbf4..7e9058049 100644
--- a/pkg/agent/steering.go
+++ b/pkg/agent/steering.go
@@ -370,8 +370,8 @@ func (al *AgentLoop) Continue(ctx context.Context, sessionKey, channel, chatID s
 		return "", err
 	}
 	if err := al.ensureMCPInitialized(ctx); err != nil {
-		al.activeTurnStates.Delete(sessionKey)
-		return "", err
+		logger.WarnCF("agent", "MCP initialization failed, continuing steering without MCP tools",
+			map[string]any{"error": err.Error(), "session_key": sessionKey})
 	}
 
 	steeringMsgs := al.dequeueSteeringMessagesForScopeWithFallback(sessionKey)
diff --git a/pkg/mcp/manager.go b/pkg/mcp/manager.go
index 92ea426a6..5de0f866a 100644
--- a/pkg/mcp/manager.go
+++ b/pkg/mcp/manager.go
@@ -12,6 +12,7 @@ import (
 	"strings"
 	"sync"
 	"sync/atomic"
+	"time"
 
 	"github.com/modelcontextprotocol/go-sdk/mcp"
 
@@ -341,14 +342,18 @@ func connectServer(
 			DisableStandaloneSSE: disableStandaloneSSE,
 		}
 
+		// Set up HTTP client with a connection timeout to avoid hanging
+		// indefinitely when the MCP server is unreachable.
+		mcpHTTPClient := &http.Client{
+			Timeout: 30 * time.Second,
+		}
+
 		// Add custom headers if provided
 		if len(cfg.Headers) > 0 {
 			// Create a custom HTTP client with header-injecting transport
-			sseTransport.HTTPClient = &http.Client{
-				Transport: &headerTransport{
-					base:    http.DefaultTransport,
-					headers: cfg.Headers,
-				},
+			mcpHTTPClient.Transport = &headerTransport{
+				base:    http.DefaultTransport,
+				headers: cfg.Headers,
 			}
 			logger.DebugCF("mcp", "Added custom HTTP headers",
 				map[string]any{
@@ -357,6 +362,8 @@ func connectServer(
 				})
 		}
 
+		sseTransport.HTTPClient = mcpHTTPClient
+
 		transport = sseTransport
 	case "stdio":
 		if cfg.Command == "" {