fix: eliminate duplicate HTTP listener on gateway port

The shared HTTP server in ChannelManager and the HealthServer both
tried to bind to the same gateway port, causing "address already in use".

Consolidate to a single listener: register channel webhooks and health
checkers on the HealthServer's mux via SetupHTTPServer, then let
HealthServer be the sole HTTP listener. Remove the separate httpServer
from ChannelManager entirely.

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

pkg/channels/manager.go

@@ -11,7 +11,6 @@ import (
 	"errors"
 	"fmt"
 	"math"
-	"net/http"
 	"sync"
 	"time"
 
@@ -84,8 +83,6 @@ type Manager struct {
 	config        *config.Config
 	mediaStore    media.MediaStore
 	dispatchTask  *asyncTask
-	mux           *http.ServeMux
-	httpServer    *http.Server
 	mu            sync.RWMutex
 	placeholders  sync.Map // "channel:chatID" → placeholderID (string)
 	typingStops   sync.Map // "channel:chatID" → func()
@@ -342,41 +339,31 @@ func (m *Manager) initChannels() error {
 	return nil
 }
 
-// SetupHTTPServer creates a shared HTTP server with the given listen address.
+// SetupHTTPServer registers channel webhook handlers and health checkers onto
-// It registers health endpoints from the health server and discovers channels
+// the health server's mux so everything is served by a single HTTP listener.
-// that implement WebhookHandler and/or HealthChecker to register their handlers.
 func (m *Manager) SetupHTTPServer(addr string, healthServer *health.Server) {
-	m.mux = http.NewServeMux()
+	if healthServer == nil {
-
+		return
-	// Register health endpoints
-	if healthServer != nil {
-		healthServer.RegisterOnMux(m.mux)
 	}
+	mux := healthServer.Mux()
 
 	// Discover and register webhook handlers and health checkers
 	for name, ch := range m.channels {
 		if wh, ok := ch.(WebhookHandler); ok {
-			m.mux.Handle(wh.WebhookPath(), wh)
+			mux.Handle(wh.WebhookPath(), wh)
 			logger.InfoCF("channels", "Webhook handler registered", map[string]any{
 				"channel": name,
 				"path":    wh.WebhookPath(),
 			})
 		}
 		if hc, ok := ch.(HealthChecker); ok {
-			m.mux.HandleFunc(hc.HealthPath(), hc.HealthHandler)
+			mux.HandleFunc(hc.HealthPath(), hc.HealthHandler)
 			logger.InfoCF("channels", "Health endpoint registered", map[string]any{
 				"channel": name,
 				"path":    hc.HealthPath(),
 			})
 		}
 	}
-
-	m.httpServer = &http.Server{
-		Addr:         addr,
-		Handler:      m.mux,
-		ReadTimeout:  30 * time.Second,
-		WriteTimeout: 30 * time.Second,
-	}
 }
 
 func (m *Manager) StartAll(ctx context.Context) error {
@@ -417,20 +404,6 @@ func (m *Manager) StartAll(ctx context.Context) error {
 	// Start the TTL janitor that cleans up stale typing/placeholder entries
 	go m.runTTLJanitor(dispatchCtx)
 
-	// Start shared HTTP server if configured
-	if m.httpServer != nil {
-		go func() {
-			logger.InfoCF("channels", "Shared HTTP server listening", map[string]any{
-				"addr": m.httpServer.Addr,
-			})
-			if err := m.httpServer.ListenAndServe(); err != nil && err != http.ErrServerClosed {
-				logger.FatalCF("channels", "Shared HTTP server error", map[string]any{
-					"error": err.Error(),
-				})
-			}
-		}()
-	}
-
 	logger.InfoC("channels", "All channels started")
 	return nil
 }
@@ -441,18 +414,6 @@ func (m *Manager) StopAll(ctx context.Context) error {
 
 	logger.InfoC("channels", "Stopping all channels")
 
-	// Shutdown shared HTTP server first
-	if m.httpServer != nil {
-		shutdownCtx, cancel := context.WithTimeout(ctx, 5*time.Second)
-		defer cancel()
-		if err := m.httpServer.Shutdown(shutdownCtx); err != nil {
-			logger.ErrorCF("channels", "Shared HTTP server shutdown error", map[string]any{
-				"error": err.Error(),
-			})
-		}
-		m.httpServer = nil
-	}
-
 	// Cancel dispatcher
 	if m.dispatchTask != nil {
 		m.dispatchTask.cancel()

pkg/gateway/gateway.go

@@ -356,6 +356,8 @@ func setupAndStartServices(
 		}
 	}
 
+	// HealthServer is the single HTTP listener. Channel webhooks and health
+	// checkers were registered on its mux via SetupHTTPServer.
 	go func() {
 		var serverErr error
 		if useTLS {
@@ -571,6 +573,13 @@ func restartServices(
 	if err = runningServices.ChannelManager.StartAll(context.Background()); err != nil {
 		return fmt.Errorf("error restarting channels: %w", err)
 	}
+
+	// Start the HealthServer listener (single HTTP server for all routes)
+	go func() {
+		if sErr := runningServices.HealthServer.Start(); sErr != nil && sErr != http.ErrServerClosed {
+			logger.ErrorCF("health", "Health server error", map[string]any{"error": sErr.Error()})
+		}
+	}()
 	fmt.Printf(
 		"  ✓ Channels restarted, health endpoints at http://%s:%d/health and ready\n",
 		cfg.Gateway.Host,