fix: adjust server WriteTimeout for WebSocket compatibility

backend/api/main_integration_test.go

@@ -34,7 +34,7 @@ func TestDatabaseInitialization(t *testing.T) {
 			Host:            "localhost",
 			Port:            "8082",
 			ReadTimeout:     10 * time.Second,
-			WriteTimeout:    10 * time.Second,
+			WriteTimeout:    time.Duration(0),
 			ShutdownTimeout: 30 * time.Second,
 		},
 		Logging: config.LogConfig{

backend/api/main_test.go

@@ -141,7 +141,7 @@ func mockLoadConfig() (*config.Config, error) {
 			Host:            "localhost",
 			Port:            "8082",
 			ReadTimeout:     10 * time.Second,
-			WriteTimeout:    10 * time.Second,
+			WriteTimeout:    time.Duration(0),
 			ShutdownTimeout: 30 * time.Second,
 		},
 		Logging: config.LogConfig{
@@ -288,5 +288,5 @@ func TestServerConfiguration(t *testing.T) {
 
 	assert.Equal(t, addr, server.Addr)
 	assert.Equal(t, 10*time.Second, server.ReadTimeout)
-	assert.Equal(t, 10*time.Second, server.WriteTimeout)
+	assert.Equal(t, time.Duration(0), server.WriteTimeout)
 }

backend/internal/config/config.go

@@ -18,9 +18,13 @@ const (
 	defaultMaxIdleConns    int32 = 5
 	defaultConnMaxLifetime       = 5 * time.Minute
 	defaultReadTimeout           = 10 * time.Second
-	defaultWriteTimeout          = 10 * time.Second
-	defaultIdleTimeout           = 30 * time.Second
-	defaultShutdownTimeout       = 30 * time.Second
+	// defaultWriteTimeout is 0 (disabled at the server level) because per-write
+	// deadlines are enforced in the WebSocket write pump (websocket/client.go).
+	// A non-zero server-level write timeout would prematurely terminate idle
+	// WebSocket connections.
+	defaultWriteTimeout    = time.Duration(0)
+	defaultIdleTimeout     = 30 * time.Second
+	defaultShutdownTimeout = 30 * time.Second
 )
 
 // CORSConfig holds CORS configuration
@@ -83,7 +87,15 @@ type AzureTableConfig struct {
 //nolint:govet // Struct field alignment has been optimized for time.Duration fields
 type ServerConfig struct {
 	// 8-byte aligned fields first
-	ReadTimeout     time.Duration
+	ReadTimeout time.Duration
+	// WriteTimeout is 0 (disabled) at the server level. Per-write deadlines are
+	// enforced inside the WebSocket write pump (websocket/client.go), so a
+	// server-level write timeout must be disabled to prevent premature
+	// termination of idle WebSocket connections. Standard REST handlers complete
+	// quickly in practice, but setting WriteTimeout to 0 does mean slow or
+	// stalled clients can hold a connection indefinitely. Operators who want
+	// protection against slow clients should set SERVER_WRITE_TIMEOUT to a
+	// positive value (e.g. 30s); per-handler context deadlines can also be applied.
 	WriteTimeout    time.Duration
 	IdleTimeout     time.Duration
 	ShutdownTimeout time.Duration
@@ -194,8 +206,10 @@ func (c *ServerConfig) Validate() error {
 		return errors.New("read timeout must be positive")
 	}
 
-	if c.WriteTimeout <= 0 {
-		return errors.New("write timeout must be positive")
+	// WriteTimeout of 0 is valid — it disables the server-level write timeout
+	// (per-write deadlines are handled in the WebSocket write pump instead).
+	if c.WriteTimeout < 0 {
+		return errors.New("write timeout must be non-negative (0 to disable)")
 	}
 
 	if c.IdleTimeout <= 0 {

backend/internal/config/config_test.go

@@ -122,9 +122,8 @@ func TestLoadConfig(t *testing.T) {
 		assert.Empty(t, config.Server.Host)
 		assert.Equal(t, "8081", config.Server.Port)
 		assert.Equal(t, 10*time.Second, config.Server.ReadTimeout)
-		assert.Equal(t, 10*time.Second, config.Server.WriteTimeout)
+		assert.Equal(t, time.Duration(0), config.Server.WriteTimeout) // disabled; per-write deadlines enforced in WebSocket write pump				assert.Equal(t, 30*time.Second, config.Server.IdleTimeout)
 		assert.Equal(t, 30*time.Second, config.Server.ShutdownTimeout)
-
 		// Check default logging config
 		assert.Equal(t, "info", config.Logging.Level)
 		assert.Empty(t, config.Logging.File)
@@ -281,6 +280,62 @@ func TestConfigValidate(t *testing.T) {
 		require.Error(t, err)
 		assert.Contains(t, err.Error(), "server config")
 	})
+
+	t.Run("zero WriteTimeout passes validation", func(t *testing.T) {
+		t.Parallel()
+		cfg := &config.Config{
+			App: config.AppConfig{
+				Name:        "myapp",
+				Environment: "production",
+			},
+			Database: config.DatabaseConfig{
+				Host:            "localhost",
+				Port:            "3306",
+				User:            "user",
+				DBName:          "dbname",
+				MaxOpenConns:    10,
+				MaxIdleConns:    5,
+				ConnMaxLifetime: 1 * time.Minute,
+			},
+			Server: config.ServerConfig{
+				Port:            "8080",
+				ReadTimeout:     5 * time.Second,
+				WriteTimeout:    0, // disabled at server level; per-write deadlines in WebSocket pump
+				IdleTimeout:     30 * time.Second,
+				ShutdownTimeout: 10 * time.Second,
+			},
+		}
+		assert.NoError(t, cfg.Validate())
+	})
+
+	t.Run("negative WriteTimeout fails validation", func(t *testing.T) {
+		t.Parallel()
+		cfg := &config.Config{
+			App: config.AppConfig{
+				Name:        "myapp",
+				Environment: "production",
+			},
+			Database: config.DatabaseConfig{
+				Host:            "localhost",
+				Port:            "3306",
+				User:            "user",
+				DBName:          "dbname",
+				MaxOpenConns:    10,
+				MaxIdleConns:    5,
+				ConnMaxLifetime: 1 * time.Minute,
+			},
+			Server: config.ServerConfig{
+				Port:            "8080",
+				ReadTimeout:     5 * time.Second,
+				WriteTimeout:    -1 * time.Second,
+				IdleTimeout:     30 * time.Second,
+				ShutdownTimeout: 10 * time.Second,
+			},
+		}
+		err := cfg.Validate()
+		require.Error(t, err)
+		assert.Contains(t, err.Error(), "write timeout")
+	})
 }
 func TestAzureTableConfigValidate(t *testing.T) {
 	t.Parallel()