add optional prefix to url

internal/config/config.go

@@ -17,6 +17,7 @@ type Config struct {
 	SecretKey        string
 	Debug            bool
 	MaxContentLength int64 // in bytes
+	URLPrefix        string
 
 	// MD Notes App settings
 	AppName                string
@@ -68,6 +69,7 @@ var defaultConfig = map[string]map[string]string{
 		"SECRET_KEY":         "change-this-secret-key",
 		"DEBUG":              "false",
 		"MAX_CONTENT_LENGTH": "16", // in MB
+		"URL_PREFIX":         "",
 	},
 	"MD_NOTES_APP": {
 		"APP_NAME":                 "Gobsidian",
@@ -148,6 +150,14 @@ func Load() (*Config, error) {
 	config.Debug, _ = SERVERSection.Key("DEBUG").Bool()
 	maxContentMB, _ := SERVERSection.Key("MAX_CONTENT_LENGTH").Int()
 	config.MaxContentLength = int64(maxContentMB) * 1024 * 1024 // Convert MB to bytes
+	// Normalize URL prefix: "" or starts with '/' and no trailing '/'
+	rawPrefix := strings.TrimSpace(SERVERSection.Key("URL_PREFIX").String())
+	if rawPrefix == "/" { rawPrefix = "" }
+	if rawPrefix != "" {
+		if !strings.HasPrefix(rawPrefix, "/") { rawPrefix = "/" + rawPrefix }
+		rawPrefix = strings.TrimRight(rawPrefix, "/")
+	}
+	config.URLPrefix = rawPrefix
 
 	// Load MD_NOTES_APP section
 	notesSection := cfg.Section("MD_NOTES_APP")
@@ -340,6 +350,14 @@ func (c *Config) SaveSetting(section, key, value string) error {
 			if size, err := strconv.ParseInt(value, 10, 64); err == nil {
 				c.MaxContentLength = size * 1024 * 1024
 			}
+		case "URL_PREFIX":
+			v := strings.TrimSpace(value)
+			if v == "/" { v = "" }
+			if v != "" {
+				if !strings.HasPrefix(v, "/") { v = "/" + v }
+				v = strings.TrimRight(v, "/")
+			}
+			c.URLPrefix = v
 		}
 	case "MD_NOTES_APP":
 		switch key {