Problem: tags are not parsed in the backend

Solution: replace tag with markdown links

editor/src/markdown-tag.js

@@ -24,7 +24,7 @@ Plugin.prototype.init = function (md) {
 export function tagParser(id, state, silent) {
     let input = state.src.slice(state.pos);
 
-    const match = /^#[^ ]+/.exec(input)
+    const match = /^#\S+/.exec(input)
     if (!match) {
         return false
     }

main.go

@@ -922,11 +922,7 @@ func (h *indexHandler) ServeHTTP(w http.ResponseWriter, r *http.Request) {
 }
 
 func renderLinks(pageText string, edit bool) string {
-	hrefRE, err := regexp.Compile(`#?\[\[\s*([^\]]+)\s*\]\]`)
-	if err != nil {
-		log.Fatal(err)
-	}
-
+	hrefRE := regexp.MustCompile(`#?\[\[\s*([^\]]+)\s*\]\]`)
 	pageText = hrefRE.ReplaceAllStringFunc(pageText, func(s string) string {
 		tag := false
 		if s[0] == '#' {
@@ -955,6 +951,14 @@ func renderLinks(pageText string, edit bool) string {
 
 		return fmt.Sprintf("[%s](/%s%s)", s, editPart, cleanNameURL(s))
 	})
+
+	tagRE := regexp.MustCompile(`#(\S+)`)
+	pageText = tagRE.ReplaceAllStringFunc(pageText, func(s string) string {
+		s = strings.TrimPrefix(s, "#")
+		s = strings.TrimSpace(s)
+		return fmt.Sprintf(`<a href="/%s" class="tag">%s</a>`, url.PathEscape(cleanNameURL(s)), s)
+	})
+
 	return pageText
 }