Do not consider edit mode as a history entry

main.go

@@ -465,6 +465,15 @@ func (h *handler) handlePost(w http.ResponseWriter, r *http.Request, urlPath, fs
 			}
 		}
 	}
+	// The editor saves via fetch so the save and its result share one history
+	// entry (see assets/history-nav.js). Hand it the target instead of a 303:
+	// the browser would follow the redirect into a second entry, and fetch
+	// drops the #section fragment from a followed redirect anyway.
+	if r.Header.Get("X-Save-Mode") == "replace" {
+		w.Header().Set("X-Target", redirectTarget)
+		w.WriteHeader(http.StatusNoContent)
+		return
+	}
 	http.Redirect(w, r, redirectTarget, http.StatusSeeOther)
 }