Add bubble timeline support on Akkoma instances

Author: Steffo99

src/components/nav-menu.jsx

@@ -349,7 +349,8 @@ function NavMenu(props) {
               <Trans>Local</Trans>
             </span>
           </MenuLink>
-          {supports("@mastodon/bubble-timeline") && (
+          {(supports("@mastodon/bubble-timeline") ||
+            supports("@akkoma/bubble-timeline")) && (
             <MenuLink to={`/${instance}/p/b`}>
               <Icon icon="star2" size="l" />{" "}
               <span>

src/locales/en.po

@@ -30,11 +30,22 @@ const platformFeatures = {
   "@akkoma/local-visibility-post": containAkkoma,
 };
 
+// Named features for which support is explicitly expressed by the instance
+const advertisedFeatures = {
+  "@akkoma/bubble-timeline": "bubble_timeline",
+};
+
 const supportsCache = {};
 
 function supports(feature) {
   try {
-    let { version, domain } = getCurrentInstance();
+    let instanceData = getCurrentInstance();
+    let version = instanceData.version;
+    let domain = instanceData.domain;
+
+    // instanceData extension exclusive to Akkoma and Pleroma
+    let pleroma = instanceData?.pleroma;
+
     let softwareName = getCurrentNodeInfo()?.software?.name || "mastodon";
 
     if (softwareName === "hometown") {
@@ -49,6 +60,13 @@ function supports(feature) {
       return (supportsCache[key] = platformFeatures[feature].test(version));
     }
 
+    // use Pleroma / Akkoma's advertised feature list to see if a given feature is supported
+    if (pleroma) {
+      return (supportsCache[key] = pleroma.metadata.features.includes(
+        advertisedFeatures[feature],
+      ));
+    }
+
     const range = features[feature];
     if (!range) return false;