fix(hub): a reconnect re-reads the index, not just the handshake

_reconnectLoop re-did the handshake and nothing else, so a page kept
whatever it last saw until someone reloaded it. That is invisible until
the node restarts: it rebuilds its index from index_cache.db, which
holds no enrichment, and Music is the one app whose enrichment is
persisted nowhere — for the length of the re-read pass it serves tracks
with no artist, and the album grid drew nothing.

onReconnected was one slot the video player took on open and cleared on
close; it is a listener set now, and carries the fresh ack.

docs/MESHBAY_DESIGN.md §15.3 records the two defects found alongside and
not fixed here.

Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>

1 files changed, 86 insertions, 28 deletions

diff --git a/packages/meshbay-hub/src/meshbay_hub/static/group-page.js b/packages/meshbay-hub/src/meshbay_hub/static/group-page.js
index 26519da..4fdf5f8 100644
--- a/packages/meshbay-hub/src/meshbay_hub/static/group-page.js
+++ b/packages/meshbay-hub/src/meshbay_hub/static/group-page.js
@@ -256,6 +256,44 @@ function GroupPage({ groupId, group, token, username, userId, userPrefs,
     }
   }, [passInput, username]);
 
+  // Everything one handshake ack tells this page, applied in one place.
+  //
+  // Called by the first connect and again by every automatic reconnect: a node
+  // that restarted is a different process, and its answers are not the ones the
+  // first handshake got. Written once because the two paths drifting is how
+  // `helloworld`'s directories went missing from one of them.
+  const applyAck = useCallback((ack) => {
+    if (!ack) return;
+    setIsNodeAdmin(!!ack.is_node_admin);
+    setEnabledApps(ack.enabled_apps || null);
+    setScanSettings(ack.scan_settings || null);
+    setTmdbConfig({
+      // Per-group (2026-08-24, used to be node-wide).
+      enabled: ack.tmdb_enabled !== false,
+      // Node-wide — one shared credential/cache.
+      tokenCustomized: !!ack.tmdb_token_customized,
+      language: ack.tmdb_language || '',
+    });
+    // Every `<app>_directories` the ack carries, keyed by the app's own
+    // name — read off the ack rather than from a list of app names held
+    // here, so an application the node knows about is one this page already
+    // handles. Three names were hardcoded until 2026-09-10 and `helloworld`
+    // was not among them, so the app that exists to prove a new one needs
+    // no special-casing had its directories dropped on arrival. The live
+    // path below (`onAppDirectories`) was always generic; this was the half
+    // that was not.
+    setAppDirectories(Object.fromEntries(
+      Object.keys(ack)
+        .filter((k) => k.endsWith('_directories'))
+        .map((k) => [k.slice(0, -'_directories'.length), ack[k] || []])));
+    setChatDirectory(ack.chat_directory || '');
+    setChatLinkPreview(ack.chat_link_preview !== false);
+    setSearchListed(ack.search_listed !== false);
+    setMusicbrainzConfig({
+      enabled: ack.musicbrainz_enabled !== false,
+    });
+  }, []);
+
   // One place that takes an index from the node and puts it everywhere it has to
   // go. Deleting a file used to refresh the table and leave the cache alone, so
   // the search page went on offering a file that no longer existed until the
@@ -298,6 +336,9 @@ function GroupPage({ groupId, group, token, username, userId, userPrefs,
 
   useEffect(() => {
     let cancelled = false;
+    // Dropped by the teardown below, so a transport handed on to a running
+    // download (`releaseWhenIdle`) stops driving a page that is gone.
+    let offReconnect = null;
 
     // The cache is written here and read only by the search page. It used to
     // seed this list too, which put a stale index on screen and then raced the
@@ -398,34 +439,7 @@ function GroupPage({ groupId, group, token, username, userId, userPrefs,
         if (!transport) throw (lastErr || new Error('no node served this group'));
         session.pendingJoinCode = null;
         if (cancelled) return;
-        setIsNodeAdmin(!!ack.is_node_admin);
-        setEnabledApps(ack.enabled_apps || null);
-        setScanSettings(ack.scan_settings || null);
-        setTmdbConfig({
-          // Per-group (2026-08-24, used to be node-wide).
-          enabled: ack.tmdb_enabled !== false,
-          // Node-wide — one shared credential/cache.
-          tokenCustomized: !!ack.tmdb_token_customized,
-          language: ack.tmdb_language || '',
-        });
-        // Every `<app>_directories` the ack carries, keyed by the app's own
-        // name — read off the ack rather than from a list of app names held
-        // here, so an application the node knows about is one this page already
-        // handles. Three names were hardcoded until 2026-09-10 and `helloworld`
-        // was not among them, so the app that exists to prove a new one needs
-        // no special-casing had its directories dropped on arrival. The live
-        // path below (`onAppDirectories`) was always generic; this was the half
-        // that was not.
-        setAppDirectories(Object.fromEntries(
-          Object.keys(ack)
-            .filter((k) => k.endsWith('_directories'))
-            .map((k) => [k.slice(0, -'_directories'.length), ack[k] || []])));
-        setChatDirectory(ack.chat_directory || '');
-        setChatLinkPreview(ack.chat_link_preview !== false);
-        setSearchListed(ack.search_listed !== false);
-        setMusicbrainzConfig({
-          enabled: ack.musicbrainz_enabled !== false,
-        });
+        applyAck(ack);
         transport.onAppsEnabled = (apps) => setEnabledApps(apps);
         // Two independent acks now (tmdb_config_ack: token/language,
         // node-wide; tmdb_enabled_ack: the per-group switch) — each merges
@@ -513,6 +527,49 @@ function GroupPage({ groupId, group, token, username, userId, userPrefs,
           if (onPresence) onPresence(groupId, 'online');
         };
 
+        // An automatic reconnect (transport.js's _reconnectLoop) re-does the
+        // handshake and nothing else: no index is fetched, and any push sent
+        // while the old channel was dying is simply lost. That was survivable
+        // while a node that came back came back with the same answers — and a
+        // restarted one does not. It rebuilds its index from
+        // `index_cache.db`, which stores path/mtime/size/hash/type and no
+        // enrichment at all, so for the ~25s its re-enrichment pass takes
+        // (measured: 6176 audio files, 6.4s of tag reads plus cover work) the
+        // index it serves has no artist and no album on any track. A client
+        // that reconnected inside that window kept exactly that view for as
+        // long as the page stayed open: Files and Videos looked right — one
+        // needs no enrichment, the other's is restored from `media_cache.db`
+        // — and Music, whose grouping *is* the enrichment, drew nothing.
+        //
+        // So the reconnect asks again, for the ack and the index both. The
+        // full fetch rather than a delta: this session was never told what it
+        // missed, and a delta is computed against a snapshot only the node
+        // has.
+        offReconnect = transport.addReconnectListener((reack) => {
+          if (cancelled) return;
+          (async () => {
+            try {
+              applyAck(reack);
+              // Re-imported, not kept: a chat epoch or a re-key while we were
+              // away means the handshake just handed us a different GEK, and
+              // gekRef is what every decrypt on this page reads.
+              if (transport.gekRaw && window.MeshBayCrypto) {
+                gekRef.current = await window.MeshBayCrypto.importGEK(
+                  window.MeshBayCrypto.b64encode(transport.gekRaw));
+              }
+              const msg = await transport.fetchIndex();
+              if (cancelled) return;
+              applyIndex(msg);
+            } catch (e) {
+              // The connection went again mid-refresh: the next reconnect
+              // runs this same handler. Saying so beats a view that is
+              // quietly one node-restart old.
+              console.warn('[MeshBay] index refresh after reconnect failed:',
+                           e.message);
+            }
+          })();
+        });
+
         // We are in: an invitation to this group has served its purpose.
         if (onJoined) onJoined(groupId);
 
@@ -591,6 +648,7 @@ function GroupPage({ groupId, group, token, username, userId, userPrefs,
 
     return () => {
       cancelled = true;
+      if (offReconnect) { offReconnect(); offReconnect = null; }
       // Nothing will update this group's dock row once the page lets go of it.
       reportIndexPush(groupId, null);
       if (transportRef.current) {