fix: advert flags are a 4-bit enum type, not individual bit flags

ADV_TYPE_ROOM=3 (0b0011) was misread as chat+repeater because decoder
treated lower nibble as individual bits. Now correctly: type & 0x0F as
enum (0=none, 1=chat, 2=repeater, 3=room, 4=sensor).

Includes startup backfill: scans all adverts and fixes any node roles
in the DB that were incorrectly set to 'repeater' when they should be
'room'. Logs count of fixed nodes on startup.

decoder.js

@@ -109,12 +109,14 @@ function decodeAdvert(buf) {
 
   if (appdata.length > 0) {
     const flags = appdata[0];
+    const advType = flags & 0x0F; // lower nibble is enum type, not individual bits
     result.flags = {
       raw: flags,
-      chat: !!(flags & 0x01),
-      repeater: !!(flags & 0x02),
-      room: !!(flags & 0x04),
-      sensor: !!(flags & 0x08),
+      type: advType,
+      chat: advType === 1,
+      repeater: advType === 2,
+      room: advType === 3,
+      sensor: advType === 4,
       hasLocation: !!(flags & 0x10),
       hasName: !!(flags & 0x80),
     };

server.js

@@ -171,6 +171,32 @@ const db = require('./db');
 const pktStore = new PacketStore(db, config.packetStore || {}).load();
 _rebuildHashSizeMap();
 
+// Backfill: fix roles for nodes whose adverts were decoded with old bitfield flags
+// ADV_TYPE is a 4-bit enum (0=none, 1=chat, 2=repeater, 3=room, 4=sensor), not individual bits
+(function _backfillRoles() {
+  const ADV_ROLES = { 1: 'companion', 2: 'repeater', 3: 'room', 4: 'sensor' };
+  let fixed = 0;
+  for (const p of pktStore.packets) {
+    if (p.payload_type !== 4 || !p.raw_hex) continue;
+    try {
+      const d = JSON.parse(p.decoded_json || '{}');
+      const pk = d.pubKey || d.public_key;
+      if (!pk) continue;
+      const appStart = p.raw_hex.length - (d.flags?.raw != null ? 2 : 0); // flags byte position varies
+      const flagsByte = d.flags?.raw;
+      if (flagsByte == null) continue;
+      const advType = flagsByte & 0x0F;
+      const correctRole = ADV_ROLES[advType] || 'companion';
+      const node = db.db.prepare('SELECT role FROM nodes WHERE public_key = ?').get(pk);
+      if (node && node.role !== correctRole) {
+        db.db.prepare('UPDATE nodes SET role = ? WHERE public_key = ?').run(correctRole, pk);
+        fixed++;
+      }
+    } catch {}
+  }
+  if (fixed > 0) console.log(`[backfill] Fixed ${fixed} node roles (advert type enum vs bitfield)`);
+})();
+
 // --- Shared cached node list (refreshed every 30s, avoids repeated SQLite queries) ---
 let _cachedAllNodes = null;
 let _cachedAllNodesWithRole = null;