fix: packet detail lookup uses transmission ID index

After dedup, table rows have transmission IDs but getById() maps
observation IDs. Added byTxId index so /api/packets/:id resolves
both observation and transmission IDs correctly.

packet-store.js

@@ -23,6 +23,7 @@ class PacketStore {
 
     // Indexes
     this.byId = new Map();           // observation_id → observation object (backward compat for packet detail links)
+    this.byTxId = new Map();         // transmission_id → transmission object
     this.byHash = new Map();         // hash → transmission object (1:1)
     this.byObserver = new Map();     // observer_id → [observation objects]
     this.byNode = new Map();         // pubkey → [transmission objects] (deduped)
@@ -102,6 +103,7 @@ class PacketStore {
         this.byTransmission.set(row.hash, tx);
         this.byHash.set(row.hash, tx);
         this.packets.push(tx);
+        this.byTxId.set(tx.id, tx);
         this._indexByNode(tx);
       }
 
@@ -188,6 +190,7 @@ class PacketStore {
       this.byTransmission.set(pkt.hash, tx);
       this.byHash.set(pkt.hash, tx);
       this.packets.push(tx);
+        this.byTxId.set(tx.id, tx);
       this._indexByNode(tx);
     }
 
@@ -250,6 +253,7 @@ class PacketStore {
       const old = this.packets.pop();
       this.byHash.delete(old.hash);
       this.byTransmission.delete(old.hash);
+      this.byTxId.delete(old.id);
       // Remove observations from byId and byObserver
       for (const obs of old.observations) {
         this.byId.delete(obs.id);
@@ -292,6 +296,7 @@ class PacketStore {
         this.byTransmission.set(row.hash, tx);
         this.byHash.set(row.hash, tx);
         this.packets.unshift(tx); // newest first
+        this.byTxId.set(tx.id, tx);
         this._indexByNode(tx);
       } else {
         // Update first_seen if earlier
@@ -517,6 +522,12 @@ class PacketStore {
     return this.byId.get(id) || null;
   }
 
+  /** Get a transmission by its transmission table ID */
+  getByTxId(id) {
+    if (this.sqliteOnly) return this.db.prepare('SELECT * FROM transmissions WHERE id = ?').get(id) || null;
+    return this.byTxId.get(id) || null;
+  }
+
   /** Get all siblings of a packet (same hash) — returns observations array */
   getSiblings(hash) {
     if (this.sqliteOnly) return this.db.prepare('SELECT * FROM packets WHERE hash = ? ORDER BY timestamp DESC').all(hash);

server.js

@@ -778,7 +778,9 @@ app.get('/api/packets/timestamps', (req, res) => {
 });
 
 app.get('/api/packets/:id', (req, res) => {
-  const packet = pktStore.getById(Number(req.params.id)) || db.getPacket(Number(req.params.id));
+  const id = Number(req.params.id);
+  // Try observation ID first, then transmission ID, then legacy packets table
+  const packet = pktStore.getById(id) || pktStore.getByTxId(id) || db.getPacket(id);
   if (!packet) return res.status(404).json({ error: 'Not found' });
 
   // Use the sibling with the longest path (most hops) for display