Per-network nostr sync + honest balance loading state

One shared d-tag let a network switch apply the mainnet snapshot to a
signet wallet (the flash of wrong balance) and clobber mainnet state on
the relays. Each network now syncs its own replaceable event (mainnet
keeps the legacy bare tag), snapshots carry netName, and a foreign-net
snapshot is never applied. The balance card spins until cache, Nostr,
or a scan has populated this network once — 'scanning' alone missed the
cache/Nostr window after wallet.load().

Co-Authored-By: Claude Fable 5 <[email protected]>

1 files changed, 13 insertions, 4 deletions

diff --git a/src/nostr.js b/src/nostr.js
index 31c9858..ccb797d 100644
--- a/src/nostr.js
+++ b/src/nostr.js
@@ -79,6 +79,10 @@ export async function fetchInboxRelays(pubkeyHex, relays = PROFILE_RELAYS) {
 }
 
 const DTAG = 'bitcoin-wallet';
+// Each network syncs to its own replaceable event — one shared d-tag would let
+// a signet snapshot overwrite the mainnet state on the relays (and vice versa).
+// Mainnet keeps the bare tag existing wallets already publish under.
+export const syncDtag = (netName) => (!netName || netName === 'mainnet' ? DTAG : `${DTAG}:${netName}`);
 const SYNC_KEY = 'btc-wallet-sync';
 export const DEFAULT_SYNC_RELAYS = ['wss://relay.coinos.io'];
 
@@ -110,8 +114,11 @@ export class NostrSync {
     this.pk = null;
     this.ck = null; // self conversation key for NIP-44
     this.relays = DEFAULT_SYNC_RELAYS;
+    this.dtag = DTAG;
   }
 
+  setDtag(d) { this.dtag = d || DTAG; }
+
   load(mnemonic, passphrase = '') {
     this.sk = nip06.privateKeyFromSeedWords(mnemonic, passphrase || undefined);
     this.pk = getPublicKey(this.sk);
@@ -124,13 +131,15 @@ export class NostrSync {
     this.relays = Array.isArray(relays) && relays.length ? relays : DEFAULT_SYNC_RELAYS;
   }
 
-  // Encrypt + publish the latest state to every relay (best-effort).
-  async publish(stateObj) {
+  // Encrypt + publish the latest state to every relay (best-effort). The d-tag
+  // is passed in so a debounced publish keeps the tag of the network the
+  // snapshot was taken on, even if the wallet switched networks meanwhile.
+  async publish(stateObj, dtag = this.dtag) {
     if (!this.sk) return;
     let evt;
     try {
       const content = nip44.encrypt(JSON.stringify(stateObj), this.ck);
-      evt = finalizeEvent({ kind: 30078, created_at: Math.floor(Date.now() / 1000), tags: [['d', DTAG]], content }, this.sk);
+      evt = finalizeEvent({ kind: 30078, created_at: Math.floor(Date.now() / 1000), tags: [['d', dtag]], content }, this.sk);
     } catch { return; }
     await Promise.allSettled(pool.publish(this.relays, evt));
   }
@@ -156,7 +165,7 @@ export class NostrSync {
   async fetch() {
     if (!this.sk) return null;
     let events;
-    try { events = await pool.querySync(this.relays, { kinds: [30078], authors: [this.pk], '#d': [DTAG] }, { maxWait: 6000 }); } catch { return null; }
+    try { events = await pool.querySync(this.relays, { kinds: [30078], authors: [this.pk], '#d': [this.dtag] }, { maxWait: 6000 }); } catch { return null; }
     for (const e of events.sort((a, b) => b.created_at - a.created_at)) {
       try { const v = JSON.parse(nip44.decrypt(e.content, this.ck)); if (v) return v; } catch {}
     }