Rebuild as single-file offline BIP84 wallet

Replace the SvelteKit/daisyUI prototype with a vanilla JS + hand-rolled CSS
app that Bun bundles (code + scure/noble crypto + QR + CSS) into one
self-contained dist/index.html runnable offline from file://.

Wallet core (src/wallet.js):
- BIP84 native-segwit HD wallet from BIP39 seed (+optional passphrase)
- gap-limit scan of receive/change chains, aggregate balance, tx history
- fresh receive/change addresses; signs with witnessUtxo only (enables
  offline signing with no prev-tx fetch)
- coin selection + fee estimation via btc-signer selectUTXO; send-max;
  manual coin control
- offline JSON snapshot export/import (keyless) + signed-tx hex/QR export
- realtime mempool.space WebSocket: track-addresses -> debounced auto
  refresh of balances/history (no polling); live status badge

UI (src/app.js): clean light paper-wallet; create (with optional, skippable
backup verification) / import flow; receive (QR) / send / history / coins /
tools tabs; clickable logo returns home.

API (src/api.js): mempool.space wrapper with retry/backoff for scan-burst
rate limiting; single network choke-point for offline enforcement.

Verified: BIP84 spec vectors, build/sign/parse for auto/max/manual flows,
snapshot roundtrip, live scan + WebSocket, headless-Chrome UI smoke tests.

Co-Authored-By: Claude Opus 4.8 (1M context) <[email protected]>

1 files changed, 25 insertions, 0 deletions

diff --git a/dev.js b/dev.js
new file mode 100644
index 0000000..099069c
--- /dev/null
+++ b/dev.js
@@ -0,0 +1,25 @@
+// Dev server: rebuilds the inlined bundle on every request so you just refresh
+// the browser to see changes. Same output as `bun run build`, unminified.
+
+import { buildHtml } from './build.js';
+
+const port = Number(process.env.PORT || 5173);
+
+Bun.serve({
+  port,
+  async fetch() {
+    try {
+      const html = await buildHtml({ minify: false });
+      return new Response(html, {
+        headers: { 'content-type': 'text/html; charset=utf-8' },
+      });
+    } catch (e) {
+      return new Response(`Build error:\n\n${e.stack || e}`, {
+        status: 500,
+        headers: { 'content-type': 'text/plain; charset=utf-8' },
+      });
+    }
+  },
+});
+
+console.log(`dev server → http://localhost:${port}`);