Build profiles: HAL_FEATURES selects which features ship

build.js swaps src/features/index.js for a generated module importing
only the enabled features (gifts,swaps,ark,sp — unset means all,
"none" means a plain on-chain wallet), so excluded feature code and
its network endpoints never enter the bundle. Minimal profile:
476KB vs 577KB, with the Ark/gRPC, Boltz, and MuSig2 code verifiably
absent. `bun run build:minimal` builds it.

tools/minimal-smoke.js proves the minimal profile end-to-end: no
receive-mode dropdown, no gift button, no swap/Ark/SP settings cards,
no page errors, and a plain on-chain receive still lands. The two
blessed profiles are full (everything, the existing e2e suites) and
minimal (this smoke test); other combos should work but aren't CI'd.

Gift and SP primitives still live inside wallet.js, so those bytes
remain in the minimal bundle for now — extracting them is the next
step if we want the core leaner still.

Co-Authored-By: Claude Fable 5 <[email protected]>
Claude-Session: https://claude.ai/code/session_01QFAcD4V284DvYZZHP7Rxxy

5 files changed, 150 insertions, 9 deletions

diff --git a/build.js b/build.js
index 97744b1..8a0805b 100644
--- a/build.js
+++ b/build.js
@@ -136,11 +136,39 @@ export async function buildSpWorker({ minify = true } = {}) {
   return result.outputs[0].text();
 }
 
-export async function buildHtml({ minify = true, pwa = minify } = {}) {
+// Optional-feature selection: HAL_FEATURES is a comma list of enabled
+// features (gifts,swaps,ark,sp). Unset means all; "none"/"" means a minimal
+// on-chain-only wallet. A build plugin swaps src/features/index.js for a
+// generated module that only imports the enabled features, so a disabled
+// feature's code (and its network endpoints) never enters the bundle.
+const ALL_FEATURES = { gifts: 'giftsFeature', swaps: 'swapsFeature', ark: 'arkFeature', sp: 'spFeature' };
+
+export function enabledFeatures(spec = process.env.HAL_FEATURES) {
+  if (spec == null) return Object.keys(ALL_FEATURES);
+  return spec.split(',').map((x) => x.trim().toLowerCase()).filter((x) => x in ALL_FEATURES);
+}
+
+function featureIndexSource(enabled) {
+  return enabled.map((f) => `import { ${ALL_FEATURES[f]} } from './${f}.js';`).join('\n')
+    + `\nexport function buildFeatures(ctx) { return [${enabled.map((f) => `${ALL_FEATURES[f]}(ctx)`).join(', ')}]; }\n`;
+}
+
+const featurePlugin = (enabled) => ({
+  name: 'hal-features',
+  setup(b) {
+    b.onLoad({ filter: /src[\/\\]features[\/\\]index\.js$/ }, () => ({
+      contents: featureIndexSource(enabled),
+      loader: 'js',
+    }));
+  },
+});
+
+export async function buildHtml({ minify = true, pwa = minify, features = process.env.HAL_FEATURES } = {}) {
   const result = await Bun.build({
     entrypoints: ['./src/app.js'],
     target: 'browser',
     minify,
+    plugins: [featurePlugin(enabledFeatures(features))],
   });
   if (!result.success) {
     for (const log of result.logs) console.error(log);
diff --git a/package.json b/package.json
index 0ca02a9..e861882 100644
--- a/package.json
+++ b/package.json
@@ -3,10 +3,11 @@
   "private": true,
   "version": "0.1.0",
   "type": "module",
-  "description": "Hal Wallet — offline-capable, single-file self-custody Bitcoin wallet for the browser, in memory of Hal Finney",
+  "description": "Hal Wallet \u2014 offline-capable, single-file self-custody Bitcoin wallet for the browser, in memory of Hal Finney",
   "scripts": {
     "dev": "bun run dev.js",
-    "build": "bun run build.js"
+    "build": "bun run build.js",
+    "build:minimal": "HAL_FEATURES=none bun run build.js"
   },
   "dependencies": {
     "@noble/ciphers": "^2.1.1",
@@ -21,4 +22,4 @@
   "devDependencies": {
     "puppeteer-core": "^25.1.0"
   }
-}
+}
\ No newline at end of file
diff --git a/src/app.js b/src/app.js
index 2c2a314..a7fed0f 100644
--- a/src/app.js
+++ b/src/app.js
@@ -9,10 +9,7 @@ import { qrSvg } from './qr.js';
 import { scanQr } from './scan.js';
 import { getSyncConfig, setSyncConfig, parseNostrPubkey, npubOf, fetchNostrProfile, decryptWithCode } from './nostr.js';
 import { dataSources, getSource, setSource, getNetwork, setNetwork, NETWORKS } from './api.js';
-import { swapsFeature } from './features/swaps.js';
-import { giftsFeature } from './features/gifts.js';
-import { arkFeature } from './features/ark.js';
-import { spFeature } from './features/sp.js';
+import { buildFeatures } from './features/index.js';
 import { t, LANGS, getLang, setLang, isRTL, loadLocale } from './i18n.js';
 import {
   fmtBtc,
@@ -2976,7 +2973,7 @@ const ctx = {
   getAccounts: () => accounts,
   claimTargets, enterWallet, activateAccount, commitAccount,
 };
-const FEATURES = [giftsFeature, swapsFeature, arkFeature, spFeature].map((f) => f(ctx));
+const FEATURES = buildFeatures(ctx);
 
 // apply text direction, then restore a wallet left open in this tab — otherwise
 // show the unlock screen.
diff --git a/src/features/index.js b/src/features/index.js
new file mode 100644
index 0000000..590020a
--- /dev/null
+++ b/src/features/index.js
@@ -0,0 +1,16 @@
+// Which optional features this build includes. In dev (and by default in
+// builds) everything is on. Release builds can exclude features entirely:
+// build.js replaces this module's contents based on HAL_FEATURES, so a
+// disabled feature's code — and its network endpoints — never enters the
+// bundle. See featureIndexSource() in build.js.
+
+import { giftsFeature } from './gifts.js';
+import { swapsFeature } from './swaps.js';
+import { arkFeature } from './ark.js';
+import { spFeature } from './sp.js';
+
+// NB order is meaningful where hooks stack: gifts' receive takeover and
+// balance line come before ark's, matching the pre-plugin layout.
+export function buildFeatures(ctx) {
+  return [giftsFeature(ctx), swapsFeature(ctx), arkFeature(ctx), spFeature(ctx)];
+}
diff --git a/tools/minimal-smoke.js b/tools/minimal-smoke.js
new file mode 100644
index 0000000..ab31619
--- /dev/null
+++ b/tools/minimal-smoke.js
@@ -0,0 +1,99 @@
+// Smoke test for the minimal build profile (HAL_FEATURES=none): a plain
+// on-chain wallet with no swap/Ark/gift/SP surfaces — and still fully working
+// (imports a wallet, receives a payment) against the regtest stack.
+//
+// Usage: bun tools/minimal-smoke.js
+
+import { execSync } from 'node:child_process';
+import puppeteer from 'puppeteer-core';
+import { generateMnemonic } from '@scure/bip39';
+import { wordlist } from '@scure/bip39/wordlists/english';
+import { buildHtml } from '../build.js';
+
+const BCLI = `bitcoin-cli -regtest -datadir=${process.env.HOME}/ark-regtest/bitcoind -rpcport=18543 -rpcwallet=miner`;
+const sleep = (ms) => new Promise((r) => setTimeout(r, ms));
+const sh = (cmd) => execSync(cmd, { shell: '/bin/bash' }).toString().trim();
+
+let ok = true;
+const check = (name, cond, detail = '') => {
+  console.log(` ${cond ? '✓' : '✗'} ${name}${detail ? ' — ' + detail : ''}`);
+  if (!cond) ok = false;
+};
+
+// --- build the minimal profile and serve it ---
+const html = await buildHtml({ minify: true, pwa: false, features: 'none' });
+const full = await buildHtml({ minify: true, pwa: false });
+console.log(`minimal bundle: ${(html.length / 1024).toFixed(0)}KB (full: ${(full.length / 1024).toFixed(0)}KB)`);
+check('meaningfully smaller than full', html.length < full.length * 0.9);
+check('no ark protocol code', !html.includes('Ark VTXO mailbox authorization'));
+check('no swap protocol code', !html.includes('swap/reverse'));
+check('no musig code', !html.includes('MuSig/noncecoef'));
+
+const server = Bun.serve({ port: 5198, fetch: () => new Response(html, { headers: { 'content-type': 'text/html' } }) });
+
+const browser = await puppeteer.launch({ executablePath: '/usr/bin/google-chrome', headless: 'new', args: ['--no-sandbox'] });
+const page = await browser.newPage();
+const errs = [];
+page.on('pageerror', (e) => errs.push(e.message));
+const bodyText = () => page.evaluate(() => document.body.innerText);
+const waitText = async (text, ms = 20000) => {
+  for (let i = 0; i < ms / 250; i++) {
+    if ((await bodyText()).toLowerCase().includes(text.toLowerCase())) return true;
+    await sleep(250);
+  }
+  return false;
+};
+const clickText = (sel, text) => page.evaluate((s, x) => {
+  const el = [...document.querySelectorAll(s)].find((e) => e.textContent.trim().toLowerCase().includes(x.toLowerCase()));
+  if (el) { el.click(); return true; }
+  return false;
+}, sel, text);
+
+try {
+  await page.goto('http://localhost:5198', { waitUntil: 'domcontentloaded' });
+  await page.evaluate(() => {
+    localStorage.setItem('btc-wallet-network', 'regtest');
+    localStorage.setItem('btc-wallet-source:regtest', JSON.stringify({ id: 'custom', url: 'http://localhost:30002' }));
+    localStorage.setItem('btc-wallet-ark-provider:regtest', 'local'); // must be ignored by this build
+  });
+  await page.reload({ waitUntil: 'domcontentloaded' });
+  await sleep(400);
+
+  console.log('\n[1] import + core wallet');
+  await clickText('button', 'Import existing');
+  await sleep(200);
+  await page.type('textarea', generateMnemonic(wordlist));
+  await clickText('button', 'Open wallet');
+  check('wallet opened', await waitText('receive', 15000));
+
+  console.log('\n[2] no feature surfaces');
+  await sleep(2500); // give any (wrongly present) feature time to appear
+  check('no receive-mode dropdown', await page.evaluate(() =>
+    ![...document.querySelectorAll('option')].some((o) => ['ln', 'ark', 'sp'].includes(o.value))));
+  await clickText('.tabs button', 'Send');
+  await sleep(300);
+  check('no gift button', !(await bodyText()).includes('Gift some Bitcoin'));
+  await clickText('.tabs button', 'Settings');
+  await sleep(300);
+  const settings = await bodyText();
+  check('no swap provider card', !settings.includes('Swap provider'));
+  check('no ark card', !/⚔ Ark/.test(settings));
+  check('no sp indexer card', !settings.includes('Silent payment indexer'));
+
+  console.log('\n[3] core receive still works');
+  await clickText('.tabs button', 'Receive');
+  await sleep(300);
+  const addr = await page.evaluate(() => document.querySelector('.addr-box')?.textContent.trim());
+  check('onchain address shown', /^bcrt1/.test(addr || ''), (addr || '').slice(0, 16) + '…');
+  sh(`${BCLI} sendtoaddress ${addr} 0.0004`);
+  sh(`${BCLI} generatetoaddress 1 $(${BCLI} getnewaddress) >/dev/null`);
+  check('payment lands', await waitText('40,000', 30000));
+  check('no page errors', errs.length === 0, errs.join(' | '));
+
+  console.log(ok ? '\n✅ SUCCESS: minimal profile is a working on-chain-only wallet'
+                : '\n❌ some checks failed');
+} finally {
+  await browser.close();
+  server.stop(true);
+}
+process.exit(ok ? 0 : 1);