feat: add Zakat calculator (per-member, Nisab + 2.5% rate)

Closes the Zakat gap identified in the competitive benchmark against
Rafiq. Per-member module (nf_zakat_records, same author-owns/family-reads
RLS pattern as Insurance/Wassiyah/Waqf) computing 2.5% due on zakatable
wealth (cash, gold, silver, business assets, investments) once above a
user-entered Nisab threshold, minus deductible short-term liabilities.
Manual entry only, matching the app's existing philosophy — no live gold
price feed. Covered by e2e-zakat.cjs (7/7).

e2e-zakat.cjs

@@ -0,0 +1,69 @@
+// Verifies the Zakat calculator: entering zakatable wealth computes the
+// correct 2.5% due once above Nisab, values autosave and persist across a
+// remount, and a fresh family (same account) doesn't see this member's figures.
+const { chromium } = require('playwright');
+const { signInFreshFamily } = require('./e2e-auth-helper.cjs');
+const BASE = 'https://moslem04.falahos.my/';
+const results = [];
+const consoleErrors = [];
+function record(name, pass, detail = '') { results.push({ name, pass, detail }); console.log(`${pass ? 'PASS' : 'FAIL'}  ${name}${detail ? '  — ' + detail : ''}`); }
+
+async function main() {
+  const browser = await chromium.launch();
+  const page = await browser.newPage({ viewport: { width: 390, height: 844 } });
+  page.on('console', m => { if (m.type() === 'error') consoleErrors.push(m.text()); });
+  page.on('pageerror', e => consoleErrors.push(e.message));
+
+  await signInFreshFamily(page, BASE, 'e2e-zakat');
+  await page.locator('nav button[aria-label="Zakat"]').click();
+  await page.waitForTimeout(600);
+
+  // Below nisab: default nisab is 24000, wealth 10000 -> no zakat due
+  await page.locator('.field:has-text("Cash") input').fill('10000');
+  await page.waitForTimeout(1000);
+  const belowNisabText = await page.locator('.result-row.main span').textContent();
+  record('Zakat: below Nisab shows "no Zakat due"', belowNisabText.includes('Below Nisab'), belowNisabText);
+
+  // Above nisab: cash 30000, gold 10000 = 40000 wealth, nisab 24000 -> due = 40000*0.025 = 1000
+  await page.locator('.field:has-text("Cash") input').fill('30000');
+  await page.locator('.field:has-text("Gold") input').fill('10000');
+  await page.waitForTimeout(1000);
+  const dueText = await page.locator('.result-row.main strong').textContent();
+  record('Zakat: correct 2.5% computed once above Nisab', dueText.trim() === '1,000', dueText);
+
+  const wealthText = await page.locator('.result-row', { hasText: 'Zakatable wealth' }).locator('strong').textContent();
+  record('Zakat: zakatable wealth sums categories correctly', wealthText.trim() === '40,000', wealthText);
+
+  // Deductible liabilities reduce the base
+  await page.locator('.field:has-text("Deductible liabilities") input').fill('5000');
+  await page.waitForTimeout(1000);
+  const wealthAfterDebt = await page.locator('.result-row', { hasText: 'Zakatable wealth' }).locator('strong').textContent();
+  record('Zakat: deductible liabilities reduce zakatable wealth', wealthAfterDebt.trim() === '35,000', wealthAfterDebt);
+
+  // Persistence: reload the tab (remount) and confirm autosave held
+  await page.locator('nav button[aria-label="Coverage"]').click();
+  await page.waitForTimeout(400);
+  await page.locator('nav button[aria-label="Zakat"]').click();
+  await page.waitForTimeout(800);
+  const cashPersisted = await page.locator('.field:has-text("Cash") input').inputValue();
+  record('Zakat: autosaved figures persist across a tab remount', cashPersisted === '30000', cashPersisted);
+
+  // Isolation: a different family (same account) starts with defaults, not this member's figures
+  const isolationPage = await browser.newPage({ viewport: { width: 390, height: 844 } });
+  await signInFreshFamily(isolationPage, BASE, 'e2e-zakat-isolation');
+  await isolationPage.locator('nav button[aria-label="Zakat"]').click();
+  await isolationPage.waitForTimeout(600);
+  const isolatedCash = await isolationPage.locator('.field:has-text("Cash") input').inputValue();
+  record('Isolation: a different family does not see this member\'s Zakat figures', isolatedCash === '', isolatedCash);
+  await isolationPage.close();
+
+  record('No uncaught JS console errors during full session', consoleErrors.length === 0, consoleErrors.join(' || '));
+
+  await browser.close();
+  const passCount = results.filter(r => r.pass).length;
+  const failCount = results.length - passCount;
+  console.log(`\n${passCount} passed, ${failCount} failed, ${results.length} total`);
+  if (failCount > 0) results.filter(r => !r.pass).forEach(r => console.log(`  - ${r.name}: ${r.detail}`));
+  process.exit(failCount > 0 ? 1 : 0);
+}
+main().catch(e => { console.error('SCRIPT ERROR:', e); process.exit(2); });

src/App.svelte

@@ -19,6 +19,7 @@
   import MutawalliDashboard from './lib/MutawalliDashboard.svelte';
   import FamilyTree from './lib/FamilyTree.svelte';
   import InsurancePolicies from './lib/InsurancePolicies.svelte';
+  import ZakatCalculator from './lib/ZakatCalculator.svelte';
 
   let currentLang = $state('en');
   lang.subscribe(v => currentLang = v);
@@ -42,8 +43,8 @@
     }
   });
 
-  const tabs = ['Coverage', 'Faraid', 'Assets', 'Insurance', 'Wassiyah', 'Hibah', 'Family Waqf', 'Nominate', 'Trigger', 'Mutawalli', 'Tree', 'Claims (H2)', 'Family', 'Settings'];
+  const tabs = ['Coverage', 'Faraid', 'Assets', 'Insurance', 'Zakat', 'Wassiyah', 'Hibah', 'Family Waqf', 'Nominate', 'Trigger', 'Mutawalli', 'Tree', 'Claims (H2)', 'Family', 'Settings'];
-  const icons = ['🎯', '📊', '📁', '🛡️', '📜', '🎁', '⛲', '📇', '⚡', '🕋', '🌳', '🔗', '👥', '⚙️'];
+  const icons = ['🎯', '📊', '📁', '🛡️', '🌙', '📜', '🎁', '⛲', '📇', '⚡', '🕋', '🌳', '🔗', '👥', '⚙️'];
   let activeTab = $state(0);
 
   function handleKeydown(e) {
@@ -101,16 +102,17 @@
     {:else if activeTab === 1}<FaraidCalculator />
     {:else if activeTab === 2}<AssetRegistry />
     {:else if activeTab === 3}<InsurancePolicies />
-    {:else if activeTab === 4}<WassiyahGenerator />
+    {:else if activeTab === 4}<ZakatCalculator />
-    {:else if activeTab === 5}<HibahTracker />
+    {:else if activeTab === 5}<WassiyahGenerator />
-    {:else if activeTab === 6}<FamilyWaqfDesignator />
+    {:else if activeTab === 6}<HibahTracker />
-    {:else if activeTab === 7}<NominationRegistry />
+    {:else if activeTab === 7}<FamilyWaqfDesignator />
-    {:else if activeTab === 8}<DeathTrigger />
+    {:else if activeTab === 8}<NominationRegistry />
-    {:else if activeTab === 9}<MutawalliDashboard />
+    {:else if activeTab === 9}<DeathTrigger />
-    {:else if activeTab === 10}<FamilyTree />
+    {:else if activeTab === 10}<MutawalliDashboard />
-    {:else if activeTab === 11}<DigitalClaims />
+    {:else if activeTab === 11}<FamilyTree />
-    {:else if activeTab === 12}<FamilyManagement />
+    {:else if activeTab === 12}<DigitalClaims />
-    {:else if activeTab === 13}
+    {:else if activeTab === 13}<FamilyManagement />
+    {:else if activeTab === 14}
       <div class="module">
         <div class="module-header">
           <h2>Settings</h2>

src/lib/ZakatCalculator.svelte

@@ -0,0 +1,105 @@
+<script>
+  import { onMount } from 'svelte';
+  import { activeFamilyId } from './family.js';
+  import { session } from './auth.js';
+  import { getZakatRecord, upsertZakatRecord } from './db.js';
+  import { zakatableWealth, zakatDue, meetsNisab } from './calc/zakat.js';
+  import Disclaimer from './Disclaimer.svelte';
+  import InfoPanel from './InfoPanel.svelte';
+
+  let familyId = $state(null);
+  activeFamilyId.subscribe(v => familyId = v);
+  // Live off the session store, not a one-time snapshot — same fix as every
+  // other per-member module (Wassiyah, Waqf, Insurance): this component
+  // remounts on tab switch, and a stale null captured once at mount would
+  // silently break every write until the next remount.
+  let memberId = $state(null);
+  session.subscribe(v => memberId = v?.user?.id ?? null);
+
+  const DEFAULT_NISAB = 24000; // rough 85g-gold-equivalent placeholder in RM; user should override with today's value
+
+  let fields = $state(emptyFields());
+  let loaded = $state(false);
+
+  function emptyFields() {
+    return { cash: '', gold: '', silver: '', businessAssets: '', investments: '', otherZakatable: '', deductibleLiabilities: '', nisabThreshold: String(DEFAULT_NISAB) };
+  }
+
+  async function refresh() {
+    if (!familyId || !memberId) return;
+    const record = await getZakatRecord(familyId, memberId);
+    fields = record
+      ? { cash: String(record.cash), gold: String(record.gold), silver: String(record.silver), businessAssets: String(record.businessAssets), investments: String(record.investments), otherZakatable: String(record.otherZakatable), deductibleLiabilities: String(record.deductibleLiabilities), nisabThreshold: String(record.nisabThreshold) }
+      : emptyFields();
+    loaded = true;
+  }
+
+  onMount(refresh);
+  $effect(() => { familyId; memberId; refresh(); });
+
+  let saveTimer;
+  function scheduleSave() {
+    clearTimeout(saveTimer);
+    saveTimer = setTimeout(() => { upsertZakatRecord(familyId, memberId, fields); }, 500);
+  }
+
+  const wealth = $derived(zakatableWealth(fields));
+  const due = $derived(zakatDue(fields));
+  const meets = $derived(meetsNisab(fields));
+</script>
+
+<div class="module">
+  <div class="module-header">
+    <h2>Zakat</h2>
+    <InfoPanel
+      title="Zakat"
+      what="Your annual Zakat obligation — 2.5% of qualifying wealth (cash, gold, silver, business assets, investments) held for a full lunar year (haul), once it's above the Nisab threshold. This is a personal obligation, separate from Faraid and Wassiyah, which only apply after death."
+      how="Enter your zakatable wealth by category, subtract any short-term deductible liabilities, and set today's Nisab value (85g gold or 595g silver equivalent — check a current gold price, this app doesn't fetch it live). Figures autosave as you type."
+      fields={[
+        { label: 'Zakatable wealth', hint: 'Cash, gold, silver, business inventory, investments — anything held for a full lunar year.' },
+        { label: 'Deductible liabilities', hint: 'Short-term debts due, subtracted before checking against Nisab.' },
+        { label: 'Nisab threshold', hint: 'The minimum wealth level before Zakat is due — varies with the current gold/silver price.' }
+      ]}
+    />
+  </div>
+  <p class="sub">Your own Zakat calculation — a personal, ongoing obligation, not tied to death or inheritance.</p>
+
+  {#if loaded}
+    <div class="form-card">
+      <label class="field"><span>Cash &amp; bank balances</span><input type="number" min="0" bind:value={fields.cash} oninput={scheduleSave} /></label>
+      <label class="field"><span>Gold (current market value)</span><input type="number" min="0" bind:value={fields.gold} oninput={scheduleSave} /></label>
+      <label class="field"><span>Silver (current market value)</span><input type="number" min="0" bind:value={fields.silver} oninput={scheduleSave} /></label>
+      <label class="field"><span>Business assets / inventory</span><input type="number" min="0" bind:value={fields.businessAssets} oninput={scheduleSave} /></label>
+      <label class="field"><span>Investments / shares / digital assets</span><input type="number" min="0" bind:value={fields.investments} oninput={scheduleSave} /></label>
+      <label class="field"><span>Other zakatable wealth</span><input type="number" min="0" bind:value={fields.otherZakatable} oninput={scheduleSave} /></label>
+      <label class="field"><span>Deductible liabilities (due within the year)</span><input type="number" min="0" bind:value={fields.deductibleLiabilities} oninput={scheduleSave} /></label>
+      <label class="field"><span>Nisab threshold (today's value)</span><input type="number" min="0" bind:value={fields.nisabThreshold} oninput={scheduleSave} /></label>
+    </div>
+
+    <div class="result-card" class:due={meets}>
+      <div class="result-row"><span>Zakatable wealth</span><strong>{wealth.toLocaleString()}</strong></div>
+      <div class="result-row"><span>Nisab threshold</span><strong>{(Number(fields.nisabThreshold) || 0).toLocaleString()}</strong></div>
+      <div class="result-row main"><span>{meets ? 'Zakat due (2.5%)' : 'Below Nisab — no Zakat due'}</span><strong>{due.toLocaleString()}</strong></div>
+    </div>
+  {/if}
+
+  <Disclaimer text="Manual entry only — Nisab is not fetched from a live gold/silver price feed. Confirm today's threshold and consult a scholar for madhab-specific rulings (this uses a single standard 2.5%/85g-gold ruleset)." />
+</div>
+
+<style>
+  .module { padding: 4px 0 40px; }
+  .module-header { display: flex; align-items: center; margin-bottom: 4px; }
+  h2 { font-family: 'DM Serif Display', serif; font-size: 24px; color: #E8E4DC; margin-bottom: 0; }
+  .sub { font-size: 13px; color: #8A8478; margin-bottom: 16px; }
+  .form-card { background: rgba(255,255,255,0.03); border-radius: 12px; padding: 14px; margin-bottom: 16px; }
+  .field { display: flex; flex-direction: column; gap: 6px; margin-bottom: 12px; }
+  .field span { font-size: 12px; color: #B8B2A6; }
+  .field input { background: rgba(255,255,255,0.05); border: 1px solid rgba(201,168,76,0.2); border-radius: 8px; padding: 10px 12px; color: #E8E4DC; font-size: 14px; width: 100%; }
+  .result-card { background: rgba(201,168,76,0.08); border: 1px solid rgba(201,168,76,0.25); border-radius: 12px; padding: 16px; margin-bottom: 18px; }
+  .result-card.due { background: rgba(46,204,113,0.08); border-color: rgba(46,204,113,0.3); }
+  .result-row { display: flex; justify-content: space-between; align-items: baseline; padding: 6px 0; font-size: 13px; color: #B8B2A6; }
+  .result-row strong { color: #E8E4DC; font-size: 14px; }
+  .result-row.main { border-top: 1px solid rgba(255,255,255,0.1); margin-top: 6px; padding-top: 12px; }
+  .result-row.main span { color: #C9A84C; font-weight: 600; }
+  .result-row.main strong { color: #2ECC71; font-size: 20px; }
+</style>

src/lib/calc/zakat.js

@@ -0,0 +1,24 @@
+// Shared Zakat calculation core — Nisab check + 2.5% (1/40) on qualifying
+// wealth held above threshold. Nisab is entered as a value, not a live gold
+// price feed — matches the app's "manual entry only" philosophy already
+// established for Asset Registry / Faraid.
+const ZAKAT_RATE = 0.025;
+
+export function zakatableWealth(fields) {
+  const gross = (Number(fields.cash) || 0) + (Number(fields.gold) || 0) + (Number(fields.silver) || 0)
+    + (Number(fields.businessAssets) || 0) + (Number(fields.investments) || 0) + (Number(fields.otherZakatable) || 0);
+  const deductible = Number(fields.deductibleLiabilities) || 0;
+  return Math.max(0, gross - deductible);
+}
+
+export function zakatDue(fields) {
+  const wealth = zakatableWealth(fields);
+  const nisab = Number(fields.nisabThreshold) || 0;
+  if (nisab <= 0 || wealth < nisab) return 0;
+  return wealth * ZAKAT_RATE;
+}
+
+export function meetsNisab(fields) {
+  const nisab = Number(fields.nisabThreshold) || 0;
+  return nisab > 0 && zakatableWealth(fields) >= nisab;
+}

src/lib/db.js

@@ -490,3 +490,25 @@ export async function setAssetVerified(assetId, verifiedBy, verified) {
   }).eq('id', assetId);
   if (error) throw error;
 }
+
+// ── Zakat — per-member, one live record per family/member pair. ──
+export async function getZakatRecord(familyId, memberId) {
+  const { data, error } = await supabase.from('nf_zakat_records').select('*').eq('family_id', familyId).eq('member_id', memberId).maybeSingle();
+  if (error) throw error;
+  if (!data) return null;
+  return {
+    cash: data.cash, gold: data.gold, silver: data.silver, businessAssets: data.business_assets,
+    investments: data.investments, otherZakatable: data.other_zakatable,
+    deductibleLiabilities: data.deductible_liabilities, nisabThreshold: data.nisab_threshold
+  };
+}
+export async function upsertZakatRecord(familyId, memberId, fields) {
+  const { error } = await supabase.from('nf_zakat_records').upsert({
+    family_id: familyId, member_id: memberId,
+    cash: Number(fields.cash) || 0, gold: Number(fields.gold) || 0, silver: Number(fields.silver) || 0,
+    business_assets: Number(fields.businessAssets) || 0, investments: Number(fields.investments) || 0,
+    other_zakatable: Number(fields.otherZakatable) || 0, deductible_liabilities: Number(fields.deductibleLiabilities) || 0,
+    nisab_threshold: Number(fields.nisabThreshold) || 0, updated_at: new Date().toISOString()
+  }, { onConflict: 'family_id,member_id' });
+  if (error) throw error;
+}