Fix interest earned calculation to measure realized profit only

app/(protected)/(tabs)/savings.tsx

@@ -88,9 +88,16 @@ function LegacySavings() {
   const { data: exchangeRate } = useVaultExchangeRate(currentVault.name);
 
   const rawAllTime = apys?.allTime;
+  // Shown in the "All time yield" panel and used for the 1Y projection.
   const vaultAPY =
     rawAllTime != null && Number.isFinite(Number(rawAllTime)) ? Number(rawAllTime) : 0;
 
+  // Rate the live counters tick at. It must be the same figure the screen
+  // advertises as "Current Yield" (maxAPY) — ticking on the all-time APY while
+  // displaying the recent one made the two disagree, so a change in the headline
+  // rate looked unrelated to how fast the numbers moved.
+  const tickAPY = Number.isFinite(maxAPY) ? maxAPY : 0;
+
   const { data: lastTimestamp } = useLatestTokenTransfer(
     user?.safeAddress ?? '',
     // Use correct token address based on selected vault
@@ -113,11 +120,10 @@ function LegacySavings() {
     currentVault.decimals,
   );
 
-  // Backend summary for soFUSE interest (FUSE has no subgraph)
-  const { data: savingsSummary } = useSavingsSummary(
-    currentVault.name,
-    currentVault.name === 'FUSE',
-  );
+  // Backend summary is the source of truth for interest earned on every vault:
+  // it measures realized profit against a high-water-mark exchange rate, so the
+  // figure can't step backwards on a transient NAV dip.
+  const { data: savingsSummary } = useSavingsSummary(currentVault.name);
 
   const isLoading = isBalanceLoading || isTransactionsLoading;
   const isEmptyStateLoading = isTotalBalanceLoading || isTransactionsLoading;
@@ -248,7 +254,7 @@ function LegacySavings() {
                           balance={balance ?? 0}
                           decimalPlaces={currentVault.name === 'ETH' ? 8 : 2}
                           decimals={currentVault.decimals}
-                          apy={vaultAPY}
+                          apy={tickAPY}
                           lastTimestamp={firstDepositTimestamp ?? 0}
                           userDepositTransactions={userDepositTransactions}
                           exchangeRate={exchangeRate}
@@ -297,7 +303,7 @@ function LegacySavings() {
                           suffix={displaySuffix ?? ''}
                           balance={balance ?? 0}
                           decimals={currentVault.decimals}
-                          apy={vaultAPY}
+                          apy={tickAPY}
                           lastTimestamp={firstDepositTimestamp ?? 0}
                           mode={SavingMode.CURRENT}
                           inputsReady={
@@ -451,7 +457,7 @@ function LegacySavings() {
                           balance={balance ?? 0}
                           decimalPlaces={currentVault.name === 'ETH' ? 8 : 2}
                           decimals={currentVault.decimals}
-                          apy={vaultAPY}
+                          apy={tickAPY}
                           lastTimestamp={firstDepositTimestamp ?? 0}
                           userDepositTransactions={userDepositTransactions}
                           exchangeRate={exchangeRate}
@@ -500,7 +506,7 @@ function LegacySavings() {
                           suffix={displaySuffix ?? ''}
                           balance={balance ?? 0}
                           decimals={currentVault.decimals}
-                          apy={vaultAPY}
+                          apy={tickAPY}
                           lastTimestamp={firstDepositTimestamp ?? 0}
                           mode={SavingMode.CURRENT}
                           inputsReady={

components/Savings/NewSavings/VaultSavingsSection.tsx

@@ -5,12 +5,7 @@ import { fuse, mainnet } from 'viem/chains';
 
 import { Text } from '@/components/ui/text';
 import { VAULTS } from '@/constants/vaults';
-import {
-  useAPYs,
-  useLatestTokenTransfer,
-  useMaxAPY,
-  useUserTransactions,
-} from '@/hooks/useAnalytics';
+import { useLatestTokenTransfer, useMaxAPY, useUserTransactions } from '@/hooks/useAnalytics';
 import { useDepositCalculations } from '@/hooks/useDepositCalculations';
 import { useNativePriceUsd } from '@/hooks/useNativePriceUsd';
 import { useSavingsSummary } from '@/hooks/useSavingsSummary';
@@ -53,12 +48,12 @@ const VaultSavingsSection = ({ vaultType }: VaultSavingsSectionProps) => {
   const display = getVaultDisplay(vaultType);
 
   const { data: balance } = useVaultBalance(user?.safeAddress as Address, vault);
-  const { maxAPY } = useMaxAPY(vault.type);
-  const { data: apys, isLoading: isAPYsLoading } = useAPYs(vault.type);
+  const { maxAPY, isAPYsLoading } = useMaxAPY(vault.type);
   const { data: exchangeRate } = useVaultExchangeRate(vault.name);
 
-  const vaultAPY =
-    apys?.allTime != null && Number.isFinite(Number(apys.allTime)) ? Number(apys.allTime) : 0;
+  // Tick the live interest counter at the rate this card displays (maxAPY), not
+  // the all-time APY — the two disagree, and the counter must match the headline.
+  const tickAPY = Number.isFinite(maxAPY) ? maxAPY : 0;
 
   const { data: lastTimestamp } = useLatestTokenTransfer(
     user?.safeAddress ?? '',
@@ -75,17 +70,19 @@ const VaultSavingsSection = ({ vaultType }: VaultSavingsSectionProps) => {
     lastTimestamp,
     vault.decimals,
   );
-  const { data: savingsSummary } = useSavingsSummary(vault.name, vault.name === 'FUSE');
+  // Source of truth for interest earned on every vault (high-water-mark based).
+  const { data: savingsSummary } = useSavingsSummary(vault.name);
 
   // USD price of the vault's native token (1 for USDC; FUSE/ETH priced live).
   const fusePriceUsd = useNativePriceUsd(fuse.id, 'fusePriceUsd', vault.name === 'FUSE');
   const ethPriceUsd = useNativePriceUsd(mainnet.id, 'ethPriceUsd', vault.name === 'ETH');
   const priceUsd = vault.name === 'USDC' ? 1 : vault.name === 'FUSE' ? fusePriceUsd : ethPriceUsd;
 
-  // Live interest (USD for USDC/FUSE; ETH-native × price for ETH).
+  // Live interest, denominated in the vault's base asset (USD for soUSD, FUSE
+  // for soFUSE, ETH for soETH) — converted to USD below.
   const interestRaw = useSavingsYield({
     balance: balance ?? 0,
-    apy: vaultAPY,
+    apy: tickAPY,
     lastTimestamp: firstDepositTimestamp ?? 0,
     mode: SavingMode.CURRENT,
     decimals: vault.decimals,
@@ -99,7 +96,10 @@ const VaultSavingsSection = ({ vaultType }: VaultSavingsSectionProps) => {
 
   const redeemableNative = (balance ?? 0) * (exchangeRate ?? 1);
   const availableUsd = vault.name === 'USDC' ? redeemableNative : redeemableNative * priceUsd;
-  const interestUsd = vault.name === 'ETH' ? interestRaw * priceUsd : interestRaw;
+  // Interest must be converted on the same basis as `availableUsd`. FUSE was
+  // previously left unconverted, so on the soFUSE card a FUSE-denominated
+  // interest figure was rendered with a $ sign and subtracted from a USD total.
+  const interestUsd = vault.name === 'USDC' ? interestRaw : interestRaw * priceUsd;
   const depositedUsd = Math.max(availableUsd - interestUsd, 0);
 
   // No exact historical "this month" breakdown exists, so approximate from APY:
@@ -133,7 +133,7 @@ const VaultSavingsSection = ({ vaultType }: VaultSavingsSectionProps) => {
           <Stat label="Interest earned" value={fmtUsd(interestUsd)} />
         </View>
         <View className="flex-row">
-          <Stat label="This month" value={`+${fmtUsd(thisMonthUsd)}`} positive />
+          <Stat label="This month (est.)" value={`+${fmtUsd(thisMonthUsd)}`} positive />
           <Stat label="Next 30 days (est.)" value={`+${fmtUsd(nextThirtyUsd)}`} positive />
         </View>
       </View>

hooks/useFinancial.ts

@@ -1,6 +1,6 @@
 import { useCallback, useEffect, useMemo, useRef, useState } from 'react';
 
-import { calculateYield } from '@/lib/financial';
+import { calculateYield, INTEREST_UNAVAILABLE } from '@/lib/financial';
 import { SavingMode } from '@/lib/types';
 
 export const useCalculateSavings = (
@@ -52,6 +52,9 @@ export const useCalculateSavings = (
       transactionsRef.current,
       calculationParams.safeAddress,
     );
+    // Interest couldn't be measured from deposit history — keep the last value
+    // rather than publishing the sentinel.
+    if (calculatedSavings === INTEREST_UNAVAILABLE) return;
     setSavings(calculatedSavings);
   }, [calculationParams]);
 

hooks/useSavingsYield.ts

@@ -3,7 +3,7 @@ import { useEffect, useState } from 'react';
 import { GetUserTransactionsQuery } from '@/graphql/generated/user-info';
 import useUser from '@/hooks/useUser';
 import { ADDRESSES } from '@/lib/config';
-import { calculateYield, SECONDS_PER_YEAR } from '@/lib/financial';
+import { calculateYield, INTEREST_UNAVAILABLE, SECONDS_PER_YEAR } from '@/lib/financial';
 import { SavingMode, SavingsSummaryResponse } from '@/lib/types';
 
 function amountGained(
@@ -17,17 +17,6 @@ function amountGained(
   return (((apy / 100) * (toTs - fromTs)) / SECONDS_PER_YEAR) * balanceUSD;
 }
 
-function totalUsdLive(
-  balance: number,
-  exchangeRate: number,
-  apy: number,
-  lastTs: number,
-  now: number,
-): number {
-  const balanceUSD = balance * exchangeRate;
-  return balanceUSD + amountGained(balance, exchangeRate, apy, lastTs, now);
-}
-
 export interface UseSavingsYieldParams {
   balance: number;
   apy: number;
@@ -39,12 +28,28 @@ export interface UseSavingsYieldParams {
   tokenAddress?: string;
   /** When true, treat interest inputs as loaded. Omit to use internal buckets. */
   inputsReady?: boolean;
-  /** Backend savings summary — used for soFUSE interest (no subgraph available) */
+  /** Backend savings summary — the preferred source for interest earned. */
   summary?: SavingsSummaryResponse | null;
-  /** Vault identifier ('USDC' | 'FUSE') — FUSE uses backend summary, USDC uses subgraph */
+  /** Vault identifier ('USDC' | 'FUSE' | 'ETH'). */
   vault?: string;
 }
 
+/**
+ * Live savings figure for a vault.
+ *
+ * For the interest modes, the value is a *measurement* of realized profit
+ * (`total value - total deposited`) taken at a known instant, plus an APY
+ * projection over only the seconds elapsed since that instant. That keeps the
+ * counter smooth without letting a rate change retroactively re-price the whole
+ * holding period — the behaviour that made "interest earned" fall when the APY
+ * dipped.
+ *
+ * Preferred source is the backend `/savings/summary`, which measures against a
+ * high-water-mark exchange rate so the figure never steps backwards on a
+ * transient NAV dip. The subgraph calculation is the fallback; if neither can
+ * establish realized profit, the last known value is held rather than replaced
+ * by a projection.
+ */
 export function useSavingsYield({
   balance,
   apy,
@@ -78,20 +83,24 @@ export function useSavingsYield({
 
   // Full calc only when inputs change (no animation). For TOTAL_USD use redeemable only so display matches withdraw.
   useEffect(() => {
-    // soFUSE CURRENT mode: interest comes from the backend summary (no subgraph
-    // for FUSE) and stays valid even if the on-chain balance read is momentarily
-    // 0 (slow/failed RPC poll or a vault switch). Handle it BEFORE the balance<=0
-    // guard so a transient 0 balance can't wipe the anchor and snap interest to 0.
-    if (mode === SavingMode.CURRENT && vault === 'FUSE') {
-      if (summary) {
-        const backendInterest = parseFloat(summary.interestEarnedUSD);
-        const calculatedAtUnix = Math.floor(new Date(summary.calculatedAt).getTime() / 1000);
-        if (backendInterest >= 0 && calculatedAtUnix > 0) {
-          setLiveYield(backendInterest);
-          setAnchor({ value: backendInterest, time: calculatedAtUnix });
-        }
+    // CURRENT mode: prefer the backend summary for every vault. It is measured
+    // against a high-water-mark rate and stays valid even if the on-chain balance
+    // read is momentarily 0 (slow/failed RPC poll or a vault switch), so it is
+    // handled BEFORE the balance<=0 guard — a transient 0 balance must not wipe
+    // the anchor and snap interest to 0.
+    if (mode === SavingMode.CURRENT && summary) {
+      const backendInterest = parseFloat(summary.interestEarnedUSD);
+      const calculatedAtUnix = Math.floor(new Date(summary.calculatedAt).getTime() / 1000);
+      if (isFinite(backendInterest) && backendInterest >= 0 && calculatedAtUnix > 0) {
+        setLiveYield(backendInterest);
+        setAnchor({ value: backendInterest, time: calculatedAtUnix });
       }
-      // No summary yet — keep current value until backend responds
+      return;
+    }
+
+    // FUSE has no subgraph to fall back on — hold the current value until the
+    // backend summary responds rather than showing a projection.
+    if (mode === SavingMode.CURRENT && vault === 'FUSE') {
       return;
     }
 
@@ -126,6 +135,9 @@ export function useSavingsYield({
       vaultDecimals,
     ).then(calculatedYield => {
       if (cancelled) return;
+      // Realized profit couldn't be established (no deposit history yet) — keep
+      // whatever is on screen instead of substituting a guess.
+      if (calculatedYield === INTEREST_UNAVAILABLE) return;
       const isSpuriousZero =
         mode === SavingMode.CURRENT && calculatedYield === 0 && balance > 0 && lastTimestamp > 0;
       if (!isSpuriousZero) {
@@ -151,7 +163,9 @@ export function useSavingsYield({
     ...(inputsReady !== undefined ? [inputsReady] : [lastTsBucket, apyBucket]),
   ]);
 
-  // Every second: update display with simple formula (no network)
+  // Every second: update display with simple formula (no network).
+  // For CURRENT this projects forward from the anchor only — the elapsed period
+  // is already accounted for by the measured value at anchor.time.
   useEffect(() => {
     if (balance <= 0) return;
     const now = Math.floor(Date.now() / 1000);

hooks/useSavingsYieldOld.ts

@@ -8,7 +8,7 @@ import { useEffect, useState } from 'react';
 import { GetUserTransactionsQuery } from '@/graphql/generated/user-info';
 import useUser from '@/hooks/useUser';
 import { ADDRESSES } from '@/lib/config';
-import { calculateYield, SECONDS_PER_YEAR } from '@/lib/financial';
+import { calculateYield, INTEREST_UNAVAILABLE, SECONDS_PER_YEAR } from '@/lib/financial';
 import { SavingMode } from '@/lib/types';
 
 function amountGained(
@@ -90,6 +90,8 @@ export function useSavingsYieldOld({
       vaultDecimals,
     ).then(calculatedYield => {
       if (cancelled) return;
+      // Interest couldn't be measured from deposit history — hold the last value.
+      if (calculatedYield === INTEREST_UNAVAILABLE) return;
       const isSpuriousZero =
         mode === SavingMode.CURRENT && calculatedYield === 0 && balance > 0 && lastTimestamp > 0;
       if (!isSpuriousZero) {