fix(balance): sum unrounded token values for the total (iOS parity)

apps/flipcash/shared/tokens/src/main/kotlin/com/flipcash/app/tokens/ui/SelectTokenViewModel.kt

@@ -10,7 +10,6 @@ import com.flipcash.shared.tokens.R
 import com.getcode.opencode.exchange.Exchange
 import com.getcode.opencode.model.financial.Fiat
 import com.getcode.opencode.model.financial.LocalFiat
-import com.getcode.opencode.model.financial.rounded
 import com.getcode.opencode.model.financial.Rate
 import com.getcode.opencode.model.financial.TokenWithLocalizedBalance
 import com.getcode.opencode.model.financial.sum
@@ -63,7 +62,11 @@ class SelectTokenViewModel @Inject constructor(
                         )
                 }
 
-                return set.map { it.balance.rounded() }.sum()
+                // Sum the UNROUNDED per-token values, letting display formatting round the total —
+                // i.e. round(sum(x)), not sum(round(x)). Rounding each token to cents first drifts the
+                // total by up to a penny and diverged from iOS (ExchangedFiat.total sums unrounded) and
+                // from our own aggregateAppreciation (which already sums unrounded).
+                return set.map { it.balance }.sum()
             }
 
         val aggregateAppreciation: LocalFiat?

apps/flipcash/shared/tokens/src/test/kotlin/com/flipcash/app/tokens/ui/SelectTokenViewModelStateTest.kt

@@ -0,0 +1,57 @@
+package com.flipcash.app.tokens.ui
+
+import com.flipcash.app.core.tokens.TokenPurpose
+import com.getcode.opencode.model.financial.CurrencyCode
+import com.getcode.opencode.model.financial.Fiat
+import com.getcode.opencode.model.financial.LocalFiat
+import com.getcode.opencode.model.financial.Rate
+import com.getcode.opencode.model.financial.Token
+import com.getcode.opencode.model.financial.TokenWithLocalizedBalance
+import com.getcode.opencode.model.financial.usdf
+import com.getcode.solana.keys.Mint
+import org.junit.Assert.assertEquals
+import org.junit.Assert.assertNotEquals
+import org.junit.Test
+
+class SelectTokenViewModelStateTest {
+
+    private fun tokenWorth(nativeUsd: Double): TokenWithLocalizedBalance {
+        val amount = Fiat(nativeUsd, CurrencyCode.USD)
+        return TokenWithLocalizedBalance(
+            token = Token.usdf,
+            balance = LocalFiat(
+                underlyingTokenAmount = amount,
+                nativeAmount = amount,
+                rate = Rate.oneToOne,
+                mint = Mint.usdf,
+            ),
+        )
+    }
+
+    /**
+     * The wallet total must be round(sum(x)), not sum(round(x)): rounding each token to cents first
+     * drifts the total by up to a penny and diverged from iOS (ExchangedFiat.total sums unrounded).
+     *
+     * Two tokens each worth $0.014 display as $0.01 apiece — so sum(round) is $0.02 — but their true
+     * sum is $0.028, which rounds to $0.03.
+     */
+    @Test
+    fun `total sums unrounded values, then rounds for display`() {
+        val state = SelectTokenViewModel.State(
+            purpose = TokenPurpose.Balance,
+            rate = Rate.oneToOne,
+            tokens = listOf(tokenWorth(0.014), tokenWorth(0.014)),
+        )
+
+        val total = state.totalBalance!!.nativeAmount
+
+        // Unrounded sum is retained; display formatting rounds it to $0.03.
+        assertEquals(0.028, total.decimalValue, 1e-3)
+        assertEquals(0.03, total.rounded(2).decimalValue, 1e-6)
+
+        // Regression guard: rounding per token first (the old behaviour) would have shown $0.02.
+        val sumOfRounded = state.tokens!!.sumOf { it.balance.nativeAmount.rounded(2).decimalValue }
+        assertEquals(0.02, sumOfRounded, 1e-6)
+        assertNotEquals(sumOfRounded, total.rounded(2).decimalValue, 1e-6)
+    }
+}