From 74a043262d02b1a6369aaa6af88bf13c0f135e5a Mon Sep 17 00:00:00 2001
From: openhands <openhands@all-hands.dev>
Date: Tue, 3 Mar 2026 19:45:46 +0000
Subject: [PATCH] feat(holdout): Add reasonable slippage assertion to
 always-leave scenario

- Modified sellAllKrk helper to return WETH delta received
- Added assertion: WETH received >= 90% of ETH spent (0.09 ETH minimum)
- Added log showing actual slippage percentage
- This proves 'always leave' with reasonable slippage, not just exit ability
---
 scripts/harb-evaluator/helpers/swap.ts               | 10 +++++++---
 .../scenarios/sovereign-exit/always-leave.spec.ts    | 12 ++++++++++--
 2 files changed, 17 insertions(+), 5 deletions(-)

diff --git a/scripts/harb-evaluator/helpers/swap.ts b/scripts/harb-evaluator/helpers/swap.ts
index 86e27a8..85e4627 100644
--- a/scripts/harb-evaluator/helpers/swap.ts
+++ b/scripts/harb-evaluator/helpers/swap.ts
@@ -119,8 +119,10 @@ export async function buyKrk(page: Page, ethAmount: string): Promise<void> {
  * Logs a warning if the WETH balance does not increase after the swap, which
  * indicates the pool returned 0 output (possible with amountOutMinimum: 0n on
  * a partially-drained pool).
+ *
+ * @returns The WETH delta (wethAfter - wethBefore) received from the swap.
  */
-export async function sellAllKrk(page: Page, config: SellConfig): Promise<void> {
+export async function sellAllKrk(page: Page, config: SellConfig): Promise<bigint> {
   const krkBalance = await erc20BalanceOf(config.rpcUrl, config.krkAddress, config.accountAddress);
   if (krkBalance === 0n) throw new Error('sellAllKrk: KRK balance is 0 — nothing to sell');
 
@@ -175,9 +177,11 @@ export async function sellAllKrk(page: Page, config: SellConfig): Promise<void>
   console.log('[swap] Swap mined');
 
   const wethAfter = await erc20BalanceOf(config.rpcUrl, WETH, config.accountAddress);
-  if (wethAfter <= wethBefore) {
+  const wethReceived = wethAfter - wethBefore;
+  if (wethReceived <= 0n) {
     console.warn('[swap] WARNING: WETH balance did not increase after sell — pool may have returned 0 output');
   } else {
-    console.log(`[swap] Received ${wethAfter - wethBefore} WETH`);
+    console.log(`[swap] Received ${wethReceived} WETH`);
   }
+  return wethReceived;
 }
diff --git a/scripts/harb-evaluator/scenarios/sovereign-exit/always-leave.spec.ts b/scripts/harb-evaluator/scenarios/sovereign-exit/always-leave.spec.ts
index cc10576..0351b8c 100644
--- a/scripts/harb-evaluator/scenarios/sovereign-exit/always-leave.spec.ts
+++ b/scripts/harb-evaluator/scenarios/sovereign-exit/always-leave.spec.ts
@@ -12,7 +12,7 @@
  * so no collision occurs.
  */
 import { expect, test } from '@playwright/test';
-import { Wallet } from 'ethers';
+import { parseEther, Wallet } from 'ethers';
 import { createWalletContext } from '../../../../tests/setup/wallet-provider';
 import { getStackConfig } from '../../../../tests/setup/stack';
 import { connectWallet, getKrkBalance } from '../../helpers/wallet';
@@ -55,7 +55,7 @@ test('I can always leave', async ({ browser }) => {
     console.log('[TEST] ✅ KRK received');
 
     // ── 4. Sell all KRK back (sovereign exit) ────────────────────────────
-    await sellAllKrk(page, {
+    const wethReceived = await sellAllKrk(page, {
       rpcUrl: config.rpcUrl,
       krkAddress: config.contracts.Kraiken,
       accountAddress: ACCOUNT_ADDRESS,
@@ -66,6 +66,14 @@ test('I can always leave', async ({ browser }) => {
     console.log(`[TEST] KRK balance after sell: ${krkAfterSell}`);
     expect(krkAfterSell).toBeLessThan(krkAfterBuy);
     console.log('[TEST] ✅ Sovereign exit confirmed: KRK sold back to WETH');
+
+    // ── 6. Assert reasonable slippage (at least 90% of ETH spent) ─────────
+    const ethSpent = parseEther('0.1');
+    const minExpected = parseEther('0.09'); // 90% of 0.1 ETH
+    expect(wethReceived).toBeGreaterThanOrEqual(minExpected);
+    const slippagePercent = ((Number(wethReceived) / Number(ethSpent)) * 100).toFixed(2);
+    console.log(`[TEST] ✅ Reasonable slippage: received ${wethReceived} WETH for 0.1 ETH spent (${slippagePercent}%)`);
+
   } finally {
     await ctx.close();
   }