fix(deepbook-v3): repay_base/repay_quote no longer drain balance on amount=0

.changeset/fix-deepbook-v3-repay-amount-zero.md

@@ -0,0 +1,5 @@
+---
+'@mysten/deepbook-v3': patch
+---
+
+Fix `MarginManagerContract.repayBase` and `repayQuote` mishandling `amount = 0`. The previous truthy guard (`amount ? … : null`) collapsed `0` onto the `Option::None` branch, causing `repay_base(mgr, 0)` / `repay_quote(mgr, 0)` to repay the full outstanding debt using whatever balance of the asset was held in the balance manager — rather than being a no-op as the numeric argument suggests. The check now uses `amount !== undefined`, so `0` correctly serializes as `Option::Some(0)` and only an omitted argument becomes `None`. Also switches the `Option<u64>` argument from `tx.object.option` to `tx.pure.option` to avoid an extra `0x1::option::some/none` PTB command, matching `marginLiquidations.ts` and `marginPool.ts`.

packages/deepbook-v3/src/transactions/marginManager.ts

@@ -383,10 +383,10 @@ export class MarginManagerContract {
 				tx.object(manager.address),
 				tx.object(this.#config.MARGIN_REGISTRY_ID),
 				tx.object(baseMarginPool.address),
-				tx.object.option({
-					type: 'u64',
-					value: amount ? tx.pure.u64(convertQuantity(amount, baseCoin.scalar)) : null,
-				}),
+				tx.pure.option(
+					'u64',
+					amount !== undefined ? convertQuantity(amount, baseCoin.scalar) : null,
+				),
 				tx.object.clock(),
 			],
 			typeArguments: [baseCoin.type, quoteCoin.type],
@@ -411,10 +411,10 @@ export class MarginManagerContract {
 				tx.object(manager.address),
 				tx.object(this.#config.MARGIN_REGISTRY_ID),
 				tx.object(quoteMarginPool.address),
-				tx.object.option({
-					type: 'u64',
-					value: amount ? tx.pure.u64(convertQuantity(amount, quoteCoin.scalar)) : null,
-				}),
+				tx.pure.option(
+					'u64',
+					amount !== undefined ? convertQuantity(amount, quoteCoin.scalar) : null,
+				),
 				tx.object.clock(),
 			],
 			typeArguments: [baseCoin.type, quoteCoin.type],

packages/deepbook-v3/test/unit/transactions/marginManager.test.ts

@@ -0,0 +1,100 @@
+// Copyright (c) Mysten Labs, Inc.
+// SPDX-License-Identifier: Apache-2.0
+
+import { bcs } from '@mysten/sui/bcs';
+import { Transaction } from '@mysten/sui/transactions';
+import { fromBase64 } from '@mysten/sui/utils';
+import { describe, expect, it } from 'vitest';
+
+import { MarginManagerContract } from '../../../src/transactions/marginManager.js';
+import { DeepBookConfig } from '../../../src/utils/config.js';
+
+const MARGIN_MANAGER_KEY = 'TEST_MGR';
+
+function newContract() {
+	const config = new DeepBookConfig({
+		network: 'testnet',
+		address: '0x1',
+		marginManagers: {
+			[MARGIN_MANAGER_KEY]: {
+				address: '0x2222222222222222222222222222222222222222222222222222222222222222',
+				poolKey: 'SUI_DBUSDC',
+			},
+		},
+	});
+	return new MarginManagerContract(config);
+}
+
+function lastMoveCall(tx: Transaction) {
+	const { commands } = tx.getData();
+	const last = commands[commands.length - 1];
+	if (last.$kind !== 'MoveCall') throw new Error('expected last command to be MoveCall');
+	return last.MoveCall;
+}
+
+function pureBytesForArg(tx: Transaction, arg: { $kind: string; Input?: number }) {
+	if (arg.$kind !== 'Input' || arg.Input === undefined) {
+		throw new Error(`expected pure Input argument, got ${JSON.stringify(arg)}`);
+	}
+	const input = tx.getData().inputs[arg.Input];
+	if (input.$kind !== 'Pure') throw new Error('expected pure input');
+	return fromBase64(input.Pure.bytes);
+}
+
+describe('MarginManagerContract.repayBase', () => {
+	it('encodes Option::Some(0) when amount=0 (not None)', () => {
+		const tx = new Transaction();
+		newContract().repayBase(MARGIN_MANAGER_KEY, 0)(tx);
+		const call = lastMoveCall(tx);
+		expect(call.function).toBe('repay_base');
+		const optionArg = call.arguments[3];
+		const bytes = pureBytesForArg(tx, optionArg);
+		const parsed = bcs.option(bcs.u64()).parse(bytes);
+		expect(parsed).toBe('0');
+	});
+
+	it('encodes Option::Some(amount) when amount is a positive number', () => {
+		const tx = new Transaction();
+		newContract().repayBase(MARGIN_MANAGER_KEY, 1.5)(tx);
+		const call = lastMoveCall(tx);
+		const bytes = pureBytesForArg(tx, call.arguments[3]);
+		// SUI base scalar is 1e9, so 1.5 -> 1_500_000_000
+		expect(bcs.option(bcs.u64()).parse(bytes)).toBe('1500000000');
+	});
+
+	it('encodes Option::None when amount is omitted', () => {
+		const tx = new Transaction();
+		newContract().repayBase(MARGIN_MANAGER_KEY)(tx);
+		const call = lastMoveCall(tx);
+		const bytes = pureBytesForArg(tx, call.arguments[3]);
+		expect(bcs.option(bcs.u64()).parse(bytes)).toBeNull();
+	});
+});
+
+describe('MarginManagerContract.repayQuote', () => {
+	it('encodes Option::Some(0) when amount=0 (not None)', () => {
+		const tx = new Transaction();
+		newContract().repayQuote(MARGIN_MANAGER_KEY, 0)(tx);
+		const call = lastMoveCall(tx);
+		expect(call.function).toBe('repay_quote');
+		const bytes = pureBytesForArg(tx, call.arguments[3]);
+		expect(bcs.option(bcs.u64()).parse(bytes)).toBe('0');
+	});
+
+	it('encodes Option::Some(amount) when amount is a positive number', () => {
+		const tx = new Transaction();
+		newContract().repayQuote(MARGIN_MANAGER_KEY, 2.5)(tx);
+		const call = lastMoveCall(tx);
+		const bytes = pureBytesForArg(tx, call.arguments[3]);
+		// DBUSDC quote scalar is 1e6, so 2.5 -> 2_500_000
+		expect(bcs.option(bcs.u64()).parse(bytes)).toBe('2500000');
+	});
+
+	it('encodes Option::None when amount is omitted', () => {
+		const tx = new Transaction();
+		newContract().repayQuote(MARGIN_MANAGER_KEY)(tx);
+		const call = lastMoveCall(tx);
+		const bytes = pureBytesForArg(tx, call.arguments[3]);
+		expect(bcs.option(bcs.u64()).parse(bytes)).toBeNull();
+	});
+});