feat: Universal Router v2.1.1 by gretzke · Pull Request #470 · Uniswap/universal-router

gretzke · 2026-02-21T18:34:47Z

Summary

PAY_PORTION_FULL_PRECISION (0x07): New payment command with 1e18 precision (vs 10,000 bips), enabling exact fractional payments like 1/3
Per-hop slippage for V2/V3: Adds uint256[] maxHopSlippage parameter to all 4 V2/V3 swap commands (V3_SWAP_EXACT_IN, V3_SWAP_EXACT_OUT, V2_SWAP_EXACT_IN, V2_SWAP_EXACT_OUT), matching V4's convention where price = amountOut * 1e36 / amountIn
v4-periphery submodule bump: Updates submodule to include maxHopSlippage in V4 single-swap structs

Test Plan

101 Foundry tests pass (including 13 new V3 mock pool tests for per-hop slippage)
12 Hardhat integration tests pass (including new tests for PAY_PORTION_FULL_PRECISION)
V3 exact-output multi-hop slippage enforcement verified (hop 0 bug fixed)
V4 single-swap planner ABI updated for maxHopSlippage field
Path length guards prevent underflow on malformed inputs

✨ Claude-Generated Content

Summary

Universal Router v2.1.1 introduces high-precision payment commands and per-hop slippage protection for V2/V3 swaps, aligning with V4's conventions.

Changes

New Commands

PAY_PORTION_FULL_PRECISION (0x07): Payment command with 1e18 precision (vs 10,000 bips), enabling exact fractional payments like 1/3

Per-hop Slippage Protection

Add uint256[] minHopPriceX36 parameter to all V2/V3 swap commands:
- V3_SWAP_EXACT_IN, V3_SWAP_EXACT_OUT
- V2_SWAP_EXACT_IN, V2_SWAP_EXACT_OUT
Price convention: amountOut * 1e36 / amountIn
Path length guards prevent underflow on malformed inputs

New Errors

V2TooLittleReceivedPerHop, V2InvalidHopPriceLength in V2SwapRouter
V3TooLittleReceivedPerHop, V3TooMuchRequestedPerHop, V3HopPriceAndPathLengthMismatch in V3SwapRouter
InvalidPortion in Payments module

Library Updates

Add toUint256Array helper in BytesLib for decoding hop slippage arrays
Add PRICE_PRECISION constant (1e36) in Constants
Add INCREASE_LIQUIDITY_FROM_DELTAS action check in V3ToV4Migrator

Build Configuration

Set bytecode_hash = "none" in foundry.toml

Dependencies

Update v4-periphery submodule to include minHopPriceX36 in V4 single-swap structs
Update forge-std submodule

Test Plan

101 Foundry tests pass (including 13 new V3 mock pool tests for per-hop slippage)
12 Hardhat integration tests pass (including new tests for PAY_PORTION_FULL_PRECISION)
V3 exact-output multi-hop slippage enforcement verified (hop 0 bug fixed)
V4 single-swap planner ABI updated for minHopPriceX36 field

Includes per-hop slippage for single swaps and flipped output/input ratio formula with 1e36 precision.

…ER_FROM

github-actions · 2026-02-21T18:35:15Z

🤖 Claude Code Review

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Summary

This PR adds two major features to the Universal Router:

Per-hop slippage checks for V2 and V3 swaps - Allows callers to specify minimum price thresholds for each individual hop in multi-hop swaps, providing more granular slippage protection beyond the existing overall amountOutMinimum/amountInMaximum checks.
PAY_PORTION_FULL_PRECISION command - A new payment command that uses 1e18 precision instead of bips (10_000), enabling more precise portion calculations (e.g., exact 1/3 splits impossible with bips).

Analysis

Per-hop Slippage Implementation

The implementation correctly handles the complex ordering of exact-output swaps where trading hops execute in reverse order:

V3 exact-input: Slippage checked in the main loop after each swap
V3 exact-output: Slippage checked in the callback, with hopIndex starting at maxHopSlippage.length - 1 and decrementing
V2: Slippage checked inline during _v2Swap loop for both exact-in and exact-out

The SLIPPAGE_PRECISION of 1e36 provides sufficient precision for price comparisons.

Breaking Change Considerations

The ABI for V2 and V3 swap commands has changed - all calls now require a 6th parameter (maxHopSlippage array). Passing an empty array disables the feature, maintaining backward compatibility at the contract level. However, off-chain integrations will need updates.

Test Coverage

The foundry tests (UniswapV3.t.sol) are well-designed:

Tests both single-hop and multi-hop scenarios
Tests both exact-input and exact-output
testV3ExactOutputMultiHopSlippageFailHop0 specifically catches bugs in hop index ordering
Invalid length validation tests

Code Quality

The implementation is clean:

Validation upfront with V2InvalidHopSlippageLength / V3InvalidHopSlippageLength errors
Graceful no-op when maxHopSlippage.length == 0
Consistent precision constant usage

Verdict

The implementation is correct and well-tested. The features are additive with sensible defaults (empty array = disabled). No bugs, security issues, or data corruption risks identified.

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github-actions

📋 Review verdict: APPROVE

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github-actions

📋 Review verdict: APPROVE

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This formal review submission is for the verdict only.

Remove the TRANSFER_FROM command and associated tests. This reverts commit e902459 and also removes integration tests added in 7206c96 that depended on it. Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

Superseded by new review after PR update

github-actions

📋 Review verdict: APPROVE

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github-actions

📋 Review verdict: APPROVE

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This formal review submission is for the verdict only.

github-actions · 2026-02-25T17:16:47Z

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github-actions · 2026-03-11T14:42:10Z

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zhongeric · 2026-03-13T16:59:50Z

contracts/modules/uniswap/v2/V2SwapRouter.sol

                uint256 amountOutput = UniswapV2Library.getAmountOut(amountInput, reserveInput, reserveOutput);
+                if (minHopPriceX36.length != 0) {
+                    uint256 price = amountOutput * Constants.PRICE_PRECISION / amountInput;


Btw this operation will overflow for any values over 2^137, which I assume is fine but just flagging since seems like V2 amounts are uint256 instead of uint128 like v3/v4

zhongeric · 2026-03-13T17:05:58Z

contracts/modules/Payments.sol

+    /// @param recipient The address that will receive payment
+    /// @param portion Portion of whole balance of the contract, where 1e18 represents 100%
+    function payPortionFullPrecision(address token, address recipient, uint256 portion) internal {
+        if (portion > 1e18) revert InvalidPortion();


Not immediately clear that 1e18 is precision value. Maybe use a constant here?

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gretzke added 5 commits February 21, 2026 16:10

feat: add PAY_PORTION_FULL_PRECISION command with 1e18 precision

f18ee8a

feat: add TRANSFER_FROM command using standard ERC20 approvals

e902459

chore: update v4-periphery submodule

2125fc2

Includes per-hop slippage for single swaps and flipped output/input ratio formula with 1e36 precision.

feat: add per-hop slippage checks to V2 and V3 swap commands

ca7f32f

test: add integration tests for PAY_PORTION_FULL_PRECISION and TRANSF…

7206c96

…ER_FROM

gretzke requested a review from a team as a code owner February 21, 2026 18:34

github-actions bot previously approved these changes Feb 21, 2026

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bytecodehash none

11a5c54

github-actions bot previously approved these changes Feb 21, 2026

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revert: remove TRANSFER_FROM command (e902459)

53b297c

Remove the TRANSFER_FROM command and associated tests. This reverts commit e902459 and also removes integration tests added in 7206c96 that depended on it. Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

github-actions bot previously approved these changes Feb 25, 2026

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update submodule, and tiny tweaks

562b48f

github-actions bot approved these changes Feb 25, 2026

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hensha256 added 2 commits February 25, 2026 12:24

linting

dbbdaa1

snapshots

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oz m01

cc89977

OZ l03

74ff047

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

snapshots

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OZ N05, plus accurage bytecode snapshot

ef061d4

OZ N08

e7f31a6

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

zhongeric reviewed Mar 13, 2026

View reviewed changes

update submodule

edf7265

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Summary

Test Plan

✨ Claude-Generated Content

Summary

Changes

New Commands

Per-hop Slippage Protection

New Errors

Library Updates

Build Configuration

Dependencies

Test Plan

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🤖 Claude Code Review

Summary

Analysis

Per-hop Slippage Implementation

Breaking Change Considerations

Test Coverage

Code Quality

Verdict

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