Merge pull request #11495 from vegaprotocol/11493-amend-to-empty-curves

fix: reject AMM amendment to a one-sided AMM if its position is alrea…
vegaprotocol · Jul 24, 2024 · 20cc9dc · 20cc9dc
2 parents 6691a3d + 5565846
commit 20cc9dc
Show file tree

Hide file tree

Showing 2 changed files with 35 additions and 0 deletions.
diff --git a/core/execution/amm/pool.go b/core/execution/amm/pool.go
@@ -16,6 +16,7 @@
 package amm
 
 import (
+	"errors"
 	"fmt"
 
 	"code.vegaprotocol.io/vega/core/idgeneration"
@@ -324,6 +325,16 @@ func (p *Pool) Update(
 		parameters = amend.Parameters
 	}
 
+	// if an AMM is amended so that it cannot be long (i.e it has no lower curve) but the existing AMM
+	// is already long then we cannot make the change since its fair-price will be undefined.
+	if parameters.LowerBound == nil && p.getPosition() > 0 {
+		return nil, errors.New("cannot remove lower bound when AMM is long")
+	}
+
+	if parameters.UpperBound == nil && p.getPosition() < 0 {
+		return nil, errors.New("cannot remove upper bound when AMM is short")
+	}
+
 	updated := &Pool{
 		log:                  p.log,
 		ID:                   p.ID,

diff --git a/core/integration/features/amm/0090-VAMM-basic.feature b/core/integration/features/amm/0090-VAMM-basic.feature
@@ -196,5 +196,29 @@ Feature: vAMM rebasing when created or amended
        | party  | market id | method           | error               |
        | party1 | ETH/MAR22 | METHOD_IMMEDIATE | trading not allowed |
 
+
+  @VAMM
+  Scenario: Cannot amend AMM to have only one side if its current position does not support it
+
+    When the parties place the following orders:
+      | party  | market id | side | volume | price | resulting trades | type       | tif     | reference |
+      | party1 | ETH/MAR22 | sell | 1      | 99    | 1                | TYPE_LIMIT | TIF_GTC |           |
+
+
+    Then the parties amend the following AMM:
+      | party | market id | amount | slippage | base | upper bound | proposed fee | error                                      |
+      | vamm1 | ETH/MAR22 | 100000  | 0.05    | 100  | 105         | 0.03         | cannot remove lower bound when AMM is long |
+
+
+    When the parties place the following orders:
+      | party  | market id | side | volume | price | resulting trades | type       | tif     | reference |
+      | party1 | ETH/MAR22 | buy  | 2      | 200   | 1                | TYPE_LIMIT | TIF_GTC |           |
+
+    Then the parties amend the following AMM:
+      | party | market id | amount | slippage | base | lower bound | proposed fee | error                                       |
+      | vamm1 | ETH/MAR22 | 100000  | 0.05    | 100  | 95          | 0.03         | cannot remove upper bound when AMM is short |
+
+
+