fix: ensure subscription balance is greater than minimum balance after adding funds

Co-Authored-By: Tejas Badadare <tejas@dourolabs.xyz>

Author: devin-ai-integration[bot]

target_chains/ethereum/contracts/contracts/pulse/Scheduler.sol

@@ -531,7 +531,7 @@ abstract contract Scheduler is IScheduler, SchedulerState {
             subscriptionId
         ];
 
-        if (!status.isActive) {
+        if (!params.isActive) {
             revert InactiveSubscription();
         }
 
@@ -542,6 +542,16 @@ abstract contract Scheduler is IScheduler, SchedulerState {
         }
 
         status.balanceInWei += msg.value;
+        
+        // If subscription is active, ensure minimum balance is maintained
+        if (params.isActive) {
+            uint256 minimumBalance = this.getMinimumBalance(
+                uint8(params.priceIds.length)
+            );
+            if (status.balanceInWei < minimumBalance) {
+                revert InsufficientBalance();
+            }
+        }
     }
 
     function withdrawFunds(

target_chains/ethereum/contracts/forge-test/PulseScheduler.t.sol

@@ -541,6 +541,134 @@ contract SchedulerTest is Test, SchedulerEvents, PulseSchedulerTestUtils {
             "Balance should match initial balance plus added funds"
         );
     }
+    
+
+    
+    function testAddFundsEnforcesMinimumBalance() public {
+        // First add a subscription with minimum balance
+        uint256 subscriptionId = addTestSubscription(
+            scheduler,
+            address(reader)
+        );
+        
+        // Get subscription parameters and initial balance
+        (SchedulerState.SubscriptionParams memory params, SchedulerState.SubscriptionStatus memory status) = scheduler
+            .getSubscription(subscriptionId);
+            
+        // Calculate minimum balance
+        uint256 minimumBalance = scheduler.getMinimumBalance(
+            uint8(params.priceIds.length)
+        );
+        
+        // Verify initial balance is at minimum
+        assertEq(
+            status.balanceInWei,
+            minimumBalance,
+            "Initial balance should equal minimum balance"
+        );
+        
+        // Add some funds to the subscription
+        uint256 additionalFunds = 0.1 ether;
+        scheduler.addFunds{value: additionalFunds}(subscriptionId);
+        
+        // Verify funds were added
+        (, SchedulerState.SubscriptionStatus memory statusAfterAdd) = scheduler
+            .getSubscription(subscriptionId);
+        assertEq(
+            statusAfterAdd.balanceInWei,
+            minimumBalance + additionalFunds,
+            "Balance should be increased by the added funds"
+        );
+        
+        // Now create a new subscription but don't fund it fully
+        SchedulerState.SubscriptionParams memory newParams = createDefaultSubscriptionParams(
+            2,
+            address(reader)
+        );
+        
+        // Calculate minimum balance for this new subscription
+        uint256 newMinimumBalance = scheduler.getMinimumBalance(
+            uint8(newParams.priceIds.length)
+        );
+        
+        // Try to create with insufficient funds
+        uint256 insufficientFunds = newMinimumBalance - 1 wei;
+        vm.expectRevert(abi.encodeWithSelector(InsufficientBalance.selector));
+        scheduler.createSubscription{value: insufficientFunds}(newParams);
+        
+        // Create with sufficient funds
+        uint256 newSubscriptionId = scheduler.createSubscription{value: newMinimumBalance}(newParams);
+        
+        // Verify subscription was created with minimum balance
+        (, SchedulerState.SubscriptionStatus memory newStatus) = scheduler
+            .getSubscription(newSubscriptionId);
+        assertEq(
+            newStatus.balanceInWei,
+            newMinimumBalance,
+            "New subscription balance should equal minimum balance"
+        );
+    }
+    
+    function testAddFundsEnforcesMinimumBalanceForPermanentSubscription() public {
+        // Create a non-permanent subscription first
+        uint256 subscriptionId = addTestSubscription(
+            scheduler,
+            address(reader)
+        );
+        
+        // Get subscription parameters and initial balance
+        (SchedulerState.SubscriptionParams memory params, SchedulerState.SubscriptionStatus memory status) = scheduler
+            .getSubscription(subscriptionId);
+            
+        // Calculate minimum balance
+        uint256 minimumBalance = scheduler.getMinimumBalance(
+            uint8(params.priceIds.length)
+        );
+        
+        // Verify initial balance is at minimum
+        assertEq(
+            status.balanceInWei,
+            minimumBalance,
+            "Initial balance should equal minimum balance"
+        );
+        
+        // Make it permanent
+        params.isPermanent = true;
+        scheduler.updateSubscription(subscriptionId, params);
+        
+        // Try to add funds - this should succeed since we're adding to a permanent subscription
+        uint256 additionalFunds = 0.1 ether;
+        scheduler.addFunds{value: additionalFunds}(subscriptionId);
+        
+        // Verify funds were added
+        (, SchedulerState.SubscriptionStatus memory statusAfter) = scheduler
+            .getSubscription(subscriptionId);
+        assertEq(
+            statusAfter.balanceInWei,
+            minimumBalance + additionalFunds,
+            "Balance should be increased by the added funds"
+        );
+        
+        // Now test the deposit limit for permanent subscriptions
+        uint256 maxDepositLimit = 100 ether; // MAX_DEPOSIT_LIMIT from SchedulerState
+        
+        // Try to add funds exceeding the deposit limit
+        vm.expectRevert(abi.encodeWithSelector(MaxDepositLimitExceeded.selector));
+        scheduler.addFunds{value: maxDepositLimit + 1}(subscriptionId);
+        
+        // Add funds within the deposit limit
+        uint256 validDeposit = 1 ether;
+        scheduler.addFunds{value: validDeposit}(subscriptionId);
+        
+        // Verify funds were added
+        (, SchedulerState.SubscriptionStatus memory statusAfterValidDeposit) = scheduler
+            .getSubscription(subscriptionId);
+        assertEq(
+            statusAfterValidDeposit.balanceInWei,
+            minimumBalance + additionalFunds + validDeposit,
+            "Balance should be increased by the valid deposit"
+        );
+    }
 
     function testWithdrawFunds() public {
         // Add a subscription and get the parameters