feat: add standardized event emission for lending contract

contracts/borrowing-contract/src/lib.rs

@@ -1,5 +1,7 @@
 #![no_std]
-use soroban_sdk::{contract, contracterror, contractimpl, contracttype, token, Address, Env};
+use soroban_sdk::{
+    contract, contracterror, contractimpl, contracttype, symbol_short, token, Address, Env,
+};
 
 mod test;
 
@@ -16,6 +18,59 @@ pub struct Loan {
     pub is_active: bool,
 }
 
+// ─────────────────────────────────────────────────
+// Events
+// ─────────────────────────────────────────────────
+
+#[contracttype]
+#[derive(Clone, Debug, Eq, PartialEq)]
+pub struct BorrowEvent {
+    pub loan_id: u64,
+    pub borrower: Address,
+    pub principal: i128,
+    pub collateral_amount: i128,
+    pub collateral_token: Address,
+    pub interest_rate: u32,
+    pub due_date: u64,
+    pub timestamp: u64,
+}
+
+#[contracttype]
+#[derive(Clone, Debug, Eq, PartialEq)]
+pub struct RepayEvent {
+    pub loan_id: u64,
+    pub borrower: Address,
+    pub amount_repaid: i128,
+    pub principal: i128,
+    pub interest_paid: i128,
+    pub collateral_returned: i128,
+    pub timestamp: u64,
+}
+
+#[contracttype]
+#[derive(Clone, Debug, Eq, PartialEq)]
+pub struct LiquidationEvent {
+    pub loan_id: u64,
+    pub borrower: Address,
+    pub liquidator: Address,
+    pub amount_liquidated: i128,
+    pub collateral_seized: i128,
+    pub health_factor: u32,
+    pub timestamp: u64,
+}
+
+#[contracttype]
+#[derive(Clone, Debug, Eq, PartialEq)]
+pub struct InterestAccrualEvent {
+    pub loan_id: u64,
+    pub borrower: Address,
+    pub principal: i128,
+    pub interest_accrued: i128,
+    pub interest_rate: u32,
+    pub elapsed_seconds: u64,
+    pub timestamp: u64,
+}
+
 #[contracttype]
 pub enum DataKey {
     Admin,
@@ -117,20 +172,35 @@ impl BorrowingContract {
         let loan_id = Self::get_next_loan_id(&env);
 
         let loan = Loan {
-            borrower,
+            borrower: borrower.clone(),
             principal,
             interest_rate,
             due_date,
             amount_repaid: 0,
             collateral_amount,
-            collateral_token,
+            collateral_token: collateral_token.clone(),
             is_active: true,
         };
 
         env.storage()
             .persistent()
             .set(&DataKey::Loan(loan_id), &loan);
 
+        // Emit borrow event
+        env.events().publish(
+            (symbol_short!("LOAN"), symbol_short!("BORROW")),
+            BorrowEvent {
+                loan_id,
+                borrower: borrower.clone(),
+                principal,
+                collateral_amount,
+                collateral_token,
+                interest_rate,
+                due_date,
+                timestamp: env.ledger().timestamp(),
+            },
+        );
+
         Ok(loan_id)
     }
 
@@ -157,6 +227,24 @@ impl BorrowingContract {
             );
         }
 
+        // Emit repay event
+        env.events().publish(
+            (symbol_short!("LOAN"), symbol_short!("REPAY")),
+            RepayEvent {
+                loan_id,
+                borrower: loan.borrower.clone(),
+                amount_repaid: amount,
+                principal: loan.principal,
+                interest_paid: 0, // Interest calculation would be needed based on contract logic
+                collateral_returned: if loan.is_active {
+                    0
+                } else {
+                    loan.collateral_amount
+                },
+                timestamp: env.ledger().timestamp(),
+            },
+        );
+
         env.storage()
             .persistent()
             .set(&DataKey::Loan(loan_id), &loan);
@@ -313,6 +401,20 @@ impl BorrowingContract {
             .persistent()
             .set(&DataKey::Loan(loan_id), &loan);
 
+        // Emit liquidation event
+        env.events().publish(
+            (symbol_short!("LOAN"), symbol_short!("LIQUIDATE")),
+            LiquidationEvent {
+                loan_id,
+                borrower: loan.borrower.clone(),
+                liquidator: liquidator.clone(),
+                amount_liquidated: liquidate_amount,
+                collateral_seized: liquidator_reward,
+                health_factor,
+                timestamp: env.ledger().timestamp(),
+            },
+        );
+
         Ok(())
     }
 

contracts/borrowing-contract/test_snapshots/test/test_create_loan.1.json

@@ -1399,6 +1399,100 @@
       },
       "failed_call": false
     },
+    {
+      "event": {
+        "ext": "v0",
+        "contract_id": "0000000000000000000000000000000000000000000000000000000000000004",
+        "type_": "contract",
+        "body": {
+          "v0": {
+            "topics": [
+              {
+                "symbol": "LOAN"
+              },
+              {
+                "symbol": "BORROW"
+              }
+            ],
+            "data": {
+              "map": [
+                {
+                  "key": {
+                    "symbol": "borrower"
+                  },
+                  "val": {
+                    "address": "CAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAK3IM"
+                  }
+                },
+                {
+                  "key": {
+                    "symbol": "collateral_amount"
+                  },
+                  "val": {
+                    "i128": {
+                      "hi": 0,
+                      "lo": 1500
+                    }
+                  }
+                },
+                {
+                  "key": {
+                    "symbol": "collateral_token"
+                  },
+                  "val": {
+                    "address": "CBUSYNQKASUYFWYC3M2GUEDMX4AIVWPALDBYJPNK6554BREHTGZ2IUNF"
+                  }
+                },
+                {
+                  "key": {
+                    "symbol": "due_date"
+                  },
+                  "val": {
+                    "u64": 1000000
+                  }
+                },
+                {
+                  "key": {
+                    "symbol": "interest_rate"
+                  },
+                  "val": {
+                    "u32": 5
+                  }
+                },
+                {
+                  "key": {
+                    "symbol": "loan_id"
+                  },
+                  "val": {
+                    "u64": 1
+                  }
+                },
+                {
+                  "key": {
+                    "symbol": "principal"
+                  },
+                  "val": {
+                    "i128": {
+                      "hi": 0,
+                      "lo": 1000
+                    }
+                  }
+                },
+                {
+                  "key": {
+                    "symbol": "timestamp"
+                  },
+                  "val": {
+                    "u64": 0
+                  }
+                }
+              ]
+            }
+          }
+        }
+      },
+      "failed_call": false
+    },
     {
       "event": {
         "ext": "v0",