diff --git a/README.md b/README.md
index 6376935..6cadb66 100644
--- a/README.md
+++ b/README.md
@@ -477,8 +477,8 @@ that matters (e.g. each voter) before its balance changes, (3) read with `balanc
 
 | Function | Auth | Parameters | Returns | Description |
 |---|---|---|---|---|
-| `create_vesting_schedule` | Admin | `beneficiary: Address, total_amount: i128, cliff_timestamp: u64, duration_seconds: u64` | — | Create a vesting schedule. |
-| `claim_vested_tokens` | Beneficiary | `beneficiary: Address` | — | Claim vested tokens. |
+| `create_vesting` | Admin | `beneficiary: Address, total_amount: i128, cliff_timestamp: u64, duration_seconds: u64` | — | Create a vesting schedule. |
+| `claim_vested` | Beneficiary | `beneficiary: Address` | — | Claim vested tokens. |
 | `get_vesting_schedule` | — | `beneficiary: Address` | `Option<VestingSchedule>` | Vesting schedule details. |
 
 #### Governance
@@ -487,7 +487,7 @@ that matters (e.g. each voter) before its balance changes, (3) read with `balanc
 |---|---|---|---|---|
 | `create_proposal` | Admin | `description: String, choices: u32, start_time: u64, end_time: u64, snapshot_ledger: u32` | `u64` | Create a proposal using a past ledger for voting power. |
 | `vote` | Token Holder | `proposal_id: u64, choice: u32` | — | Cast a vote using the voter's recorded balance at the proposal snapshot. |
-| `execute_proposal` | — | `proposal_id: u64` | — | Execute a passed proposal. |
+| `execute_proposal` | Admin | `proposal_id: u64` | `u32` | Execute a passed proposal. Returns the winning choice index. |
 | `get_proposal` | — | `proposal_id: u64` | `Option<Proposal>` | Proposal details. |
 
 ### credential-nft
diff --git a/contracts/learn-token/src/lib.rs b/contracts/learn-token/src/lib.rs
index ed1865a..ec4e487 100644
--- a/contracts/learn-token/src/lib.rs
+++ b/contracts/learn-token/src/lib.rs
@@ -5,8 +5,8 @@ mod storage;
 
 use chainlearn_shared::{BASE_REWARD_PER_POINT, MAX_QUIZ_SCORE};
 use soroban_sdk::{
-    contract, contracterror, contractimpl, contracttype, Address, BytesN, Env, IntoVal,
-    String as SorobanString, Symbol, Vec,
+    contract, contracterror, contractimpl, contracttype, panic_with_error, Address, BytesN, Env,
+    IntoVal, String as SorobanString, Symbol, Vec,
 };
 
 // Re-export governance/vesting/admin types so tests can use them.
@@ -473,17 +473,17 @@ impl LearnToken {
         from.require_auth();
 
         if from == to {
-            return;
+            panic_with_error!(&env, ContractError::TransferToSelf);
         }
 
         // Prevent transfers to the contract itself, which would lock tokens
         // irretrievably (#76).
         if to == env.current_contract_address() {
-            panic!("cannot transfer to contract");
+            panic_with_error!(&env, ContractError::TransferToContract);
         }
 
         if amount < 0 {
-            panic!("negative amount");
+            panic_with_error!(&env, ContractError::NegativeAmount);
         }
 
         if amount == 0 {
@@ -492,7 +492,7 @@ impl LearnToken {
 
         let from_balance = storage::get_balance(&env, &from);
         if from_balance < amount {
-            panic!("insufficient balance");
+            panic_with_error!(&env, ContractError::InsufficientBalance);
         }
 
         // Check transfer restrictions (#191)
@@ -520,17 +520,17 @@ impl LearnToken {
         spender.require_auth();
 
         if from == to {
-            return;
+            panic_with_error!(&env, ContractError::TransferToSelf);
         }
 
         // Prevent transfers to the contract itself, which would lock tokens
         // irretrievably (#76).
         if to == env.current_contract_address() {
-            panic!("cannot transfer to contract");
+            panic_with_error!(&env, ContractError::TransferToContract);
         }
 
         if amount < 0 {
-            panic!("negative amount");
+            panic_with_error!(&env, ContractError::NegativeAmount);
         }
 
         if amount == 0 {
@@ -545,12 +545,12 @@ impl LearnToken {
 
         let allowance = storage::get_allowance(&env, &from, &spender);
         if allowance < amount {
-            panic!("insufficient allowance");
+            panic_with_error!(&env, ContractError::InsufficientAllowance);
         }
 
         let from_balance = storage::get_balance(&env, &from);
         if from_balance < amount {
-            panic!("insufficient balance");
+            panic_with_error!(&env, ContractError::InsufficientBalance);
         }
 
         // Check transfer restrictions (#191)
@@ -584,11 +584,11 @@ impl LearnToken {
         owner.require_auth();
 
         if amount < 0 {
-            panic!("negative amount");
+            panic_with_error!(&env, ContractError::NegativeAmount);
         }
 
         if expiration_ledger <= env.ledger().sequence() {
-            panic!("expiration_ledger must be in the future");
+            panic_with_error!(&env, ContractError::ExpirationInPast);
         }
 
         storage::set_allowance(&env, &owner, &spender, amount, expiration_ledger);
@@ -624,12 +624,12 @@ impl LearnToken {
         from.require_auth();
 
         if amount < 0 {
-            panic!("negative amount");
+            panic_with_error!(&env, ContractError::NegativeAmount);
         }
 
         let from_balance = storage::get_balance(&env, &from);
         if from_balance < amount {
-            panic!("insufficient balance");
+            panic_with_error!(&env, ContractError::InsufficientBalance);
         }
 
         storage::set_balance(&env, &from, from_balance - amount);
@@ -661,7 +661,7 @@ impl LearnToken {
         spender.require_auth();
 
         if amount < 0 {
-            panic!("negative amount");
+            panic_with_error!(&env, ContractError::NegativeAmount);
         }
 
         // Surface an expired allowance the same way transfer_from does, so
@@ -674,12 +674,12 @@ impl LearnToken {
 
         let allowance = storage::get_allowance(&env, &from, &spender);
         if allowance < amount {
-            panic!("insufficient allowance");
+            panic_with_error!(&env, ContractError::InsufficientAllowance);
         }
 
         let from_balance = storage::get_balance(&env, &from);
         if from_balance < amount {
-            panic!("insufficient balance");
+            panic_with_error!(&env, ContractError::InsufficientBalance);
         }
 
         storage::reduce_allowance(&env, &from, &spender, amount);
@@ -702,7 +702,7 @@ impl LearnToken {
         Self::require_not_paused(&env);
         caller.require_auth();
         if !storage::has_role(&env, &caller, &storage::AdminRole::Minter) {
-            panic!("not authorized");
+            panic_with_error!(&env, ContractError::NotAuthorized);
         }
 
         let zero_address = chainlearn_shared::zero_address(&env);
@@ -711,7 +711,7 @@ impl LearnToken {
         }
 
         if amount < 0 {
-            panic!("negative amount");
+            panic_with_error!(&env, ContractError::NegativeAmount);
         }
 
         if amount == 0 {
@@ -755,7 +755,7 @@ impl LearnToken {
         learner.require_auth();
 
         if storage::is_reward_claimed(&env, &learner, &course_id, &quiz_id) {
-            panic!("reward already claimed");
+            panic_with_error!(&env, ContractError::RewardAlreadyClaimed);
         }
 
         // Verify score by querying the progress-tracker contract via a single
@@ -775,7 +775,7 @@ impl LearnToken {
         }
 
         if score > MAX_QUIZ_SCORE {
-            panic!("score exceeds maximum");
+            panic_with_error!(&env, ContractError::InvalidScore);
         }
 
         let reward_amount = (score as i128) * BASE_REWARD_PER_POINT;
@@ -993,7 +993,7 @@ impl LearnToken {
     pub fn grant_role(env: Env, caller: Address, address: Address, role: storage::AdminRole) {
         caller.require_auth();
         if !storage::has_role(&env, &caller, &storage::AdminRole::Admin) {
-            panic!("not authorized");
+            panic_with_error!(&env, ContractError::NotAuthorized);
         }
         storage::add_admin(&env, &address, &role);
         events::role_granted(&env, &address, &role);
@@ -1003,7 +1003,7 @@ impl LearnToken {
     pub fn revoke_role(env: Env, caller: Address, address: Address, role: storage::AdminRole) {
         caller.require_auth();
         if !storage::has_role(&env, &caller, &storage::AdminRole::Admin) {
-            panic!("not authorized");
+            panic_with_error!(&env, ContractError::NotAuthorized);
         }
         storage::remove_admin(&env, &address, &role);
         events::role_revoked(&env, &address, &role);
@@ -1015,7 +1015,7 @@ impl LearnToken {
     pub fn add_admin(env: Env, caller: Address, admin_info: AdminInfo) {
         caller.require_auth();
         if !storage::has_role(&env, &caller, &storage::AdminRole::Admin) {
-            panic!("not authorized");
+            panic_with_error!(&env, ContractError::NotAuthorized);
         }
 
         storage::add_admin(&env, &admin_info.address, &admin_info.role);
@@ -1028,7 +1028,7 @@ impl LearnToken {
     pub fn remove_admin(env: Env, caller: Address, admin_info: AdminInfo) {
         caller.require_auth();
         if !storage::has_role(&env, &caller, &storage::AdminRole::Admin) {
-            panic!("not authorized");
+            panic_with_error!(&env, ContractError::NotAuthorized);
         }
 
         storage::remove_admin(&env, &admin_info.address, &admin_info.role);
@@ -1052,7 +1052,7 @@ impl LearnToken {
         if !storage::has_role(&env, &caller, &storage::AdminRole::Admin)
             || !storage::has_role(&env, &co_signer, &storage::AdminRole::Admin)
         {
-            panic!("not authorized");
+            panic_with_error!(&env, ContractError::NotAuthorized);
         }
 
         env.events().publish(
@@ -1078,7 +1078,7 @@ impl LearnToken {
         if !storage::has_role(&env, &caller, &storage::AdminRole::Admin)
             || !storage::has_role(&env, &co_signer, &storage::AdminRole::Admin)
         {
-            panic!("not authorized");
+            panic_with_error!(&env, ContractError::NotAuthorized);
         }
 
         env.deployer()
@@ -1116,7 +1116,7 @@ impl LearnToken {
     pub fn pause(env: Env, caller: Address) {
         caller.require_auth();
         if !storage::has_role(&env, &caller, &storage::AdminRole::Pauser) {
-            panic!("not authorized");
+            panic_with_error!(&env, ContractError::NotAuthorized);
         }
 
         if storage::is_paused(&env) {
@@ -1131,7 +1131,7 @@ impl LearnToken {
     pub fn unpause(env: Env, caller: Address) {
         caller.require_auth();
         if !storage::has_role(&env, &caller, &storage::AdminRole::Pauser) {
-            panic!("not authorized");
+            panic_with_error!(&env, ContractError::NotAuthorized);
         }
 
         if !storage::is_paused(&env) {
@@ -1413,11 +1413,11 @@ impl LearnToken {
         owner.require_auth();
 
         if additional_amount < 0 {
-            panic!("negative amount");
+            panic_with_error!(&env, ContractError::NegativeAmount);
         }
 
         if expiration_ledger <= env.ledger().sequence() {
-            panic!("expiration_ledger must be in the future");
+            panic_with_error!(&env, ContractError::ExpirationInPast);
         }
 
         let current = storage::get_allowance(&env, &owner, &spender);
@@ -1521,7 +1521,7 @@ impl LearnToken {
         owner.require_auth();
 
         if decrease_amount < 0 {
-            panic!("negative amount");
+            panic_with_error!(&env, ContractError::NegativeAmount);
         }
 
         let current = storage::get_allowance(&env, &owner, &spender);
@@ -1572,11 +1572,11 @@ impl LearnToken {
         owner.require_auth();
 
         if amount < 0 {
-            panic!("negative amount");
+            panic_with_error!(&env, ContractError::NegativeAmount);
         }
 
         if expiration_ledger <= env.ledger().sequence() {
-            panic!("expiration_ledger must be in the future");
+            panic_with_error!(&env, ContractError::ExpirationInPast);
         }
 
         let current_nonce = storage::get_permit_nonce(&env, &owner);
@@ -2595,7 +2595,7 @@ mod tests {
     }
 
     #[test]
-    #[should_panic(expected = "reward already claimed")]
+    #[should_panic(expected = "Error(Contract, #12)")]
     fn test_claim_reward_prevents_double_claim() {
         let env = Env::default();
         let (_, lt_contract_id, pt_contract_id) = setup(&env);
@@ -2708,7 +2708,7 @@ mod tests {
     // ── #76: transfer to contract address ───────────────────────────────────
 
     #[test]
-    #[should_panic(expected = "cannot transfer to contract")]
+    #[should_panic(expected = "Error(Contract, #9)")]
     fn test_transfer_to_contract_address_panics() {
         let env = Env::default();
         let (admin, lt_contract_id, _) = setup(&env);
@@ -2723,7 +2723,7 @@ mod tests {
     }
 
     #[test]
-    #[should_panic(expected = "cannot transfer to contract")]
+    #[should_panic(expected = "Error(Contract, #9)")]
     fn test_transfer_from_to_contract_address_panics() {
         let env = Env::default();
         let (admin, lt_contract_id, _) = setup(&env);
@@ -2740,6 +2740,20 @@ mod tests {
         client.transfer_from(&spender, &owner, &lt_contract_id, &200);
     }
 
+    #[test]
+    #[should_panic(expected = "Error(Contract, #8)")]
+    fn test_transfer_to_self_is_rejected() {
+        let env = Env::default();
+        let (admin, lt_contract_id, _) = setup(&env);
+        let client = LearnTokenClient::new(&env, &lt_contract_id);
+
+        let alice = Address::generate(&env);
+        env.mock_all_auths();
+
+        client.mint(&admin, &alice, &500);
+        client.transfer(&alice, &alice, &100);
+    }
+
     // ── #77: increase_allowance / decrease_allowance ─────────────────────────
 
     #[test]
@@ -2858,7 +2872,7 @@ mod tests {
     }
 
     #[test]
-    #[should_panic(expected = "insufficient balance")]
+    #[should_panic(expected = "Error(Contract, #5)")]
     fn test_burn_more_than_balance_panics() {
         let env = Env::default();
         let (admin, lt_contract_id, _) = setup(&env);
@@ -2872,7 +2886,7 @@ mod tests {
     }
 
     #[test]
-    #[should_panic(expected = "negative amount")]
+    #[should_panic(expected = "Error(Contract, #4)")]
     fn test_burn_negative_amount_panics() {
         let env = Env::default();
         let (admin, lt_contract_id, _) = setup(&env);
@@ -2922,7 +2936,7 @@ mod tests {
     }
 
     #[test]
-    #[should_panic(expected = "insufficient allowance")]
+    #[should_panic(expected = "Error(Contract, #6)")]
     fn test_burn_from_beyond_allowance_panics() {
         let env = Env::default();
         let (admin, lt_contract_id, _) = setup(&env);
@@ -2939,7 +2953,7 @@ mod tests {
     }
 
     #[test]
-    #[should_panic(expected = "insufficient balance")]
+    #[should_panic(expected = "Error(Contract, #5)")]
     fn test_burn_from_beyond_balance_panics() {
         let env = Env::default();
         let (admin, lt_contract_id, _) = setup(&env);
@@ -2957,7 +2971,7 @@ mod tests {
     }
 
     #[test]
-    #[should_panic(expected = "insufficient allowance")]
+    #[should_panic(expected = "Error(Contract, #6)")]
     fn test_burn_from_without_allowance_panics() {
         let env = Env::default();
         let (admin, lt_contract_id, _) = setup(&env);
diff --git a/docs/security.md b/docs/security.md
index ce69175..ab35d89 100644
--- a/docs/security.md
+++ b/docs/security.md
@@ -165,7 +165,7 @@ if new_max_supply > max_allowed {
 **Threat**: Attacker gains control of admin key.
 
 **Mitigation**:
-- **Delayed admin transfer**: 24-hour delay before new admin can accept
+- **Delayed admin transfer**: 48-hour delay (172,800 seconds) before new admin can accept
 - **Cancel window**: Current admin can cancel pending transfer
 - **Multi-sig for critical ops**: Upgrades require two admin signatures
 - **Emergency pause**: Can freeze all operations
diff --git a/examples/cli_usage_examples.sh b/examples/cli_usage_examples.sh
index 2759eb8..b4d3a92 100755
--- a/examples/cli_usage_examples.sh
+++ b/examples/cli_usage_examples.sh
@@ -1,7 +1,9 @@
 #!/bin/bash
 # Example Soroban CLI commands for ChainLearn
+#
+# Set STELLAR_SECRET_KEY in the environment before running this script.
+# This file must not export a placeholder; that would overwrite a real key.
 
-export STELLAR_SECRET_KEY="S..."
 PROGRESS_ID="C..."
 TOKEN_ID="C..."
 CREDENTIAL_ID="C..."
diff --git a/examples/javascript_client.js b/examples/javascript_client.js
index 8d30d17..12c0879 100644
--- a/examples/javascript_client.js
+++ b/examples/javascript_client.js
@@ -11,7 +11,8 @@
  *
  * Environment variables:
  *   STELLAR_RPC_URL        - Soroban RPC endpoint (default: testnet)
- *   STELLAR_SECRET_KEY      - Admin/learner secret key
+ *   STELLAR_SECRET_KEY      - Admin secret key
+ *   LEARNER_SECRET_KEY      - Learner secret key (must be different from the admin key)
  *   PROGRESS_TRACKER_ID     - Deployed progress-tracker contract ID
  *   LEARN_TOKEN_ID          - Deployed learn-token contract ID
  *   CREDENTIAL_NFT_ID       - Deployed credential-nft contract ID
@@ -222,12 +223,18 @@ async function mintCredential(adminKeypair, learnerKeypair) {
 // ── Main Flow ─────────────────────────────────────────────────────────
 
 async function main() {
-  const adminKeypair = StellarSdk.Keypair.fromSecret(
-    process.env.STELLAR_SECRET_KEY
-  );
-  const learnerKeypair = StellarSdk.Keypair.fromSecret(
-    process.env.STELLAR_SECRET_KEY // In production, use a different key
-  );
+  const adminSecret = process.env.STELLAR_SECRET_KEY;
+  const learnerSecret = process.env.LEARNER_SECRET_KEY;
+  if (!adminSecret || !learnerSecret) {
+    throw new Error(
+      "Set STELLAR_SECRET_KEY and LEARNER_SECRET_KEY before running this example"
+    );
+  }
+  if (adminSecret === learnerSecret) {
+    throw new Error("Admin and learner must use separate secret keys");
+  }
+  const adminKeypair = StellarSdk.Keypair.fromSecret(adminSecret);
+  const learnerKeypair = StellarSdk.Keypair.fromSecret(learnerSecret);
 
   console.log("=== ChainLearn Full Flow ===\n");
 
diff --git a/examples/javascript_client_example.js b/examples/javascript_client_example.js
index afe418e..f5af615 100644
--- a/examples/javascript_client_example.js
+++ b/examples/javascript_client_example.js
@@ -1,14 +1,14 @@
 /**
  * Example JavaScript client to interact with ChainLearn contracts using Stellar SDK.
  */
-import { Keypair, SorobanRpc, Contract, Networks, TransactionBuilder, BASE_FEE, xdr } from 'stellar-sdk';
+import { Keypair, rpc, Contract, Networks, TransactionBuilder, BASE_FEE, xdr } from '@stellar/stellar-sdk';
 
 const RPC_URL = 'https://soroban-testnet.stellar.org:443';
 const NETWORK_PASSPHRASE = Networks.TESTNET;
 const PROGRESS_TRACKER_ID = 'C...'; // Replace with actual contract ID
 
 export async function enrollLearner(secretKey, courseId) {
-    const server = new SorobanRpc.Server(RPC_URL);
+    const server = new rpc.Server(RPC_URL);
     const keypair = Keypair.fromSecret(secretKey);
     const contract = new Contract(PROGRESS_TRACKER_ID);
 
diff --git a/examples/rust_client.rs b/examples/rust_client.rs
index 21ae803..5bc6f8c 100644
--- a/examples/rust_client.rs
+++ b/examples/rust_client.rs
@@ -14,19 +14,35 @@
 //! Run with:
 //!   cargo run --example rust_client
 
-use soroban_sdk::{testutils::Address as _, Address, Env, Symbol};
+use soroban_sdk::{Address, Env, String as SorobanString, Symbol};
 
 fn main() {
     let env = Env::default();
-    let _admin = Address::generate(&env);
-    let _learner = Address::generate(&env);
-
-    let _progress_tracker = Address::generate(&env);
-    let _learn_token = Address::generate(&env);
-    let _credential_nft = Address::generate(&env);
+    // Address::from_string is the soroban_sdk constructor. Address::from_str does not exist.
+    let _admin = Address::from_string(&SorobanString::from_str(
+        &env,
+        "GABAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAABVCX",
+    ));
+    let _learner = Address::from_string(&SorobanString::from_str(
+        &env,
+        "GAAQAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAHV4",
+    ));
+
+    let _progress_tracker = Address::from_string(&SorobanString::from_str(
+        &env,
+        "CAAQAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAABDQF",
+    ));
+    let _learn_token = Address::from_string(&SorobanString::from_str(
+        &env,
+        "CABAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAARHO",
+    ));
+    let _credential_nft = Address::from_string(&SorobanString::from_str(
+        &env,
+        "CABQAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAVX",
+    ));
 
     // ── Admin: Create a course ─────────────────────────────────────────
-    let course_id = Symbol::new(&env, "rust_101");
+    let _course_id = Symbol::new(&env, "rust_101");
     let mut module_ids = soroban_sdk::Vec::new(&env);
     module_ids.push_back(Symbol::new(&env, "mod_basics"));
     module_ids.push_back(Symbol::new(&env, "mod_ownership"));
diff --git a/examples/rust_client_example.rs b/examples/rust_client_example.rs
index 1dc3b63..cd4b5c2 100644
--- a/examples/rust_client_example.rs
+++ b/examples/rust_client_example.rs
@@ -1,6 +1,5 @@
 //! Example Rust client using the soroban-sdk to interact with the ChainLearn progress-tracker contract.
-#![no_std]
-use soroban_sdk::{contract, contractimpl, Address, Env, Symbol, IntoVal};
+use soroban_sdk::{contract, contractimpl, Address, Env, IntoVal, Symbol};
 
 #[contract]
 pub struct ChainLearnClient;
@@ -11,7 +10,7 @@ impl ChainLearnClient {
     pub fn enroll_learner(env: Env, tracker_id: Address, learner: Address, course_id: Symbol) {
         // Authorize the learner
         learner.require_auth();
-        
+
         // Invoke the enroll function on the progress-tracker contract
         let args = soroban_sdk::vec![&env, learner.into_val(&env), course_id.into_val(&env)];
         env.invoke_contract::<()>(&tracker_id, &Symbol::new(&env, "enroll"), args);
@@ -19,4 +18,3 @@ impl ChainLearnClient {
 }
 
 fn main() {}
-
diff --git a/tests/integration/security_double_spending_tests.rs b/tests/integration/security_double_spending_tests.rs
index be94080..b2d62de 100644
--- a/tests/integration/security_double_spending_tests.rs
+++ b/tests/integration/security_double_spending_tests.rs
@@ -61,7 +61,7 @@ fn create_course_and_complete(
 // ── Double-claim reward ─────────────────────────────────────────────────────
 
 #[test]
-#[should_panic(expected = "reward already claimed")]
+#[should_panic(expected = "Error(Contract, #12)")]
 fn test_double_claim_reward_is_prevented() {
     let env = Env::default();
     let (_admin, token_client, _credential_client, progress_client) = setup_env(&env);
diff --git a/tests/integration/token_flow.rs b/tests/integration/token_flow.rs
index 21ec8a3..58a59c8 100644
--- a/tests/integration/token_flow.rs
+++ b/tests/integration/token_flow.rs
@@ -60,7 +60,7 @@ fn test_end_to_end_reward_flow() {
 }
 
 #[test]
-#[should_panic(expected = "reward already claimed")]
+#[should_panic(expected = "Error(Contract, #12)")]
 fn test_double_claim_prevented() {
     let setup = fixtures::setup_chainlearn_env();
     let env = &setup.env;
diff --git a/tests/unit/error_message_tests.rs b/tests/unit/error_message_tests.rs
index 2e77bc7..c07fb6c 100644
--- a/tests/unit/error_message_tests.rs
+++ b/tests/unit/error_message_tests.rs
@@ -280,7 +280,7 @@ mod error_message_tests {
     // ── Learn Token Error Message Tests ───────────────────────────────────
 
     #[test]
-    #[should_panic(expected = "insufficient balance")]
+    #[should_panic(expected = "Error(Contract, #5)")]
     fn test_learn_token_insufficient_balance_error_message() {
         let env = Env::default();
         let (_admin, contract_id, _) = setup_token(&env);
@@ -294,7 +294,7 @@ mod error_message_tests {
     }
 
     #[test]
-    #[should_panic(expected = "negative amount")]
+    #[should_panic(expected = "Error(Contract, #4)")]
     fn test_learn_token_negative_amount_error_message() {
         let env = Env::default();
         let (_admin, contract_id, _) = setup_token(&env);
@@ -308,7 +308,7 @@ mod error_message_tests {
     }
 
     #[test]
-    #[should_panic(expected = "cannot transfer to contract")]
+    #[should_panic(expected = "Error(Contract, #9)")]
     fn test_learn_token_transfer_to_contract_error_message() {
         let env = Env::default();
         let (admin, contract_id, _) = setup_token(&env);
@@ -318,11 +318,11 @@ mod error_message_tests {
         env.mock_all_auths();
 
         client.mint(&admin, &alice, &1000);
-        client.transfer(&alice, &env.current_contract_address(), &100);
+        client.transfer(&alice, &contract_id, &100);
     }
 
     #[test]
-    #[should_panic(expected = "insufficient allowance")]
+    #[should_panic(expected = "Error(Contract, #6)")]
     fn test_learn_token_insufficient_allowance_error_message() {
         let env = Env::default();
         let (_admin, contract_id, _) = setup_token(&env);
@@ -338,7 +338,7 @@ mod error_message_tests {
     }
 
     #[test]
-    #[should_panic(expected = "reward already claimed")]
+    #[should_panic(expected = "Error(Contract, #12)")]
     fn test_learn_token_reward_already_claimed_error_message() {
         let env = Env::default();
         let (_admin, contract_id, pt_contract_id) = setup_token(&env);
@@ -399,7 +399,7 @@ mod error_message_tests {
     }
 
     #[test]
-    #[should_panic(expected = "not authorized")]
+    #[should_panic(expected = "Error(Contract, #13)")]
     fn test_learn_token_not_authorized_error_message() {
         let env = Env::default();
         let (_admin, contract_id, _) = setup_token(&env);
@@ -407,8 +407,9 @@ mod error_message_tests {
 
         let non_admin = Address::generate(&env);
         let recipient = Address::generate(&env);
-        
-        // Don't mock auths, so mint should fail
+        env.mock_all_auths();
+
+        // Authorization succeeds, but this address does not hold the minter role.
         client.mint(&non_admin, &recipient, &1000);
     }
 
@@ -455,7 +456,7 @@ mod error_message_tests {
     }
 
     #[test]
-    #[should_panic(expected = "expiration_ledger must be in the future")]
+    #[should_panic(expected = "Error(Contract, #10)")]
     fn test_learn_token_past_expiration_error_message() {
         let env = Env::default();
         let (_admin, contract_id, _) = setup_token(&env);
@@ -464,6 +465,7 @@ mod error_message_tests {
         let owner = Address::generate(&env);
         let spender = Address::generate(&env);
         env.mock_all_auths();
+        env.ledger().with_mut(|li| li.sequence_number = 10);
 
         let past_ledger = env.ledger().sequence() - 1;
         client.approve(&owner, &spender, &500, &past_ledger);
diff --git a/tests/unit/security_arithmetic_tests.rs b/tests/unit/security_arithmetic_tests.rs
index 22c79c3..1906e78 100644
--- a/tests/unit/security_arithmetic_tests.rs
+++ b/tests/unit/security_arithmetic_tests.rs
@@ -5,7 +5,7 @@ use progress_tracker::ProgressTracker;
 use soroban_sdk::{testutils::Address as _, Address, Env, String as SorobanString};
 
 #[test]
-#[should_panic(expected = "insufficient balance")]
+#[should_panic(expected = "Error(Contract, #5)")]
 fn test_underflow_balance_subtraction() {
     let env = Env::default();
     let admin = Address::generate(&env);
@@ -29,7 +29,7 @@ fn test_underflow_balance_subtraction() {
 }
 
 #[test]
-#[should_panic(expected = "insufficient balance")]
+#[should_panic(expected = "Error(Contract, #5)")]
 fn test_underflow_balance_burn() {
     let env = Env::default();
     let admin = Address::generate(&env);
@@ -79,7 +79,7 @@ fn test_overflow_supply() {
 }
 
 #[test]
-#[should_panic(expected = "insufficient allowance")]
+#[should_panic(expected = "Error(Contract, #6)")]
 fn test_underflow_allowance_spend() {
     let env = Env::default();
     let admin = Address::generate(&env);
diff --git a/tests/unit/token_tests.rs b/tests/unit/token_tests.rs
index 67433ba..dda9cd5 100644
--- a/tests/unit/token_tests.rs
+++ b/tests/unit/token_tests.rs
@@ -96,7 +96,7 @@ mod token_unit_tests {
     }
 
     #[test]
-    #[should_panic(expected = "insufficient balance")]
+    #[should_panic(expected = "Error(Contract, #5)")]
     fn test_transfer_insufficient_balance() {
         let env = Env::default();
         let (admin, contract_id, _) = setup_token(&env);
@@ -132,7 +132,7 @@ mod token_unit_tests {
     }
 
     #[test]
-    #[should_panic(expected = "reward already claimed")]
+    #[should_panic(expected = "Error(Contract, #12)")]
     fn test_claim_reward_double_claim() {
         let env = Env::default();
         let (_admin, contract_id, pt_contract_id) = setup_token(&env);
@@ -187,7 +187,7 @@ mod token_unit_tests {
     }
 
     #[test]
-    #[should_panic(expected = "insufficient allowance")]
+    #[should_panic(expected = "Error(Contract, #6)")]
     fn test_transfer_from_insufficient_allowance() {
         let env = Env::default();
         let (admin, contract_id, _) = setup_token(&env);
@@ -204,7 +204,7 @@ mod token_unit_tests {
     }
 
     #[test]
-    #[should_panic(expected = "insufficient allowance")]
+    #[should_panic(expected = "Error(Contract, #6)")]
     fn test_transfer_from_expired_allowance() {
         let env = Env::default();
         let (admin, contract_id, _) = setup_token(&env);
@@ -724,7 +724,7 @@ mod token_unit_tests {
     }
 
     #[test]
-    #[should_panic(expected = "insufficient balance")]
+    #[should_panic(expected = "Error(Contract, #5)")]
     fn test_security_transfer_balance_underflow_reverts() {
         let env = Env::default();
         let (_admin, contract_id, _) = setup_token(&env);
@@ -767,7 +767,7 @@ mod token_unit_tests {
     }
 
     #[test]
-    #[should_panic(expected = "insufficient balance")]
+    #[should_panic(expected = "Error(Contract, #5)")]
     fn test_security_burn_balance_underflow_reverts() {
         let env = Env::default();
         let (_admin, contract_id, _) = setup_token(&env);
@@ -891,8 +891,6 @@ mod token_unit_tests {
     #[test]
     #[should_panic(expected = "no snapshot available at specified ledger")]
     fn test_vote_rejects_missing_snapshot_instead_of_using_current_balance() {
-    #[should_panic(expected = "contract is paused")]
-    fn test_create_proposal_fails_while_paused() {
         let env = Env::default();
         let (admin, contract_id, _) = setup_token(&env);
         let client = LearnTokenClient::new(&env, &contract_id);
@@ -928,6 +926,16 @@ mod token_unit_tests {
             &0,
             &1_000,
             &100,
+        );
+    }
+
+    #[test]
+    #[should_panic(expected = "contract is paused")]
+    fn test_create_proposal_fails_while_paused() {
+        let env = Env::default();
+        let (admin, contract_id, _) = setup_token(&env);
+        let client = LearnTokenClient::new(&env, &contract_id);
+        env.mock_all_auths();
         client.pause(&admin);
         client.create_proposal(
             &SorobanString::from_str(&env, "Paused proposal"),
@@ -939,7 +947,6 @@ mod token_unit_tests {
     }
 
     #[test]
-    fn test_vesting_schedule_cliff_linear_vesting_and_claiming() {
     #[should_panic(expected = "contract is paused")]
     fn test_vote_fails_while_paused() {
         let env = Env::default();