diff --git a/crates/mega-evm/tests/rex1/compute_gas_reset.rs b/crates/mega-evm/tests/rex1/compute_gas_reset.rs
new file mode 100644
index 00000000..037bab9f
--- /dev/null
+++ b/crates/mega-evm/tests/rex1/compute_gas_reset.rs
@@ -0,0 +1,279 @@
+//! Tests for the Rex1 fix: detained compute gas limit resets between transactions.
+//!
+//! Before Rex1, volatile data access (oracle call, TIMESTAMP, etc.) in TX1 would lower the
+//! detained compute gas limit, and that lowered limit persisted to subsequent transactions,
+//! causing unrelated transactions to fail with `ComputeGasLimitExceeded`.
+
+use alloy_primitives::{address, Bytes, U256};
+use mega_evm::{
+    test_utils::{BytecodeBuilder, MemoryDatabase},
+    EmptyExternalEnv, EvmTxRuntimeLimits, MegaContext, MegaEvm, MegaHaltReason, MegaSpecId,
+    MegaTransaction, ORACLE_CONTRACT_ADDRESS,
+};
+use revm::{
+    bytecode::opcode::{CALL, GAS, KECCAK256, MSTORE, POP, PUSH0, STOP, TIMESTAMP},
+    context::tx::TxEnvBuilder,
+    handler::EvmTr,
+    inspector::NoOpInspector,
+};
+
+const CALLER: alloy_primitives::Address = address!("2000000000000000000000000000000000000002");
+const CONTRACT_VOLATILE: alloy_primitives::Address =
+    address!("1000000000000000000000000000000000000001");
+const CONTRACT_EXPENSIVE: alloy_primitives::Address =
+    address!("1000000000000000000000000000000000000002");
+
+// TX compute gas limits. Block-env limit must exceed BLOCK_ENV_DETENTION_CAP so the cap binds.
+const TX_COMPUTE_GAS_LIMIT_ORACLE: u64 = 10_000_000;
+const TX_COMPUTE_GAS_LIMIT_BLOCK_ENV: u64 = 30_000_000;
+
+const ORACLE_DETENTION_CAP: u64 = 1_000_000; // pre-Rex3 oracle cap
+const BLOCK_ENV_DETENTION_CAP: u64 = 20_000_000;
+
+/// Build a contract that calls the oracle contract, triggering oracle detention (1M cap).
+fn build_oracle_call_contract() -> Bytes {
+    BytecodeBuilder::default()
+        .append_many([PUSH0, PUSH0, PUSH0, PUSH0])
+        .push_number(0u8)
+        .push_address(ORACLE_CONTRACT_ADDRESS)
+        .append(GAS)
+        .append(CALL)
+        .append(POP)
+        .append(STOP)
+        .build()
+}
+
+/// Build a contract that reads TIMESTAMP, triggering block-env detention (20M cap).
+fn build_timestamp_access_contract() -> Bytes {
+    BytecodeBuilder::default().append(TIMESTAMP).append(POP).append(STOP).build()
+}
+
+/// Build a contract that burns compute gas via KECCAK256 loops (~38 gas/iter).
+/// 55_000 iters ≈ 2.1M gas; 600_000 iters ≈ 22.8M gas.
+fn build_expensive_contract(iterations: u32) -> Bytes {
+    let mut builder =
+        BytecodeBuilder::default().push_number(0xdeadbeefu32).push_number(0u8).append(MSTORE);
+    for _ in 0..iterations {
+        builder = builder.push_number(32u8).push_number(0u8).append(KECCAK256).append(POP);
+    }
+    builder.append(STOP).build()
+}
+
+fn make_evm(
+    spec: MegaSpecId,
+    db: MemoryDatabase,
+    tx_compute_gas_limit: u64,
+    oracle_cap: u64,
+    block_env_cap: u64,
+) -> MegaEvm<MemoryDatabase, NoOpInspector, EmptyExternalEnv> {
+    let mut context = MegaContext::new(db, spec).with_tx_runtime_limits(
+        EvmTxRuntimeLimits::no_limits()
+            .with_tx_compute_gas_limit(tx_compute_gas_limit)
+            .with_oracle_access_compute_gas_limit(oracle_cap)
+            .with_block_env_access_compute_gas_limit(block_env_cap),
+    );
+    context.modify_chain(|c| {
+        c.operator_fee_scalar = Some(U256::ZERO);
+        c.operator_fee_constant = Some(U256::ZERO);
+    });
+    context.modify_cfg(|c| {
+        c.disable_nonce_check = true;
+    });
+    MegaEvm::new(context).with_inspector(NoOpInspector)
+}
+
+fn make_tx(target: alloy_primitives::Address) -> MegaTransaction {
+    MegaTransaction {
+        base: TxEnvBuilder::new()
+            .caller(CALLER)
+            .call(target)
+            .gas_limit(1_000_000_000_000)
+            .gas_price(0)
+            .build_fill(),
+        enveloped_tx: Some(Bytes::new()),
+        ..Default::default()
+    }
+}
+
+fn compute_gas_limit(evm: &MegaEvm<MemoryDatabase, NoOpInspector, EmptyExternalEnv>) -> u64 {
+    evm.ctx_ref().additional_limit.borrow().compute_gas_limit()
+}
+
+// =============================================================================
+// Oracle detention tests
+// =============================================================================
+
+/// Rex1: TX2 succeeds after TX1 oracle detention — detained limit resets at TX start.
+#[test]
+fn test_rex1_oracle_detention_resets_between_txs() {
+    // 55_000 iters ≈ 2.1M gas: above 1M oracle cap, below 10M TX limit
+    let db = MemoryDatabase::default()
+        .account_balance(CALLER, U256::from(1_000_000_000_000u64))
+        .account_code(CONTRACT_VOLATILE, build_oracle_call_contract())
+        .account_code(CONTRACT_EXPENSIVE, build_expensive_contract(55_000));
+
+    let mut evm =
+        make_evm(MegaSpecId::REX1, db, TX_COMPUTE_GAS_LIMIT_ORACLE, ORACLE_DETENTION_CAP, u64::MAX);
+
+    let r1 = alloy_evm::Evm::transact_raw(&mut evm, make_tx(CONTRACT_VOLATILE)).unwrap();
+    assert!(r1.result.is_success(), "TX1 should succeed, got: {:?}", r1.result);
+    assert_eq!(compute_gas_limit(&evm), ORACLE_DETENTION_CAP, "TX1 should detain limit to 1M");
+
+    let r2 = alloy_evm::Evm::transact_raw(&mut evm, make_tx(CONTRACT_EXPENSIVE)).unwrap();
+    assert!(r2.result.is_success(), "TX2 should succeed after limit resets, got: {:?}", r2.result);
+    assert_eq!(
+        compute_gas_limit(&evm),
+        TX_COMPUTE_GAS_LIMIT_ORACLE,
+        "limit should reset to base TX limit after TX2"
+    );
+}
+
+/// Pre-Rex1 (REX): detained limit from TX1 oracle access leaks into TX2, causing it to fail.
+#[test]
+fn test_pre_rex1_oracle_detention_leaks_to_next_tx() {
+    let db = MemoryDatabase::default()
+        .account_balance(CALLER, U256::from(1_000_000_000_000u64))
+        .account_code(CONTRACT_VOLATILE, build_oracle_call_contract())
+        .account_code(CONTRACT_EXPENSIVE, build_expensive_contract(55_000));
+
+    let mut evm =
+        make_evm(MegaSpecId::REX, db, TX_COMPUTE_GAS_LIMIT_ORACLE, ORACLE_DETENTION_CAP, u64::MAX);
+
+    let r1 = alloy_evm::Evm::transact_raw(&mut evm, make_tx(CONTRACT_VOLATILE)).unwrap();
+    assert!(r1.result.is_success(), "TX1 should succeed, got: {:?}", r1.result);
+    assert_eq!(compute_gas_limit(&evm), ORACLE_DETENTION_CAP, "TX1 should detain limit to 1M");
+
+    let r2 = alloy_evm::Evm::transact_raw(&mut evm, make_tx(CONTRACT_EXPENSIVE)).unwrap();
+    assert!(!r2.result.is_success(), "TX2 should fail: detained limit not reset in pre-Rex1");
+    assert!(
+        matches!(
+            r2.result,
+            revm::context::result::ExecutionResult::Halt {
+                reason: MegaHaltReason::ComputeGasLimitExceeded { .. },
+                ..
+            }
+        ),
+        "expected ComputeGasLimitExceeded, got: {:?}",
+        r2.result
+    );
+    assert_eq!(
+        compute_gas_limit(&evm),
+        ORACLE_DETENTION_CAP,
+        "limit should still be stuck at oracle cap in pre-Rex1"
+    );
+}
+
+// =============================================================================
+// Block-env detention tests (TIMESTAMP opcode)
+// =============================================================================
+
+/// Rex1: TX2 succeeds after TX1 block-env detention — detained limit resets at TX start.
+#[test]
+fn test_rex1_block_env_detention_resets_between_txs() {
+    // 600_000 iters ≈ 22.8M gas: above 20M block-env cap, below 30M TX limit
+    let db = MemoryDatabase::default()
+        .account_balance(CALLER, U256::from(1_000_000_000_000u64))
+        .account_code(CONTRACT_VOLATILE, build_timestamp_access_contract())
+        .account_code(CONTRACT_EXPENSIVE, build_expensive_contract(600_000));
+
+    let mut evm = make_evm(
+        MegaSpecId::REX1,
+        db,
+        TX_COMPUTE_GAS_LIMIT_BLOCK_ENV,
+        u64::MAX, // oracle cap — not relevant here
+        BLOCK_ENV_DETENTION_CAP,
+    );
+
+    let r1 = alloy_evm::Evm::transact_raw(&mut evm, make_tx(CONTRACT_VOLATILE)).unwrap();
+    assert!(r1.result.is_success(), "TX1 should succeed, got: {:?}", r1.result);
+    assert_eq!(
+        compute_gas_limit(&evm),
+        BLOCK_ENV_DETENTION_CAP,
+        "TX1 should detain limit to 20M"
+    );
+
+    let r2 = alloy_evm::Evm::transact_raw(&mut evm, make_tx(CONTRACT_EXPENSIVE)).unwrap();
+    assert!(r2.result.is_success(), "TX2 should succeed after limit resets, got: {:?}", r2.result);
+    assert_eq!(
+        compute_gas_limit(&evm),
+        TX_COMPUTE_GAS_LIMIT_BLOCK_ENV,
+        "limit should reset to base TX limit after TX2"
+    );
+}
+
+/// Pre-Rex1 (REX): detained limit from TX1 block-env access leaks into TX2, causing it to fail.
+#[test]
+fn test_pre_rex1_block_env_detention_leaks_to_next_tx() {
+    let db = MemoryDatabase::default()
+        .account_balance(CALLER, U256::from(1_000_000_000_000u64))
+        .account_code(CONTRACT_VOLATILE, build_timestamp_access_contract())
+        .account_code(CONTRACT_EXPENSIVE, build_expensive_contract(600_000));
+
+    let mut evm = make_evm(
+        MegaSpecId::REX,
+        db,
+        TX_COMPUTE_GAS_LIMIT_BLOCK_ENV,
+        u64::MAX,
+        BLOCK_ENV_DETENTION_CAP,
+    );
+
+    let r1 = alloy_evm::Evm::transact_raw(&mut evm, make_tx(CONTRACT_VOLATILE)).unwrap();
+    assert!(r1.result.is_success(), "TX1 should succeed, got: {:?}", r1.result);
+    assert_eq!(
+        compute_gas_limit(&evm),
+        BLOCK_ENV_DETENTION_CAP,
+        "TX1 should detain limit to 20M"
+    );
+
+    let r2 = alloy_evm::Evm::transact_raw(&mut evm, make_tx(CONTRACT_EXPENSIVE)).unwrap();
+    assert!(!r2.result.is_success(), "TX2 should fail: detained limit not reset in pre-Rex1");
+    assert!(
+        matches!(
+            r2.result,
+            revm::context::result::ExecutionResult::Halt {
+                reason: MegaHaltReason::ComputeGasLimitExceeded { .. },
+                ..
+            }
+        ),
+        "expected ComputeGasLimitExceeded, got: {:?}",
+        r2.result
+    );
+}
+
+// =============================================================================
+// Multi-transaction reset test
+// =============================================================================
+
+/// Rex1: detention resets on every transaction boundary, not just once.
+///
+/// Runs two rounds of (volatile TX → expensive TX) to verify the reset is persistent.
+#[test]
+fn test_rex1_detention_resets_across_multiple_txs() {
+    let db = MemoryDatabase::default()
+        .account_balance(CALLER, U256::from(1_000_000_000_000u64))
+        .account_code(CONTRACT_VOLATILE, build_oracle_call_contract())
+        .account_code(CONTRACT_EXPENSIVE, build_expensive_contract(55_000));
+
+    let mut evm =
+        make_evm(MegaSpecId::REX1, db, TX_COMPUTE_GAS_LIMIT_ORACLE, ORACLE_DETENTION_CAP, u64::MAX);
+
+    for round in 1..=2 {
+        let r_volatile =
+            alloy_evm::Evm::transact_raw(&mut evm, make_tx(CONTRACT_VOLATILE)).unwrap();
+        assert!(r_volatile.result.is_success(), "round {round} volatile TX should succeed");
+        assert_eq!(
+            compute_gas_limit(&evm),
+            ORACLE_DETENTION_CAP,
+            "round {round}: limit should be detained after volatile TX"
+        );
+
+        let r_expensive =
+            alloy_evm::Evm::transact_raw(&mut evm, make_tx(CONTRACT_EXPENSIVE)).unwrap();
+        assert!(r_expensive.result.is_success(), "round {round} expensive TX should succeed");
+        assert_eq!(
+            compute_gas_limit(&evm),
+            TX_COMPUTE_GAS_LIMIT_ORACLE,
+            "round {round}: limit should reset after expensive TX"
+        );
+    }
+}
diff --git a/crates/mega-evm/tests/rex1/main.rs b/crates/mega-evm/tests/rex1/main.rs
new file mode 100644
index 00000000..fb869c8d
--- /dev/null
+++ b/crates/mega-evm/tests/rex1/main.rs
@@ -0,0 +1,3 @@
+//! Tests for Rex1 hardfork features.
+
+mod compute_gas_reset;