feat(tests): MIP-4 and reserve balance tests

[pdobacz]

A couple of gaps filled:

1. Calling MIP-4 precompile as tx.to, with various reasons to fail, similar to how calling from EVM is tested
2. A new multi block scenario for reserve balance rules (intertwining a credit of various shapes and values into a sequence of txs)

[greptile-apps]

Greptile Summary

This PR fills two testing gaps for Monad's execution specs: (1) direct-transaction (tx.to) calls to the MIP-4 checkReserveBalance precompile with various failure scenarios, mirroring the existing EVM-opcode call tests; and (2) a new multi-block test_credit_with_value scenario that interleaves value sends and credits of varying amounts/timing/delivery-methods into the reserve-balance test matrix.

Key changes:

• helpers.py: Adds an opt-in status field to verify_transaction_receipt, which is used by the new tx-level precompile tests to assert success/failure of each transaction receipt.
• test_precompile_call.py: Introduces _tx_params, test_tx_revert_scenarios, and test_tx_revert_scenario_pairs. NOT_CALL is correctly excluded (no opcodes at tx level), and a new LOW_GAS + EXTRA_CALLDATA incompatible pair is documented with the EIP-7623 floor explanation.
• test_multi_block.py: Adds test_credit_with_value exercising send/credit position combinations across 4 blocks with both statically-visible (direct transfer) and non-statically-visible (SELFDESTRUCT) credit delivery. The 4-block design is intentional — it places block-0 sends outside the k=3 window, making the "emptying exception" reachable for undelegated senders. Balance accounting (initial_balance = RESERVE_BALANCE + send_value + prepare_tx_fee) and the violation/exception logic are internally consistent.

Confidence Score: 4/5

• PR is safe to merge; all test logic is consistent with Monad's full-gas-charge model and only one minor style issue was found.
• The balance arithmetic, violation/exception conditions, and incompatible-scenario sets were verified against the Monad gas model and the EIP-7623 floor. No logic errors found. A minor dead-code branch in the receipt status expression of test_tx_revert_scenario_pairs is the only note.
• No files require special attention, though the minor style issue in test_precompile_call.py at line 892-896 is worth a quick look.

Important Files Changed

Filename	Overview
packages/testing/src/execution_testing/specs/helpers.py	Adds an optional status field check in verify_transaction_receipt, gated by is not None to preserve backwards compatibility. Straightforward and correct.
tests/monad_eight/reserve_balance/test_multi_block.py	Adds test_credit_with_value — a new 4-block scenario exercising the reserve-balance credit path with parametrised send/credit positions, values, and credit delivery methods (direct vs SELFDESTRUCT). Balance accounting and violation/exception logic are internally consistent after the previously-addressed prepare_tx_gas fix.
tests/monad_nine/mip4_checkreservebalance/test_precompile_call.py	Adds tx-level precompile-call tests (test_tx_revert_scenarios, test_tx_revert_scenario_pairs) mirroring the existing EVM-call tests. Correctly excludes NOT_CALL (opcode-only scenario), adds LOW_GAS+EXTRA_CALLDATA as a tx-incompatible pair, and leverages the new TransactionReceipt.status field for receipt assertions. A minor dead-code branch exists in test_tx_revert_scenario_pairs receipt status expression.

Flowchart

%%{init: {'theme': 'neutral'}}%%
flowchart TD
    A[tx to precompile] --> B{DELEGATE_TO_PRECOMPILE?}
    B -- Yes --> C[to = delegated EOA, priority-1 check]
    B -- No --> D[to = RESERVE_BALANCE_PRECOMPILE]
    C --> E[Derive gas_limit / calldata / value from scenarios]
    D --> E
    E --> F[sender funded: gas_limit x gas_price + value]
    F --> G[Execute tx - Monad charges full gas_limit]
    G --> H{Any scenario fails?}
    H -- Yes --> I[status=0, value not transferred, sender balance = value]
    H -- No, SUCCESS only --> J[status=1, value transferred, sender balance = value]
    I --> K[post: sender Account with balance=value]
    J --> K

    subgraph test_credit_with_value
    L[initial_balance = RESERVE_BALANCE + send_value + prepare_tx_fee] --> M[blocks 0-2: setup txs + optional credit]
    M --> N[balance at test tx = RESERVE_BALANCE + credit_value]
    N --> O{credit_value less than 1?}
    O -- Yes, violation=True --> P{is_exception? not pre_delegated AND send outside k=3 window}
    P -- Yes --> Q[tx succeeds]
    P -- No --> R[tx reverts]
    O -- No, violation=False --> Q
    end

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[pdobacz]

@greptileai re review

[QEDK]

LGTM.