starknet_os_flow_tests: add multicall prove test; drop balance_of test

[Yoni-Starkware]

Stack:

• ▶ starknet_os_flow_tests: add multicall prove test; drop balance_of test #14082 (this PR)
• workspace,starknet_proof_verifier: bump privacy-{prove,circuit-verify} to 039e52c, add v0/v1 aliases #14017
• apollo_starknet_os_program: restore keccak syscall in virtual OS #14071

Summary

• Add multi_call(Array<Call>) to account_with_dummy_validate.cairo, with a TODO above the existing __execute__ to eventually replace it with this multicall shape so INVOKE calldata can be Array<Call> natively.
• Add prove_and_verify_multicall_tx in crates/starknet_os_flow_tests/src/virtual_os_test.rs: one virtual-OS tx forwards through __execute__ to the account's multi_call, currently dispatching only test_ec_op (with a TODO to restore the test_keccak inner call — added by stacked PR apollo_starknet_os_program: restore keccak syscall in virtual OS #14071, which re-enables the keccak syscall in the virtual OS).
• Local serialize_call(name, args) helper mutates multi_call_args and bumps the leading num_calls counter so each call site is one line. Marked #[ignore].
• Remove test_prove_balance_of_transaction from crates/starknet_transaction_prover/src/proving/virtual_snos_prover_test.rs — the remaining test_prove_transfer_transaction already covers the same VirtualSnosProver::prove_transaction Sepolia path.
• Wire the new test into the prover CI workflow alongside virtual_snos_prover_test. Widen the workflow's path triggers to include apollo_starknet_os_program/**, blockifier_test_utils/**, and starknet_os_flow_tests/** (path triggers aren't transitive).
• Regenerate downstream snapshots whose values depend on the new account class hash: bouncer::test::class_hash_migration_data_from_state, stack_trace_regression/test_contract_ctor_frame_stack_trace_cairo1_casm.txt, the FUZZ_ADDRESS_* constants in starknet_os_flow_tests::fuzz_tests, and test_experimental_libfuncs_contract blakes count.

Test plan

• cargo test -p blockifier --lib bouncer:: execution::stack_trace::test::test_contract_ctor_frame_stack_trace
• cargo test -p starknet_os_flow_tests --lib fuzz_tests test_experimental_libfuncs_contract
• cargo clippy -p starknet_os_flow_tests --all-targets --all-features
• cargo +nightly-2025-07-14 test -p starknet_os_flow_tests --features starknet_transaction_prover/stwo_proving --release prove_and_verify_multicall_tx -- --ignored --nocapture (runs as the --ignored step in starknet_transaction_prover_ci)

[cursor]

PR Summary

Medium Risk
Updates a shared Cairo1 dummy account contract (changing its compiled output/class hash) and adds a new ignored proof/verify test that is now executed in CI with --ignored, which could cause snapshot churn or CI instability if proofs become flaky.

Overview
Adds a Cairo1 multi_call(Array<Call>) entrypoint to the account_with_dummy_validate test account contract (while keeping the legacy single-call __execute__), enabling tests to drive multicall-style invokes.

Introduces an ignored prove_and_verify_multicall_tx virtual-OS proving+verification integration test in starknet_os_flow_tests (using starknet_proof_verifier) and wires it into the Starknet-Transaction-Prover-CI workflow to run under --ignored with proving features.

Removes the redundant Sepolia balanceOf proving integration test from virtual_snos_prover_test, and updates various expectation snapshots/fixtures impacted by the contract/output changes (gas numbers, stack trace PC, fuzz deployment addresses, and a blake opcode count).

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[reviewable-StarkWare]

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[Yoni-Starkware]

@Yoni-Starkware resolved 1 discussion.
Reviewable status: 0 of 4 files reviewed, 1 unresolved discussion.

[Yoni-Starkware]

@Yoni-Starkware resolved 1 discussion.
Reviewable status: 0 of 4 files reviewed, all discussions resolved.

[github-actions]

Artifacts upload workflows:

• Started at 2026-05-19T11:31:50Z
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[AvivYossef-starkware]

@AvivYossef-starkware reviewed 10 files and all commit messages, and made 1 comment.
Reviewable status: all files reviewed, 1 unresolved discussion (waiting on Yoni-Starkware).

---

crates/starknet_os_flow_tests/src/virtual_os_test.rs line 299 at r6 (raw file):

        multi_call_args.push(Felt::from(args.len()));
        multi_call_args.extend_from_slice(args);
    };

PLTAL

Code quote:

    let mut multi_call_args: Vec<Felt> = vec![Felt::ZERO];
    let mut serialize_call = |func_name: &str, args: &[Felt]| {
        multi_call_args[0] += Felt::ONE;
        multi_call_args.push(*contract_address.0.key());
        multi_call_args.push(selector_from_name(func_name).0);
        multi_call_args.push(Felt::from(args.len()));
        multi_call_args.extend_from_slice(args);
    };

[Yoni-Starkware]

@Yoni-Starkware resolved 1 discussion.
Reviewable status: complete! all files reviewed, all discussions resolved (waiting on Yoni-Starkware).