Scarb build reproducibility and toolchain versioning

Development Environment Consistency

Ensuring repeatable builds in Cairo 1.0 relies on the Scarb package manager and the underlying Cairo-VM. Because the toolchain stability is closely tied to the specific Rust compiler version used for the VM implementation, discrepancies in the local environment can lead to inconsistent build outputs.

Toolchain Constraints

While Scarb manages dependencies, the interaction between the compiler version and the VM's deterministic execution environment requires strict alignment to ensure that the generated STARK proofs remain valid across different developer machines.

• Dependency on specific Rust compiler versions for VM stability.
• Requirement for deterministic execution traces in the Cairo-VM.

What is the recommended mechanism for locking the exact compiler and VM toolchain versions within a Scarb project to prevent build drift? How can developers verify that the resulting execution trace is identical across disparate environments?