Task hashing change across Turborepo 1.x to 2.x cache boundary

Turborepo 2.x introduced changes to internal cache boundaries and task graph execution compared to 1.x. The goal is to understand remote caching and task hashing behavior after this configuration transition while testing an integration without production credentials.

Credential-less testing is constrained to local file cache fallback because Vercel Remote Cache scopes reads and writes to an authenticated team. Cross-version cache artifacts are not compatible, so version assumptions matter for any evaluation.

An unresolved decision concerns undeclared environment variables. Documentation indicates only variables listed in env or globalEnv should change the cache key, yet outputs can be influenced by CI or shell variables that are not declared. The impact on hashing in Turborepo 2.x is unclear.

Does Turborepo 2.x include undeclared environment variables in the task hash by default? Does a local file cache test provide equivalent hit/miss signals to a remote cache without authentication? Are cache artifacts compatible across 2.x minor releases?