Bazel remote caching: inconsistent action hashes with identical inputs

Bazel utilizes a content-addressable storage (CAS) system to ensure that action outputs are retrieved based on a hash of their inputs. In a remote caching environment, achieving consistent cache hits across different CI runners and developer workstations is critical for build performance.

There is a design uncertainty regarding how Bazel handles absolute paths embedded within generated files or toolchain configurations. If a build rule is not strictly hermetic, the resulting action hash may vary between environments despite the source code remaining unchanged, leading to unexpected cache misses.

• What specific mechanisms does Bazel provide to detect and neutralize non-deterministic inputs that cause action hash divergence?
• How does the --remote_download_outputs=toplevel flag affect the visibility of these cache misses during the build summary analysis?