Function try_cache_checkpoint 

pub fn try_cache_checkpoint(
    store: &dyn ConfigStore,
    cache_path: &Path,
    new_checkpoint: &SignedCheckpoint,
    consistency_proof: Option<&ConsistencyProof>,
) -> Result<ConsistencyReport, TransparencyWorkflowError>

Cache a checkpoint using trust-on-first-use (TOFU) semantics.

If no cached checkpoint exists, the new checkpoint is accepted and written. If a cached checkpoint exists with the same or smaller tree size and matching root, the cache is left unchanged. If the cached checkpoint has the same size but a different root, this is equivocation — returns a hard error. If a consistency proof is provided, full Merkle consistency is verified.

Args:

• store — File-access port for the checkpoint cache file.
• cache_path — Path to the cached checkpoint JSON file (~/.auths/log_checkpoint.json).
• new_checkpoint — The checkpoint to cache.
• consistency_proof — Optional consistency proof for cache-hit cases.

Usage:

try_cache_checkpoint(
    &store,
    &Path::new("~/.auths/log_checkpoint.json"),
    &bundle.signed_checkpoint,
    None,
)?;