HydraCache 0.64.0

HydraCache 0.64.0

0.64.0 strengthens HydraCache's correctness evidence around Raft snapshots,
membership changes, recovery, concurrency, and asynchronous cancellation. This
release intentionally prioritizes executable proof over new product surface: it
adds deterministic, model-based, adversarial, and real-process test tiers while
keeping the public cache and protocol scope stable.

Highlights

• Added immutable snapshot and committed-tail replay proofs, including snapshots
  taken during membership changes and fail-loud handling of malformed,
  truncated, stale, swapped, and misdirected durable artifacts.
• Expanded the Raft fault matrix with deterministic message filtering,
  composed-fault nemesis schedules, shrinking, bad-seed replay, bounded model
  checking, leadership handoff, snapshot-delivery fan-out, retry idempotency,
  clock-skew safety, rejoin, and recovery scenarios.
• Added independent concurrency evidence through loom, Miri, ThreadSanitizer,
  mutation testing, invariant canaries, and ordinary contention tests. These
  tiers remain separate so one green detector cannot stand in for another.
• Added trace-driven cache-policy characterization against Belady, cache-core
  race and expiry-storm tests, connection/resource chaos, adapter/configuration
  property corpora, parser fuzz corpora, and differential behavior checks.
• Added an executable TLA+/TLC election model and a separate Rust state-space
  model, each with a negative canary and explicit traceability to implementation
  invariants.
• Added W39 cancellation-safety contracts for local single-flight loading, the
  Axum client and token-safe lock path, and Raft proposal/shutdown recovery.
  Cancellation outcomes are classified explicitly and retries remain
  command-idempotent.
• Added machine-readable release governance: registered gated tests, exact-commit
  evidence receipts, dynamic expected-red canaries, quarantine expiry, fast-tier
  budgets, deterministic logical digests, and a coverage ratchet.
• Added tag-gated crates.io automation. A successful full CI run for a release
  tag publishes workspace crates in dependency order through the protected
  release environment, verifies fresh crates.io consumers, and only then
  creates the GitHub Release.

Compatibility And Scope

• The workspace MSRV remains Rust 1.88.
• The Redis RESP facade and protocol-v4 lock subset introduced in 0.63.0
  remain unchanged; this release does not add Redis Cluster, general Lua,
  multi-endpoint lock, or cross-daemon RESP key-visibility claims.
• In-process and deterministic snapshot/backpressure proofs do not claim
  production slow-TCP or receiver-process-kill behavior. Those stronger
  real-process and operational rows remain assigned to 0.66.
• Previous-version compatibility is proved against the frozen v0.63.0
  wire/snapshot/API baseline. Mixed-version daemon rollout remains a later
  operational gate.
• Test-only failpoints, canaries, fuzz harnesses, and cluster testkits are not
  part of the published runtime dependency graph.

Verification

The release candidate is accepted only when the ordinary Rust/MSRV checks and
all registered 0.64 evidence lanes are green, including performance and
coverage budgets, Redis compatibility proof, DST/soak, Raft corner cases, loom,
fuzz corpus replay, mutation shards, Miri, ThreadSanitizer, dynamic canaries,
TLA+/TLC, cancellation safety, packaging, and post-publish consumer checks.

The authoritative implementation boundaries and exact commands are recorded in
V0_64_RAFT_SNAPSHOT_AND_AGENTIC_DEBUGGING_TEST_EXPANSION_PLAN.md,
GATES.md, and TESTING.md.

Not Shipped In 0.64.0

• New cache, Redis, Hazelcast, ownership-routing, or consensus APIs.
• Production snapshot streaming and slow-receiver process-kill guarantees.
• Mixed-version daemon rolling upgrades and external Jepsen process drivers.
• Backup/PITR, operator scale chaos, or new disk-backed compaction product
  features beyond the existing tested seams.