Module cache Future

Cache Module - Future Enhancements

Scope

• hardening and refinement of adaptive/embedding cache runtime paths
• expansion of deterministic reliability for invalidation, warmup, and replication behavior
• stricter benchmark-backed guardrails for cache hot paths
• operator-grade diagnostics for tenant isolation and degraded coordination incidents

Design Constraints

• cache contracts remain backward compatible within major release line.
• tenant isolation remains mandatory where tenant mode is enabled.
• degraded coordination paths remain bounded and observable.
• invalidation and replication behavior remains deterministic and auditable.
• no legacy/compatibility shim paths are introduced without explicit human approval.

Required Interfaces

Interface	Requirement
adaptive cache interfaces	deterministic get/put/invalidate behavior under backend permutations and feature flags
tenant/isolation interfaces	clear segregation, bounded tenant ID validation, and quota-aware semantics
replication/coordination interfaces	explicit delivery guarantees, degraded-state semantics, and failure classification
ops/monitoring interfaces	stable SLO, health, and diagnostics exposure with correlation-friendly error envelopes

Implementation Notes

• tighten consistency behavior for distributed invalidation and replication across:
  • distributed_cache_coordinator.cpp
  • redis_cache_coordinator.cpp
  • cache_replication_coordinator.cpp
• standardize diagnostics for tenant, warmup, and coordinator failure classes using stable categories (validation, degraded, unavailable, conflict).
• expand resilience for backend outages and partial-degradation scenarios with deterministic fail-closed outcomes for unsafe operations.
• continue replacing proxy-like mappings with dedicated cache benchmarks and release-manifest coverage checks.

Test Strategy

• unit and integration suites for adaptive/embedding/tenant paths.
• distributed consistency regressions for replication/coordination behavior.
• degraded-backend and warmup/prefetch deterministic tests.
• release-profile benchmark runs for mapped cache targets.
• minimum acceptance expansion (Q4 2026):
  • invalidation/replication edge permutation matrix (ordering, duplication, delayed delivery, partial backend availability)
  • tenant isolation negative-path validation (malformed tenant IDs, missing tenant contexts, trailing path segments)
  • coordinator degraded-state determinism checks (stable non-2xx response mapping and diagnostics fields)

Performance Targets

• cache put/get/invalidate hot paths remain within release regression budgets.
• concurrent cache and tenant-aware operations remain stable at p95/p99.
• benchmark manifests for mapped cache targets reach no-missing-case status.
• measurable targets for release profiles:
  • regression threshold: <= 10% vs baseline for mapped cache benchmark cases
  • p99 hot-path budget: must remain within module release threshold definitions in PERFORMANCE_EXPECTATIONS.md
  • manifest completeness: 100% of mapped cache benchmark cases present in release evidence

Security / Reliability

• maintain strict tenant isolation and fail-closed invalid access behavior.
• preserve auditable invalidation and replication decision paths.
• enforce bounded resource behavior for cache tiers and warmup paths.
• keep diagnostics actionable for production incidents.
• reliability gate intent:
  • degraded coordination must remain bounded, observable, and explicitly surfaced to operators
  • partial backend participation must never silently report success for invalidation/replication operations

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