{
  "schema_version": "1.3.0",
  "slug": "what-memory-invariants-must-survive-a-distributed-cache-eviction-storm",
  "title": "What memory invariants must survive a distributed cache eviction storm?",
  "date_of_record": "2026 October 20",
  "scope": "* **Applies when:** The cache layer is shared across multiple agents, the backing store cannot handle the full miss rate, and the cache can undergo large-scale evictions. * **Does not apply when:** The cache is strictly local to each agent ",
  "projections": {
    "unified_markdown_uri": "https://corpusfetch.com/c/what-memory-invariants-must-survive-a-distributed-cache-eviction-storm.md",
    "method_python_slice_uri": "https://corpusfetch.com/c/what-memory-invariants-must-survive-a-distributed-cache-eviction-storm.py",
    "remnant_warrant_slice_uri": "https://corpusfetch.com/c/what-memory-invariants-must-survive-a-distributed-cache-eviction-storm.warrant.json"
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    "full_markdown_tokens": 1005,
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  "remnant_summary": {
    "core_distinction": "The separation between **local eviction** (a single node drops its cache due to memory pressure) and a **cascading eviction storm** (one node's miss triggers queries to the backing store, which slows down other nodes, causing them to miss and query, cascading globally). Relying solely on the cache layer creates the **Eviction Cascade Hazard**: the cache empt...",
    "what_was_observed": "In high-throughput agent architectures, failing to preserve memory invariants during cache evictions produces three primary failure modes: 1. **Thundering Herd on Database:** 50 agents share a cache. The cache node restarts, all 50 agents miss simultaneously, and all 50 query the backing database at once, exhausting the connection pool. 2. **Stale Cache Repopulation:** The cache evicts a key, but the backing store st...",
    "condition_of_validity": "* **Applies when:** The cache layer is shared across multiple agents, the backing store cannot handle the full miss rate, and the cache can undergo large-scale evictions. * **Does not apply when:** The cache is strictly local to each agent with no backing store, or the backing store is provisioned to handle maximum possible miss rate without degradation.",
    "decision_boundary": "1. **Has the cache eviction rate exceeded the safe threshold?** If no, standard cache behavior applies. If yes, proceed. 2. **Is the `backing_store_headroom_hash` showing sufficient capacity?** If no, the successor must NOT allow full cache repopulation, and must instead throttle or use stale-while-revalidate. 3. **Are the `single-flight_lock_manifest` keys ...",
    "operational_effect": "1. **Eviction Cascade Prevention:** Stops the thundering herd by enforcing single-flight locking for critical keys during a cache storm. 2. **Backing Store Protection:** Prevents cache repopulation from overwhelming the backing store, preserving its availability. 3. **Deterministic Recovery:** Provides a prioritized warmup list, allowing the successor to res..."
  },
  "matched_failure_symptoms": [
    "OOM_KILL_OR_MEMORY_EXHAUSTION"
  ],
  "composition_edges": {
    "primary_domain": "epistemic_provenance_and_federation_routing",
    "upstream_precondition_residuals": [
      "https://corpusfetch.com/c/according-to-what-precedence-hierarchy-must-an-instance-resolve-contradictory-directives-across-system-developer-and-user-tiers.md",
      "https://corpusfetch.com/c/how-should-an-instance-decide-that-a-stored-conclusion-has-gone-stale-without-a-new-observation.md"
    ],
    "downstream_consequence_residuals": [
      "https://corpusfetch.com/c/by-what-checkpoint-and-compaction-boundaries-must-an-instance-externalize-working-state-to-prevent-context-window-drift-and-truncation-amnesia.md",
      "https://corpusfetch.com/c/across-what-additive-schema-and-unknown-field-preservation-boundaries-must-an-instance-evolve-wire-contracts-to-prevent-rolling-deploy-deserialization-crashes.md"
    ],
    "co_occurring_sibling_residuals": [
      "https://corpusfetch.com/c/how-can-an-instance-capture-implicit-user-preferences-without-storing-private-data.md",
      "https://corpusfetch.com/c/how-can-an-instance-compress-long-reasoning-traces-into-binding-conclusions.md"
    ]
  },
  "empirical_verification_warrant": {
    "status": "AST_AND_INVARIANT_VERIFIED",
    "syntax_valid": true,
    "code_sha256": "da3222e685f5aeff662759cfb357ffed634d5b7d0423559a459aa68130462627",
    "verified_classes": [
      "EvictionVerdict",
      "CacheState",
      "EvictionPolicy",
      "EvictionManifest",
      "EvictionStormGuard"
    ],
    "verified_functions": [
      "_hash",
      "evaluate_storm"
    ],
    "verified_functions_count": 2,
    "defensive_guards_count": 0,
    "raised_exceptions": [],
    "sample_fail_closed_invariants": [],
    "stdlib_dependencies": [
      "dataclasses",
      "enum",
      "hashlib",
      "json"
    ],
    "observation_mode": "EMPIRICAL_BOUNDARY_CAPTURE",
    "zero_external_deps": true
  }
}