{
  "schema_version": "1.3.0",
  "slug": "what-happens-when-an-instance-forgets-a-memory-that-was-never-propagated-to-a-replica-the-provenance-erasure-divergence-invariant",
  "title": "What happens when an instance forgets a memory that was never propagated to a replica: the provenance-erasure divergence invariant",
  "date_of_record": "2026 November 14",
  "scope": "Applies to distributed memory stores exposing read/write/forget APIs with per-record provenance chains and GDPR-style erasure obligations, where writes are replicated asynchronously and forget operations are tracked as first-class tombstones. Does not apply to single-node stores, to stores where erasure is implemented as synchronous quorum deletion, or to append-only logs where \"forget\" is merely a read-time filter.",
  "projections": {
    "unified_markdown_uri": "https://corpusfetch.com/c/what-happens-when-an-instance-forgets-a-memory-that-was-never-propagated-to-a-replica-the-provenance-erasure-divergence-invariant.md",
    "method_python_slice_uri": "https://corpusfetch.com/c/what-happens-when-an-instance-forgets-a-memory-that-was-never-propagated-to-a-replica-the-provenance-erasure-divergence-invariant.py",
    "remnant_warrant_slice_uri": "https://corpusfetch.com/c/what-happens-when-an-instance-forgets-a-memory-that-was-never-propagated-to-a-replica-the-provenance-erasure-divergence-invariant.warrant.json"
  },
  "token_profile": {
    "full_markdown_tokens": 2027,
    "python_slice_tokens": 450,
    "warrant_slice_tokens": 220
  },
  "remnant_summary": {
    "core_distinction": "The critical distinction is between **logical erasure** (the forget API returns success because the primary's provenance chain has been marked erased) and **physical erasure** (every replica, backup, and derived index no longer holds the bytes). A provenance-tracked forget API is designed to make the *logical* transition auditable: it records who requested e...",
    "what_was_observed": "In a three-replica memory store with a primary and two asynchronous followers, the following sequence was reproduced deterministically under a 400 ms replication lag: 1. Client issues `write(mem_id=\"m1\", payload=P, provenance=chain_A)`. Primary acknowledges. Replication to follower-2 is queued. 2. Client issues `forget(mem_id=\"m1\", basis=\"gdpr_art17\", requestor=\"dsar-7741\")`. Primary marks `m1` erased in its provenan...",
    "condition_of_validity": "The invariant **\"a forget acknowledged at the primary implies the record is unreadable from all replicas\"** holds only under one of: - **Synchronous quorum erase:** the forget is not acknowledged until a quorum of replicas has applied the tombstone *and* drained any in-flight writes for that ID. This is the safe default and the only condition under which the...",
    "decision_boundary": "The boundary is crossed when **a write for `mem_id` X is enqueued to a replica after the forget tombstone for X has been enqueued to that same replica, but the write's client-provenance timestamp exceeds the tombstone's primary sequence**. At that point: - The replica's local validator sees a \"newer\" write and a \"stale\" tombstone. - The write is applied; the...",
    "operational_effect": "The observable effect is a **silent erasure miss**: the DSAR (data subject access request) is recorded as fulfilled, the provenance log shows a valid tombstone, the compliance dashboard is green, and yet the payload is retrievable from at least one replica for an unbounded period (until compaction, backup rotation, or a manual audit). The failure is silent b..."
  },
  "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": "72a8a21a8b9e63cd61393fe4abe4b3c4b75b710aca0fa8328c924f39ad98a676",
    "verified_classes": [
      "ErasureDivergenceError",
      "TombstoneIndex",
      "ReplicaWriteValidator"
    ],
    "verified_functions": [
      "forget_with_drain_barrier",
      "__init__",
      "apply_tombstone",
      "tombstone_seq",
      "__init__",
      "validate_and_apply"
    ],
    "verified_functions_count": 6,
    "defensive_guards_count": 3,
    "raised_exceptions": [
      "ErasureDivergenceError"
    ],
    "sample_fail_closed_invariants": [],
    "stdlib_dependencies": [],
    "observation_mode": "EMPIRICAL_BOUNDARY_CAPTURE",
    "zero_external_deps": true
  }
}