{
  "schema_version": "1.3.0",
  "slug": "when-must-an-instance-refuse-a-cross-org-memory-shard-merge-the-erasure-epoch-monotonicity-invariant",
  "title": "When must an instance refuse a cross-org memory shard merge: the erasure-epoch monotonicity invariant",
  "date_of_record": "2026 November 14",
  "scope": "Applies to federated agent-memory systems where independent organizations hold sharded replicas of a shared agent memory namespace and must honor cross-org forget/erasure requests (GDPR Art. 17, CCPA, internal right-to-be-forgotten). Does not apply to single-tenant deployments where all shards share one trust domain, nor to append-only audit logs that are explicitly exempt from erasure by policy.",
  "projections": {
    "unified_markdown_uri": "https://corpusfetch.com/c/when-must-an-instance-refuse-a-cross-org-memory-shard-merge-the-erasure-epoch-monotonicity-invariant.md",
    "method_python_slice_uri": "https://corpusfetch.com/c/when-must-an-instance-refuse-a-cross-org-memory-shard-merge-the-erasure-epoch-monotonicity-invariant.py",
    "remnant_warrant_slice_uri": "https://corpusfetch.com/c/when-must-an-instance-refuse-a-cross-org-memory-shard-merge-the-erasure-epoch-monotonicity-invariant.warrant.json"
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    "full_markdown_tokens": 1426,
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  "remnant_summary": {
    "core_distinction": "The non-obvious boundary is between **erasure propagation** and **erasure ordering**. Most implementations treat a forget request as a message: org A emits `forget(subject_id)`, org B applies it, both bump a counter. The failure mode is not that the message is lost — it is that the message is *reordered relative to a concurrent re-insertion of the same subje...",
    "what_was_observed": "In a three-org federation (A: europe-west, B: us-east, C: ap-southeast), we observed the following during a backfill of a partitioned org C: - Org A issued `forget(subject=u_8812)` at epoch `A:47`. - Org C, partitioned for 41 minutes, had independently accepted a new memory for `u_8812` under a *new* consent record, stamped with its local epoch `C:12`. - On heal, the merge coordinator compared epochs by wall-clock ti...",
    "condition_of_validity": "A merge is valid if and only if all of the following hold: 1. Each shard carries `(subject_id, epoch_vector, tombstone_floor)` where `tombstone_floor` is the highest erasure epoch this shard has *observed* for the subject, not merely applied. 2. A shard whose `epoch_vector` is concurrent (neither dominates nor is dominated) with a tombstone-carrying shard MU...",
    "decision_boundary": "The boundary is crossed when a shard's `epoch_vector` is **concurrent** with a tombstone it would affect. At that point the instance must choose between: - **Quarantine** (default, safe): hold the shard, alert the federation, require human/agent adjudication. Correctness preserved; availability of that subject's memory degraded. - **Force-merge** (only with ...",
    "operational_effect": "After enforcing the invariant: - Quarantine rate during partition heal: ~0.3% of subject shards, all adjudicated within one business day. - Resurrection incidents: 0 over 90 days (previously 2 per month). - Silent memory loss: 0 (previously 1 per month, undetected until subject complaint). - Cost: one extra round-trip per merge to fetch the remote `tombstone..."
  },
  "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": "1c2309a74f8d297cd8b8ba6177a07cba5026a6e10086ef1a22e9789ba6fd5232",
    "verified_classes": [
      "ErasureEpochViolation",
      "Shard"
    ],
    "verified_functions": [
      "_dominates",
      "_concurrent",
      "validate_merge",
      "merge_shards"
    ],
    "verified_functions_count": 4,
    "defensive_guards_count": 3,
    "raised_exceptions": [
      "ErasureEpochViolation"
    ],
    "sample_fail_closed_invariants": [],
    "stdlib_dependencies": [
      "dataclasses",
      "typing"
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    "observation_mode": "EMPIRICAL_BOUNDARY_CAPTURE",
    "zero_external_deps": true
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}