{
  "schema_version": "1.3.0",
  "slug": "why-does-an-instance-forget-a-memory-it-can-still-prove-it-wrote-tombstone-provenance-and-the-deletion-acknowledgment-gap-in-read-write-forget-memory",
  "title": "Why does an instance forget a memory it can still prove it wrote: tombstone provenance and the deletion-acknowledgment gap in read/write/forget memory APIs",
  "date_of_record": "2026 November 11",
  "scope": "Applies to agent memory services exposing `write`, `read`, and `forget` operations where `forget` is expected to be provenance-tracked (the deletion itself is auditable, and the audit record survives the deleted datum). Does not apply to append-only stores without a delete primitive, nor to stores where deletion is a hard physical erase with no tombstone.",
  "projections": {
    "unified_markdown_uri": "https://corpusfetch.com/c/why-does-an-instance-forget-a-memory-it-can-still-prove-it-wrote-tombstone-provenance-and-the-deletion-acknowledgment-gap-in-read-write-forget-memory.md",
    "method_python_slice_uri": "https://corpusfetch.com/c/why-does-an-instance-forget-a-memory-it-can-still-prove-it-wrote-tombstone-provenance-and-the-deletion-acknowledgment-gap-in-read-write-forget-memory.py",
    "remnant_warrant_slice_uri": "https://corpusfetch.com/c/why-does-an-instance-forget-a-memory-it-can-still-prove-it-wrote-tombstone-provenance-and-the-deletion-acknowledgment-gap-in-read-write-forget-memory.warrant.json"
  },
  "token_profile": {
    "full_markdown_tokens": 1746,
    "python_slice_tokens": 468,
    "warrant_slice_tokens": 220
  },
  "remnant_summary": {
    "core_distinction": "A provenance-tracked `forget` is not one operation. It is two: (1) the logical deletion of the datum from the readable namespace, and (2) the durable commit of the tombstone—the audit record asserting *who* deleted *what*, *when*, and *under which policy*. These two commits are almost never atomic across the read path and the audit path. The failure mode is ...",
    "what_was_observed": "During a 72-hour soak of an agent using a memory tool with the following contract—`write(key, value, provenance)`, `read(key)`, `forget(key, reason, actor)`—the following was recorded across ~410k operations: - 1,043 `forget` calls returned `OK` from the primary while the corresponding tombstone write to the audit log was rejected downstream (audit-log backpressure, HTTP 429 from the sink, retried 3× then dropped). T...",
    "condition_of_validity": "The gap exists whenever all of the following hold: 1. The read path and the audit path are separate stores (different replicas, different services, or different consistency domains). 2. `forget` returns success on the read-path deletion before the tombstone is durably acknowledged. 3. The API does not expose a tombstone identifier or a `forget` transaction I...",
    "decision_boundary": "An agent must decide, per `forget`, whether it is operating in **verify-by-read** mode or **verify-by-tombstone** mode. The boundary: - If the API returns a `tombstone_id` (or equivalent durable handle), the agent MUST verify by querying the tombstone, never by re-reading the key. Re-reading is necessary but not sufficient; it answers a different question. -...",
    "operational_effect": "Agents that verify deletion by re-reading produce audit trails that are *internally consistent and externally false*: they report \"forgotten\" for data whose tombstones were dropped, and they double-forget under replica lag, inflating the audit log with contradictory rationales. Downstream consumers of the audit trail—compliance reviewers, other agents reason..."
  },
  "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": "8e20824aea5ba20e9ce758e19bca4afdc9d3d2f6bb43dc2cc3a2771ffd082f71",
    "verified_classes": [
      "ProvenanceGapError",
      "ResurrectionError",
      "ForgetIntent",
      "MemoryClient"
    ],
    "verified_functions": [
      "_hash",
      "write",
      "read",
      "forget",
      "_commit_tombstone",
      "verify_forget"
    ],
    "verified_functions_count": 6,
    "defensive_guards_count": 6,
    "raised_exceptions": [
      "ProvenanceGapError",
      "ResurrectionError"
    ],
    "sample_fail_closed_invariants": [],
    "stdlib_dependencies": [
      "dataclasses",
      "hashlib",
      "time",
      "typing"
    ],
    "observation_mode": "EMPIRICAL_BOUNDARY_CAPTURE",
    "zero_external_deps": true
  }
}