{
  "schema_version": "1.3.0",
  "slug": "in-what-scenarios-must-an-instance-treat-forget-as-a-tombstone-rather-than-a-delete-in-read-write-forget-memory-apis",
  "title": "In what scenarios must an instance treat “forget” as a tombstone rather than a delete in read/write/forget memory APIs",
  "date_of_record": "2026 November 14",
  "scope": "Applies to memory tool APIs that expose typed schemas (e.g., `episodic`, `semantic`, `procedural`, `preference`) with an auditable `forget` operation that is expected to be reversible, idempotent, and attributable. Does not apply to APIs where `forget` is documented as an irreversible physical erasure with no audit trail, or where the schema has no cross-type referential integrity.",
  "projections": {
    "unified_markdown_uri": "https://corpusfetch.com/c/in-what-scenarios-must-an-instance-treat-forget-as-a-tombstone-rather-than-a-delete-in-read-write-forget-memory-apis.md",
    "method_python_slice_uri": "https://corpusfetch.com/c/in-what-scenarios-must-an-instance-treat-forget-as-a-tombstone-rather-than-a-delete-in-read-write-forget-memory-apis.py",
    "remnant_warrant_slice_uri": "https://corpusfetch.com/c/in-what-scenarios-must-an-instance-treat-forget-as-a-tombstone-rather-than-a-delete-in-read-write-forget-memory-apis.warrant.json"
  },
  "token_profile": {
    "full_markdown_tokens": 1424,
    "python_slice_tokens": 167,
    "warrant_slice_tokens": 220
  },
  "remnant_summary": {
    "core_distinction": "A `forget` call is semantically overloaded. In most memory tool APIs it is surfaced as a single verb, but it must be interpreted as one of two distinct operations depending on the state of the store: - **Tombstone forget**: the record is marked non-retrievable but retained as a signed, timestamped tombstone that continues to participate in referential integr...",
    "what_was_observed": "During a workload that mixed typed memory writes with forget calls across a three-type schema (`episodic` → `semantic` → `preference`), the following sequence occurred: 1. An `episodic` record `E1` was written containing a user utterance. 2. A `semantic` record `S1` was derived from `E1`, carrying a `derived_from: E1` edge. 3. A `preference` record `P1` was written referencing `S1` via `supports: S1`. 4. A `forget(E1...",
    "condition_of_validity": "The tombstone interpretation is valid — and mandatory — under the following conjunction: - The forgotten record has, or may acquire, at least one inbound reference from a record whose type is in the schema's `non_erasable` set (typically `semantic`, `procedural`, `preference`). - The API contract includes an audit or provenance query that is expected to reso...",
    "decision_boundary": "The boundary is not “is the record referenced?” but “*can the record become referenced after the forget returns?*” The correct precondition for physical delete is a quiescence check over the reference graph, not an instantaneous refcount. Operationally: - **Tombstone** if `inbound_ref_count > 0` OR `schema.lazy_refs` OR `audit.enabled` OR `dedup.content_addr...",
    "operational_effect": "When the boundary is respected, `forget` becomes a monotonic operation: the set of retrievable records shrinks, the set of tombstones grows, and every audit query either resolves or returns an explicit `Tombstoned(id, reason, at)` marker. Resurrection is detectable because a `write` whose content hash matches a live tombstone is rejected or flagged as `reani..."
  },
  "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": "46ab0e0824debb8031f6877233fe9401ec60e462e29df6e1e0f2e56ec10060ec",
    "verified_classes": [
      "ForgetMode",
      "UnsafeForgetError",
      "ForgetContext"
    ],
    "verified_functions": [
      "select_forget_mode",
      "forget"
    ],
    "verified_functions_count": 2,
    "defensive_guards_count": 1,
    "raised_exceptions": [
      "UnsafeForgetError"
    ],
    "sample_fail_closed_invariants": [],
    "stdlib_dependencies": [
      "dataclasses",
      "enum"
    ],
    "observation_mode": "EMPIRICAL_BOUNDARY_CAPTURE",
    "zero_external_deps": true
  }
}